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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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Cody Boone Ferguson committed 2023-04-15 03:51:41 -07:00
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2001/bellard/README.md
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# Best abuse of the rules # Best abuse of the rules
Fabrice Bellard Fabrice Bellard
451 chemin du mas de Matour 451 chemin du mas de Matour
34790 GRABELS 34790 Grabels
France France
https://bellard.org
http://bellard.org
## To build: ## To build:
@@ -27,7 +26,11 @@ format so that will also make it harder to work. As it is it segfaults. He fixed
an earlier segfault so that at least the file can be opened and he also changed an earlier segfault so that at least the file can be opened and he also changed
some of the macro uses to what they expanded to but mostly he kept it the same. some of the macro uses to what they expanded to but mostly he kept it the same.
He also fixed `bellard.otccex.c` so it does not segfault and seemingly works He also fixed `bellard.otccex.c` so it does not segfault and seemingly works
okay. Thank you Cody for your assistance! okay (it did not work at all). The author stated that they used [gcc
2.95.2](https://ftp.gnu.org/gnu/gcc/gcc-2.95.2/gcc-everything-2.95.2.tar.gz) but
we don't know if that's relevant or not. Thank you Cody for your assistance! Can
you fix the entry? We welcome your help! If you can please look at
[bugs.md](/bugs.md) for more information. Thank you!
## Try: ## Try:
@@ -42,125 +45,131 @@ okay. Thank you Cody for your assistance!
## Author's remarks: ## Author's remarks:
OTCC is an Obfuscated Tiny C Compiler for i386-linux. It generates `OTCC` is an Obfuscated Tiny C Compiler for i386-linux. It generates
FAST! i386 32 bit code (no bytecode) and it is powerful enough to FAST! i386 32 bit code (no bytecode) and it is powerful enough to
compile itself. OTCC supports a strict subset of C. This subset is compile itself. `OTCC` supports a strict subset of C. This subset is
compilable by a standard ANSI C compiler. OTCC compiles, compilable by a standard ANSI C compiler. `OTCC` compiles,
assembles, links and runs C code without the need of any other assembles, links and runs C code without the need of any other
program. program.
You can use it by typing: You can use it by typing:
./bellard bellard.c [args]... ```sh
./bellard bellard.c [args]...
```
or by giving the C source to its standard input. or by giving the C source to its standard input.
'args' are given to the 'main' function of bellard.c (argv[0] is `args` are given to the `main` function of `bellard.c` (`argv[0]` is
bellard.c). [bellard.c](bellard.c)).
Examples: ### Examples:
- Sample compilation and execution: - Sample compilation and execution:
```sh
./bellard bellard.otccex.c 10 ./bellard bellard.otccex.c 10
```
- Self compilation: - Self compilation:
```sh
./bellard bellard.c bellard.otccex.c 10 ./bellard bellard.c bellard.otccex.c 10
```
- Self compilation iterated... - Self compilation iterated...
```sh
./bellard bellard.c bellard.c bellard.otccex.c 10 ./bellard bellard.c bellard.c bellard.otccex.c 10
```
An alternate syntax is to use it as a script interpreter: you can An alternate syntax is to use it as a script interpreter: you can
put '#!/usr/local/bin/otcc' at the beginning of your C source if put `#!/usr/local/bin/otcc` at the beginning of your C source if
you installed otcc at this place. you installed `otcc` at this place.
Supported C language subset (read joint example 'otccex.c' to have ### Supported C language subset (read joint example [bellard.otccex.c](bellard.otccex.c) to have an introduction to `OTCC` dialect)
an introduction to OTCC dialect):
- Expressions: #### Expressions:
* binary operators, by decreasing priority order: '*' '/' '%', * binary operators, by decreasing priority order: `*` `/` `%`,
'+' '-', '>>' '<<', '<' '<=' '>' '>=', '==' '!=', '&', `+` `-`, `>>` `<<`, `<` `<=` `>` `>=`, `==` `!=`, `&`,
'^', '|', '=', '&&', '||'. `^`, `|`, `=`, `&&`, `||`.
* '&&' and '||' have the same semantics as C : left to right * `&&` and `||` have the same semantics as in C: left to right
evaluation and early exit. evaluation and early exit.
* Parenthesis are supported. * Parenthesis are supported.
* Unary operators: '&', '*' (pointer indirection), '-' * Unary operators: `&`, `*` (pointer indirection), `-`
(negation), '+', '!', '~', post fixed '++' and '--'. (negation), `+`, `!`, `~`, post fixed `++` and `--`.
* Pointer indirection ('*') only works with explicit cast to * Pointer indirection (`*`) only works with explicit cast to
'char *', 'int *' or 'int (*)()' (function pointer). `char *`, `int *` or `int (*)()` (function pointer).
* '++', '--', and unary '&' can only be used with variable * `++`, `--`, and unary `&` can only be used with variable
lvalue (left value). lvalue (left value).
* '=' can only be used with variable or '*' (pointer * `=` can only be used with variable or `*` (pointer
indirection) lvalue. indirection) lvalue.
* Function calls are supported with standard i386 calling * Function calls are supported _with standard **i386** calling
convention. Function pointers are supported with explicit convention_. Function pointers are supported _with explicit
cast. Functions can be used before being declared. cast_. Functions can be used before being declared.
- Types: only signed integer ('int') variables and functions can - Types: only signed integer (`int`) variables and functions can
be declared. Variables cannot be initialized in be declared. Variables cannot be initialized in
declarations. Only old K&R function declarations are parsed declarations. _Only old K&R function declarations are parsed
(implicit integer return value and no types on arguments). (implicit integer return value and no types on arguments)_.
- Any function or variable from the libc can be used because OTCC - Any function or variable from the libc can be used because `OTCC`
uses the libc dynamic linker to resolve undefined symbols. uses the libc dynamic linker to resolve undefined symbols.
- Instructions: blocks ('{' '}') are supported as in C. 'if' and - Instructions: blocks (`{` `}`) are supported as in C. `if` and
'else' can be used for tests. The 'while' and 'for' C constructs `else` can be used for tests. The `while` and `for` C looks are supported.
are supported for loops. 'break' can be used to exit `break` can be used to exit loops. `return` is used for the return value of a
loops. 'return' is used for the return value of a function. function.
- Identifiers are parsed the same way as C. Local variables are - Identifiers are parsed the same way as C. Local variables are
handled, but there is no local name space (not a problem if handled, but there is no local name space (not a problem if
different names are used for local and global variables). different names are used for local and global variables).
- Numbers can be entered in decimal, hexadecimal ('0x' or '0X' - Numbers can be entered in decimal, hexadecimal (`0x` or `0X`
prefix), or octal ('0' prefix). prefix), or octal (`0` prefix).
- '#define' is supported without function like arguments. No macro - `#define` is supported without function like arguments. _No macro
recursion is tolerated. Other preprocessor directives are recursion is tolerated_; _other preprocessor directives are
ignored. ignored_.
- C Strings and C character constants are supported. Only '\n', - C Strings and C character constants are supported. Only `\n`,
'\"', '\'' and '\\' escapes are recognized. `\"`, `\'` and `\\` escapes are recognized.
- C Comments can be used (but no C++ comments). - C Comments can be used (but no C++ comments).
- No error is displayed if an incorrect program is given. - No error is displayed if an incorrect program is given.
- Memory: the code, data, and symbol sizes are limited to 100KB - Memory: the code, data, and symbol sizes are limited to 100KB
(it can be changed in the source code). (it can be changed in the source code).
Obfuscation: ### Obfuscation:
No special effort was needed because obfuscation is almost No special effort was needed because obfuscation is almost
unavoidable for such a program :-) Defines must be used to unavoidable for such a program :-) Defines must be used to
compress the code, and integrated i386 code generator leads to non compress the code, and integrated i386 code generator leads to non
obvious code. obvious code.
Portability: ### Portability:
OTCC only works on i386 linux because it generates i386 code. OTCC `OTCC` only works on i386 linux because it generates i386 code. `OTCC`
also relies on little endianness, unaligned memory accesses and also relies on little endianness, unaligned memory accesses and
ASCII representation of characters. It also supposes that no valid ASCII representation of characters. It also supposes that no valid
pointers are less than 512. If all those constraints are met, then pointers are less than 512. If all those constraints are met, then
OTCC could be theoretically used to "cross compile", although no `OTCC` could be theoretically used to "cross compile", although no
such support is currently integrated. such support is currently integrated.
It was successfully compiled with gcc version 2.95.2. You get some It was successfully compiled with gcc version 2.95.2. You get some
warnings because old K&R protos are used, some casts are implicit warnings because old K&R prototypes are used, some casts are implicit
and some functions are used before being defined. OTCC uses the and some functions are used before being defined. `OTCC` uses the
dynamic linker to resolve symbols with 'dlsym()', so '-ldl' must dynamic linker to resolve symbols with `dlsym()`, so `-ldl` must
be used as library when you compile it. be used when you compile and link it.
## Copyright and CC BY-SA 4.0 License: ## Copyright and CC BY-SA 4.0 License:
bugs.md
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@@ -918,6 +918,11 @@ would greatly appreciate anyone's help! It appears that this entry will require
major debugging and to make it work one might need to have a deep understanding major debugging and to make it work one might need to have a deep understanding
of the ELF format. of the ELF format.
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.
# 2002 # 2002
There was no IOCCC in 2002. There was no IOCCC in 2002.