mirror of
https://github.com/radareorg/radare2.git
synced 2024-12-05 20:17:43 +00:00
.. | ||
p | ||
t | ||
egg.c | ||
emit_arm.c | ||
emit_trace.c | ||
emit_x64.c | ||
emit_x86.c | ||
Jamroot | ||
lang.c | ||
Makefile | ||
README |
r_egg ===== --pancake This is a rewrite of rarc2, a relocatable code compiler for radare. Syntax of the language ====================== The code of r_egg is compiled as in a flow. It is a one-pass compiler; this means that you have to define the proper stackframe size at the beginning of the function, and you have to define the functions in order to avoid getting compilation errors. The compiler generates assembly code for x86-{32,64} and arm. But it aims to support more platforms. This code is the compiled with r_asm and injected into a tiny binary with r_bin. You may like to use r_egg to create standalone binaries, position- independent raw eggs to be injected on running processes or to patch on-disk binaries. The generated code is not yet optimized, but it's safe to be executed at any place in the code. Preprocessor ------------ There's no standard preprocessor integrated with it. But if you feel the need to use one you may use cpp or spp*. * hg clone http://hg.youterm.com/spp Aliases ------- Sometimes you just need to replace at compile time a single entity on multiple places. Aliases are translated into 'equ' statements in assembly language. This is just an assembler-level keyword redefinition. AF_INET@alias(2); printf@alias(0x8053940); Includes -------- Use cat(1) or the preprocessor to concatenate multiple files to be compiled. It's not a task of a compiler to look for external sources, so it's a delegated task right now.. but we will probably add native support for spp (merge into) TODO: this is not yet implemented INCDIR@alias("/usr/include/ragg2"); sys-osx.r@include(INCDIR); Hashbang -------- eggs can use a hashbang to make them executable. $ head -n1 hello.r #!/usr/bin/ragg2 -X $ ./hello.r Hello World! Main ---- The execution of the code is done as in a flow. The first function to be defined will be the first one to be executed. If you want to run main() just do like this: #!/usr/bin/ragg2 -X main(); ... main@global(128,64) { ... Function definition ------------------- You may like to split up your code into several code blocks. Those blocks are bound to a label followed by root brackets '{ ... }' Function signatures ------------------- name@type(stackframesize,staticframesize) { body } name : name of the function to define type : see function types below stackframesize : get space from stack to store local variables staticframesize : get space from stack to store static variables (strings) body : code of the function Function types -------------- alias ; Used to create aliases data ; the body of the block is defined in .data inline ; the function body is inlined when called global ; make the symbol global fastcall ; function that is called using the fast calling convention syscall ; define syscall calling convention signature Syscalls -------- r_egg offers a syntax sugar for defining syscalls. The syntax is like this: exit@syscall(1); @syscall() { : mov eax, `.arg` : int 0x80 } main@global() { exit (0); } Libraries --------- At the moment there is no support for linking r_egg programs to system libraries. but if you inject the code into a program (disk/memory) you can define the address of each function using the @alias syntax. Core library ------------ There's a work-in-progress libc-like library written completely in r_egg Variables --------- .arg .arg0 .arg1 .arg2 .var0 .var2 .fix .ret ; eax for x86, r0 for arm .bp .pc .sp Arrays ------ Supported as raw pointers. TODO: enhace this feature Tracing ------- Sometimes r_egg programs will break or just not work as expected. Use the 'trace' architecture to get a arch-backend call trace: $ ragg2 -a trace -s yourprogram.r Pointers -------- TODO: Theorically '*' is used to get contents of a memory pointer. Virtual registers ----------------- TODO: a0, a1, a2, a3, sp, fp, bp, pc Return values ------------- The return value is stored in the a0 register, this register is set when calling a function or when typing a variable name without assignment. $ cat test.r add@global(4) { .var0 = .arg0 + .arg1; .var0; } main@global() { add (3,4); } $ ragg2 -F -o test test.r $ ./test $ echo $? 7 Traps ----- Each architecture have a different instruction to break the execution of the program. REgg language captures calls to 'break()' to run the emit_trap callback of the selected arch. The break(); --> compiles into 'int3' on x86 break; --> compiles into 'int3' on x86 Inline assembly --------------- Lines prefixed with ':' char are just inlined in the output assembly. : jmp 0x8048400 : .byte 33,44 Labels ------ You can define labels using the ':' keyword like this: :label_name: /* loop forever */ goto(label_name) Control flow ------------ goto (addr) -- branch execution while (cond) if (cond) break () -- executes a trap instruction Comments -------- Supported syntax for comments are: /* multiline comment */' // single line comment # single line comment