# Bugs and (mis)features ## Table of Contents If you are going to try and fix any bugs **PLEASE READ THE NEXT SECTIONS _FIRST_**. If however you want to jump to a specific year or you have already read the below and you wish to help with a year, you can use these links: - [1984 entries](#1984) | [1985 entries](#1985) | [1986 entries](#1986) | [1987 entries](#1987) - [1988 entries](#1988) | [1989 entries](#1989) | [1990 entries](#1990) | [1991 entries](#1991) - [1992 entries](#1992) | [1993 entries](#1993) | [1994 entries](#1994) | [1995 entries](#1995) - [1996 entries](#1996) | [1998 entries](#1998) | [2000 entries](#2000) | [2001 entries](#2001) - [2004 entries](#2004) | [2005 entries](#2005) | [2006 entries](#2006) | [2011 entries](#2011) - [2012 entries](#2012) | [2013 entries](#2013) | [2014 entries](#2014) | [2015 entries](#2015) - [2018 entries](#2018) | [2019 entries](#2019) | [2020 entries](#2020) | [2024 entries](#2024) - [2025 entries](#2025) Jump to: [top](#) ## PLEASE read the next sections if you wish to help There are a number of known problems with IOCCC entries: many of which have to do with differences between today's compiler environments and those of today. In some cases the original code has a bug, some of which were recently discovered and many of which were fixed. In some cases attempt to port older code to more modern environments introduced bugs. The following is a known list of **BUGS and (mis)FEATURES** in IOCCC entries. Can you fix/improve entries not under the INABIAF (it's not a bug it's a feature)? You are **VERY WELCOME** to try. As far as how to help: please submit your fixes in a [GitHub pull request](https://github.com/ioccc-src/winner/pulls) (with ONE PULL REQUEST *PER* FIX, please)! We will be **happy to credit anyone who submits successful [GitHub pull requests](https://github.com/ioccc-src/winner/pulls)** in the [thanks](thanks-for-help.html) file. If you're the author of an entry that win the IOCCC, we will add a link to your winning entries in the file (if you're not an author, we can add a link to your GitHub page or personal website if you have one, should you wish). If you do fix an entry please feel free to delete the entry from this file! Otherwise if you wish to not worry about it we can do that to make sure the format is consistent and clean. THANK YOU! Jump to: [top](#) ## To the winning authors: If you're the author of an entry that has been fixed and you find it against your liking **PLEASE** let us know and we'll be happy to undo any fixes even if it takes away some instructional value or even usability. _In this case we're **VERY SORRY** about it: it's a fine line, we know, and we tried to use careful judgement but invariably some might have been the wrong decision. Thank you for understanding! When working on getting entries to compile, sometimes some things were changed that should not have been. Also the definition of `INABIAF` was changed a number of times. At one point some things were changed to a bug (a usability problem for example) to be fixed but when looking at the index.html file it was noticed it was documented so the fixes were undone at that point. Jump to: [top](#) ### ON **ALL** FIXES / IMPROVEMENTS / CHANGES Make **ABSOLUTE CERTAIN** that you test the entry _BEFORE_ **AND** _AFTER_ your changes! This includes output and the same input functionality! Sometimes it might seem to be fine but is actually not! We will note some where this is known to happen (if it's not yet fixed). This has actually already happened to us. Sometimes it is okay: some entries are known to not work but they can still have improvements (rarer situation but it's happened). Some might have slightly different output but which is not a problem for instance a newline after output. This is not the most ideal but it is okay. Make **ABSOLUTE CERTAIN** that you read the index.html file _BEFORE_ your changes as it's important to see that the code is doing what it is supposed to. In the case that it's not obvious (some index.html files do not even have commands to try or even explain how to use it!) then you should either skip the entry OR ask someone who will know for instance the Judges. Make **ABSOLUTE CERTAIN** that you read the next section, the list of statuses and the related information, BEFORE you submit a pull request! **BE VERY AWARE** that sometimes fixing an entry for one platform will break it under another so if you have more than one platform (e.g. macOS and linux) it would be wise to test it under all that you have access to. Otherwise we can do that. Of course if the entry does not work under any platform and you fix it for one that's more than fine (and it has been done numerous times). Again, THANK YOU! Jump to: [top](#)
# LIST OF STATUSES ## PLEASE READ BEFORE FIXING **BTW**: You may skip if you're only interested in knowing about entries with known issues. Entries below have one or more of the following _**STATUS**_ values. Please see the text below for more information. If an entry has more than one status it means that either they all apply or they complement each other. Jump to: [top](#) ## General notes about the statuses and making fixes Jump to: [top](#) ### Compiler warnings are very rarely a problem In general warnings should NOT be addressed. The only time they should be CONSIDERED is when the entry does not work. However note that sometimes trying to fix the warnings will actually introduce bugs! Other times 'fixing' them will break the entry (see below). Below in some entries we do list some warnings that definitely should be ignored (including some introduced by fixes) but we do not list them all: trying to keep track of them all would be impractical especially as different compilers give different warnings. Another type of warning that would be hard to keep track of is different data sizes on different platforms. These tend to be required at the risk that sometimes the entry will not work for certain platforms, some of which might or might not be fixable; a good example where it was required to change and is okay is the fix of the segfault in macOS of [1989/paul](%%REPO_URL%%/1989/paul/paul.c): changing the `int *` to a `long *` was required and it works just as well with linux. But even if they are fixable (which will likely be hard to do) it's almost certain that such code would be just as non-portable (importable ? :-) ). In rare cases they are valid. For instance in linux the following warning in [1985/applin](%%REPO_URL%%/1985/applin/applin.c) with gcc: ``` applin.c:1:78: warning: incompatible implicit declaration of built-in function 'execlp' [-Wbuiltin-declaration-mismatch] 1 | main(v,c)char**c;{for(v[c++]=strdup("Hello, world!\n");(!!c)[*c]&&(v--||--c&&execlp(*c,*c,c[!!c]+!!c,!c));**c=!c)write(!!*c,*c,!!**c);} | ^~~~~~ ``` and this is is kind of like the fix to [1984/anonymous](%%REPO_URL%%/1984/anonymous/anonymous.c). In the case of `1984/anonymous` it was a bit more involved but with `1985/applin` one need only add to the Makefile `-include unistd.h`. So there are some cases where fixing warnings can fix a problem but in general they should be ignored even if they're annoying. Hopefully with the example entries listed above you get the idea. Jump to: [top](#) ### General request on original code: If you're fixing an entry please make as _FEW CHANGES AS POSSIBLE_! This is to make it as close to the original but allowing it to work. This might be less of a problem when providing alternate versions but it might still be nice to have it as close as possible to the original. See also below two points. Jump to: [top](#) ### Request for one-liners: For one-liners _PLEASE KEEP THE FILE ONE LINE IF AT ALL POSSIBLE_! See the [guidelines](next/guidelines.html) for what constitutes a one-liner. If it needs an include you can update the Makefile `CINCLUDE` variable. For instance if it needs `stdio.h` you could do `-include stdio.h`. Please leave a space after the `=` in the Makefile. You may also have extra long lines if this seems useful to make it a one-liner even if it kind of makes it longer than what the judges consider a one-liner, at least within reason. Thank you! Jump to: [top](#) ### On layout of program source: If you make changes _PLEASE TRY AND KEEP THE SOURCE CODE LAYOUT AS CLOSE TO THE ORIGINAL AS POSSIBLE_. This might not always be possible and if you have an editor that does formatting it can cause problems. Sometimes formatters can even break code! Some have experienced this many times with vim so he tends to disable all format options when formatting code. In vim you should be able to do that with: ``` :set formatoptions= ``` Jump to: [top](#) ## STATUS: known bug **Please help us fix**! Entries with this status have one or more bugs that need to be fixed. Are you able to fix it? We welcome your help! An important point to note is that there is a very fine line when fixing bugs where it might sometimes border on tampering with the program. And after all, these are not meant to be maintainable or even good programming style! Use careful judgement when fixing bugs please! Jump to: [top](#) ## STATUS: possible bug Jump to: [top](#) ### System dependent bug possibly **Please help test, and if necessary fix this bug**! Entries with this status might or might not have a bug possibly depending on the system. In these entries it's unknown if there is a bug and sometimes it's because we do not remember and sometimes we don't have the appropriate system or environment to test and fix any possible problems. Jump to: [top](#) ### STATUS: might not be completely functional **Can you confirm there is a bug?** Although these entries _appear_ to work for one or more reasons we're unsure if they are completely functional. Can you confirm this? Please let us know so we can fix it! Jump to: [top](#) ## STATUS: probable bug Jump to: [top](#) ### Possible system dependent bug **Please help test and if necessary fix this bug**! Entries with this status almost certainly have a bug or some other problem. The issue or issues might depend on the system much like the above _STATUS: possible bug (possibly depending on system)_. Jump to: [top](#) ## STATUS: doesn't work with some platforms **Please help us fix this bug**! Entries with this status do not work under some OSes and/or architectures (and/or something else?). Please help us to fix it! Jump to: [top](#) ## STATUS: doesn't work with some compilers **Please provide alternative code or fix for more compilers**! Some entries do not work with some compilers. A good example is [1992/lush](%%REPO_URL%%/1992/lush/lush.c) which uses error messages from the compiler to generate its output. If you can provide code that works for multiple compilers without too much tampering this is okay though it's probably not possible with the above mentioned entry; otherwise it would be better to provide alternate code. In some cases it might be better to provide alternate code anyway. Use a judgement call here as best you can manage. Jump to: [top](#) ## STATUS: main() function args not allowed **Please help us fix the main() function**! **NOTE**: it appears that most if not all of these have been fixed except perhaps for [1989/westley](%%REPO_URL%%/1989/westley/westley.c) but this has probably been fixed as much as possible given the nature of how it generates code: the entry itself compiles but two versions of code it generates does not work with clang. However some still might have problems of some kind or another and some might not yet be located as an additional defect of clang was noticed where `main()` is not allowed four args or one arg (see below). This is what the status means, however. Entries with this status have a problem in that the args to main() are not of a specific type or there are too many due to this being allowed in earlier C. Some compilers like clang have a defect where they do not allow this and some versions have an additional defect where they only allow 0, 2 or 3 args, the latter of which affected `1989/westley`, so these entries do not work with clang. Looking at the source code of clang, it appears that there is no way to override the requirement of arg types so these entries will fail to compile with clang. That's why in some entries the fix was done with a new function, often called `pain()` :-) **NOTE for macOS users**: please be aware that _gcc_ under macOS **is actually clang** despite the fact it might appear to be gcc: no symlink and both gcc and clang exist but the gcc is clang which you'll see if you run `gcc --version`. A tip and some fix methods: in the older days args to `main()` not given a type were implicit `int`s but when they're required to be `char **` this can cause a problem. In some cases it was possible to use a `char *` inside `main()` (see [1989/tromp/tromp.c](%%REPO_URL%%/1989/tromp/tromp.c) and [1986/holloway/holloway.c](1986/holloway/index.html) for two examples though done slightly differently). In other cases it was possible to dereference the pointers to be used like an int and other times a cast was necessary. There are various techniques to get these to compile. In some cases this introduced a problem but typically if not always that problem exists with compilers that are less strict. Jump to: [top](#) ## STATUS: main() has only one arg **Please help modify so that main() as 2 or 3 args**! Because some versions of clang complain about the number of args of `main()` and in particular say (when it has four, for instance) that it's only allowed to have 0, 2 or 3 args, numerous entries had a second arg added to `main()` (if they only had one). This is in case clang adds further restrictions which is not impossible especially as it already claims having only one arg is not allowed. At this time (04 Feb 2024) there is one entry known (it is possible that not all were checked) that has this problem but it's not as simple as the others to fix without breaking it. Jump to: [top](#) ## STATUS: compiled executable crashes **Please help us fix this bug**! While such entries can compile, the resulting executable sometimes or always crashes. **NOTE**: this does NOT apply to entries under the INABIAF status (though they're not mutually exclusive in some cases). REMINDER: if you're debugging a crash it will be very helpful to have `-O0 -g` or if you can `-ggdb3` when compiling as that will help with debugging symbols. Jump to: [top](#) ## STATUS: uses gets() **Please help us change use of gets() to fgets()**, if possible. Entries with this status use `gets()` which is unsafe because it has no limit on the length of the string. Many were fixed but not all. There's a very good reason for this change even though it is bordering on tampering entries: in modern systems one will get possibly alarming and certainly annoying warnings during at least one of compiling, linking and execution. In macOS it's most annoying as it happens during execution (also compilation) with the warning being interspersed with the output of the program, often causing confusing output with the entry. A good example that was fixed is [1990/tbr](%%REPO_URL%%/1990/tbr/tbr.c). Some important notes on this status with respect to fixing / changing the entries: 0. In some cases changing the entry to use `fgets()` will break the entry and in some cases cause it to crash. Where this is known we will document it. 1. You **MUST** check the output before and after to make sure that it remains the same. Sometimes the output might not be immediately obviously wrong but is. We will document known examples as we come across them. 2. `gets()` does NOT STORE the `'\n'` but `fgets()` DOES! This is one of the reasons some of the entries break when changed to `fgets()`. Some of those have been fixed but there are others that have not been. 3. Just because you don't see the string `gets` in the code does not mean it's not used. It is after all the International _Obfuscated C Code_ Contest! :-) Sometimes it will be in the Makefile and other times it will be obfuscated in other ways; a good example of that that was fixed is [1991/dds](1991/dds/index.html): in this case the string was encrypted. Compilers and linkers tend to warn about its use (and as noted in macOS it also happens at execution) and this is a good way to find entries that use it even if it's not visible in the code. **NOTE**: this status is _NOT necessarily mutually exclusive_ with the _INABIAF_ (it's not a bug it's a feature) status. The reason for this is due to warnings during compiling, linking and/or runtime, sometimes causing confusing output (as noted above). Sometimes `getline(3)` will work but note that this function also stores the newline just like `fgets(3)`. Jump to: [top](#) ## STATUS: missing file(s) **Please help is by finding missing file(s)**! In these entries one file or multiple files are missing from the repo. In some cases these files can be found on the [IOCCC website](https://www.ioccc.org) but in other cases they are entirely absent. In this case you'll probably have to contact the author (unless you are the author! :-) ). Jump to: [top](#) ## STATUS: missing or dead link **Please help is fix missing or dead link(s)**! This is as they sound: a link is either missing or it's no longer valid. In many cases the [Internet Wayback Machine](https://web.archive.org) will be very useful but there happens to be numerous links that this is not helpful. In other cases the URL has changed. Some of these have been discovered by the Internet Wayback Machine with the orange status. Jump to: [top](#) ### Statuses of Internet Wayback Machine archive: - Green (3xx): redirect (this has been used to find changes in URL). - Orange (4xx): not found etc. - Blue: this is a good link (but note that this doesn't mean that it's correct!). The archive website will tell you if the link was never captured. Jump to: [top](#) ## STATUS: INABIAF - please **DO NOT** fix ### INABIAF: It's not a bug it's a feature :-) Entries with this status should NOT be touched (unless they have another status that suggests that _that_ issue can be changed): they are system specific by design or are other things that are not actually bugs or bugs even if they appear to be. Or they might be documented bugs or things that simply are part of the entry. Nonetheless they are noteworthy. **NOTE**: the definition of this status changed over time. At one point it was when something was noted by the author, the judges, a consequence of earlier requirements for winning entries or the purpose was to do something that might appear to be buggy. An example of system specific entries: [1984/mullender](%%REPO_URL%%/1984/mullender/mullender.c) (see below for a version that works in modern systems) is very system specific and was before system specific winning entries were discouraged. This is an all time personal favourite of Landon Curt Noll. Run the alternate code to understand why this might be (along with how strange the source code is :-) ). An example where a crash is not a bug: [2019/endoh](2019/endoh/index.html) is supposed to crash. There are others that are also supposed to crash or that are known to segfault but are considered features. An important note is that if the index.html of the entry has a bug status that says it can be fixed it can be. Otherwise it should not be. Nonetheless we challenge you to fix these entries for educational/instructional value and/or enjoyment but we kindly request that you **DO NOT** submit a pull request unless it's a bug or (mis)feature we would like you to fix! **NOTE**: in the case of `gets()` we've fixed some to avoid the warning of the compiler, linker or even during runtime, depending on the system. In [some cases like 1990/tbr](1990/tbr/index.html) the fix actually prevents confusing output (though that was not the only fix made in that entry). Jump to: [top](#) ### Exception: your own entries Of course if you're the author you're welcome to fix your own entry, prefer your own fix or suggest that they're fixed! Jump to: [top](#)
# List of entries by year, sorted in alphabetical order per year
# 1984
Jump to: [top](#)
## 1984/decot
Jump to: [top](#) ### STATUS: INABIAF - please **DO NOT** fix ### Source code: [1984/decot/decot.c](%%REPO_URL%%/1984/decot/decot.c) ### Information: [1984/decot/index.html](1984/decot/index.html) The purpose of this program is to print out what looks like a fragment of C code. In particular you should see something like: ``` $ ./decot '",x); /* \ ``` without a newline after the `\`. This is not a bug. Jump to: [top](#)
## 1984/laman
Jump to: [top](#) ### STATUS: INABIAF - please **DO NOT** fix ### Source code: [1984/laman/laman.c](%%REPO_URL%%/1984/laman/laman.c) ### Information: [1984/laman/index.html](1984/laman/index.html) This program will very likely crash or do something funny without an arg. Jump to: [top](#)
## 1984/mullender
Jump to: [top](#) ### STATUS: INABIAF - please **DO NOT** fix ### Source code: [1984/mullender/mullender.c](%%REPO_URL%%/1984/mullender/mullender.c) ### Information: [1984/mullender/index.html](1984/mullender/index.html) Although there is an alt version and supplementary program added, that will work in modern systems, if you do not have a [VAX-11](https://en.wikipedia.org/wiki/VAX-11) or [PDP-11](https://en.wikipedia.org/wiki/PDP-11) to run the original entry on it will not work. See the index.html for details on the alternate versions. The file [gentab.c](%%REPO_URL%%/1984/mullender/gentab.c) which is from the author's (or one of them, Mullender) remarks, was fixed for modern systems, at least as best as can be determined: running the code on the binary itself does produce a `short[]` that can compile in modern systems but it will not work. Before the fix it would fail in some cases and it is possible that in some cases it might still fail. Jump to: [top](#)
# 1985
There are no known bugs or (mis)features for entries in 1985. Jump to: [top](#)
# 1986
Jump to: [top](#)
## 1986/august
Jump to: [top](#) ### STATUS: INABIAF - please **DO NOT** fix ### Source code: [1986/august/august.c](%%REPO_URL%%/1986/august/august.c) ### Information: [1986/august/index.html](1986/august/index.html) This entry is known to segfault after printing its output. It was documented by the judges and shouldn't be fixed. Jump to: [top](#)
# 1987
There are no known bugs or (mis)features for entries in 1987. Jump to: [top](#)
# 1988
Jump to: [top](#)
## 1988/dale
Jump to: [top](#) ### STATUS: INABIAF - please **DO NOT** fix ### Source code: [1988/dale/dale.c](%%REPO_URL%%/1988/dale/dale.c) ### Information: [1988/dale/index.html](1988/dale/index.html) In linux it might happen that despite no error message or message about doing so, the program drops a core file into the directory even though the entry works and does not crash. Jump to: [top](#)
# 1989
Jump to: [top](#)
## 1989/fubar
Jump to: [top](#) ### STATUS: INABIAF - please **DO NOT** fix ### Source code: [1989/fubar/fubar.c](%%REPO_URL%%/1989/fubar/fubar.c) ### Information: [1989/fubar/index.html](1989/fubar/index.html) If you use either `fubar` or `ouroboros.c` (it's executable, see index.html for details) with a number < 0 or larger than, say 20, it's very likely that the program will turn into an infinite loop trying to compile code and end up with with syntax errors. As this was documented it is not a bug to be fixed. Jump to: [top](#)
## 1989/robison
Jump to: [top](#) ### STATUS: INABIAF - please **DO NOT** fix ### Source code: [1989/robison/robison.c](%%REPO_URL%%/1989/robison/robison.c) ### Information: [1989/robison/index.html](1989/robison/index.html) This program will very likely crash or break into tiny bits :-) if you feed it numbers with non-binary digits. There are also other cases where this can happen for instance using unsupported operators like `/`. To see what operators are supported check the source code. Jump to: [top](#)
## 1989/westley
Jump to: [top](#) ### STATUS: known bug - please help us fix ### Source code: [1989/westley/westley.c](%%REPO_URL%%/1989/westley/westley.c) ### Information: [1989/westley/index.html](1989/westley/index.html) With version 2 it sometimes segfaults even with the same input where other times it does not. We don't believe this is because of the fix that lets some versions be compiled with clang. An example invocation is: ``` ./ver2 < westley.c ``` Jump to: [top](#) ### A useful note on changing/fixing this program It should be noted that in additional to rot13 names there is code that is the reverse of other code (also with respect to names). See the source file and the index.html (in the author's remarks) for more details. Fixing the (mis)feature is likely to be a very difficult challenge especially without breaking something else which is far more likely (see below tips from). You are welcome to try and fix it if you can but unless you can get all to compile with `clang` **AND** `gcc`, which seems unlikely (see below), this should not be touched further. Nonetheless you are welcome to try and fix it if you can. Be aware, however, that even if you can get it to compile with both `gcc` and `clang`, different versions will have errors so that it's not actually a fix. For instance it was fixed to work for both `clang` and `gcc` but when testing the fix in fedora linux it failed to even compile! Jump to: [top](#) ### Tips: The reason this is crashing is that the array `irk` is being accessed way out of bounds by the int `gnat`. For instance: ``` Program terminated with signal SIGSEGV, Segmentation fault. #0 0x0000000000401335 in main (ABBA@entry=, tang@entry=, gnat@entry=, Near@entry=) at ver2.c:23 23 &&gnat!({)Near,noon,/*krelc*/)<0&&(Near= - irk[-gnat--]-2)))&&main(ABBA, (gdb) p gnat $1 = -518733305 ``` Jump to: [top](#) ### Magic of the entry: The real trouble is that the code is generated and in a complex way or rather ways. Trying to explain this might be tricky but here is an attempt. The program, when used without any args, will print out what it reads. If one arg is specified it will do a ROT13 of it. If two args are specified it will print out the text backwards (_WITHOUT ROT13!_). If three args are specified it will do both **_reversal AND ROT13_**. So `ver0` is the same as the main program; `ver1` is the ROT13 of the code (but see below); `ver2` will reverse the code and `ver3` will both reverse and ROT13 the code. But it's trickier than that as one might expect. The comments are processed too. Furthermore it happens that the last line becomes the first and the first line becomes the last! Now if you look at the code you'll see on the first line: ``` /**//*/};)/**/pain(*//**/tang ,gnat/**//*/,ABBA~,0-0(avnz;)0-0,tang,raeN ``` In `ver0` it'll be the same but the others are more interesting. In `ver1` you'll see on the last line: ``` cnva((vag)NOON&2/*//*\\**/,gnat,tang ,NOON/**//*/(niam/**/);}/*//**/ ``` and on the first line: ``` /**//*/};)/**/cnva(*//**/gnat ,tang/**//*/,NOON~,0-0(niam;)0-0,gnat,enrA ``` Observe that the ROT13 of `pain` is `cnva` and the ROT13 of `main` is `znva`. The ROT13 of `NOON` is `ABBA`. `vag` is ROT13 of `int`, `gnat` and `tang` are ROT13 of each other as well which is the reverse of the original (this is not because it goes backwards (it doesn't in this version) but because they are ROT13 pairs!). `main` spelt backwards is `niam` and `pain` spelt backwards is `niap`. Furthermore see the Makefile for other defines that had to be specified and for `ver2` and `ver3` (that both work with gcc) one had to be undefined (search for `CDEFINE` and `-U`). These details will be important momentarily. As far as `NOON` and `ABBA` being ROT13 pairs, notice how `NOON` is not in the original code but `ABBA` is; but in other versions it becomes `NOON` and they also have `abba` which the original code does not! Now notice how the `avnz` in the first line got changed to `niam`, its ROT13 value. Notice also how some of these are in comments! `main()` is in there somewhere and that had to be changed to call `pain()` (see the [thanks](thanks-for-help.html#1989_westley) file (see the _1989/westley_ section for details on how as this was not as straight forward as it is for other entries) as well. Now if you notice on that line you have in a comment `niam`. If you were to change that to `niap` (pain backwards) that function would end up as `pain()` in generated code! That's assuming that it's just the reversal version, of course but ver1 is the ROT13 version. These facts are bad enough but then you throw in the reverse of it without ROT13 and then another version that has the reversal _and_ ROT13 then you can see it's nigh impossible to fix if not impossible. The fix to get it to even compile with clang and then get the first two (counting the original, `ver0`) to work was quite hard due to how the comments in reverse and ROT13 of it all works together, especially allowing all versions to compile with gcc. The only reason that it doesn't work completely with clang is the arg types of main() (see if you can figure out how the change of `main()` in `westley.c` is not carried over to versions 2 and 3!); originally none of them compiled with clang. But it was possible to get the ROT13 code to compile with clang but the other versions, reversed as well as ROT13 and reversed code, proved much more problematic. It is now possible to compile (or maybe mostly compile) all versions with clang but on another system and it had syntax errors. Enjoy! :-) Jump to: [top](#)
# 1990
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## 1990/baruch
Jump to: [top](#) ### STATUS: INABIAF - please **DO NOT** fix ### Source code: [1990/baruch/baruch.c](%%REPO_URL%%/1990/baruch/baruch.c) ### Information: [1990/baruch/index.html](1990/baruch/index.html) A point worth considering is that as the number passed into the program gets bigger the number of lines of output gets substantially larger and it takes much more time and resources to run as well. For instance, on a relatively generic computer in 2025, the following execution times and output quantities were recorded: ``` | input | clock | user | system | lines of | | value | time | time | time | output | |-------|---------------------|---------------------|------------------|--------------| | 4 | 0.001s | 0.001s | 0.001s | 11 | | 5 | 0.002s | 0.001s | 0.002s | 61 | | 6 | 0.002s | 0.002s | 0.002s | 29 | | 7 | 0.003s | 0.002s | 0.002s | 321 | | 8 | 0.003s | 0.002s | 0.003s | 829 | | 9 | 0.006s | 0.004s | 0.006s | 3521 | | 10 | 0.016s | 0.014s | 0.006s | 7965 | | 11 | 0.071s | 0.068s | 0.008s | 32161 | | 12 | 0.419s | 0.418s | 0.014s | 184601 | | 13 | 2.589s | 2.564s | 0.075s | 1031969 | | 14 | 16.509s | 16.457s | 0.331s | 5483941 | | 15 | 1m 55.913s | 1m 55.173s | 2.397s | 36466945 | | 16 | 14m 7.307s | 14m 2.427s | 16.652s | 251132705 | | 17 | 1h 49m 37.938s | 1h 48m 59.355s | 2m 2.812s | 1724671873 | | 18 | 14h 58m 13.506s | 14h 50m 22.572s | 14m 33.652s | 12655721857 | | 19 | 5d 6h 9m 59.983s | 5d 5h 18m 31.147s | 2h 9m 29.490s | 99361156961 | | 20 | 46d 9h 23m 23.095s | 46d 3h 31m 11.600s | 17h 58m 55.478s | 819612966565 | ``` This is a feature, not a bug! Jump to: [top](#)
## 1990/jaw
Jump to: [top](#) ### STATUS: known bug - please help us fix ### Source code: [1990/jaw/jaw.c](%%REPO_URL%%/1990/jaw/jaw.c) ### Information: [1990/jaw/index.html](1990/jaw/index.html) Some issues in this program were fixed and [Yusuke Endoh](authors.html#Yusuke_Endoh) then provided the `btoa` script but it appears there is a bug in this entry. The judges wrote that to test the entry one can do: ``` echo "Quartz glyph jocks vend, fix, BMW." | compress | ./btoa | ./jaw ``` which should apply the identity transformation to a minimal holoalphabetic sentence. But doing this shows instead: ``` echo "Quartz glyph jocks vend, fix, BMW." | compress | ./btoa | ./jaw a얖?)V...?????777??hC??h??-? )SSSSXXX????r?L=???*?-???ppp,,,?R ?j 111-)))? '..F@E ???b111? ..F..F.?n,,,,,L@E$ ``` Notice how there's no newline at the end: that final `$` is the prompt. If one does, however: ``` echo "Quartz glyph jocks vend, fix, BMW." | compress | ./btoa | ./jaw | ./jaw ``` they will get just > oops which seems to be an error message (one of the fixes was to make it not use `perror(3)` - this fixed something else though it's no longer known what except that in macOS if `errno` is 0 it reports what looks like an error, rather than success in, say, linux). The script [shark.sh](%%REPO_URL%%/1990/jaw/shark.sh) has some issues too in that due to path not having `.` (this and maybe some other things were fixed) and `tar` not wanting to accept reading from `stdin` (this in particular) even with the right options used, seemingly, it has to write to disk the tarball which seems to defeat the purpose. This would ideally be fixed. Jump to: [top](#)
## 1990/tbr
Jump to: [top](#) ### STATUS: INABIAF - please **DO NOT** fix ### Source code: [1990/tbr/tbr.c](%%REPO_URL%%/1990/tbr/tbr.c) ### Information: [1990/tbr/index.html](1990/tbr/index.html) The authors provided a list of features in the [BUGS](1990/tbr/index.html#bugs) section in their remarks. Jump to: [top](#)
## 1990/theorem
Jump to: [top](#) ### STATUS: INABIAF - please **DO NOT** fix ### Source code: [1990/theorem/theorem.c](%%REPO_URL%%/1990/theorem/theorem.c) ### Information: [1990/theorem/index.html](1990/theorem/index.html) Many bugs that prevented this from working properly (including segfaults) were fixed but one thing to note is that if you pass two zeroes to `theorem_bkp` or `fibonacci` the program will enter an infinite loop, printing 0 over and over again; another condition where this occurred was fixed but this one should not be fixed. Jump to: [top](#)
## 1990/westley
Jump to: [top](#) ### STATUS: INABIAF - please **DO NOT** fix ### Source code: [1990/westley/westley.c](%%REPO_URL%%/1990/westley/westley.c) ### Information: [1990/westley/index.html](1990/westley/index.html) Although this was fixed to not enter an infinite loop if the arg (converted to a number) is < 0 the lack of an arg check at all was kept in to make it like the original. The reason for the < 0 check is it floods the screen (yes this is indeed inconsistent with some other entries but it is not worth the time spent, maybe, to change it back, especially as it is annoying to have the screen flooded). Jump to: [top](#)
# 1991
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## 1991/buzzard
Jump to: [top](#) ### STATUS: INABIAF - please **DO NOT** fix ### Source code: [1991/buzzard/buzzard.c](%%REPO_URL%%/1991/buzzard/buzzard.c) ### Information: [1991/buzzard/index.html](1991/buzzard/index.html) If the maze file cannot be opened, either because the path specified does not exist or because the default (whatever the source file was at compilation time) file does not exist in the directory, this program will very likely crash. This is a feature, not a bug. Jump to: [top](#)
## 1991/westley
Jump to: [top](#) ### STATUS: INABIAF - please **DO NOT** fix ### Source code: [1991/westley/westley.c](%%REPO_URL%%/1991/westley/westley.c) ### Information: [1991/westley/index.html](1991/westley/index.html) There is a very simple way to always win. The program doesn't catch you and as someone called Cody's late grandmother said to him: '_it's not cheating unless you're caught_'. :-) Please don't try and fix it as it's not a bug and was actually documented as a possibility. Can you find out how? There's also a way to make it so that even when you're cheating it ends up winning! Can you figure that out as well? Jump to: [top](#)
# 1992
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## 1992/adrian
Jump to: [top](#) ### STATUS: INABIAF - please **DO NOT** fix ### Source code: [1992/adrian/adrian.c](%%REPO_URL%%/1992/adrian/adrian.c) ### Information: [1992/adrian/index.html](1992/adrian/index.html) The author stated that if the file cannot be opened then it will print a system error but this is not the case unless it's showing a fault. This was fixed as part of another problem that was detected. Also, if _some_ of the programs are not given an arg they will very likely crash or do something funny. For instance `adsleep` and `adbasename`. This is very simple to fix but the author explicitly noted that this will segfault and it is that that is the error message. Another thing is that the code: ``` printf((W,Y)); ``` appears to be wrong because `W` is a `FILE *` and `Y` is a `char[]` but if one changes it to use `fprintf()` on the file (which, incidentally, is opened in read only mode which is another reason) with the `%s` specifier it will make `adhead` not work: it'll print nothing at all! So this code should not be changed either even if it appears to be wrong. Notice too a curious thing: if you did change it to `fprintf()`, even if you have the right number of args, you'd have to remove the outer `()` pair. Jump to: [top](#)
## 1992/albert
Jump to: [top](#) ### STATUS: known bug - please help us fix ### Source code: [1992/albert/albert.c](%%REPO_URL%%/1992/albert/albert.c) ### Information: [1992/albert/index.html](1992/albert/index.html) Leo Broukhis, before he was an IOCCC judge, sent the IOCCC judges an email: > From: leo _at_ zycad -dot- com (Leo Broukhis)
> Date: Tue, 30 Jan 96 17:37:51 PST
> To: judges _at_ toad -dot- com
> Subject: IOCCC 1992 - a bug
> > Dear Judges, > > `albert.c` (even in its fixed form) still has a bug. Although I don't > remember the number that exposed the bug (afair, resulting in coredump) > in `albert.orig.c` that has been fixed in `albert.c`, > > I've found a number exposing another bug: 10000000001 (that's 9 0's). > Both albert and albert.orig loop without printing anything, although > the first factor is 101 and is usually found in an instant. A quick debugging session suggests that the problem with this value is that: ``` if ( ppp->qq!=48 ) return; ``` is never reached because the value is never 48 (it is in other cases but not for the example input). It varies in value at this point. Observe that the next lines of code are: ``` while ( ppp->qq==48 ) { printf("%ld\n",qqq-45); *pp = ppp; ppp = ppp->p; } ``` so it is expected that that value is 48, before printing the numbers, but if it's not it should not proceed at all, not even to go past that loop. In other words that loop should always be entered for at least one iteration. The check for the `!= 48` is also required. Perhaps more useful to know is that at this point in the code the code: ``` if ((((( !(aa=setjmp(ppp->ppp))||aa==aaaaaa ))))) ``` appears to be entered because of the return value of `setjmp()`, not the other condition. The alt version does fix the problem but it is not obfuscated and not like the entry itself. Can you fix the actual entry? You are welcome to try and do so. Jump to: [top](#)
## 1992/gson
Jump to: [top](#) ### STATUS: uses gets() - change to fgets() if possible ### Source code: [1992/gson/gson.c](%%REPO_URL%%/1992/gson/gson.c) ### Information: [1992/gson/index.html](1992/gson/index.html) This code uses `gets(3)` on a buffer size of 256 to read from the dictionary. It is highly unlikely that a line in a dictionary file will be this long but it could happen and it would be ideal if the code used `fgets(3)` instead. Unfortunately with this entry it's not as simple due to how `gets(3)` is used, which can be described simply as: first `m` is set to `*++p` in a for loop where `p` is argv. Later `m` is set to point to `h` which was of size 256\. `gets(3)` is called as `m = gets(m)`) but trying to change it to use `fgets(3)` breaks the program. Jump to: [top](#) ### STATUS: INABIAF - please **DO NOT** fix On the other hand, the author noted the following bugs and limitations: - There is no error checking. - Standard input must be seekable, so you can't pipe the dictionary into `AG`. - The input sentence and each line in the dictionary may contain at most 32 distinct letters, and each letter may occur at most 15 times. - Words in the dictionary may be at most 255 bytes long. - `AG` cannot handle characters that sign-extend to negative values. - Although `AG` works on both 16-bit and 32-bit machines, the size of the problems it can solve is severely limited on machines that limit the stack size to 64k or less. ... so whether or not the `gets(3)` should be changed to `fgets(3)` is up to debate. Jump to: [top](#)
## 1992/kivinen
Jump to: [top](#) ### STATUS: known bug - please help us fix ### Source code: [1992/kivinen/kivinen.c](%%REPO_URL%%/1992/kivinen/kivinen.c) ### Information: [1992/kivinen/index.html](1992/kivinen/index.html) When you start the program everything starts to move over to the right side and then ends. [Yusuke Endoh](authors.html#Yusuke_Endoh) pointed out that if you click the mouse it takes it back towards the centre. Jump to: [top](#)
## 1992/lush
Jump to: [top](#) ### STATUS: doesn't work with some compilers - please provide alternative code or fix for more compilers ### Source code: [1992/lush/lush.c](%%REPO_URL%%/1992/lush/lush.c) ### Information: [1992/lush/index.html](1992/lush/index.html) This was fixed but it only properly works with gcc; it was also changed to use `fgets()` instead of `gets()` and a script was provided to run the entry properly. Nonetheless it will only work with gcc. Unfortunately due to the way the entry works and the fact that other compilers like clang have different warnings and errors this simply does not work with them. #### Some tips: This entry relies on specific compiler warnings. With gcc it will look something like: ``` [...] lush.c: In function 'main': lush.c:40: warning: "f" redefined 40 | main | lush.c:1: note: this is the location of the previous definition 1 | #define gets(_) fgets((_),999,stdin) | lush.c:42: warning: "f" redefined 42 | #define f 001: | lush.c:40: note: this is the location of the previous definition 40 | main | lush.c:44: warning: "f" redefined 44 | #define f 100: | lush.c:42: note: this is the location of the previous definition 42 | #define f 001: | lush.c:45: warning: "f" redefined 45 | _[i-- | lush.c:44: note: this is the location of the previous definition 44 | #define f 100: | lush.c:46: warning: "f" redefined 46 | #define f 126: | lush.c:45: note: this is the location of the previous definition 45 | _[i-- | ``` Now one can use `sed` to get the `warning:` line correct but there is more to it than that. For instance this is what it looks like with clang: ``` lush.c:40:9: warning: 'f' macro redefined [-Wmacro-redefined] #define f 001: ^ lush.c:1:9: note: previous definition is here #define f 000: ^ lush.c:42:9: warning: 'f' macro redefined [-Wmacro-redefined] #define f 100: ^ lush.c:40:9: note: previous definition is here #define f 001: ^ ``` As you might see the part under the `warning:` line is different. The entry is supposed to show warnings and then print: ``` Hello World. ``` Jump to: [top](#)
## 1992/vern
Jump to: [top](#) ### STATUS: INABIAF - please **DO NOT** fix ### Source code: [1992/vern/vern.c](%%REPO_URL%%/1992/vern/vern.c) ### Information: [1992/vern/index.html](1992/vern/index.html) When your own checkmate is imminent it prints `"Har har"` but does not exit so it can '_rub your nose in defeat_', as the author puts it. You will have to exit it yourself through ctrl-c or killing it in some other fashion. Jump to: [top](#)
## 1992/westley
Jump to: [top](#) ### STATUS: INABIAF - please **DO NOT** fix ### Source code: [1992/westley/westley.c](%%REPO_URL%%/1992/westley/westley.c) ### Information: [1992/westley/index.html](1992/westley/index.html) The usability of this program was improved by making it so that as long as the terminal columns is >= 80 it will display properly, rather than having to wrap at 80 columns. However due to the nature of the program if the terminal is < 80 in column width it will not display right. To see the number of columns in your terminal try: ``` echo $COLUMNS ``` Jump to: [top](#)
# 1993
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## 1993/ant
Jump to: [top](#) ### STATUS: INABIAF - please **DO NOT** fix ### Source code: [1993/ant/ant.c](%%REPO_URL%%/1993/ant/ant.c) ### Information: [1993/ant/index.html](1993/ant/index.html) The author stated that: > The expression `(a*)*` compiles but loops forever. > > There is no check for trailing backslash (`\`) in the pattern. > > There is no check for unbalanced brackets. Omitting a closing bracket will generate a "Pattern too long" error, which is not the real error. Jump to: [top](#)
## 1993/cmills
Jump to: [top](#) ### STATUS: known bug - please help us fix ### Source code: [1993/cmills/cmills.c](%%REPO_URL%%/1993/cmills/cmills.c) ### Information: [1993/cmills/index.html](1993/cmills/index.html) In multiple platforms, both macOS and also linux (in particular a RHEL 9.3 system), this entry just shows a blank screen. Jump to: [top](#)
## 1993/lmfjyh
Jump to: [top](#) ### STATUS: INABIAF - please **DO NOT** fix ### Source code: [1993/lmfjyh/lmfjyh.c](%%REPO_URL%%/1993/lmfjyh/lmfjyh.c) ### Information: [1993/lmfjyh/index.html](1993/lmfjyh/index.html) This entry relied on a bug in gcc that was fixed with gcc version 2.3.3. This cannot be fixed for modern systems as the bug is long gone. An alternate version that will work for modern systems, however, does exist. See the index.html file for details. Jump to: [top](#)
## 1993/rince
Jump to: [top](#) ### STATUS: INABIAF - please **DO NOT** fix ### Source code: [1993/rince/rince.c](%%REPO_URL%%/1993/rince/rince.c) ### Information: [1993/rince/index.html](1993/rince/index.html) Although the code checks if the file can be opened or not, badly formatted files will cause problems. No other checks are performed either. There is no end of game checking function so you will have to quit the game through ctrl-c or such. Jump to: [top](#)
## 1993/schnitzi
Jump to: [top](#) ### STATUS: INABIAF - please **DO NOT** fix ### Source code: [1993/schnitzi/schnitzi.c](%%REPO_URL%%/1993/schnitzi/schnitzi.c) ### Information: [1993/schnitzi/index.html](1993/schnitzi/index.html) If the file cannot be opened it will very likely segfault. This should not be fixed except for an exercise to yourself, should you wish to try. This program uses `system(3)` so if you provide invalid characters in the question you might cause an error. For instance don't do this: ``` $ ./schnitzi schnitzi.info This program answers questions about paragraphs of text posed to it in English. It is written in C. Mark Schnitzius is the author of this program. The Loch Ness monster has been captured. Elvis is alive. Hostler was a woman. The NASA moon landings were clearly faked. ? What is foo'? ``` because doing so will result in something like: ``` sh: -c: line 0: unexpected EOF while looking for matching `'' sh: -c: line 1: syntax error: unexpected end of file ``` with the program terminating. Other characters will also cause this problem. Of course if you do something like: ``` What is 'foo'? ``` it will work fine. This is a feature, not a bug! Jump to: [top](#)
## 1993/vanb
Jump to: [top](#) ### STATUS: INABIAF - please **DO NOT** fix ### Source code: [1993/vanb/vanb.c](%%REPO_URL%%/1993/vanb/vanb.c) ### Information: [1993/vanb/index.html](1993/vanb/index.html) No spaces are allowed in the expression. The program does no error checking so erroneous expressions will produce spurious results. The unary `-` is an operator so decimal `-46` should be entered as `-d46` and not `d-46`. Jump to: [top](#)
# 1994
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## 1994/dodsond2
Jump to: [top](#) ### STATUS: INABIAF - please **DO NOT** fix ### Source code: [1994/dodsond2/dodsond2.c](%%REPO_URL%%/1994/dodsond2/dodsond2.c) ### Information: [1994/dodsond2/index.html](1994/dodsond2/index.html) When you initiate shooting via the `s` command you immediately lose an arrow **before you choose _where to_ shoot**. Also, when you shoot it will move you to that room so if you end up shooting into a pit room you will end up dying even though you didn't explicitly move there. Jump to: [top](#)
## 1994/ldb
Jump to: [top](#) ### STATUS: INABIAF - please **DO NOT** fix ### Source code: [1994/ldb/ldb.c](%%REPO_URL%%/1994/ldb/ldb.c) ### Information: [1994/ldb/index.html](1994/ldb/index.html) This was fixed to compile with modern systems but the entry also used `gets(3)` which in some systems would print out a warning along with the output of the program. Naturally it could also overflow long lines, of which there are many, though that is more considered a feature, not a bug, as it was documented by the author. It was changed to use `fgets(3)` to prevent the display problem but this introduces another problem namely that newlines can be printed if the line length < 231. This seems like a worthy compromise to not have messed up output and although it would be ideal for it to never print a newline (unless that's the line itself) it might be tampering too much with the entry to fix this problem, as it's not a real problem and as a one liner it's already quite long. See the FAQ on "[gets and fgets](faq.html#gets)" for more information on the change to `fgets(3)`. Jump to: [top](#)
## 1994/schnitzi
Jump to: [top](#) ### STATUS: uses gets() - change to fgets() if possible ### Source code: [1994/schnitzi/schnitzi.c](%%REPO_URL%%/1994/schnitzi/schnitzi.c) ### Information: [1994/schnitzi/index.html](1994/schnitzi/index.html) **NOTE**: the generated code of all versions, when fed its own source, will differ even when it works. See the author's remarks in the index.html for details. Increasing the buffer size and having it, when fed its own source code, generate code that will compile with the same buffer size is difficult: it just uses the original size. This is explained later down. Getting it to use `fgets()` is even harder as when fed its own code it will generate code that cannot even compile let alone use `fgets(3)`. In both cases, changing the buffer size and changing it to use `fgets(3)`, will cause compilation errors without other adjustments. See the below magic for details. Along with the author's remarks in the index.html file it might prove possible to get it to use `fgets(3)`. Here is the magic of how this entry works, to help anyone who wishes to work on this. You might wish to run the commands: ``` diff schnitzi.alt.c schnitzi.alt2.c diff schnitzi.alt2.c schnitzi.alt.c ``` to see how the buffer size and how the `gets(3)` was changed to use `fgets()`, in the two alternate versions. Notice that the `fgets(3)` version can compile it just can't **generate** compilable code (let alone using `fgets(3)`) when fed itself (to reiterate, just changing the call to `fgets(3)` does not mean it can compile and there's a further problem in that `fgets(3)` retains the newline whereas `gets(3)` does not). Nevertheless looking at these commands will be of help to understand how it works, in case one wishes to try and fix it. For the alternate versions the other functionality is unaffected. Jump to: [top](#) ### The magic of [1994/schnitzi](1994/schnitzi/index.html) and how it flips text The problem is getting the generated code to use `fgets()` (once it even compiles which was easy to do) and also have the updated buffer size be the same (which was easy to do too at least in the original version). The generated output, when changed to `fgets()` failed to compile and it also used `gets(3)` and these are the bugs here. The buffer size, when using `gets()` is still the same but as noted above the original code has had a buffer size increase. The real problem is with formatting the code. Take a look at the `#include `, `int r=0,x,y=0` and the interesting comment below it, at the top of the file. If you look at each column and go down that column you can see how it spells out the code! For instance the first column looks like: ``` # i n c l u d e < s t d i o . h > ``` If you join the lines you end up with: ``` #include ``` If you look at column 25 which is the end of the word 'mh111' and you go down to the next row you'll see a 0 and if you go one row down another 0. This is the buffer size, 100, for `u`! The column to the left is the same for the `t` variable. Thus it seems that in order to get the generated output correct one needs to provide the correct input in comments or possibly by rearranging some of the code (this was actually required to make the generated code compile at all when changing the buffer size, see below). Jump to: [top](#) ### Important points: Getting this entry to use `fgets(3)` is easy but the problem is you're supposed to be able to feed the source to the program and the output of that will be compilable. It however will create compiler errors. So it's not just changing the code to get it to use `fgets(3)`! This was done but the other part is why that part was rolled back. The buffer size was increased but that only works on the original source. To say just how sensitive this entry is: even a space, lack of space or a character, wrong character, lack of character or character in the wrong place can cause a compilation error! Make sure that the output of: ``` ./schnitzi < schnitzi.c ``` can be compiled and the output of that new program when fed itself can also be compiled! Jump to: [top](#)
## 1994/shapiro
Jump to: [top](#) ### STATUS: INABIAF - please **DO NOT** fix ### Source code: [1994/shapiro/shapiro.c](%%REPO_URL%%/1994/shapiro/shapiro.c) ### Information: [1994/shapiro/index.html](1994/shapiro/index.html) This program will likely crash if the source code file (by the name of the file that's compiled) cannot be opened in the directory it is run from. Jump to: [top](#) ### Important reminder and a note about the `-1` value check for `getc()`: This code was fixed to not use `-1` for the return value of `getc()`; this is important because `EOF` is **NOT** guaranteed to be `-1` but rather any negative value. On systems where `EOF != -1` the program would enter an infinite loop until the program crashed, by chance reads a `-1` or was killed (it is for this same reason that one should not use `EOF` for the `getopt()` functions as they return `-1` when all options are parsed (for details on the definition of `EOF` see `7.21 Input/output` subsection 1 of the standard)). An interesting problem occurred where changing the `-1` to `EOF` caused both `warning: illegal character encoding in string literal` and `error: source file is not valid UTF-8`. But since `EOF` is simply an int < 0 and making the loop condition check that the return value is >= 0 does not cause a compilation error and it functions correctly it will address the systems where `EOF != -1` just as if it checked for `!= EOF`. Since it works there is no need to fix this except for a challenge to yourself. Jump to: [top](#)
## 1994/tvr
Jump to: [top](#) ### STATUS: INABIAF - please **DO NOT** fix ### Source code: [1994/tvr/tvr.c](%%REPO_URL%%/1994/tvr/tvr.c) ### Information: [1994/tvr/index.html](1994/tvr/index.html) The judges said the following in their remarks: > The fractally minded may be able to detect that mode 0 does not calculate Mandelbrot/Julian sets correctly. Can you find the bug? Better still, can you fix it without breaking something else? However, the author stated that this is a feature so this should not be fixed. See also the other [bugs](1994/tvr/index.html#bugs) the author mentioned that, as documented, are considered features. Jump to: [top](#)
# 1995
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## 1995/cdua
Jump to: [top](#) ### STATUS: INABIAF - please **DO NOT** fix ### Source code: [1995/cdua/cdua.c](%%REPO_URL%%/1995/cdua/cdua.c) ### Information: [1995/cdua/index.html](1995/cdua/index.html) This did not originally compile under macOS and after it did compile under macOS, it crashed. These problems were fixed. It should be noted however that there is a condition where the program will prompt you to press return again. This was thought to be a bug but looking at the code it can clearly be seen that if `g - a` is 0 then the message is supposed to be printed again and one is supposed to press a key as at that point it calls `getchar()` via the pointer `m`. So this is a feature not a bug. Jump to: [top](#)
## 1995/leo
Jump to: [top](#) ### STATUS: known bug - please help us fix ### Source code: [1995/leo/leo.c](%%REPO_URL%%/1995/leo/leo.c) ### Information: [1995/leo/index.html](1995/leo/index.html) The judges suggested that the following commands should result in output: ``` ./leo 1 | cat - /dev/tty | gs - ./leo 37 80 | cat - /dev/tty | gs - ``` The first one can work if one does instead: ``` echo "" | ./leo 1 > foo.ps gs foo.ps ``` but it is supposed to work in the pipeline as is. The second one does not appear to work at all even if one redirects to a file (like the workaround for the first) as it appears to just block. It is not known if this is platform specific but this was observed in macOS and it would be good if it was fixed. Jump to: [top](#)
## 1995/savastio
Jump to: [top](#) ### STATUS: INABIAF - please **DO NOT** fix ### Source code: [1995/savastio/savastio.c](%%REPO_URL%%/1995/savastio/savastio.c) ### Information: [1995/savastio/index.html](1995/savastio/index.html) This program expects a POSITIVE number. If you specify a negative number it will not show any output, stuck in a loop. Jump to: [top](#)
## 1995/vanschnitz
Jump to: [top](#) ### STATUS: missing file - please provide it ### Source code: [1995/vanschnitz/vanschnitz.c](%%REPO_URL%%/1995/vanschnitz/vanschnitz.c) ### Information: [1995/vanschnitz/index.html](1995/vanschnitz/index.html) The authors stated that they included a version that allows people with just K&R compilers to use the program but this file is missing. Can you provide it? Jump to: [top](#)
# 1996
Jump to: [top](#)
## 1996/gandalf
Jump to: [top](#) ### STATUS: missing or dead link or links - please provide it or them ### Source code: [1996/gandalf/gandalf.c](%%REPO_URL%%/1996/gandalf/gandalf.c) ### Information: [1996/gandalf/index.html](1996/gandalf/index.html) The link was `http://www.tc3.co.uk/~gandalf/G.HTML` but this no longer exists as it was instead requiring a login / password. Do you have an updated link? We welcome your help! Jump to: [top](#)
## 1996/huffman
Jump to: [top](#) ### STATUS: uses gets() - change to fgets() if possible ### Source code: [1996/huffman/huffman.c](%%REPO_URL%%/1996/huffman/huffman.c) ### Information: [1996/huffman/index.html](1996/huffman/index.html) The changing to using `fgets(3)` in this entry is a bit more complicated. It can almost be done except that some of the output of the [try.sh](%%REPO_URL%%/1996/huffman/try.sh) is wrong, especially the last one. This diff almost does it but not quite: ``` diff --git i/1996/huffman/huffman.c w/1996/huffman/huffman.c index a5745bc7f4fa28b834c004f4cf19633e40ad9165..5e5e5334f33f9dbd95c70eddece3189d9bcff5e9 100644 --- i/1996/huffman/huffman.c +++ w/1996/huffman/huffman.c @@ -1,15 +1,16 @@ #define x char #define z else #define w gets +#define gets(b) ((b)[0]='\0',(fgets((b), 100, stdin))) #define r if #define u int #define s main #define v putchar #define y while #define t " A?B?K?L?CIF?MSP?E?H?O?R?DJG?NTQ?????U?V?????X???????Z????W??Y??" - s ( ) { x* c , b[ 5 * 72 ]; u a, e , d [ 9 + s ( ) { x* c , b[ 5 * 72 ]; u a, e , d [ 9 *9 *9 ] ; y (w ( b) ){ r ( 0 [ b] -7 * 5 ) { c = b ; y ( (* c - 6 * 7 )* * c )c = c+ 1 ; r (( -0 ) [ c ] && w ( b + 8 * 5* 3 ) && w (b +8 *5 * 6) ) { a = 0; y ( a [ b ] ``` But since it does not for the time being it is advisable to just redirect `stderr` to `/dev/null` (`2>/dev/null`). Jump to: [top](#)
## 1996/jonth
Jump to: [top](#) ### STATUS: INABIAF - please **DO NOT** fix ### Source code: [1996/jonth/jonth.c](%%REPO_URL%%/1996/jonth/jonth.c) ### Information: [1996/jonth/index.html](1996/jonth/index.html) If X is not running this program will very likely crash or do something funny. This should NOT be fixed. **NOTE**: the two boards will be on top of each other so you will have to drag one off the other so that you can properly play. Jump to: [top](#) ### STATUS: missing or dead link or links - please provide it or them As well: the link which was `http://www.uio.no/~jonth` is no longer valid and there's no archive on the Internet Wayback Machine. Do you know of a proper URL? We greatly appreciate your help here! Jump to: [top](#)
# 1997
There was no IOCCC in 1997. Jump to: [top](#)
# 1998
Jump to: [top](#)
## 1998/chaos
Jump to: [top](#) ### STATUS: INABIAF - please **DO NOT** fix ### Source code: [1998/chaos/chaos.c](%%REPO_URL%%/1998/chaos/chaos.c) ### Information: [1998/chaos/index.html](1998/chaos/index.html) The author stated the following: > Memory `malloc(3)`ed is never freed. This shouldn't be a big deal, since only one block is ever allocated, and the OS should recover it. > > My local flavor of lint doesn't seem to like the fact that I never `return` from `main()`. Feh, what does it know? Otherwise, ignoring lint's over protectiveness ("Of course I'm not using all of the functions defined in `curses.h`!"), it's lint clean. > > If the compiler happens to generate the byte sequence "AlWuzEre" in the executable by chance, the program may be unable to locate the embedded string. As a result, running the program without an external data file may act in undefined ways. > If the compiler doesn't store `char * P`'s data in a nice contiguous stream, it would be bad. As above, it would break running the program without an external data file. > > If the incoming data is corrupt, the results are undefined. (Although dumping core is a popular result.) > > When a point passes behind the camera, it is still plotted. The object will "bounce" off the camera, but the result (some points in front, some reflected from the rear) looks really odd. And it sometimes hangs. So just don't fly through objects. You'll be happier. Jump to: [top](#)
## 1998/dlowe
Jump to: [top](#) ### STATUS: missing or dead link or links - please provide it or them ### Source code: [1998/dlowe/dlowe.c](%%REPO_URL%%/1998/dlowe/dlowe.c) ### Information: [1998/dlowe/index.html](1998/dlowe/index.html) The domain `http://pootpoot.com` no longer exists as it once did. The judges have given a script that can be used to make a similar page (**warning: not checked for security in modern days!**). Do you have a server with enough bandwidth and would like to set it up? We'll gladly thank you in the [thanks file](thanks-for-help.html) file and link to the page as well! You'll also have IOCCC fame for reviving a pootifier! :-) Jump to: [top](#)
## 1998/dloweneil
Jump to: [top](#) ### STATUS: missing or dead link or links - please provide it or them ### Source code: [1998/dloweneil/dloweneil.c](%%REPO_URL%%/1998/dloweneil/dloweneil.c) ### Information: [1998/dloweneil/index.html](1998/dloweneil/index.html) The domain `http://pootpoot.com` no longer exists as it once did. The judges have given a script that can be used to make a similar page (**warning: not checked for security in modern days!**). Do you have a server with enough bandwidth and would like to set it up? We'll gladly thank you in the [thanks file](thanks-for-help.html) file and link to the page as well! You'll also have IOCCC fame for reviving a pootifier! :-) Jump to: [top](#)
## 1998/schnitzi
Jump to: [top](#) ### STATUS: INABIAF - please **DO NOT** fix ### Source code: [1998/schnitzi/schnitzi.c](%%REPO_URL%%/1998/schnitzi/schnitzi.c) ### Information: [1998/schnitzi/index.html](1998/schnitzi/index.html) A point worth considering is that as the number passed into the program gets bigger the number of lines of output gets substantially larger. For instance: ``` $ ./schnitzi 9|wc -l 771999 ``` The larger the number the bigger the file can become too, even becoming gigabytes in size. The range is checked for `>0 && <27` as not having this can be a problem including a segfault. If you use the generated program and do not give enough numbers in input something funny will happen, very possibly with different results per run. This is in the index.html file as something to try and ponder. Jump to: [top](#)
# 1999
There was no IOCCC in 1999. Jump to: [top](#)
# 2000
Jump to: [top](#)
## 2000/dlowe
Jump to: [top](#) ### STATUS: INABIAF - please **DO NOT** fix The author states that in perl < 5.6.0 there is a bug with a core dump in what they said is in `Perl_sv_upgrade`. As this is documented it is not considered a bug to be fixed. For the curious this will crash in macOS. It was noted that the code that crashes is: ``` perl_eval_sv (newSVpv("_:$_= <> ; defined or exit; @ARGV" "=split; __:$_= shift;defined or goto _; chomp " ";(m*^\\x70oO" "\\x74$*i)?(pri" "nt \"$_ w\\x" "61s h\\145r\\x" "65!\\n\"):((m*" "^\\s\\*(-?\\d+" "(\\.\\d+)?)\\s" "\\*$*)?(push@SS ,$1):(&{chr(((o" "rd)%39)+3**4)x2 } )); goto __; sub ff { @SS= (" ")} sub __{print \"stack empty\\" "n\"} sub ss{$#" "SS<0 and goto & __; print $SS[$" "#SS].\"\\n\"} " "sub SS{ $#SS<0 and goto &__ ; print pop @SS}" "sub _ { print \"divide by zer" "o\\n\"}sub ii{" "map{ print\"$_" "\\n\" } reverse @SS} sub AUTOLO" "AD { print\"un" "implemented\\n" "\"} sub gg{ $#" "SS<0 and goto &__;push@SS,$SS[ $#SS]} sub uu{ " "$#SS<1 and goto &__;$SS[ $#SS]+= $SS[$#SS-1];$SS" "[$#SS-1]=$SS[$" "#SS]-$SS[$#SS-" "1]; $SS[$#SS]-" "=$SS[$#SS-1]} ",0),0 ); ``` and in particular it appears that it is the perl itself. In other words if one changes it to be: ``` perl_eval_sv(newSVpv("",0),0); ``` it will not crash. But of course it won't do anything either. So it's more specifically that the call to `newSVpv()` crashes the code but _INSIDE_ (key point!) the call to `perl_eval_sv()` that does it. Given what the author stated and that the version of perl is < than 5.6.0 which the author states can crash this makes sense. The example command above _should_ print: ``` $ echo "13 14 15 16 17 + - * / p" | ./dlowe -0.0515873015873016 ``` and that's what it shows in linux. Note that with different perl libraries in macOS (for instance from [Homebrew](https://brew.sh) and [MacPorts](https://www.macports.org) package managers) it will likely print different warnings when compiling. It was observed that with Homebrew it does not report any warnings but with MacPorts it results in a total of 92 warnings! Nonetheless neither works okay and both crash. Jump to: [top](#)
## 2000/primenum
Jump to: [top](#) ### STATUS: INABIAF - please **DO NOT** fix ### Source code: [2000/primenum/primenum.c](%%REPO_URL%%/2000/primenum/primenum.c) ### Information: [2000/primenum/index.html](2000/primenum/index.html) This program does not do what you might think it does! Running it like: ``` ./primenum 13 ``` will seemingly wait for input exactly because it is waiting for input. See the index.html file or look at the source. Although the name of the program suggests it prints prime numbers this is not the case. This is by design. See the author's comments for more details or better yet look at the code and if necessary try it out. Please do not try and fix this. A crash in the program is known as well. This is also a feature. Please do not try to fix the crashing of this code except to challenge yourself (if you think that it'll be worth your two second fix :-) ). If you do fix it please do not make a pull request. Jump to: [top](#)
## 2000/rince
Jump to: [top](#) ### STATUS: INABIAF - please **DO NOT** fix ### Source code: [2000/rince/rince.c](%%REPO_URL%%/2000/rince/rince.c) ### Information: [2000/rince/index.html](2000/rince/index.html) If `DISPLAY` is not set the program will very likely crash, do something strange (or if you're very unlucky your computer might [halt and catch fire](https://en.wikipedia.org/wiki/Halt_and_Catch_Fire_(computing))! :-) ). Jump to: [top](#)
# 2001
Jump to: [top](#)
## 2001/anonymous
Jump to: [top](#) ### STATUS: INABIAF - please **DO NOT** fix ### Source code: [2001/anonymous/anonymous.c](%%REPO_URL%%/2001/anonymous/anonymous.c) ### Information: [2001/anonymous/index.html](2001/anonymous/index.html) This was fixed so that it doesn't segfault and then also fixed the functionality of it (but see below). The [anonymous.ten.c](%%REPO_URL%%/2001/anonymous/anonymous.ten.c) program was also fixed (it also segfaulted) but note that it **MUST** be compiled as a **32-bit ELF binary** so it will NOT work in macOS (for example); if you cannot use `-m32` or even if you can but it cannot compile as an ELF binary (not elf binary :-) ) (but see below) then the `anonymous` program itself will very likely crash if you run it on the compiled [anonymous.ten.c](%%REPO_URL%%/2001/anonymous/anonymous.ten.c); if nothing else it will not modify the target executable (this part of the fix at least should be correct). Note also that if you don't specify a file or you specify a non-32-bit ELF file this program will very likely crash or do something strange like slaughter the [Elves](https://www.glyphweb.com/arda/e/elves.html) of [Imladris](https://www.glyphweb.com/arda/i/imladris.php) :-( Jump to: [top](#)
## 2001/bellard
Jump to: [top](#) ### STATUS: INABIAF - please **DO NOT** fix ### Source code: [2001/bellard/bellard.c](%%REPO_URL%%/2001/bellard/bellard.c) ### Information: [2001/bellard/index.html](2001/bellard/index.html) The author stated that it only works with i386 linux so the fact it doesn't work in modern systems is considered a feature and not a bug. An initial segfault was fixed (trying to open the file) and the [supplementary program bellard.otccex.c](%%REPO_URL%%/2001/bellard/bellard.otccex.c) was also fixed but this still crashes in systems not i386 linux which is what the author stated. The author said that they compiled it with [gcc version 2.95.2](https://ftp.gnu.org/gnu/gcc/gcc-2.95.2/gcc-everything-2.95.2.tar.gz). We don't know if a certain gcc version is necessary but it might be helpful to download and compile that version to test it - or it might not. Yusuke was able to get this to work with `-m32` but only in an emulator. As such, it might be that the changes made should be rolled back but at least now the supplementary program will work in modern systems. On the author's [web page for this program](https://bellard.org/otcc/) it is explicitly stated that it requires i386 linux. There it was found what should be a more portable version which is included as [otccelf.c](%%REPO_URL%%/2001/bellard/otccelf.c) (after adding some `#include`s and the modification but it appears this *also* requires i386 linux; indeed looking at the code it hard codes paths that are i386 specific to linux. Another point of interest is that the author provided unobfuscated versions which might be of value to look at. Jump to: [top](#) #### Aside: why were there changes made if INABIAF ? This is a good question. The reason is we believe it better to fix some obvious problems: there were some bugs that would very possibly prevent it from working even if it was in i386 linux though it did seem to work in an emulator, so perhaps not. Still it's better to have the type of the file pointer correct and so that the file can at least be opened in modern systems even if the compiler won't work there. Also the supplementary program, which did not work at all, was fixed and it can be run by itself for fun in modern systems, which was not possible before the fixes there. Jump to: [top](#)
## 2001/cheong
Jump to: [top](#) ### STATUS: INABIAF - please **DO NOT** fix ### Source code: [2001/cheong/cheong.c](%%REPO_URL%%/2001/cheong/cheong.c) ### Information: [2001/cheong/index.html](2001/cheong/index.html) This program will crash without an arg. Jump to: [top](#)
## 2001/dgbeards
Jump to: [top](#) ### STATUS: INABIAF - please **DO NOT** fix ### Source code: [2001/dgbeards/dgbeards.c](%%REPO_URL%%/2001/dgbeards/dgbeards.c) ### Information: [2001/dgbeards/index.html](2001/dgbeards/index.html) This program deliberately crashes if it loses (which is what it aims to do). Jump to: [top](#)
## 2001/herrmann1
Jump to: [top](#) ### STATUS: known bug - please help us fix During compilation you're supposed to see some animation but this does not seem to work with modern gcc versions. It appears that version 2.95 works but maybe others do as well. If you have a fix for modern versions of gcc, your help is welcome. Jump to: [top](#)
## 2001/kev
Jump to: [top](#) ### STATUS: INABIAF - please **DO NOT** fix ### Source code: [2001/kev/kev.c](%%REPO_URL%%/2001/kev/kev.c) ### Information: [2001/kev/index.html](2001/kev/index.html) Sometimes when one player presses `q` it will result in broken pipe on the other end. The author also noted that some versions of `curses` have problems with `getch()` having a delay. The program is very likely to segfault if the specified port can't be bound or connected to. If the terminal is too wide (the author suggests over 500 characters) the program can segfault. It's also possible to crash the program if a player scores over a billion points. Although it is independent of endianness both systems need the same character set. In other words both have to be ASCII or EBCDIC - not one of each. Jump to: [top](#)
## 2001/ollinger
Jump to: [top](#) ### STATUS: INABIAF - please **DO NOT** fix ### Source code: [2001/ollinger/ollinger.c](%%REPO_URL%%/2001/ollinger/ollinger.c) ### Information: [2001/ollinger/index.html](2001/ollinger/index.html) This program will very likely crash or do something unexpected if you do not provide enough args. Jump to: [top](#)
## 2001/rosten
Jump to: [top](#) ### STATUS: INABIAF - please **DO NOT** fix ### Source code: [2001/rosten/rosten.c](%%REPO_URL%%/2001/rosten/rosten.c) ### Information: [2001/rosten/index.html](2001/rosten/index.html) See list of bugs [here](2001/rosten/index.html#bugs). Jump to: [top](#)
## 2001/schweikh
Jump to: [top](#) ### STATUS: INABIAF - please **DO NOT** fix ### Source code: [2001/schweikh/schweikh.c](%%REPO_URL%%/2001/schweikh/schweikh.c) ### Information: [2001/schweikh/index.html](2001/schweikh/index.html) The glob pattern must match the whole string. See the author's comments for details and a workaround. There's also no way to escape meta characters. See also the author's list of bugs [here](2001/schweikh/index.html#bugs). Jump to: [top](#)
## 2001/westley
Jump to: [top](#) ### STATUS: uses gets() - change to fgets() if possible ### Source code: [2001/westley/westley.c](%%REPO_URL%%/2001/westley/westley.c) ### Information: [2001/westley/index.html](2001/westley/index.html) This function uses `gets(3)` but it would be ideal if it used `fgets(3)`. This one is rather complicated but you are welcome to try and fix this if you wish. Jump to: [top](#) ### STATUS: main() has only one arg - try and make it have 2 or 3 This program only has one arg to `main()`. However changing it to have 2 is not as simple as it might seem. Doing this breaks things. If memory serves changing it to two will, for instance, break the punch card code output. It might be that that is for `fgets(3)`, however, but the point remains: in order to test any fixes you must determine if the extra files generated (some from `sort(1)`) - see the index.html file - generate correct output as well as that the main entry does too. You might try running the `try.sh` script and redirect it to a file first so that you can compare the output. Make sure to recreate the extra files as described by the author if you do fix this. This might be looked at later if nobody else takes up the challenge. Jump to: [top](#)
## 2001/williams
Jump to: [top](#) ### STATUS: known bug - please help us fix ### Source code: [2001/williams/williams.c](%%REPO_URL%%/2001/williams/williams.c) ### Information: [2001/williams/index.html](2001/williams/index.html) There seem to be a couple bugs at least in this entry. The first one is that when it does reach a certain point it crashes. This is in the function `J()` (or one it calls?). But sometimes it seems to not get that far, just showing lines moving back and forth. This is also in `J()`. It is not confirmed but it might be that the lines are drawn by `XDrawString()`, the last part in `J()`. `J()` has a `for` loop identified by `for` and also a couple `while` loops, identified by `R`. Since the game never ends properly the score is not printed either. It appears that the crash happens in more than one place. For instance it has happened at ``` XCheckMaskEvent(d, 4,&e) ``` but it's also happened at ``` else XDrawPoint(d ,w,g,(l.s+=l.a)>>9, h=(l.c+=l.b)>>9) ``` In both cases the pointer `d` was corrupted: ``` (lldb) p d (Display *) 0x0000000000000001 ``` It is believed that it also happened at ``` XDrawString(d,w,g,W/3,H/2,m,B); ``` in `J()` and for the same reason. The loop seems to be stuck in the call to `usleep(3)` like: ``` usleep(p*200); ``` which happens to be in a `while()` loop. There is a way to get the code to crash. If you don't do anything until everything is destroyed (where you'd lose the game if it ended) and then you start to shoot your missiles repeatedly it will eventually crash. It appears not to be the case (though this was not tried as many times) if you start shooting when the missiles come down. The fact you can shoot after it starts that sleeping in a loop does suggest that it's not stuck only showing those lines and sleeping. Jump to: [top](#)
# 2002
There was no IOCCC in 2002. Jump to: [top](#)
# 2003
There was no IOCCC in 2003. Jump to: [top](#)
# 2004
Jump to: [top](#)
## 2004/gavin
Jump to: [top](#) ### STATUS: INABIAF - please **DO NOT** fix ### Source code: [2004/gavin/gavin.c](%%REPO_URL%%/2004/gavin/gavin.c) ### Information: [2004/gavin//index.html](2004/gavin//index.html) This program is x86 linux specific; it is extremely likely that a segmentation fault will occur in other systems but even if it does not it is highly unlikely it will work. Below we will give some examples as well as a change that was made to let it compile with clang. In macOS with the arm64 chip this will segfault: ``` ./gavin > kernel ``` When trying to link `gavin.o` to produce `sh`, the linker generates: ``` Undefined symbols for architecture arm64: "start", referenced from: -u command line option (maybe you meant: __start) ld: symbol(s) not found for architecture arm64 ``` Jump to: [top](#) #### Recent 2004/gavin mods: Although not related some recent changes were made to [2004/gavin](2004/gavin/index.html) to let it compile under clang. The following patch was applied: ``` diff --git a/2004/gavin/gavin.c b/2004/gavin/gavin.c index c967b7e..2082b49 100644 --- a/2004/gavin/gavin.c +++ b/2004/gavin/gavin.c @@ -1,8 +1,9 @@ +int main(int t, char **q, char **d) { return cain(t, (int)q, (int)d); } #define G(n) int n(int t, int q, int d) #define X(p,t,s) (p>=t&&p<(t+s)&&(p-(t)&1023)<(s&1023)) #define U(m) *((signed char *)(m)) #define F if(!--q){ -#define I(s) (int)main-(int)s +#define I(s) (int)cain-(int)s #define P(s,c,k) for(h=0; h>>14==0; h+=129)Y(16*c+h/1024+Y(V+36))&128>>(h&7)?U(s+(h&15367))=k:k G (B) @@ -52,7 +53,7 @@ else G (_); G (o); -G (main) +G (cain) { Z, k = K; if (!t) ``` The original Makefile from 2004 had the following to say about this entry: ``` # Special flags for the gavin entry # # FYI: Older versions of GCC have a bug in -O2 optimization, hence -O1 # GAVIN_OPT= -O1 GAVIN_FLAGS=\ '-DY(m)=*((int*)(m))'\ '-DE(f,a,b,c)=((G((*)))(f))(a,b,c)'\ '-DM=for(D=0;D<786432;D++)'\ '-DZ=int i=0,j=0,h,n,p=393728,s=26739,C,D'\ '-DV=0x90200'\ '-DK=0'\ '-DR=while((C=E(V-8,100,0,0))&3&&(D=E(V-8,96,0,0))|3){'\ '-DL(c,d)=E(V+8,100,c,0);R}E(V+8,96,d,0);R}' # ... # Best of Show # gavin: gavin.c ${CC} ${GAVIN_OPT} -o gavin ${GAVIN_FLAGS} gavin.c ${RM} -f kernel ./gavin > kernel ${CC} ${GAVIN_OPT} -c ${GAVIN_FLAGS} -DB=_start '-Dputchar(a)=' gavin.c ${RM} -f sh ${LD} -s -o sh gavin.o ${RM} -f vi ${CP} sh vi ${RM} -f fs.tar ${TAR} -cvf fs.tar sh vi gavin.c index.html prim gavin_clean: ${RM} -f sh vi kernel gavin.o gavin_clobber: gavin_clean ${RM} -f gavin fs.tar gavin_files: boot.b lilo.conf prim gavin_install.txt ``` The current [Makefile](%%REPO_URL%%/2004/gavin/Makefile) was modified to try and fit into the current IOCCC build environment. Please also see [known features in the index.html](2004/gavin/index.html#known-features) for things that are not bugs but documented (mis)features. Jump to: [top](#)
## 2004/hibachi
Jump to: [top](#) ### STATUS: INABIAF - please **DO NOT** fix ### Source code: [2004/hibachi/hibachi.c](%%REPO_URL%%/2004/hibachi/hibachi.c) ### Information: [2004/hibachi//index.html](2004/hibachi//index.html) The author stated that: > The links (text) web browser does not support RFC 2616 section 7.2.1 paragraph 3 sentence 2, and so fails to display responses from `hibachi`. Jump to: [top](#)
## 2004/jdalbec
Jump to: [top](#) ### STATUS: INABIAF - please **DO NOT** fix ### Source code: [2004/jdalbec/jdalbec.c](%%REPO_URL%%/2004/jdalbec/jdalbec.c) ### Information: [2004/jdalbec/index.html](2004/jdalbec/index.html) The author stated that: > Arguments matching `/[^2]22$/` cause the program to segfault after rapidly exhausting the available stack space. I could probably fix this by adding some special cases to the code, but [Blaine the Mono] it's quite a bit more exciting this way, don't you think?[/Blaine] Since the trailing `22` will be its own atom anyway, you can just insert a space in front of it if you run into this feature (e.g. `1 22` instead of `122`). > > Arguments matching `/(?:.){10,}/` will produce visually incorrect results (e.g., generation 1 starting from 1111111111 will print as `: 1`), but there's nothing interesting about these arguments that can't be modeled using shorter runs of the same symbol. > > Arguments matching `/(?:.){257,}/` may produce mathematically incorrect results (e.g., generation 1 starting from a string of 257 `1`s will be calculated as `11`); the remark from the previous paragraph applies here also. Jump to: [top](#)
## 2004/sds
Jump to: [top](#) ### STATUS: INABIAF - please **DO NOT** fix ### Source code: [2004/sds/sds.c](%%REPO_URL%%/2004/sds/sds.c) ### Information: [2004/sds/index.html](2004/sds/index.html) The generated code will very likely segfault or do something not intended if not given the right args. See the index.html file for the correct syntax. Jump to: [top](#)
# 2005
Jump to: [top](#)
## 2005/anon
Jump to: [top](#) ### STATUS: INABIAF - please **DO NOT** fix ### Source code: [2005/anon/anon.c](%%REPO_URL%%/2005/anon/anon.c) ### Information: [2005/anon/index.html](2005/anon/index.html) This program sometimes will create unsolvable puzzles :-) just to hook you. As a protection against this - and to prevent you from spending too much time on such puzzles (or too big puzzles if you insist on doing this) - it deliberately destroys its runtime stack. See the [index.html](2005/anon/index.html) for more details on this. If you specify more than three args the program might also crash or do something strange. This might also happen if you specify excessively large board dimensions. Try `100 100 100` for instance and see what happens! Jump to: [top](#)
## 2005/giljade
Jump to: [top](#) ### STATUS: INABIAF - please **DO NOT** fix ### Source code: [2005/giljade/giljade.c](%%REPO_URL%%/2005/giljade/giljade.c) ### Information: [2005/giljade/index.html](2005/giljade/index.html) This entry will very likely segfault or do something strange if the source code does not exist. This entry will, according to the author, likely segfault if `sizeof(int) != sizeof(FILE *)`. This entry requires that `sed` and `make` are in your `$PATH`. Jump to: [top](#)
## 2005/mikeash
Jump to: [top](#) ### STATUS: INABIAF - please **DO NOT** fix ### Source code: [2005/mikeash/mikeash.c](%%REPO_URL%%/2005/mikeash/mikeash.c) ### Information: [2005/mikeash/index.html](2005/mikeash/index.html) The author states: > The only built-in functions are `defvar`, `format`, `substitute`, `char-upcase`, `+`, `-`, `*`, and `/`.
> > Only one variable is available. This variable is called `q`, although any symbol name starting with the letter `q` will be mapped to this variable.
> > Only the first letter of a function name is significant. For example, `format`, `f`, `farm`, and various other words starting with `f` will all map to the `format` function.
> > The `defvar` function completely ignores its first parameter. It will always store the result of evaluating its second parameter in `q`. Unlike in [Common Lisp](https://en.wikipedia.org/wiki/Common_Lisp), multiple invocations of `defvar` on the same variable will overwrite old values.
> > Character constants are limited to `#\Newline` and single-character constants such as `#\x`.
> > The `char-upcase` function will give strange results if passed something other than a lowercase character.
> > The `format` function takes exactly three parameters. The first parameter is ignored; output always goes to `stdout`. The second parameter must have exactly one `~s` format specifier in it, and no other format specifiers are permitted.
> > The arithmetic functions take exactly two parameters.
> > All tokens must be separated from a following `)` by whitespace.
> > A lot of other things. Notably, the language which this program interprets is nowhere near [Turing-complete](https://en.wikipedia.org/wiki/Turing_completeness).
> > Basically, the LISP interpreter is good for some basic math operations, and for running itself. Jump to: [top](#)
## 2005/mynx
Jump to: [top](#) ### STATUS: INABIAF - please **DO NOT** fix ### Source code: [2005/mynx/mynx.c](%%REPO_URL%%/2005/mynx/mynx.c) ### Information: [2005/mynx/index.html](2005/mynx/index.html) Probably this is obvious, but this entry will not work with https. An alt version exists that _SCANS_ for https in case someone wants to set up a pipeline or other workaround (perhaps with `stunnel`) or even add additional code to it to make it work with https but the problem otherwise is a secure connection has to first be set up in order to give http commands. This is not a bug but it's worth pointing out as it won't work on as many websites as it used to including the [IOCCC website](https://www.ioccc.org) itself. The author noted that someone did make a version that supports `https` but it is not known where this might be. Jump to: [top](#)
## 2005/sykes
Jump to: [top](#) ### STATUS: INABIAF - please **DO NOT** fix ### Source code: [2005/sykes/sykes.c](%%REPO_URL%%/2005/sykes/sykes.c) ### Information: [2005/sykes/index.html](2005/sykes/index.html) The author stated the below points of interest. The machine emulated is an older 40 column one so 80 column programs will not show up correctly. There is no emulation of [PET](https://en.wikipedia.org/wiki/Commodore_PET) graphics characters. The parameter controls the speed of the 60Hz "jiffy clock", and not the processor speed. This means many games may run too fast to be usable - it really depends on the speed of your machine. Although the PET [emulator](https://en.wikipedia.org/wiki/Emulator) can do `LOAD` and `SAVE`, it cannot `VERIFY` or `OPEN` and `CLOSE` files. The [PET](https://en.wikipedia.org/wiki/Commodore_PET) hardware [emulation](https://en.wikipedia.org/wiki/Emulator) is not at all complete - features such as the hardware timers are completely missing. Some programs will not run correctly. The [6502](https://en.wikipedia.org/wiki/MOS_Technology_6502#Technical_description) [emulation](https://en.wikipedia.org/wiki/Emulator) does not include the seldom used decimal mode, or any of the "undocumented" instructions. Jump to: [top](#)
# 2006
Jump to: [top](#)
## 2006/birken
Jump to: [top](#) ### STATUS: uses gets() - change to fgets() if possible ### Source code: [2006/birken/birken.c](%%REPO_URL%%/2006/birken/birken.c) ### Information: [2006/birken/index.html](2006/birken/index.html) This entry uses `gets(3)` which is unsafe and provides annoying warnings, most obnoxious in macOS as it shows it at runtime (redirecting `stderr` to `/dev/null` will silence it). The following diff will almost work but it crashes with at least `computer.tofu` input file: ``` 12a13 #define gets(c) fgets((c),PI,stdin)&&(((c)[strlen((c))-1]='\0'),c!=NULL) ``` Jump to: [top](#)
## 2006/borsanyi
Jump to: [top](#) ### STATUS: INABIAF - please **DO NOT** fix ### Source code: [2006/borsanyi/borsanyi.c](%%REPO_URL%%/2006/borsanyi/borsanyi.c) ### Information: [2006/borsanyi/index.html](2006/borsanyi/index.html) The string specified must be <= 42 characters and may only consist of the characters in the regex `a-z_A-Z0-9@.-`. Breaking these constraints will end up with possibly corrupt GIF files. Jump to: [top](#)
## 2006/hamre
Jump to: [top](#) ### STATUS: INABIAF - please **DO NOT** fix ### Source code: [2006/hamre/hamre.c](%%REPO_URL%%/2006/hamre/hamre.c) ### Information: [2006/hamre/index.html](2006/hamre/index.html) This program will likely crash or do something funny without an arg. Jump to: [top](#)
## 2006/monge
Jump to: [top](#) ### STATUS: doesn't work with some platforms - please help us fix it ### Source code: [2006/monge/monge.c](%%REPO_URL%%/2006/monge/monge.c) ### Information: [2006/monge/index.html](2006/monge/index.html) This program requires x86 (with an x87 FPU) or x86_64 machine and it requires the SDL1 library. This program also requires being able to read, write and execute memory. With the Apple silicon chips this is not allowed. Fixing this might be quite challenging but you are welcome to try and fix it. If you do fix this it might be good to fix the alternate code as well or else provide it as an additional alt version. Fixing this is very likely to be very challenging and in some systems it will not be possible to fix but you are welcome to try and fix it if you wish to! Jump to: [top](#) ### STATUS: INABIAF - please **DO NOT** fix Incorrect formulas will ungracefully crash the program. Jump to: [top](#)
## 2006/stewart
Jump to: [top](#) ### STATUS: INABIAF - please **DO NOT** fix ### Source code: [2006/stewart/stewart.c](%%REPO_URL%%/2006/stewart/stewart.c) ### Information: [2006/stewart/index.html](2006/stewart/index.html) This program will likely crash or do something funny if the file cannot be opened. The number of args is however checked. Jump to: [top](#)
## 2006/sykes1
Jump to: [top](#) ### STATUS: INABIAF - please **DO NOT** fix ### Source code: [2006/sykes1/sykes1.c](%%REPO_URL%%/2006/sykes1/sykes1.c) ### Information: [2006/sykes1/index.html](2006/sykes1/index.html) The author stated: > If you pick a number higher than 19186, the program will return a solution but it will be a rotation of one of the first 19186. This is because the cross shaped piece fits 48 ways in the 4x4 cube, but only 2 of those ways are unique - you can rotate one of those to make any of the other 46. The algorithm used always places the cross piece first, so the first two placings of that piece result in the 19186 unique solutions. > > If you pick a number higher than 460464 (24x19186) the program will return without outputting a solution. If you can wait that long. Jump to: [top](#)
## 2006/toledo2
Jump to: [top](#) ### STATUS: INABIAF - please **DO NOT** fix ### Source code: [2006/toledo2/toledo2.c](%%REPO_URL%%/2006/toledo2/toledo2.c) ### Information: [2006/toledo2/index.html](2006/toledo2/index.html) This was fixed to not crash in macOS (it appeared to work fine in fedora linux on an `x86_64` architecture but it is not known if it crashed in macOS Ventura due to the fact it is an `arm64` CPU - the Apple silicon chip, but given that the author later made some slight changes to make it not crash in `x86_64` macOS that might be the case). Nevertheless there are two features that are not bugs. By design this program is supposed to crash on termination. This actually no longer seems to happen but we don't need this to be added even if it might be called a bug :-) You must type in caps (except in strings) and this program is indeed case-sensitive. Jump to: [top](#)
# 2007
There was no IOCCC in 2007. Jump to: [top](#)
# 2008
There was no IOCCC in 2008. Jump to: [top](#)
# 2009
There was no IOCCC in 2009. Jump to: [top](#)
# 2010
There was no IOCCC in 2010. Jump to: [top](#)
# 2011
Jump to: [top](#)
## 2011/borsanyi
Jump to: [top](#) ### STATUS: INABIAF - please **DO NOT** fix ### Source code: [2011/borsanyi/borsanyi.c](%%REPO_URL%%/2011/borsanyi/borsanyi.c) ### Information: [2011/borsanyi/index.html](2011/borsanyi/index.html) - For a great amount of data points the program will crash, depending on your available stack space. - Giving too few (distinct) points can also cause a crash or division by zero. - The program expects plain numbers separated by whitespace. - This program assumes ASCII. - If you give the program any arg it might flood the screen. - It requires both syscalls `fork(2)` and `wait(2)`. - Giving any arg to the program is likely to flood your screen. - Rounding errors might cause an omission in the highest bin. There might be empty bins at the edges. Jump to: [top](#)
## 2011/dlowe
Jump to: [top](#) ### STATUS: missing or dead link or links - please provide it or them ### Source code: [2011/dlowe/dlowe.c](%%REPO_URL%%/2011/dlowe/dlowe.c) ### Information: [2011/dlowe/index.html](2011/dlowe/index.html) The domain `http://pootpoot.com` no longer exists as it once did. The judges have given a script that can be used to make a similar page (**warning: not checked for security in modern days!**). Do you have a server with enough bandwidth and would like to set it up? We'll gladly thank you in the [thanks file](thanks-for-help.html) file and link to the page as well! You'll also have IOCCC fame for reviving a pootifier! :-) Jump to: [top](#) ### STATUS: INABIAF - please **DO NOT** fix The author states the following: * Bad input (e.g. nonexistent files, non-numeric number of iterations, etc.) tends to result in empty output. * Given exactly one corpus, the program will crash or produce garbage. * Leaks memory and file descriptors while processing files. * Will crash and die horribly if it runs out of memory. Jump to: [top](#)
## 2011/fredriksson
Jump to: [top](#) ### STATUS: INABIAF - please **DO NOT** fix ### Source code: [2011/fredriksson/fredriksson.c](%%REPO_URL%%/2011/fredriksson/fredriksson.c) ### Information: [2011/fredriksson/index.html](2011/fredriksson/index.html) The author stated that there are a number of features and limitations. As the list is rather long see [other features](2011/fredriksson/index.html#other-features) and [limitations and remarks](2011/fredriksson/index.html#limitations-and-remarks) instead. Jump to: [top](#)
## 2011/konno
Jump to: [top](#) ### STATUS: INABIAF - please **DO NOT** fix ### Source code: [2011/konno/konno.c](%%REPO_URL%%/2011/konno/konno.c) ### Information: [2011/konno/index.html](2011/konno/index.html) This program will very likely crash or do something funny without an arg. Jump to: [top](#)
## 2011/richards
### STATUS: doesn't work with some platforms - please help us fix it ### Source code: [2011/richards/richards.c](%%REPO_URL%%/2011/richards/richards.c) ### Information: [2011/richards/index.html](2011/richards/index.html) This does not appear to work with macOS, resulting in a segfault (and sometimes a bus error). We're not sure if this is to do with the Apple silicon chip or not but it seems like it _might_ (see Apple resources below) be but it could also be a wider problem with macOS. It appears that Apple does not allow certain combinations of memory protections with the arm64 processor. Some of the workarounds have been tried but at this time it did not seem to work. Some earlier debugging sessions are below as well as a resource from the author as well as some resources on Apple's website should anyone wish to take a crack at it. A starting point might be in [richards.alt.c](%%REPO_URL%%/2011/richards/richards.alt.c). Jump to: [top](#) ### Debugging At first glance it appeared to be that it might be the function pointers or the fact it is trying to execute code in memory (as noted above). The function pointers were changed a bit but this has not helped solve the problem with macOS. A few things that were noticed depending on `asan` sanitisers specified. With `address` in linux: ``` richards.c:101:9: runtime error: null pointer passed as argument 2, which is declared to never be null ``` but it actually works. This code is: ``` } else p++; W(c)} /* LINE 101 */ } ``` Okay but what about argument 2? Well `W` is defined as: ``` #define W(c) e=memmove(e,x[(u)c], y[(u)c])+y[(u)c]; ``` so it would appear that ``` x[(u)c] ``` is NULL. But why does it work then? **NOTE**: `u` is `int`. Under macOS (with the arm64 chip) we get: ``` UndefinedBehaviorSanitizer:DEADLYSIGNAL ==10834==ERROR: UndefinedBehaviorSanitizer: SEGV on unknown address 0xffffffffffffffff (pc 0x00019f446748 bp 0x00016f353100 sp 0x00016f352b90 T139066) ==10834==The signal is caused by a WRITE memory access. #0 0x19f446748 in _platform_memmove+0xa8 (libsystem_platform.dylib:arm64e+0x3748) (BuildId: 756cd10d62a032839e57cbaa810c95ac32000000200000000100000000030d00) #1 0x100c33c2c in main richards.c:202 #2 0x19f0bff24 () ==10834==Register values: x[0] = 0xffffffffffffffff x[1] = 0x0000000100ab18c1 x[2] = 0x00000000000000cf x[3] = 0x0000000000000000 x[4] = 0x0000000100ab18a1 x[5] = 0x0000000000000001 x[6] = 0x000000000000000a x[7] = 0x0000000000000000 x[8] = 0x00000001015972b8 x[9] = 0xffffffffffffffff x[10] = 0x0000000000000001 x[11] = 0x00000000000001f0 x[12] = 0x0000000000000001 x[13] = 0x00000000000003e0 x[14] = 0x0000000000000001 x[15] = 0x0000000000000084 x[16] = 0x000000019f4466a0 x[17] = 0x00000001ff3ad908 x[18] = 0x0000000000000000 x[19] = 0x0000000100c32a80 x[20] = 0x00000001017e0000 x[21] = 0x00000001017e1910 x[22] = 0x000000016f353530 x[23] = 0x000000019f13a366 x[24] = 0x000000016f3534b0 x[25] = 0x0000000000000001 x[26] = 0x0000000000000000 x[27] = 0x0000000000000000 x[28] = 0x0000000000000000 fp = 0x000000016f353100 lr = 0x0000000100aaf880 sp = 0x000000016f352b90 UndefinedBehaviorSanitizer can not provide additional info. SUMMARY: UndefinedBehaviorSanitizer: SEGV (libsystem_platform.dylib:arm64e+0x3748) (BuildId: 756cd10d62a032839e57cbaa810c95ac32000000200000000100000000030d00) in _platform_memmove+0xa8 ==10834==ABORTING ``` and naturally it does not work. Adding the proper `PROT_WRITE` constant to the `mmap()` call does not seem to help. Of course with the address this is not surprising so why is a different address allocated in macOS? Or is it? Now with `address` sanitiser both linux and macOS crash at: ``` ================================================================= ==10983==ERROR: AddressSanitizer: stack-buffer-overflow on address 0x00016f8d5e78 at pc 0x0001005dd910 bp 0x00016f8d5cd0 sp 0x00016f8d5cc8 READ of size 8 at 0x00016f8d5e78 thread T0 #0 0x1005dd90c in rd richards.c:132 #1 0x1005ddf8c in re richards.c:149 #2 0x1005110a0 in t richards.c:108 #3 0x1005df72c in main richards.c:189 #4 0x19f0bff24 () Address 0x00016f8d5e78 is located in stack of thread T0 at offset 56 in frame #0 0x1005dd678 in rd richards.c:129 This frame has 2 object(s): [32, 36) 'v.addr' [48, 56) 'a' (line 130) <== Memory access at offset 56 overflows this variable HINT: this may be a false positive if your program uses some custom stack unwind mechanism, swapcontext or vfork (longjmp and C++ exceptions *are* supported) SUMMARY: AddressSanitizer: stack-buffer-overflow richards.c:132 in rd Shadow bytes around the buggy address: 0x00702df3ab70: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 0x00702df3ab80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 0x00702df3ab90: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 0x00702df3aba0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 0x00702df3abb0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 =>0x00702df3abc0: 00 00 00 00 00 00 00 00 f1 f1 f1 f1 04 f2 00[f3] 0x00702df3abd0: f3 f3 f3 f3 00 00 00 00 00 00 00 00 00 00 00 00 0x00702df3abe0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 0x00702df3abf0: 00 00 00 00 f1 f1 f1 f1 00 f3 f3 f3 00 00 00 00 0x00702df3ac00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 0x00702df3ac10: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 Shadow byte legend (one shadow byte represents 8 application bytes): Addressable: 00 Partially addressable: 01 02 03 04 05 06 07 Heap left redzone: fa Freed heap region: fd Stack left redzone: f1 Stack mid redzone: f2 Stack right redzone: f3 Stack after return: f5 Stack use after scope: f8 Global redzone: f9 Global init order: f6 Poisoned by user: f7 Container overflow: fc Array cookie: ac Intra object redzone: bb ASan internal: fe Left alloca redzone: ca Right alloca redzone: cb ==10983==ABORTING /bin/bash: line 1: 10983 Abort trap: 6 ./richards ``` which corresponds to the code: ``` o rd(u v) { o *a = 0, **b = &a, **c = b + 32; x[v] = w; for (; b < c && (*b < (o *)w || *b > (o *) T || *b == &v); b++); /* LINE 132 */ ``` but this seems to not necessarily be relevant since without it it works in linux. A warning of interest when compiling is: ``` richards.c:169:15: warning: incompatible pointer types initializing 'f *' (aka 'void (**)(volatile void *)') with an expression of type 'o ()' (aka 'void ()') [-Wincompatible-pointer-types] f *lib1[] = { T, T, T, T, T } ; ... richards.c:170:15: warning: incompatible pointer types initializing 'f *' (aka 'void (**)(volatile void *)') with an expression of type 'o ()' (aka 'void ()') [-Wincompatible-pointer-types] f *lib2[] = { T, ld, lp, lx, l1 } ; ^ richards.c:170:18: warning: incompatible pointer types initializing 'f *' (aka 'void (**)(volatile void *)') with an expression of type 'void (volatile dt)' (aka 'void (struct (unnamed at richards.c:36:3) *volatile)') [-Wincompatible-pointer-types] f *lib2[] = { T, ld, lp, lx, l1 } ; ^~ richards.c:170:22: warning: incompatible pointer types initializing 'f *' (aka 'void (**)(volatile void *)') with an expression of type 'void (volatile dt)' (aka 'void (struct (unnamed at richards.c:36:3) *volatile)') [-Wincompatible-pointer-types] f *lib2[] = { T, ld, lp, lx, l1 } ; ^~ richards.c:170:26: warning: incompatible pointer types initializing 'f *' (aka 'void (**)(volatile void *)') with an expression of type 'void (volatile dt)' (aka 'void (struct (unnamed at richards.c:36:3) *volatile)') [-Wincompatible-pointer-types] f *lib2[] = { T, ld, lp, lx, l1 } ; ^~ richards.c:170:30: warning: incompatible pointer types initializing 'f *' (aka 'void (**)(volatile void *)') with an expression of type 'void (volatile dt)' (aka 'void (struct (unnamed at richards.c:36:3) *volatile)') [-Wincompatible-pointer-types] f *lib2[] = { T, ld, lp, lx, l1 } ; ^~ ``` This can be fixed easily enough however but it doesn't appear to matter in this case. Jump to: [top](#) ### Testing fixes It might be helpful to use the [try.alt.sh](%%REPO_URL%%/2011/richards/try.alt.sh) script to test that it does not crash and functions properly. Jump to: [top](#) ### Resources Jump to: [top](#) #### More from the author The author has more about the entry at . Jump to: [top](#) #### Apple resources [Porting Just-In-Time Compilers to Apple Silicon](https://developer.apple.com/documentation/apple-silicon/porting-just-in-time-compilers-to-apple-silicon?language=objc) [Allow Execution of JIT-compiled Code Entitlement](https://developer.apple.com/documentation/bundleresources/entitlements/com_apple_security_cs_allow-jit?language=objc) Looking at A curious thing is in the `mprotect()` function: `#if CONFIG_DYNAMIC_CODE_SIGNING` and the protection variable has the `VM_PROT_TRUSTED` set it might allow overriding the problem but this is unconfirmed and it's not known when `CONFIG_DYNAMIC_CODE_SIGNING` would be defined. Jump to: [top](#)
## 2011/vik
Jump to: [top](#) ### STATUS: INABIAF - please **DO NOT** fix ### Source code: [2011/vik/vik.c](%%REPO_URL%%/2011/vik/vik.c) ### Information: [2011/vik/index.html](2011/vik/index.html) The author stated that the program will crash if no argument is passed to the program though we note that your computer might also [halt and catch fire](https://en.wikipedia.org/wiki/Halt_and_Catch_Fire_(computing)) :-) Jump to: [top](#)
# 2012
Jump to: [top](#)
## 2012/blakely
Jump to: [top](#) ### STATUS: INABIAF - please **DO NOT** fix ### Source code: [2012/blakely/blakely.c](%%REPO_URL%%/2012/blakely/blakely.c) ### Information: [2012/blakely/index.html](2012/blakely/index.html) The author stated: > If there is a division by zero, square-root of a negative number, or similar operation, then the results are undefined. Jump to: [top](#)
## 2012/deckmyn
Jump to: [top](#) ### STATUS: INABIAF - please **DO NOT** fix ### Source code: [2012/deckmyn/deckmyn.c](%%REPO_URL%%/2012/deckmyn/deckmyn.c) ### Information: [2012/deckmyn/index.html](2012/deckmyn/index.html) The author stated: > The memory locations of `argv` are used for various purposes. Therefore, the program name (default `deckmyn`) must be *at least 4 characters long*, including possibly the path. This, along with the ending `'\0'`, gives a minimum 5 bytes of useful memory space. Otherwise, the program may attempt to write outside the string. > > The code is quite sensitive. Errors in the input can lead to strange results. The code does not read beyond the end of the music input, but that is about the only error checking available. Any input that is not according to the rules in the deckmyn.html, may cause errors. > > The program has no special hardware limitations or requirements, other than 8bit `char` (`signed` or `unsigned`) and two's complement negatives. > > The limitations of using `char` as counters for e.g. the number of music staves are minor. 127 staves to a page is rather a lot. > > The file layout must be exactly the same as deckmyn.c though, only the locations of space (`" "`) may differ. > > Every element in the music is given by a string of *exactly* 3 characters. Any violation of this will result in the rest of the music being interpreted in some randomly wrong way. Notice that in a file, the newline is also a character! Therefore, when preparing music in a file, care should be taken that the last musical element of a line is only 2 characters! The manual referred to is [here](2012/deckmyn/deckmyn.html). Jump to: [top](#)
## 2012/dlowe
Jump to: [top](#) ### STATUS: INABIAF - please **DO NOT** fix ### Source code: [2012/dlowe/dlowe.c](%%REPO_URL%%/2012/dlowe/dlowe.c) ### Information: [2012/dlowe/index.html](2012/dlowe/index.html) The author stated: * Flicker, especially at high speeds, and in spite of "double-buffering" (X11 doesn't make it possible to lock drawing to the display refresh rate.) * Cannot be run outside of the directory containing the data files (`splash.d`, `dead.d` and `sprites.d`). * Cannot build or run without X11 (or an X11 compatibility layer). Jump to: [top](#)
## 2012/tromp
Jump to: [top](#) ### STATUS: INABIAF - please **DO NOT** fix ### Source code: [2012/tromp/tromp.c](%%REPO_URL%%/2012/tromp/tromp.c) ### Information: [2012/tromp/index.html](2012/tromp/index.html) The author stated: > If the input doesn't start with a valid program, that is, if the interpreter reaches end-of-file during program parsing, it will crash in some way. E.g. the following might dump core: > > `echo -n "U" | ./tromp` > > Furthermore, the interpreter requires the initial encoded lambda term to be closed, that is, variable n can only appear within at least 'n' enclosing lambdas. For instance, here the term `'\ 5'` is not closed, causing the interpreter to crash when looking into a null-pointer environment: > > `echo ">Hello, world" | ./tromp` > > will likely dump core. Jump to: [top](#)
## 2012/vik
Jump to: [top](#) ### STATUS: INABIAF - please **DO NOT** fix ### Source code: [2012/vik/vik.c](%%REPO_URL%%/2012/vik/vik.c) ### Information: [2012/vik/index.html](2012/vik/index.html) The author stated that the program will crash if no argument is passed to the program or if invalid arguments (e.g. file does not exist) or images of mismatching sizes or unsupported pixel formats though we note that your computer might also [halt and catch fire](https://en.wikipedia.org/wiki/Halt_and_Catch_Fire_(computing)) :-) Jump to: [top](#)
# 2013
Jump to: [top](#)
## 2013/cable2
Jump to: [top](#) ### STATUS: INABIAF - please **DO NOT** fix ### Source code: [2013/cable2/cable2.c](%%REPO_URL%%/2013/cable2/cable2.c) ### Information: [2013/cable2/index.html](2013/cable2/index.html) The author stated: - The width of input images must be a multiple of 4. - Input images can be 8-bit greyscale, 24-bit color or 32-bit color only. 8-bit color and 16-bit color are not supported. If you use the "color" command-line feature, do not use a greyscale input file! - Normal Windows BMP files are stored "upside-down", i.e. the bottom line in the image is written first. Some (old) graphics programs actually write BMP files "top-to-bottom" and the program does not support such files. - Using anti-aliased brush strokes to draw your letters is fine; however, antialiasing interferes with color detection in "color" mode. - Only runs on little endian machines (since the BMP format is little endian, and endianness conversion would make the source too large for IOCCC rule 2). Jump to: [top](#)
## 2013/dlowe
Jump to: [top](#) ### STATUS: INABIAF - please **DO NOT** fix ### Source code: [2013/dlowe/dlowe.c](%%REPO_URL%%/2013/dlowe/dlowe.c) ### Information: [2013/dlowe/index.html](2013/dlowe/index.html) This program will possibly crash or draw something strange with 0 args. Then again it might not. :-) This is easy to fix but would add bytes and since the author noted it is a feature and not a bug. You of course can try and fix it yourself but please do NOT open a pull request for this: just do it as an exercise to see if you understand the code. You can try and answer the questions, too: when will it crash? When will it draw something funny (or will it? :-) ) and when will it just do nothing? The author also stated: * Produces bogus graphs when given > about 5000 arguments. * Only works if your terminal is UTF-8 and your font supports the 8 glyphs used. Jump to: [top](#)
## 2013/endoh1
Jump to: [top](#) ### STATUS: INABIAF - please **DO NOT** fix ### Source code: [2013/endoh1/endoh1.c](%%REPO_URL%%/2013/endoh1/endoh1.c) ### Information: [2013/endoh1/index.html](2013/endoh1/index.html) > This program supports only "Combinator-calculus style notation" of Lazy K. "Unlambda style" and "Iota and Jot" style are not supported. > > > Also, it requires a space between identifiers. In short, use `(S K)` instead of > `(SK)`, "\`sk", `**i*i*i*ii*i*i*ii`, or `11111100011100`. > > Huge memory may be required to compile the program (about 300 MB on my machine). > > In addition, there are some limitations (and workarounds) mentioned in the [obfuscation section](2013/endoh1/index.html#obfuscation). Jump to: [top](#)
## 2013/endoh3
Jump to: [top](#) ### STATUS: INABIAF - please **DO NOT** fix ### Source code: [2013/endoh3/endoh3.c](%%REPO_URL%%/2013/endoh3/endoh3.c) ### Information: [2013/endoh3/index.html](2013/endoh3/index.html) From the author: > You can *NOT* write a note length immediately followed by a note `E`, such as `C2E2`. > > Can you figure out why? > > A workaround is inserting a whitespace: `C2 E2`. Jump to: [top](#)
## 2013/endoh4
Jump to: [top](#) ### STATUS: INABIAF - please **DO NOT** fix ### Source code: [2013/endoh4/endoh4.c](%%REPO_URL%%/2013/endoh4/endoh4.c) ### Information: [2013/endoh4/index.html](2013/endoh4/index.html) Invalid input files will very likely crash the program. Jump to: [top](#)
## 2013/hou
Jump to: [top](#) ### STATUS: INABIAF - please **DO NOT** fix ### Source code: [2013/hou/hou.c](%%REPO_URL%%/2013/hou/hou.c) ### Information: [2013/hou/index.html](2013/hou/index.html) This program will not terminate on its own; you must kill `hou` (but not Qiming Hou :-) ) yourself. This should not be fixed. Jump to: [top](#)
## 2013/mills
Jump to: [top](#) ### STATUS: INABIAF - please **DO NOT** fix ### Source code: [2013/mills/mills.c](%%REPO_URL%%/2013/mills/mills.c) ### Information: [2013/mills/index.html](2013/mills/index.html) The author reminds us that if you kill the program you will have to wait a short bit of time before you can start it again if you want it to be able to bind to the socket (which obviously you do). The source is out the scope of this document but the author does mention the well known (at least to those of us who have experience with socket programming :-) ) fix. However as the author pointed it out as a known limitation it is not a bug but a feature. Jump to: [top](#)
# 2014
Jump to: [top](#)
## 2014/maffiodo1
Jump to: [top](#) ### STATUS: INABIAF - please **DO NOT** fix ### Source code: [2014/maffiodo1/prog.c](%%REPO_URL%%/2014/maffiodo1/prog.c) ### Information: [2014/maffiodo1/index.html](2014/maffiodo1/index.html) The author noted that in macOS the colours might be wrong and gives a solution, though it is unclear if this is still true or if there was any problem at all. The author noted that the character cannot go through walls and the impression is that this is how it was believed but someone did ironically point out that there are known glitches where in some places you actually could go through walls. This might even have applied to the arcade version, Mario Bros, though that can no longer be confirmed by said person. The point here is that in this game you cannot go through walls but it's not a bug. On the other hand, the author also stated: > When the `Super character` becomes bigger (`ZOOM` flag), the character can collide with blocks and get stuck inside them. This is a KNOWN BUG. When your player become bigger, stay away from blocks! Jump to: [top](#)
## 2014/maffiodo2
Jump to: [top](#) ### STATUS: INABIAF - please **DO NOT** fix ### Source code: [2014/maffiodo2/prog.c](%%REPO_URL%%/2014/maffiodo2/prog.c) ### Information: [2014/maffiodo2/index.html](2014/maffiodo2/index.html) This program will very likely crash if no arg is given. Jump to: [top](#)
## 2014/vik
Jump to: [top](#) ### STATUS: known bug - please help us fix ### Source code: [2014/vik/prog.c](%%REPO_URL%%/2014/vik/prog.c) ### Information: [2014/vik/index.html](2014/vik/index.html) [Cody Boone Ferguson](authors.html#Cody_Boone_Ferguson) discovered a bug to do with translating sound to text that shows itself in some cases (it works in others) when working on his winning [2020 Enigma machine](%%REPO_URL%%/2020/ferguson2/prog.c) ('Most enigmatic') entry. See his [index.html](2020/ferguson2/index.html) for details (search for `vik` in the file). This one might be more of a limitation but this is not known. He provides a tip in testing the problem: it might help to use his Enigma machine to find problems as it will allow you to verify what is correct and what is not. Again see his index.html for details. However it is also possible to not rely on the entry as the below shows. One should be able to do: ``` echo 'No. I want chocolate!' | ./prog > chocolate.raw ./prog e < chocolate.raw ``` and get: ``` No. I want some chocolate! ``` but instead we get: ``` IT FHOCOLITE! ``` which is very wrong. If however one does: ``` echo IOCCC | ./prog > ioccc.raw ./prog e < ioccc.raw ``` they will properly get: ``` IOCCC ``` Jump to: [top](#)
# 2015
Jump to: [top](#)
## 2015/duble
Jump to: [top](#) ### STATUS: INABIAF - please **DO NOT** fix ### Source code: [2015/duble/prog.c](%%REPO_URL%%/2015/duble/prog.c) ### Information: [2015/duble/index.html](2015/duble/index.html) This program is known to, in some cases, segfault, and as the judges and the author noted this, it should not be fixed. Jump to: [top](#)
## 2015/hou
Jump to: [top](#) ### STATUS: INABIAF - please **DO NOT** fix ### Source code: [2015/hou/prog.c](%%REPO_URL%%/2015/hou/prog.c) ### Information: [2015/hou/index.html](2015/hou/index.html) The author stated: > Hard requirements: > > The platform must implement the `double` type as IEEE754-compliant 64-bit floating point numbers. The 80-bit intermediate format used by x87 is considered as an violation of this. The code should print an error message on such platforms. > > The program must start with the CPU / FPU in round-to-nearest mode. > > Soft requirements: > > The compiler must respect `volatile`. The code is formatted to warn about that, though. > > The printed result is only correct on little-endian machines. The program takes care to warn about this issue after printing an incorrect big-endian result. Error messages become garbled, though. Jump to: [top](#)
## 2015/howe
Jump to: [top](#) ### STATUS: known bug - please help us fix The test scripts do not seem to work properly with bash but this would be ideal as not all systems have a compatible shell (they assume a POSIX compliant shell). One, with bash, might see: ``` ./prog-test.sh <<< A='1' B='1' prog: : No such file or directory >>> got=0 expect=0 -OK- <<< A='1' B='A' prog: : No such file or directory >>> got=0 expect=2 FAIL ``` It would appear that the variable passed to the command in the function, `distance`, is empty. The same problem exists in the [prog.alt-test.sh](%%REPO_URL%%/2015/howe/prog.alt-test.sh), particularly because it is the same thing as the other, just updated to use `prog.alt`. Jump to: [top](#)
## 2015/mills2
Jump to: [top](#) ### STATUS: INABIAF - please **DO NOT** fix ### Source code: [2015/mills2/prog.c](%%REPO_URL%%/2015/mills2/prog.c) ### Information: [2015/mills2/index.html](2015/mills2/index.html) The program doesn't look at the header of files so if it's passed something hat is not compressed data it's likely to crash. The program depends on little endian systems. Jump to: [top](#)
## 2015/schweikhardt
Jump to: [top](#) ### STATUS: INABIAF - please **DO NOT** fix ### Source code: [2015/schweikhardt/prog.c](%%REPO_URL%%/2015/schweikhardt/prog.c) ### Information: [2015/schweikhardt/index.html](2015/schweikhardt/index.html) The program assumes that `EOF` is `-1`. This can be fixed but at this time it is uncertain if it should be. The author also stated: > While the program works best when bytes/characters are octets and the number of bits in a type is `sizeof(typ) << 3`, it will work correctly on 24-bit or 36-bit systems with 9 bits/byte, or systems where `sizeof(typ)` is 1 even for `int` and so on. On such systems, it will only use `8 * sizeof(typ)` bits per place. It does not work when `CHAR_BIT <= 7`. Jump to: [top](#)
# 2016
There was no IOCCC in 2016. Jump to: [top](#)
# 2017
There was no IOCCC in 2017. Jump to: [top](#)
# 2018
Jump to: [top](#)
## 2018/algmyr
Jump to: [top](#) ### STATUS: INABIAF - please **DO NOT** fix ### Source code: [2018/algmyr/prog.c](%%REPO_URL%%/2018/algmyr/prog.c) ### Information: [2018/algmyr/index.html](2018/algmyr/index.html) The author wrote: * There is no error checking done when opening files, so expect segfaults if you provide the wrong path to a file. * This program is bound to misbehave if `int` is less than 32 bits. * Flags will only be interpreted correctly if they are the first argument. Reading a file named `-d` or `-h` is fully possible if it is not the first file provided, even though I am not sure why you would want to do that. * Providing invalid/unexpected arguments to the decode flag will result in odd behavior. Some erroneous arguments cause segfaults (negative number of channels, channel id outside valid range). One argument in particular causes an infinite loop printing whitespace. Jump to: [top](#)
## 2018/hou
Jump to: [top](#) ### STATUS: INABIAF - please **DO NOT** fix ### Source code: [2018/hou/prog.c](%%REPO_URL%%/2018/hou/prog.c) ### Information: [2018/hou/index.html](2018/hou/index.html) When you run it on a JSON file you will see something like: ``` $ ./prog < ioccc.json > ioccc.html Assertion failed: (rulez), function C, file prog.c, line 124. Abort trap: 6 ``` (from say running `./try.sh`) but this is expected and the file `ioccc.html` will be generated properly. Some JSON files might cause the program to continue to run and seemingly infinitely increase the size of the output file. This can happen if you try fixing the syntax error in the generated `ioccc.json` file. Jump to: [top](#)
## 2018/mills
Jump to: [top](#) ### STATUS: known bug - please help us fix ### Source code: [2018/mills/prog.c](%%REPO_URL%%/2018/mills/prog.c) ### Information: [2018/mills/index.html](2018/mills/index.html) After exiting the program (with ctrl-e) if you try running it again you will likely see: ``` >bootT5pw ]h_ 8D3[] ``` where `[]` is the cursor. When this happens if you hit enter (this is necessary or else it'll happen again) and then exit again (ctrl-e) and run `prog` again it'll be okay. Jump to: [top](#) ### STATUS: INABIAF - please **DO NOT** fix The author stated that if you make a typo it can happen that the boot loader can crash and halt. If this is the case type ctrl-e to quit the emulator and try again. The author also stated that it is possible to corrupt the virtual disk. If you do this you should type `make clobber all` and try again. A funny problem where it showed `ERROR` after each command was noticed. The solution was to hit ctrl-e and start again. It is not known if this is what was referred to by the author but there was likely no typo involved. Another issue noticed is that if you are using the saved mode you must type `sync` prior to exiting the program or else the next time you run it the file will not exist (or in the case of compiled code it won't be executable). Jump to: [top](#)
## 2018/vokes
Jump to: [top](#) ### STATUS: INABIAF - please **DO NOT** fix ### Source code: [2018/vokes/prog.c](%%REPO_URL%%/2018/vokes/prog.c) ### Information: [2018/vokes/index.html](2018/vokes/index.html) The author wrote the following: - Despite appearances, it does not handle numbers in hex, or provide a `curses(3)`-based interface. - The expected input format is zero or more lines of space-separated integers. If other characters appear in the input, it will either reject the input entirely and exit with a non-zero status, or skip number(s) adjacent to the non-digit characters, depending on where the characters appear. Tabs and multiple consecutive spaces are handled correctly, however. - Individual lines of input longer than `0x3543 - 1` bytes will be split and processed as if they were multiple lines of input, which can produce incorrect results. This magic number's significance is described earlier. - The algorithm expects its input to represent a fully connected graph. While the output is otherwise topologically sorted, if there are nodes completely unconnected to the rest of the graph (with or without self-cycles), they will be output as soon as they are processed -- this means that, when there are disconnected nodes, reordering the input lines can produce different output. Addressing this by adding another pass is would put the program over the size limit. - While the node IDs don't need to be consecutive or start at 0, the implementation doesn't have special handling for sparse graphs. If you give it a graph with nodes numbered 0 and 2147483647, it will attempt to allocate sufficient memory (potentially around 32 GB) for the entire range of graph nodes, even if those are the only ones. If memory allocation returns NULL, it will gracefully exit, otherwise it will succeed, eventually, perhaps after a great deal of swapping. - Node IDs >= 2147483648 will cause the program to print an error message and exit with a non-zero status. This shrinks the code that detects overflowing the array size by a bit. - A very large group of nodes in a cycle can cause a stack overflow. This typically takes over 100,000 nodes, and depends on the order the nodes are visited. Addressing this would put the program over the size limit. - The implementation depends on the characters `'0'`, `'1'`, ... `'9'` having the values `48` through `57`, rather than using `isdigit(3)`. As noted above, this program has nothing to do with a hand. Jump to: [top](#)
# 2019
Jump to: [top](#)
## 2019/adamovsky
Jump to: [top](#) ### STATUS: INABIAF - please **DO NOT** fix ### Source code: [2019/adamovsky/prog.c](%%REPO_URL%%/2019/adamovsky/prog.c) ### Information: [2019/adamovsky/index.html](2019/adamovsky/index.html) Certain input can crash this program. The file [crash.unl](%%REPO_URL%%/2019/adamovsky/crash.unl) is an example file. Jump to: [top](#)
## 2019/burton
Jump to: [top](#) ### STATUS: INABIAF - please **DO NOT** fix ### Source code: [2019/burton/prog.c](%%REPO_URL%%/2019/burton/prog.c) ### Information: [2019/burton/index.html](2019/burton/index.html) The author pointed out that some implementations of `wc(1)` show different values but his implementation matches that of macOS and FreeBSD. Jump to: [top](#)
## 2019/ciura
Jump to: [top](#) ### STATUS: INABIAF - please **DO NOT** fix ### Source code: [2019/ciura/prog.c](%%REPO_URL%%/2019/ciura/prog.c) ### Information: [2019/ciura/index.html](2019/ciura/index.html) The scripts were fixed so that they can work but it might end up that the scripts don't show any output anyway as they use the full alphabet. To test that it works one can have a script like: ``` LC_ALL=C aäbcdefghijklmnoöpqrsßtuüvwxyz | LC_ALL=C grep .. | LC_ALL=de_DE.UTF-8 ./prog aäbcdefghijklmnoöpqrsßtuüvwxyz ``` If you run this you should see: ``` aäbcdefghijklmnoöpqrsßtuüvwxyz ``` which shows it works. However as the de.sh script refers to all letters it can't find a perfect pangram. BTW, as far as the question of whether the umlaut letters or the Eszett are considered letters in the German alphabet, it is noted in the de.sh/de.alt.sh scripts: ``` # Are the umlauts ä, ö, ü and Eszett (ß) letters in the German alphabet? There # is more than one opinion on the subject but a lot of words do have an umlaut # (or Umlaut in German). In some (probably all) systems this script outputs # nothing probably because it's very hard to form a perfect pangram in German, # if it's not impossible. Nevertheless, we do include the other characters # whether or not they are in your view considered part of the alphabet for the # reason that so many words have them. ``` Jump to: [top](#)
## 2019/dogon
Jump to: [top](#) ### STATUS: uses gets() - change to fgets() if possible ### Source code: [2019/dogon/prog.c](%%REPO_URL%%/2019/dogon/prog.c) ### Information: [2019/dogon/index.html](2019/dogon/index.html) The entry calls `gets(3)` and it would be better if the code called `fgets()` instead. See the FAQ on "[gets and fgets](faq.html#gets)" for more information on the change to `fgets(3)`. Jump to: [top](#)
## 2019/duble
Jump to: [top](#) ### STATUS: INABIAF - please **DO NOT** fix ### Source code: [2019/duble/prog.c](%%REPO_URL%%/2019/duble/prog.c) ### Information: [2019/duble/index.html](2019/duble/index.html) There are two things to be aware of with this entry. If the file being used (to draw) is deleted it might lock any session still in use. These will have to be killed from another shell session or by closing the terminal tab. This will also happen if the file cannot be opened in the beginning. This program will also very likely leave sockets lying about in the current working directory. For instance [Cody Boone Ferguson](authors.html#Cody_Boone_Ferguson) showed us this: ``` $ ls -al |grep '^s' srwxr-xr-x 1 cody staff 0 Apr 6 08:19 .BDHFHALG= srwxr-xr-x 1 cody staff 0 Apr 6 08:15 .CGGHAMGC= srwxr-xr-x 1 cody staff 0 Apr 6 08:16 .CMDGAELH= srwxr-xr-x 1 cody staff 0 Apr 3 08:47 .CMLBCCDA= [...] ``` This is NOT a bug and you'll have to delete the files manually. You shouldn't have to worry about these being added to git: it seems to ignore sockets (it did at least in macOS). Tips on this situation. A simpler way to find sockets in the directory: ``` file .*|grep socket|cut -f1 -d: ``` To delete them you can do: ``` find . -exec file '{}' \;|grep socket|cut -f 1 -d: | xargs rm -f ``` though one might want to check that the program is not currently running. :-) Jump to: [top](#)
## 2019/endoh
Jump to: [top](#) ### STATUS: INABIAF - please **DO NOT** fix ### Source code: [2019/endoh/prog.c](%%REPO_URL%%/2019/endoh/prog.c) ### Information: [2019/endoh/index.html](2019/endoh/index.html) As a backtrace quine this entry is **SUPPOSED to segfault** so this should not be touched either. Jump to: [top](#)
## 2019/karns
Jump to: [top](#) ### STATUS: INABIAF - please **DO NOT** fix ### Source code: [2019/karns/prog.c](%%REPO_URL%%/2019/karns/prog.c) ### Information: [2019/karns/index.html](2019/karns/index.html) The author stated the following: - The program must be ran in a terminal that supports ANSI escape codes for moving the cursor and changing colors. - Segfaults happen sometimes. - I don't know what memory management there is, if any. - The program will not compile by an ANSI C compiler: it uses for loops, and it uses C++ style comments. It should compile cleanly using a C99 standard. - Breadth first search is slow (and very slow on certain maps), but my A star version of this program is too big. - Lots of extra whitespace may be needed if you want to feed in an arbitrary file. - It fails to compile on GCC sometimes (according to a friend of mine, I've not encountered this myself). - The program could be obfuscated much further. - The program contains some unused code and data. **NOTE**: the segfault problem might have been fixed when the optimiser was disabled (which was necessary as part of a bug fix). Jump to: [top](#)
## 2019/lynn
Jump to: [top](#) ### STATUS: INABIAF - please **DO NOT** fix ### Source code: [2019/lynn/prog.c](%%REPO_URL%%/2019/lynn/prog.c) ### Information: [2019/lynn/index.html](2019/lynn/index.html) The author wrote that there are a number of differences from what one might expect. Rather than duplicate the information we refer you to the author's remarks in the sections [Syntax](2019/lynn/index.html#syntax) and [Caveats](2019/lynn/index.html#caveats). Jump to: [top](#)
## 2019/mills
Jump to: [top](#) ### STATUS: INABIAF - please **DO NOT** fix ### Source code: [2019/mills/prog.c](%%REPO_URL%%/2019/mills/prog.c) ### Information: [2019/mills/index.html](2019/mills/index.html) The author wrote that if you decide to change networks or use a different input file you should delete all the checkpoint files because the format depends on both the network and the input -- using the wrong checkpoint is likely to cause a crash. The author also wrote: > IMPORTANT NOTE: Since OMLET uses the system stack for network storage, larger networks may cause OMLET to crash (typically with a message like Segmentation fault) unless the system stack size is first increased. The exact command for doing so depends on your shell and your system's hard limits. On sh/ksh/bash shells, you can view the hard limit with ulimit -Hs and set it with ulimit -s 65532 (replacing 65532 with the actual hard limit). On csh/tcsh shells, you can view the hard limit with limit -h stacksize and set it with limit stacksize 65532 (replacing 65532 with the actual hard limit). Jump to: [top](#)
## 2019/poikola
Jump to: [top](#) ### STATUS: INABIAF - please **DO NOT** fix ### Source code: [2019/poikola/prog.c](%%REPO_URL%%/2019/poikola/prog.c) ### Information: [2019/poikola/index.html](2019/poikola/index.html) This program will not validate input so it might fail or get stuck if invoked erroneously. Also, the maximum file size is 1GB. Jump to: [top](#)
## 2019/yang
Jump to: [top](#) ### STATUS: INABIAF - please **DO NOT** fix ### Source code: [2019/yang/prog.c](%%REPO_URL%%/2019/yang/prog.c) ### Information: [2019/yang/index.html](2019/yang/index.html) The author noted that if the program runs out of memory it is likely to crash. The author also stated that 'if input contains CR-LF end of line sequences, those `CR`s are silently dropped. In fact, most control codes are silently ignored except line feeds (preserved) and tabs (expanded to 8 spaces).' Jump to: [top](#)
# 2020
Jump to: [top](#)
## 2020/burton
Jump to: [top](#) ### STATUS: INABIAF - please **DO NOT** fix ### Source code: [2020/burton/prog.c](%%REPO_URL%%/2020/burton/prog.c) ### Information: [2020/burton/index.html](2020/burton/index.html) This entry is known to crash if no arg is specified. Although easy to fix it is documented and should not be fixed (of course you may fix it to see if you can but it shouldn't be made into a pull request). It will also show funny output with more than one arg. This should not be fixed either. But can you figure out why this happens? Jump to: [top](#)
## 2020/carlini
Jump to: [top](#) ### STATUS: INABIAF - please **DO NOT** fix ### Source code: [2020/carlini/prog.c](%%REPO_URL%%/2020/carlini/prog.c) ### Information: [2020/carlini/index.html](2020/carlini/index.html) The author stated that bad things happen if the entered move is outside of the range [1..9]. We observed a crash but we also observed a tie and other things besides (say with the input `-1`, `-`, `-10` and others). If a player makes a move over their opponent's place they will automatically lose. If a player tries to play a move they already played they will forfeit their move. If you have audible bells enabled the program will beep at every turn. Jump to: [top](#)
## 2020/ferguson1
Jump to: [top](#) ### STATUS: INABIAF - please **DO NOT** fix ### Source code: [2020/ferguson1/prog.c](%%REPO_URL%%/2020/ferguson1/prog.c) ### Information: [2020/ferguson1/index.html](2020/ferguson1/index.html) There are some things that might appear to be bugs but are actually features or things that are misinterpreted as bugs. See the [bugs.html](2020/ferguson1/bugs.html) and [troubleshooting.html](2020/ferguson1/troubleshooting.html) files for details. Jump to: [top](#)
## 2020/giles
Jump to: [top](#) ### STATUS: INABIAF - please **DO NOT** fix ### Source code: [2020/giles/prog.c](%%REPO_URL%%/2020/giles/prog.c) ### Information: [2020/giles/index.html](2020/giles/index.html) The author noted that the program only supports WAV files that have exactly 16 bits per sample, but it allows any sample rate and any number of audio channels. Jump to: [top](#)
## 2020/otterness
Jump to: [top](#) ### STATUS: INABIAF - please **DO NOT** fix ### Source code: [2020/otterness/prog.c](%%REPO_URL%%/2020/otterness/prog.c) ### Information: [2020/otterness/index.html](2020/otterness/index.html) The author listed the following limitations: 1. The program does not support MIDI files over 4 MB (specifically, it will not take input files larger than `2^22 - 1` bytes). This is unlikely to be a big limitation in practice, since even lengthy MIDIs are rarely over a couple hundred KB. 2. Not all MIDIs set (or *correctly* set) their timing information, which will lead to the tempo of the drum beat not matching the track. This will be especially true for "live performance" .mid files. 3. There may be some types of MIDI messages that the program is unable to correctly parse, but I have rarely seen this in practice. The largest cause of program failures, in my experience, has been Limitation 2. See also the [Program error codes](2020/otterness/index.html#program-error-codes) written by the author which lists some other conditions which should be considered features, not bugs. Jump to: [top](#)
# 2021
There was no IOCCC in 2021. Jump to: [top](#)
# 2022
There was no IOCCC in 2022. Jump to: [top](#)
# 2023
There was no IOCCC in 2023. Jump to: [top](#)
# 2024
Jump to: [top](#)
## 2024/carlini
Jump to: [top](#) ### STATUS: known bug - please help us fix ### Source code: [2024/carlini/prog.c](%%REPO_URL%%/2024/carlini/prog.c) ### Information: [2024/carlini/index.html](2024/carlini/index.html) When printing a 0 digit, the `fib.bin` 4004 program will print a space instead of a "0". Jump to: [top](#)
## 2024/ferguson2
Jump to: [top](#) ### STATUS: INABIAF - please **DO NOT** fix ### Source code: [2024/ferguson2/prog.c](%%REPO_URL%%/2024/ferguson2/prog.c) ### Information: [2024/ferguson2/index.html](2024/ferguson2/index.html) As the language is a spoken language and as spaces are required to separate words and as words sometimes have to be spelt out (where each letter in the word might be multiple words) and as the program checks words ignoring punctuation, along with the problem of word boundaries and spaces, described [here](2024/ferguson2/index.html#spaces), certain input can cause funny output. Here are some examples: ``` $ ./prog.alt $(./prog cat '" "' attack) cat""attackattack ``` As you can see the quotations cause the word (or words if more than one) after the quotes to be duplicated. Another example is circumvented in the try.sh script. Note that if the command was: ``` $ ./prog.alt $(./prog cat attack) catattack ``` there would still be no spaces but this is how it has to be. So the fact the Navajo to English translation sometimes repeats words (if it can translate at all - again see the spaces issue) or does not have spaces is a consequence of how the language worked and thus how this must work too. Thus this is not a bug to be fixed as doing so would cause other problems (and also take it way over the size limit). The author did experiment with ways to solve this but the closest method broke output where it would otherwise work. The try.sh script demonstrates how you can often get the same output but because of words being multiple words (if it is not in the Navajo military dictionary) translation back to English is not perfect.
## 2024/howe
Jump to: [top](#) ### STATUS: known bug - please help us fix ### Source code: [2024/howe/prog.c](%%REPO_URL%%/2024/howe/prog.c) ### Information: [2024/howe/index.html](2024/howe/index.html) NetBSD Curses `mvgetnstr()` does not display UTF-8 characters correctly with echo on, but the input is valid (see the program's `/search` command). A suggested fix is to a `prog.alt.c` to implement a static `mvgetnstr()` function to collect input and display via `addch()` and `refresh()`. CRLF newlines (DOS, Windows) and other non-spacing control characters are not visible. Try modifying the suggested `prog.alt.c` to address this limitation. Jump to: [top](#)
## 2024/kramer
Jump to: [top](#) ### STATUS: known bug - please help us fix ### Source code: [2024/kramer/prog.c](%%REPO_URL%%/2024/kramer/prog.c) ### Information: [2024/kramer/index.html](2024/kramer/index.html) This program computes using signed int values. On a 64-bit processor the largest signed 64-bit value is `9223372036854775807`. The [English name of that number](http://www.isthe.com/cgi-bin/chongo/number.cgi): ``` nine quintillion, two hundred twenty three quadrillion, three hundred seventy two trillion, thirty six billion, eight hundred fifty four million, seven hundred seventy five thousand, eight hundred seven ``` However, the program is limited the command line numerical word, "**trillion**". Can you extend this program to use larger names of English numbers such as "**quadrillion**" and "**quintillion**"? If you are even more daring, and which to extend the numerical calculation beyond a single 64-bit value, you may wish to extend this program even further using the list of [English number names](http://www.isthe.com/chongo/tech/math/number/howhigh.html). Jump to: [top](#)
## 2024/kurdyukov4
Jump to: [top](#) ### STATUS: INABIAF - please **DO NOT** fix ### Source code: [2024/kurdyukov4/prog.c](%%REPO_URL%%/2024/kurdyukov4/prog.c) ### Information: [2024/kurdyukov4/index.html](2024/kurdyukov4/index.html) The [2024/kurdyukov4/try.sh](%%REPO_URL%%/2024/kurdyukov4/try.sh) script will very likely run into problems such as compile taking a long time, compilers crashing and/or executables crashing when used with random input sizes larger than 64K bytes. **PLEASE NOTE**: The above problems are **NOT** code bugs. They represent compiler mis-features, linker limitations, and/or architecture limitations. For more information see the "**Large input size issues**" section of [2024/kurdyukov4/index.html](2024/kurdyukov4/index.html#large-input-size-issues). Jump to: [top](#)
# 2025
Jump to: [top](#) ### STATUS: INABIAF - please **DO NOT** fix ### Source code: [2025/ferguson/prog.c](%%REPO_URL%%/2025/ferguson/prog.c) ### Information: [2025/ferguson/index.html](2025/ferguson/index.html) This program necessarily scales the arrows to a larger size for those who, like the author, cannot see them otherwise. This means that locations are a bit off **on the rendered map**, especially when coordinates are not on the edge of the map (even so it might or might not be that part of the arrow is in the 'right' place and in all cases obviously only a part of the arrow can be in the correct place).
# Final words
We hope this document was of use to you in determining which entries are known to have a problem, what entries are known to have features that are not bugs and so on. We also thank you for going through this document and, if you propose any fixes] via a [GitHub pull request](https://github.com/ioccc-src/winner/pulls) or otherwise, we thank you as well for the help! We will happily add you to the [thanks](thanks-for-help.html) file as well. Jump to: [top](#)