StdLib

StdLib

Currently a very thin wrapper around a small number of Linux syscalls

Usage Idioms

FrontEndC - Generation of IR From C (C -> IR)

Use this include instead of the usual libc includes.

 #include "std_lib.h"

This includes the prototypes for StdLib.

CodeGenC - Generation of Executables via C (IR -> C -> EXE)

Assuming test.asm contains the IR, we need to concatenate library files to simulated linking, e.g.

cat syscall.extern32.asm  std_lib.32.asm test.asm | CodeGenC/codegen.py - > test.32.c

or

cat syscall.extern64.asm  std_lib.64.asm test.asm | CodeGenC/codegen.py - > test.64.c

syscall.externXX.asm are just stubs that need to be replaced in the final link with syscall.c which contain the actual syscall implementation.

gcc -O -static -m32 -nostdlib StdLib/syscall.c test.32.c -o test.32.exe

or

gcc -O -static -m64 -nostdlib StdLib/syscall.c test.64.c -o test.64.exe

By going to C code as an intermediate step we can generate code for X86-32 and X86-64.

CodeGenA32/CodeGenA64 - Direct Generation of Executables (IR -> EXE)

cat syscall.a32.asm  std_lib.32.asm test.asm | CodeGenA32/codegen.py  binary - test.a32.exe

or

cat syscall.a64.asm  std_lib.64.asm test.asm | CodeGenA64/codegen.py  binary - test.a64.exe

This is fully hermetic in that we also provide actual syscall implementations via syscall.a32.asm or syscall.a64.asm.

References

See syscall.c for experiments.

Linux syscall overview (covers multiple architectures) https://chromium.googlesource.com/chromiumos/docs/+/master/constants/syscalls.md

Linux nolibc https://github.com/torvalds/linux/blob/master/tools/include/nolibc/nolibc.h

Calling conventions for Linux syscall https://stackoverflow.com/questions/2535989/what-are-the-calling-conventions-for-unix-linux-system-calls-and-user-space-f

Error codes: https://mariadb.com/kb/en/operating-system-error-codes/