1#include "libc.h"
2#include <errno.h>
3#include <signal.h>
4#include <spawn.h>
5#include <stdlib.h>
6#include <sys/wait.h>
7#include <unistd.h>
8
9int system(const char* cmd) {
10    pid_t pid;
11    sigset_t old, reset;
12    struct sigaction sa = {.sa_handler = SIG_IGN}, oldint, oldquit;
13    int status = 0x7f00, ret;
14    posix_spawnattr_t attr;
15
16    if (!cmd)
17        return 1;
18
19    sigaction(SIGINT, &sa, &oldint);
20    sigaction(SIGQUIT, &sa, &oldquit);
21    sigaddset(&sa.sa_mask, SIGCHLD);
22    sigprocmask(SIG_BLOCK, &sa.sa_mask, &old);
23
24    sigemptyset(&reset);
25    if (oldint.sa_handler != SIG_IGN)
26        sigaddset(&reset, SIGINT);
27    if (oldquit.sa_handler != SIG_IGN)
28        sigaddset(&reset, SIGQUIT);
29    posix_spawnattr_init(&attr);
30    posix_spawnattr_setsigmask(&attr, &old);
31    posix_spawnattr_setsigdefault(&attr, &reset);
32    posix_spawnattr_setflags(&attr, POSIX_SPAWN_SETSIGDEF | POSIX_SPAWN_SETSIGMASK);
33    ret = posix_spawn(&pid, "/bin/sh", 0, &attr, (char* []){(char*)"sh", (char*)"-c", (char*)cmd, 0}, __environ);
34    posix_spawnattr_destroy(&attr);
35
36    if (!ret)
37        while (waitpid(pid, &status, 0) < 0 && errno == EINTR)
38            ;
39    sigaction(SIGINT, &oldint, NULL);
40    sigaction(SIGQUIT, &oldquit, NULL);
41    sigprocmask(SIG_SETMASK, &old, NULL);
42
43    if (ret)
44        errno = ret;
45    return status;
46}
47