1#include <fcntl.h>
 2#include <unistd.h>
 3#include <errno.h>
 4#include <string.h>
 5#include <spawn.h>
 6#include "stdio_impl.h"
 7#include "syscall.h"
 8
 9extern char **__environ;
10
11FILE *popen(const char *cmd, const char *mode)
12{
13	int p[2], op, e;
14	pid_t pid;
15	FILE *f;
16	posix_spawn_file_actions_t fa;
17
18	if (*mode == 'r') {
19		op = 0;
20	} else if (*mode == 'w') {
21		op = 1;
22	} else {
23		errno = EINVAL;
24		return 0;
25	}
26	
27	if (pipe2(p, O_CLOEXEC)) return NULL;
28	f = fdopen(p[op], mode);
29	if (!f) {
30		__syscall(SYS_close, p[0]);
31		__syscall(SYS_close, p[1]);
32		return NULL;
33	}
34
35	e = ENOMEM;
36	if (!posix_spawn_file_actions_init(&fa)) {
37		for (FILE *l = *__ofl_lock(); l; l=l->next)
38			if (l->pipe_pid && posix_spawn_file_actions_addclose(&fa, l->fd))
39				goto fail;
40		if (!posix_spawn_file_actions_adddup2(&fa, p[1-op], 1-op)) {
41			if (!(e = posix_spawn(&pid, "/bin/sh", &fa, 0,
42			    (char *[]){ "sh", "-c", (char *)cmd, 0 }, __environ))) {
43				posix_spawn_file_actions_destroy(&fa);
44				f->pipe_pid = pid;
45				if (!strchr(mode, 'e'))
46					fcntl(p[op], F_SETFD, 0);
47				__syscall(SYS_close, p[1-op]);
48				__ofl_unlock();
49				return f;
50			}
51		}
52fail:
53		__ofl_unlock();
54		posix_spawn_file_actions_destroy(&fa);
55	}
56	fclose(f);
57	__syscall(SYS_close, p[1-op]);
58
59	errno = e;
60	return 0;
61}