ref: cbc79a2cfff4aa23e628158c2aa2b7035753cbe4
dir: /lib/c/syscall.h/
extern void *_brk(void *addr); extern int _open(char *path, int flags, int perm); extern int _close(int fd); extern int _read(int fd, void *buf, size_t n); extern int _write(int fd, void *buf, size_t n); extern int _lseek(int fd, long off, int whence); extern void _Exit(int status); extern void _access(char *path, int mode); extern int raise(int sig); extern void (*signal(int sig, void (*func)(int)))(int); extern getenv(const char *var); extern int rename(const char *from, const char *to); extern int remove(const char *path);