MiniLibC

A shared library that contains libc functions recoded in x86-64 Assembly.

Requirements

• A Linux distribution
• Make
• GCC

Get started

Compile the library

Navigate to the root of the repository from your Terminal and run make to build the libasm.so shared library.

Use MiniLibC

• Make sure you compile your project with GCC's -fno-builtin option. otherwise GCC will replace some libc functions by its own builtins that you won't be able to override.
• Use these commands to override the libc functions used in your program by the MiniLibC functions:

  LD_LIBRARY_PATH=$(pwd)
  LD_PRELOAD=/path/to/libasm.so ./your_executable

Functions

Here is a list of the prototypes of the libc functions recoded in libasm.so:

void	*memcpy(void *dest, const void *src, size_t n);
void	*memmove(void *dest, const void *src, size_t n);
void	*memset(void *s, int c, size_t n);
char	*rindex(const char *s, int c);
int	strcasecmp(const char *s1, const char *s2);
char	*strchr(const char *s, int c);
int	strcmp(const char *s1, const char *s2);
size_t	strcspn(const char *s, const char *reject);
size_t	strlen(const char *s);
int	strncmp(const char *s1, const char *s2, size_t n);
char	*strpbrk(const char *s, const char *accept);