posix/tst-spawn3.c

   1 /* Check posix_spawn add file actions.
   2    Copyright (C) 2016-2022 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <https://www.gnu.org/licenses/>.  */
  18
  19 #include <stdio.h>
  20 #include <spawn.h>
  21 #include <error.h>
  22 #include <errno.h>
  23 #include <stdlib.h>
  24 #include <string.h>
  25 #include <unistd.h>
  26 #include <sys/wait.h>
  27 #include <sys/resource.h>
  28 #include <fcntl.h>
  29 #include <paths.h>
  30
  31 #include <support/check.h>
  32 #include <support/temp_file.h>
  33
  34 static int
  35 do_test (void)
  36 {
  37   /* The test checks if posix_spawn open file action close the file descriptor
  38      before opening a new one in case the input file descriptor is already
  39      opened.  It does by exhausting all file descriptors on the process before
  40      issue posix_spawn.  It then issues a posix_spawn for '/bin/sh echo $$'
  41      and add two rules:
  42
  43      1. Redirect stdout to a temporary filepath
  44      2. Redirect stderr to stdout
  45
  46      If the implementation does not close the file 1. will fail with
  47      EMFILE.  */
  48
  49   struct rlimit rl;
  50   int max_fd = 24;
  51   int ret;
  52
  53   /* Set maximum number of file descriptor to a low value to avoid open
  54      too many files in environments where RLIMIT_NOFILE is large and to
  55      limit the array size to track the opened file descriptors.  */
  56
  57   if (getrlimit (RLIMIT_NOFILE, &rl) == -1)
  58     FAIL_EXIT1 ("getrlimit (RLIMIT_NOFILE): %m");
  59
  60   max_fd = (rl.rlim_cur < max_fd ? rl.rlim_cur : max_fd);
  61   rl.rlim_cur = max_fd;
  62
  63   if (setrlimit (RLIMIT_NOFILE, &rl) == 1)
  64     FAIL_EXIT1 ("setrlimit (RLIMIT_NOFILE): %m");
  65
  66   /* Exhauste the file descriptor limit with temporary files.  */
  67   int files[max_fd];
  68   int nfiles = 0;
  69   for (;;)
  70     {
  71       int fd = create_temp_file ("tst-spawn3.", NULL);
  72       if (fd == -1)
  73         {
  74           if (errno != EMFILE)
  75             FAIL_EXIT1 ("create_temp_file: %m");
  76           break;
  77         }
  78       files[nfiles++] = fd;
  79     }
  80
  81   posix_spawn_file_actions_t a;
  82   if (posix_spawn_file_actions_init (&a) != 0)
  83     FAIL_EXIT1 ("posix_spawn_file_actions_init");
  84
  85   /* Executes a /bin/sh echo $$ 2>&1 > ${objpfx}tst-spawn3.pid .  */
  86   const char pidfile[] = OBJPFX "tst-spawn3.pid";
  87   if (posix_spawn_file_actions_addopen (&a, STDOUT_FILENO, pidfile, O_WRONLY
  88                                         | O_CREAT | O_TRUNC, 0644) != 0)
  89     FAIL_EXIT1 ("posix_spawn_file_actions_addopen");
  90
  91   if (posix_spawn_file_actions_adddup2 (&a, STDOUT_FILENO, STDERR_FILENO) != 0)
  92     FAIL_EXIT1 ("posix_spawn_file_actions_adddup2");
  93
  94   /* Since execve (called by posix_spawn) might require to open files to
  95      actually execute the shell script, setup to close the temporary file
  96      descriptors.  */
  97   for (int i=0; i<nfiles; i++)
  98     {
  99       if (posix_spawn_file_actions_addclose (&a, files[i]))
 100         FAIL_EXIT1 ("posix_spawn_file_actions_addclose");
 101     }
 102
 103   char *spawn_argv[] = { (char *) _PATH_BSHELL, (char *) "-c",
 104                          (char *) "echo $$", NULL };
 105   pid_t pid;
 106   if ((ret = posix_spawn (&pid, _PATH_BSHELL, &a, NULL, spawn_argv, NULL))
 107        != 0)
 108     {
 109       errno = ret;
 110       FAIL_EXIT1 ("posix_spawn: %m");
 111     }
 112
 113   int status;
 114   int err = waitpid (pid, &status, 0);
 115   if (err != pid)
 116     FAIL_EXIT1 ("waitpid: %m");
 117
 118   /* Close the temporary files descriptor so it can check posix_spawn
 119      output.  */
 120   for (int i=0; i<nfiles; i++)
 121     {
 122       if (close (files[i]))
 123         FAIL_EXIT1 ("close: %m");
 124     }
 125
 126   int pidfd = open (pidfile, O_RDONLY);
 127   if (pidfd == -1)
 128     FAIL_EXIT1 ("open: %m");
 129
 130   char buf[64];
 131   ssize_t n;
 132   if ((n = read (pidfd, buf, sizeof (buf))) < 0)
 133     FAIL_EXIT1 ("read: %m");
 134
 135   unlink (pidfile);
 136
 137   /* We only expect to read the PID.  */
 138   char *endp;
 139   long int rpid = strtol (buf, &endp, 10);
 140   if (*endp != '\n')
 141     FAIL_EXIT1 ("*endp != \'n\'");
 142   if (endp == buf)
 143     FAIL_EXIT1 ("read empty line");
 144
 145   if (rpid != pid)
 146     FAIL_EXIT1 ("found \"%s\", expected pid %ld\n", buf, (long int) pid);
 147
 148   return 0;
 149 }
 150
 151 #include <support/test-driver.c>