github.com/afumu/libc@v0.0.6/musl/src/process/system.c (about)

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