17th International Obfuscated C Code Contest Guidelines, Hints and Comments Copyright (C) 2004 Leonid A. Broukhis, Simon Cooper, Landon Curt Noll and Peter Seebach. All Rights Reserved. Permission for personal, education or non-profit use is granted provided this this copyright and notice are included in its entirety and remains unaltered. All other uses must receive prior permission in writing from the contest judges. ABOUT THIS FILE: This file contains guidelines intended to help people who wish to submit entries to the International Obfuscated C Code Contest (IOCCC for short). This is not the IOCCC rules, though it does contain comments about them. The guidelines should be viewed as hints and suggestions. Entries that violate the guidelines but remain within the rules are allowed. Even so, you are safer if you remain within the guidelines. You should read the current IOCCC rules, prior to submitting entries. The rules are typically sent out with these guidelines. WHAT'S NEW IN 2004: The contest runs from 07-Jan-2004 00:00 UTC to 29-Feb-2004 23:59:59 UTC An online submission mechanism will be available after 26-Jan-2004, 00:00 UTC. See the following for details, https://www.ioccc.org/2004/submit HINTS AND SUGGESTIONS: You are encouraged to examine the winners of previous contests. See FOR MORE INFORMATION for details on how to get previous winners. Keep in mind that rules change from year to year, so some winning entries may not be valid entries this year. What was unique and novel one year might be 'old' the next year. An entry is usually examined in a number of ways. We typically apply a number of tests to an entry: * look at the original source * convert ANSI trigraphs to ASCII * C pre-process the source ignoring '#include' lines * C pre-process the source ignoring '#define' and '#include' lines * run it through a C beautifier * examine the algorithm * compile it (with flags to enable all warnings) * execute it You should consider how your entry looks in each of the above tests. You should ask yourself if your entry remains obscure after it has been 'cleaned up' by the C pre-processor and a C beautifier. Your entry need not pass all of the above tests. In certain cases, a test is not important. Entries that compete for the 'strangest/most creative source layout' need not do as well as others in terms of their algorithm. On the other hand, given two such entries, we are more inclined to pick the entry that does something interesting when you run it. We try to avoid limiting creativity in our rules. As such, we leave the contest open for creative rule interpretation. As in real life programming, interpreting a requirements document or a customer request is important. For this reason, we often award 'worst abuse of the rules' to an entry that illustrates this point in an ironic way. We do realize that there are holes in the rules, and invite entries to attempt to exploit them. We will award 'worst abuse of the rules' and then plug the hole next year. Even so, we will attempt to use the smallest plug needed, if not smaller. :-) Check out your program and be sure that it works. We sometimes make the effort to debug an entry that has a slight problem, particularly in or near the final round. On the other hand, we have seen some of the best entries fall down because they didn't work. We tend to look down on a prime number printer, that claims that 16 is a prime number. If you do have a bug, you are better off documenting it. Noting "this entry sometimes prints the 4th power of a prime by mistake" would save the above entry. And sometimes, a strange bug/feature can even help the entry! Of course, a correctly working entry is best. People who are considering to just use some complex mathematical function or state machine to spell out something such as "hello, world!" may want to try and be more creative. Ultra-obfuscated programs are in some cases some cases easier to deobfuscate than subtly-obfuscated programs. Consider using misleading or subtle tricks layered on top of or under an appropriate level of obfuscation. Programs that use VTxxx/ANSI sequences that are NOT limited to a specific terminal brand and that can also work in a standard xterm are considered portable. OUR LIKES AND DISLIKES: Doing masses of #defines to obscure the source has become 'old'. We tend to 'see thru' masses of #defines due to our pre-processor tests that we apply. Simply abusing #defines or -Dfoo=bar won't go as far as a program that is more well rounded in confusion. Many ANSI C compilers dislike the following code, and so do we: #define d define #d foo <-- don't expect this to turn into #define foo When declaring local or global variables, you should declare the type: int this_is_ok; this_is_not; <-- don't use such implicit type declarations We suggest that you compile your entry with an ANSI C compiler. If you must use non-ANSI C, such as K&R C, you must avoid areas that result in compile/link errors for ANSI C compilers. For example, using gcc local function declarations, such as: int main() { void blah() { printf("blah\n"); } blah(); } are not allowed even though their existence seems tailor made for this contest! But for now, since they are not in wide spread use we cannot accept entries that use them. If your entry uses functions that have a variable number of arguments, be careful. Systems implement va_list as a wide variety of ways. Because of this, a number of operations using va_list are not portable and must not be used: * assigning a non-va_list variable to/from a va_list variable * casting a non-va_list variable into/from a va_list variable * passing a va_list variable to a function expecting a non-va_list arg * passing a non-va_list variable to a function expecting a va_list arg * performing arithmetic on va_list variables * using va_list as a structure or union In particular, do not treat va_list variables as if they were a char **'s. Avoid using . Use instead. If you use C preprocessor directives (#define, #if, #ifdef, ...), the leading '#' must be the first non-whitespace character on a line. While some broken C preprocessors do not allow whitespace before a '#', most do. The exit() function returns void. On some broken systems have exit() return int. Your entry should assume that exit() returns a void. Small programs are best when they are short, obscure and concise. While such programs are not as complex as other winners, they do serve a useful purpose. They are often the only program that people attempt to completely understand. For this reason, we look for programs that are compact, and are instructional. One line programs should be short one line programs, say around 80 bytes long. Getting close to 160 bytes is a bit too long in our opinion. We tend to dislike programs that: * are very hardware specific * are very OS version specific (index/strchr differences are ok, but socket/streams specific code is likely not to be) * dump core or have compiler warnings (it is ok only if you warn us in the 'remark' header item) * won't compile or run under a POSIX P1003.1/P1003.2 like systems * depend on a utility or application not normally found on most most POSIX P1003.1/P1003.2 like systems * abuse the build file to get around the size limit * obfuscate by excessive use of ANSI trigraphs * are longer than they need to be * are similar to previous winners * are identical to previous losers :-) Unless you are cramped for space, or unless you are entering the 'best one liner' category, we suggest that you format your program in a more creative way than simply forming excessively long lines. The build file should not be used to try and get around the size limit. It is one thing to make use of a several -D's to help out, but it is quite another to use 200+ bytes of -D's in order to try and squeeze the source under the size limit. You should feel free to make use of the build file space, but you are better off if you show some amount of restraint. You should try to restrict commands used on the build file to POSIX-like or common Unix-like commands. You can also compile and use your own programs. If you do, try to build and execute from the current directory. This restriction is not a hard and absolute one. The intent is to ensure that the building if your program is reasonably portable. Don't forget that the building of your program should be done ***without human intervention***. So don't do: cat > prog.c cc prog.c -o prog However, you can do something cute such as making your program do something dumb (or cute) when build 'automatically'. However when it is run with a human involved, do something more clever. For example, one could use the build instructions: cc prog.c -DNONHUMAN -o prog echo "See remarks section about alternate ways to compile" and then include special notes in the program "remarks" for alternate / human intervention based building. We want to get away from source that is simply a compact blob of characters. To help, we give a break to source that contains whitespace, and in certain cases ; { or } characters. While the number of characters excluding whitespace (tab, space, newline), and excluding any ; { or } followed immediately by either whitespace or end of file, must be <= 2048, the total size may be less than 4096 bytes. This means that one may use "free of charge" up to 2048 bytes of whitespace, or ; { or } followed by either whitespace or end of file. Please do not use things like gzip to get around the size limit. Given two versions of the same program, one that is a compact blob of code, and the other that is formatted more like a typical C program, we tend to favor the second version. Of course, a third version of the same program that is formatted in an interesting and/or obfuscated way, would definitely win over the first two! We suggest that you avoid trying for the 'smallest self-replicating' source. The smallest, a zero byte entry, won in 1994. We do not like writable strings. That is, we don't want stuff like: char *T = "So many primes, so little time!"; ... T[14] = ';'; Please don't make use of this feature, even if your system allows it. However, initialized char arrays are OK to write over. This is OK: char b[] = "Is this Ok"; b[9] = 'K'; X client entries should be as portable as possible. Entries that adapt to a wide collection of environments will be favored. Don't depend on a particular type of display. For example, don't depend on color or a given size. Don't require backing store. X client entries should avoid using X related libraries and software that is not in wide spread use. We don't like entries that use proprietary M*tif, Xv*ew, or OpenL*ok toolkits, since not everyone has them. Use of OpenMotif is permitted because it is more widely and freely available. You should avoid depending on a particular window manager. X client entries should not to depend on particular items on .Xdefaults. If you must do so, be sure to note the required lines in the program "remarks". While we recognize that UNIX is not a universal operating system, the contest does have a bias towards such systems. In an effort to expand the scope of the contest, we phrase our bias in terms of POSIX P1003.1 and P1003.2 standards. This will allow certain non-UNIX OS users to submit entries. On the other hand, this is a guideline and not a rule. We will not reject an entry based on some POSIX technicality. When dealing with OS and application environments, we suggest that you be reasonable with a nod towards vanilla UNIX-like systems. POSIX will evolve but not as much as the contest, so avoid stuff like POSIX real time, security, etc. We like programs that: * are as concise and small as they need to be * do something at least quasi-interesting * are portable * are unique or novel in their obfuscation style * MAKE USE OF A NUMBER OF DIFFERENT TYPES OF OBFUSCATION <== HINT!! * make us laugh and/or throw up :-) (humor helps!) Some types of programs can't excel (tm) in some areas. Of course, your program doesn't have to excel in all areas, but doing well in several areas really does help. You are better off explaining what your entry does in the program "remarks" section rather than leaving it obscure for the judges as we might miss something and/or be too tired to notice. We freely admit that interesting, creative or humorous comments in the program "remarks" help your chances of winning. If you had to read so many twisted entries, you too would enjoy a good laugh or two. We think the readers of the contest winners do as well. We do read the program "remarks" during the judging process, so it is worth your while to write remarkable program "remarks". We dislike C code with trailing control-M's (\r or \015) that results in compilation failures. Some non-Unix/non-Linux tools such as MS Visual C and MS Visual C++ leave trailing control-M's on lines. Users of such tools should strip off such control-M's before submitting their entries. In some cases tools have a "Save As" option that will prevent such trailing control-M's being added. We dislike entries that depend on non-portable libcurses features such as halfdelay(). One should restrict libcurses to portable features found on BSD and SVR4/System V curses. The rules disallow source that contains unescaped octets with values between 128 and 255. You must use \octal or \hex escapes instead: /* 123456789 123456789 123456789 123456 */ char *foo = "This string is 36 octets in length \263"; /* This octet requires 4 octets of source ^^^^ */ if (strlen(foo) == 36) printf("foo is 36 octets a final NUL\n"); Be creative! ABUSING THE RULES: Legal abuse of the rules is somewhat encouraged. Legal rule abuse may involve, but is not limited to, doing things that are technically allowed by the rules and yet do not fit the spirit of what we intended to be submitted. Legal rule abuse is encouraged to help promote creativity. Rule abuse entries, regardless of if they receive an award, result in changes to the next year's rules and guidelines. Legal abuse of the rules is NOT an invitation to violate the rules. An entry that violates the rules in the opinion of the judges, WILL be disqualified. RULE ABUSE CARRIES A CERTAIN LEVEL OF RISK! If you have an entry that might otherwise be interesting, you might want to submit two versions; one that does not abuse the rules and one that does. If you intend to abuse the rules, indicate so in the program "remarks". You must try to justify why you consider your rule abuse to be allowed under the rules. That is, you must plead your case as to why your entry is valid. Humor and/or creativity help plead a case. Abusing the entry format tends to annoy us more than amuse us. We are often asked why the contest rules and guidelines seem too strange or contain mistakes, flaws or grammatical errors. One reason is that we sometimes make genuine mistakes. But in many cases such problems, flaws or areas of confusion are deliberate. Changes to rules and guidelines in response to rule abuses, are done in a minimal fashion. Often we will deliberately leave behind holes (or introduce new ones) so that future rule abuse may continue. At the risk of stating the obvious, this contest is a parody of the software development process. The rules and guidelines are only a small part of the overall contest. Even so, one may think the contest rules and guideline process as a parody of the sometimes tragic mismatch between what a customer (or marketing) wants and what engineering delivers. JUDGING PROCESS: Entries are judged by Leonid A. Broukhis, Simon Cooper, Landon Curt Noll and Peter Seebach. Each entry submitted is given an id number and subdirectory. The "program", "info", "build" and "remarks" portions of a submission are stored and judged from this directory. Any "author" and identifiable "entry" information is not read until the judging process is complete, and then only from entries that have won an award. The above process helps keep us biased for/against any one particular individual. We are usually kept in the dark as much as you are until the final awards are given. We like the surprise of finding out in the end, who won and where they were from. We attempt to keep all entries anonymous, unless they win an award. Because the main 'prize' of winning is being announced, we make all attempts to send non-winners into oblivion. We remove all non-winning files, and shred all related paper. By tradition, we do not even reveal the number of entries that we received. (For the curious, we do indicate the volume of paper consumed when presenting the IOCCC winners at talks) After the initial announcement, we attempt to send an email to the authors of the winning entries. One reason we do this is to give the authors a chance to comment on the way we have presented their entry. They are given the chance to correct mistakes and typos. We often accept their suggestions/comments about our remarks as well. This is done prior to posting the winners to the wide world. Judging consists of a number of elimination rounds. During a round, the collection of entries are divided into two roughly equal piles; the pile that advances on to the next round, and the pile that does not. We also re-examine the entries that were eliminated in the previous round. Thus, an entry gets at least two readings. A reading consists of a number of actions: * reading the "build" information * reading the "program" * reading the program "info", if any * passing the source thru the C pre-processor skipping over any #include files * performing a number of C beautify/cleanup edits on the source * passing the beautified source thru the C pre-processor skipping over any #include files In later rounds, other actions are performed: * compiling/building the source * running the program * performing miscellaneous tests on the source and binary Until we reduce the stack of entries down to about 25 entries, entries are judged on an individual basis. An entry is set aside because it does not, in our opinion, meet the standard established by the round. When the number of entries thins to about 25 entries, we begin to form award categories. Entries begin to compete with each other for awards. An entry will often compete in several categories. The actual award category list will vary depending on the types of entries we receive. A typical category list might be: * best small one line program * best small program * strangest/most creative source layout * most useful obfuscated program * best game that is obfuscated * most creatively obfuscated program * most deceptive C code * best X client (see OUR LIKES AND DISLIKES) * best abuse of ANSI C * worst abuse of the rules * (anything else so strange that it deserves an award) We do not limit ourselves to this list. For example, a few entries are so good/bad that they are declared winners at the start of the final round. We will invent awards categories for them, if necessary. In the final round process, we perform the difficult tasks of reducing the remaining entries (typically about 25) down to 8 or 10 winners. Often we are confident that the entries that make it into the final round are definitely better than the ones that do not make it. The selection of the winners out of the final round, is less clear cut. Sometimes a final round entry os good enough to win, but is beat out by a similar, but slightly better entry. For this reason, it is sometimes worthwhile to re-enter an improved version of an entry that failed to win in a previous year. This assumes, of course, that the entry is worth improving in the first place! More often than not, we select a small entry (usually one line), a strange/creative layout entry, and an entry that abuses the contest rules in some way. In the end, we traditionally pick one entry as 'best'. Sometimes such an entry simply far exceeds any of the other entries. More often, the 'best' is picked because it does well in a number of categories. ANNOUNCEMENT OF WINNERS: The judges will post an initial announcement of who won, the name of their award, and a very brief description of the winning entry on the IOCCC website: https://www.ioccc.org/whowon.html We will also submit a brief announcement story to /.: https://slashdot.org that, depending on the willingness of the /. editors, may be posted to their site at the same time. Note that initial announcement will NOT contain source. This is because the winning authors are given a chance to review the judges comments, and test our Makefile. This review process typically takes a few weeks. Sometime after the initial announcement, and once the review by the winners has been completed, the winning source will be posted to the IOCCC website: https://www.ioccc.org/years.html NOTE: previous winners are available at that URL We will submit a story announcing the availability of the winners to /. at the same time. Finally the winning entries will be posted to the following groups: comp.lang.c comp.lang.c.moderated alt.sources In addition, pointers to these postings are posted to the following comp.sources.misc comp.windows.x comp.programming misc.misc comp.std.c alt.folklore.computers Often, winning entries are published in selected magazines from around the world. Winners have appeared in books ("The New Hackers Dictionary") and on T-Shirts. Last, but not least, winners receive international fame and flames! :-) FOR MORE INFORMATION: You may contact the judges by sending an email to the following address: q.2004@ioccc.org (not the address for submitting entries) You must include the words 'ioccc 2004 question' in the subject of your email when sending email to the judges. Questions and comments about the contest are welcome. Comments about confusing rules and guidelines are also welcome. The rules and the guidelines may (and often do) change from year to year. You should be sure you have the current rules and guidelines prior to submitting entries. Check out the IOCCC Web page: https://www.ioccc.org It has rules, guidelines and winners of previous contests (1984 to date). Leonid A. Broukhis Simon Cooper chongo (Landon Curt Noll) /\cc/\ Peter Seebach