2001/bellard updates
README.md format fixes. Update bugs.md with a note that the author used gcc 2.95.2 with a link to the download of that version at the GNU gcc website. This was also added to the top of the README.md file.
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@@ -1,11 +1,10 @@
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# Best abuse of the rules
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Fabrice Bellard
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451 chemin du mas de Matour
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34790 GRABELS
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France
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http://bellard.org
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Fabrice Bellard
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451 chemin du mas de Matour
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34790 Grabels
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France
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https://bellard.org
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## To build:
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@@ -27,7 +26,11 @@ format so that will also make it harder to work. As it is it segfaults. He fixed
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an earlier segfault so that at least the file can be opened and he also changed
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some of the macro uses to what they expanded to but mostly he kept it the same.
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He also fixed `bellard.otccex.c` so it does not segfault and seemingly works
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okay. Thank you Cody for your assistance!
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okay (it did not work at all). The author stated that they used [gcc
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2.95.2](https://ftp.gnu.org/gnu/gcc/gcc-2.95.2/gcc-everything-2.95.2.tar.gz) but
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we don't know if that's relevant or not. Thank you Cody for your assistance! Can
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you fix the entry? We welcome your help! If you can please look at
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[bugs.md](/bugs.md) for more information. Thank you!
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## Try:
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@@ -42,125 +45,131 @@ okay. Thank you Cody for your assistance!
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## Author's remarks:
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OTCC is an Obfuscated Tiny C Compiler for i386-linux. It generates
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FAST! i386 32 bit code (no bytecode) and it is powerful enough to
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compile itself. OTCC supports a strict subset of C. This subset is
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compilable by a standard ANSI C compiler. OTCC compiles,
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assembles, links and runs C code without the need of any other
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program.
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`OTCC` is an Obfuscated Tiny C Compiler for i386-linux. It generates
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FAST! i386 32 bit code (no bytecode) and it is powerful enough to
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compile itself. `OTCC` supports a strict subset of C. This subset is
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compilable by a standard ANSI C compiler. `OTCC` compiles,
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assembles, links and runs C code without the need of any other
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program.
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You can use it by typing:
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You can use it by typing:
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./bellard bellard.c [args]...
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```sh
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./bellard bellard.c [args]...
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```
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or by giving the C source to its standard input.
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or by giving the C source to its standard input.
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'args' are given to the 'main' function of bellard.c (argv[0] is
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bellard.c).
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`args` are given to the `main` function of `bellard.c` (`argv[0]` is
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[bellard.c](bellard.c)).
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Examples:
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### Examples:
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- Sample compilation and execution:
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- Sample compilation and execution:
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```sh
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./bellard bellard.otccex.c 10
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```
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- Self compilation:
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- Self compilation:
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```sh
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./bellard bellard.c bellard.otccex.c 10
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```
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- Self compilation iterated...
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- Self compilation iterated...
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```sh
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./bellard bellard.c bellard.c bellard.otccex.c 10
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```
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An alternate syntax is to use it as a script interpreter: you can
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put '#!/usr/local/bin/otcc' at the beginning of your C source if
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you installed otcc at this place.
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put `#!/usr/local/bin/otcc` at the beginning of your C source if
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you installed `otcc` at this place.
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Supported C language subset (read joint example 'otccex.c' to have
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an introduction to OTCC dialect):
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### Supported C language subset (read joint example [bellard.otccex.c](bellard.otccex.c) to have an introduction to `OTCC` dialect)
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- Expressions:
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#### Expressions:
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* binary operators, by decreasing priority order: '*' '/' '%',
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'+' '-', '>>' '<<', '<' '<=' '>' '>=', '==' '!=', '&',
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'^', '|', '=', '&&', '||'.
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* binary operators, by decreasing priority order: `*` `/` `%`,
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`+` `-`, `>>` `<<`, `<` `<=` `>` `>=`, `==` `!=`, `&`,
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`^`, `|`, `=`, `&&`, `||`.
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* '&&' and '||' have the same semantics as C : left to right
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evaluation and early exit.
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* `&&` and `||` have the same semantics as in C: left to right
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evaluation and early exit.
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* Parenthesis are supported.
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* Parenthesis are supported.
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* Unary operators: '&', '*' (pointer indirection), '-'
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(negation), '+', '!', '~', post fixed '++' and '--'.
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* Unary operators: `&`, `*` (pointer indirection), `-`
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(negation), `+`, `!`, `~`, post fixed `++` and `--`.
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* Pointer indirection ('*') only works with explicit cast to
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'char *', 'int *' or 'int (*)()' (function pointer).
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* Pointer indirection (`*`) only works with explicit cast to
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`char *`, `int *` or `int (*)()` (function pointer).
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* '++', '--', and unary '&' can only be used with variable
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lvalue (left value).
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* `++`, `--`, and unary `&` can only be used with variable
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lvalue (left value).
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* '=' can only be used with variable or '*' (pointer
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indirection) lvalue.
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* `=` can only be used with variable or `*` (pointer
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indirection) lvalue.
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* Function calls are supported with standard i386 calling
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convention. Function pointers are supported with explicit
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cast. Functions can be used before being declared.
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* Function calls are supported _with standard **i386** calling
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convention_. Function pointers are supported _with explicit
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cast_. Functions can be used before being declared.
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- Types: only signed integer ('int') variables and functions can
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be declared. Variables cannot be initialized in
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declarations. Only old K&R function declarations are parsed
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(implicit integer return value and no types on arguments).
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- Types: only signed integer (`int`) variables and functions can
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be declared. Variables cannot be initialized in
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declarations. _Only old K&R function declarations are parsed
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(implicit integer return value and no types on arguments)_.
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- Any function or variable from the libc can be used because OTCC
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uses the libc dynamic linker to resolve undefined symbols.
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- Any function or variable from the libc can be used because `OTCC`
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uses the libc dynamic linker to resolve undefined symbols.
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- Instructions: blocks ('{' '}') are supported as in C. 'if' and
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'else' can be used for tests. The 'while' and 'for' C constructs
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are supported for loops. 'break' can be used to exit
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loops. 'return' is used for the return value of a function.
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- Instructions: blocks (`{` `}`) are supported as in C. `if` and
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`else` can be used for tests. The `while` and `for` C looks are supported.
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`break` can be used to exit loops. `return` is used for the return value of a
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function.
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- Identifiers are parsed the same way as C. Local variables are
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handled, but there is no local name space (not a problem if
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different names are used for local and global variables).
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- Identifiers are parsed the same way as C. Local variables are
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handled, but there is no local name space (not a problem if
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different names are used for local and global variables).
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- Numbers can be entered in decimal, hexadecimal ('0x' or '0X'
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prefix), or octal ('0' prefix).
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- Numbers can be entered in decimal, hexadecimal (`0x` or `0X`
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prefix), or octal (`0` prefix).
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- '#define' is supported without function like arguments. No macro
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recursion is tolerated. Other preprocessor directives are
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ignored.
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- `#define` is supported without function like arguments. _No macro
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recursion is tolerated_; _other preprocessor directives are
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ignored_.
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- C Strings and C character constants are supported. Only '\n',
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'\"', '\'' and '\\' escapes are recognized.
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- C Strings and C character constants are supported. Only `\n`,
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`\"`, `\'` and `\\` escapes are recognized.
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- C Comments can be used (but no C++ comments).
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- C Comments can be used (but no C++ comments).
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- No error is displayed if an incorrect program is given.
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- No error is displayed if an incorrect program is given.
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- Memory: the code, data, and symbol sizes are limited to 100KB
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(it can be changed in the source code).
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- Memory: the code, data, and symbol sizes are limited to 100KB
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(it can be changed in the source code).
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Obfuscation:
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### Obfuscation:
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No special effort was needed because obfuscation is almost
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unavoidable for such a program :-) Defines must be used to
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compress the code, and integrated i386 code generator leads to non
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obvious code.
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No special effort was needed because obfuscation is almost
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unavoidable for such a program :-) Defines must be used to
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compress the code, and integrated i386 code generator leads to non
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obvious code.
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Portability:
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### Portability:
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OTCC only works on i386 linux because it generates i386 code. OTCC
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also relies on little endianness, unaligned memory accesses and
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ASCII representation of characters. It also supposes that no valid
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pointers are less than 512. If all those constraints are met, then
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OTCC could be theoretically used to "cross compile", although no
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such support is currently integrated.
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`OTCC` only works on i386 linux because it generates i386 code. `OTCC`
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also relies on little endianness, unaligned memory accesses and
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ASCII representation of characters. It also supposes that no valid
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pointers are less than 512. If all those constraints are met, then
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`OTCC` could be theoretically used to "cross compile", although no
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such support is currently integrated.
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It was successfully compiled with gcc version 2.95.2. You get some
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warnings because old K&R protos are used, some casts are implicit
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and some functions are used before being defined. OTCC uses the
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dynamic linker to resolve symbols with 'dlsym()', so '-ldl' must
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be used as library when you compile it.
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It was successfully compiled with gcc version 2.95.2. You get some
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warnings because old K&R prototypes are used, some casts are implicit
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and some functions are used before being defined. `OTCC` uses the
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dynamic linker to resolve symbols with `dlsym()`, so `-ldl` must
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be used when you compile and link it.
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## Copyright and CC BY-SA 4.0 License:
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@@ -918,6 +918,11 @@ would greatly appreciate anyone's help! It appears that this entry will require
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major debugging and to make it work one might need to have a deep understanding
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of the ELF format.
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The author said that they compiled it with [gcc version
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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
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a certain gcc version is necessary but it might be helpful to download and
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compile that version to test it.
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# 2002
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There was no IOCCC in 2002.
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