ref: 22c3bdf20b42098542640447cd409de2b999e23b
dir: /src/libc/syscall.h/
extern int _brk(void *); extern void _exit(int); extern int _close(int); extern int _getpid(void); extern int _kill(int, int); extern int _open(const char *, int, int); extern int _read(int, void *, size_t); extern int _unlink(const char *); extern int _write(int, void *, size_t);