src/stdio/popen.c

   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
   9 extern char **__environ;
  10
  11 FILE *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                 }
  52 fail:
  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 }