make
The current status of this entry is:
STATUS: INABIAF - please **DO NOT** fix
STATUS: doesn't work with some platforms - please help us fix
For more detailed information see 2001 bellard bugs.
./bellard file
./bellard bellard.otccex.c
<JUDGES_COMMENTS>
:-)
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
compile itself. OTCC
supports a strict subset of C. This subset is
compilable by a standard ANSI C compiler. OTCC
compiles,
assembles, links and runs C code without the need of any other
program.
You can use it by typing:
./bellard bellard.c [args]...
or by giving the C source to its standard input.
args
are given to the main()
function of bellard.c
(argv[0]
is
bellard.c).
./bellard bellard.otccex.c 10
./bellard 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
put #!/usr/local/bin/otcc
at the beginning of your C source if
you installed otcc
at this place.
OTCC
dialect)binary operators, in decreasing precedence order: *
/
%
,
+
-
, >>
<<
, <
<=
>
>=
, ==
!=
, &
,
^
, |
, =
, &&
, ||
.
&&
and ||
have the same semantics as in C: left to right
evaluation and early exit (short-circuited).
Parenthesis are supported.
Unary operators: &
, *
(pointer indirection), -
(negation), +
, !
, ~
, postfix ++
and --
.
Pointer indirection (*
) only works with explicit cast to
char *
, int *
or int (*)()
(function pointer).
++
, --
, and unary &
can only be used with variable
lvalue (left value).
=
can only be used with variable or *
(pointer
indirection) lvalue.
Function calls are supported with standard i386 calling convention. Function pointers are supported with explicit cast. Functions can be used before being declared.
Types: only signed integer (int
) variables and functions can
be declared. Variables cannot be initialized in
declarations. Only old K&R function declarations are parsed
(implicit integer return value and no types on arguments).
Any function or variable from the libc can be used because OTCC
uses the libc dynamic linker to resolve undefined symbols.
Instructions: blocks ({
}
) are supported as in C. if
and
else
can be used for tests. The while
and for
C loops are supported.
break
can be used to exit loops. return
is used for the return value of a
function.
Identifiers are parsed the same way as C. Local variables are handled, but there is no local name space (not a problem if different names are used for local and global variables).
Numbers can be entered in decimal, hexadecimal (0x
or 0X
prefix), or octal (0
prefix).
#define
is supported without function like arguments. No macro
recursion is tolerated; other preprocessor directives are
ignored.
C Strings and C character constants are supported. Only \n
,
\"
, \'
and \\
escapes are recognized.
C Comments can be used (but no C++ comments).
No error is displayed if an incorrect program is given.
Memory: the code, data, and symbol sizes are limited to 100KB (it can be changed in the source code).
No special effort was needed because obfuscation is almost
unavoidable for such a program :-) #define
s must be used to
compress the code, and integrated i386 code generator leads to non
obvious code.
OTCC
only works on i386 linux because it generates i386 code. OTCC
also relies on little endianness, unaligned memory accesses and
ASCII representation of characters. It also supposes that no valid
pointers are less than 512. If all those constraints are met, then
OTCC
could be theoretically used to “cross compile”, although no
such support is currently integrated.
It was successfully compiled with gcc version 2.95.2. You get some
warnings because old K&R prototypes are used, some casts are implicit
and some functions are used before being defined. OTCC
uses the
dynamic linker to resolve symbols with dlsym(3)
, so -ldl
must
be used when you compile and link it.