posix/tst-fork.c

   1 /* Tests for fork.
   2    Copyright (C) 2000 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4    Contributed by Ulrich Drepper <drepper@cygnus.com>, 2000.
   5
   6    The GNU C Library is free software; you can redistribute it and/or
   7    modify it under the terms of the GNU Lesser General Public
   8    License as published by the Free Software Foundation; either
   9    version 2.1 of the License, or (at your option) any later version.
  10
  11    The GNU C Library is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14    Lesser General Public License for more details.
  15
  16    You should have received a copy of the GNU Lesser General Public
  17    License along with the GNU C Library; if not, write to the Free
  18    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  19    02111-1307 USA.  */
  20
  21 #include <errno.h>
  22 #include <error.h>
  23 #include <stdlib.h>
  24 #include <string.h>
  25 #include <unistd.h>
  26 #include <wait.h>
  27
  28
  29 static const char testdata[] = "This is a test";
  30 static const char testdata2[] = "And here we go again";
  31
  32
  33 int
  34 main (void)
  35 {
  36   const char *tmpdir = getenv ("TMPDIR");
  37   char buf[100];
  38   size_t tmpdirlen;
  39   char *name;
  40   int fd;
  41   pid_t pid;
  42   pid_t ppid;
  43   off_t off;
  44   int status;
  45
  46   if (tmpdir == NULL || *tmpdir == '\0')
  47     tmpdir = "/tmp";
  48   tmpdirlen = strlen (tmpdir);
  49
  50   name = (char *) malloc (tmpdirlen + strlen ("/forkXXXXXX") + 1);
  51   if (name == NULL)
  52     error (EXIT_FAILURE, errno, "cannot allocate file name");
  53
  54   mempcpy (mempcpy (name, tmpdir, tmpdirlen),
  55            "/forkXXXXXX", sizeof ("/forkXXXXXX"));
  56
  57   /* Open our test file.   */
  58   fd = mkstemp (name);
  59   if (fd == -1)
  60      error (EXIT_FAILURE, errno, "cannot open test file `%s'", name);
  61
  62   /* Make sure it gets removed.  */
  63   unlink (name);
  64
  65   /* Write some data.  */
  66   if (write (fd, testdata, strlen (testdata)) != strlen (testdata))
  67     error (EXIT_FAILURE, errno, "cannot write test data");
  68
  69   /* Get the position in the stream.  */
  70   off = lseek (fd, 0, SEEK_CUR);
  71   if (off == (off_t) -1 || off != strlen (testdata))
  72     error (EXIT_FAILURE, errno, "wrong file position");
  73
  74   /* Get the parent PID.  */
  75   ppid = getpid ();
  76
  77   /* Now fork of the process.  */
  78   pid = fork ();
  79   if (pid == 0)
  80     {
  81       /* One little test first: the PID must have changed.  */
  82       if (getpid () == ppid)
  83         error (EXIT_FAILURE, 0, "child and parent have same PID");
  84
  85       /* Test the `getppid' function.  */
  86       pid = getppid ();
  87       if (pid == (pid_t) -1 ? errno != ENOSYS : pid != ppid)
  88         error (EXIT_FAILURE, 0,
  89                "getppid returned wrong PID (%ld, should be %ld)",
  90                (long int) pid, (long int) ppid);
  91
  92       /* This is the child.  First get the position of the descriptor.  */
  93       off = lseek (fd, 0, SEEK_CUR);
  94       if (off == (off_t) -1 || off != strlen (testdata))
  95         error (EXIT_FAILURE, errno, "wrong file position in child");
  96
  97       /* Reset the position.  */
  98       if (lseek (fd, 0, SEEK_SET) != 0)
  99         error (EXIT_FAILURE, errno, "cannot reset position in child");
 100
 101       /* Read the data.  */
 102       if (read (fd, buf, sizeof buf) != strlen (testdata))
 103         error (EXIT_FAILURE, errno, "cannot read data in child");
 104
 105       /* Compare the data.  */
 106       if (memcmp (buf, testdata, strlen (testdata)) != 0)
 107         error (EXIT_FAILURE, 0, "data comparison failed in child");
 108
 109       /* Reset position again.  */
 110       if (lseek (fd, 0, SEEK_SET) != 0)
 111         error (EXIT_FAILURE, errno, "cannot reset position again in child");
 112
 113       /* Write new data.  */
 114       if (write (fd, testdata2, strlen (testdata2)) != strlen (testdata2))
 115         error (EXIT_FAILURE, errno, "cannot write new data in child");
 116
 117       /* Close the file.  This must not remove it.  */
 118       close (fd);
 119
 120       _exit (0);
 121     }
 122   else if (pid < 0)
 123     /* Something went wrong.  */
 124     error (EXIT_FAILURE, errno, "cannot fork");
 125
 126   /* Wait for the child.  */
 127   if (waitpid (pid, &status, 0) != pid)
 128     error (EXIT_FAILURE, 0, "Oops, wrong test program terminated");
 129
 130   if (WTERMSIG (status) != 0)
 131     error (EXIT_FAILURE, 0, "Child terminated incorrectly");
 132   status = WEXITSTATUS (status);
 133
 134   if (status == 0)
 135     {
 136       /* Test whether the child wrote the right data.  First test the
 137          position.  It must be the same as in the child.  */
 138       if (lseek (fd, 0, SEEK_CUR) != strlen (testdata2))
 139         error (EXIT_FAILURE, 0, "file position not changed");
 140
 141       if (lseek (fd, 0, SEEK_SET) != 0)
 142         error (EXIT_FAILURE, errno, "cannot reset file position");
 143
 144       if (read (fd, buf, sizeof buf) != strlen (testdata2))
 145         error (EXIT_FAILURE, errno, "cannot read new data");
 146
 147       if (memcmp (buf, testdata2, strlen (testdata2)) != 0)
 148         error (EXIT_FAILURE, 0, "new data not read correctly");
 149     }
 150
 151   return status;
 152 }