#include <errno.h>
#include <signal.h>
#include <spawn.h>
#include <stdlib.h>
#include <sys/wait.h>
#include <unistd.h>

#include "libc.h"

int system(const char* cmd) {
  pid_t pid;
  sigset_t old, reset;
  struct sigaction sa = {.sa_handler = SIG_IGN}, oldint, oldquit;
  int status = 0x7f00, ret;
  posix_spawnattr_t attr;

  if (!cmd)
    return 1;

  sigaction(SIGINT, &sa, &oldint);
  sigaction(SIGQUIT, &sa, &oldquit);
  sigaddset(&sa.sa_mask, SIGCHLD);
  sigprocmask(SIG_BLOCK, &sa.sa_mask, &old);

  sigemptyset(&reset);
  if (oldint.sa_handler != SIG_IGN)
    sigaddset(&reset, SIGINT);
  if (oldquit.sa_handler != SIG_IGN)
    sigaddset(&reset, SIGQUIT);
  posix_spawnattr_init(&attr);
  posix_spawnattr_setsigmask(&attr, &old);
  posix_spawnattr_setsigdefault(&attr, &reset);
  posix_spawnattr_setflags(&attr, POSIX_SPAWN_SETSIGDEF | POSIX_SPAWN_SETSIGMASK);
  ret = posix_spawn(&pid, "/bin/sh", 0, &attr, (char*[]){(char*)"sh", (char*)"-c", (char*)cmd, 0},
                    __environ);
  posix_spawnattr_destroy(&attr);

  if (!ret)
    while (waitpid(pid, &status, 0) < 0 && errno == EINTR)
      ;
  sigaction(SIGINT, &oldint, NULL);
  sigaction(SIGQUIT, &oldquit, NULL);
  sigprocmask(SIG_SETMASK, &old, NULL);

  if (ret)
    errno = ret;
  return status;
}