/* Tests for fork.

   Copyright (C) 2000-2018 Free Software Foundation, Inc.

   This file is part of the GNU C Library.

   Contributed by Ulrich Drepper <drepper@cygnus.com>, 2000.

   The GNU C Library is free software; you can redistribute it and/or

   modify it under the terms of the GNU Lesser General Public

   License as published by the Free Software Foundation; either

   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,

   but WITHOUT ANY WARRANTY; without even the implied warranty of

   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public

   License along with the GNU C Library; if not, see

   <http://www.gnu.org/licenses/>.  */

#include <errno.h>

#include <error.h>

#include <stdlib.h>

#include <string.h>

#include <unistd.h>

#include <wait.h>

static const char testdata[] = "This is a test";

static const char testdata2[] = "And here we go again";

int

main (void)

{

  const char *tmpdir = getenv ("TMPDIR");

  char buf[100];

  size_t tmpdirlen;

  char *name;

  int fd;

  pid_t pid;

  pid_t ppid;

  off_t off;

  int status;

  if (tmpdir == NULL || *tmpdir == '\0')

    tmpdir = "/tmp";

  tmpdirlen = strlen (tmpdir);

  name = (char *) malloc (tmpdirlen + strlen ("/forkXXXXXX") + 1);

  if (name == NULL)

    error (EXIT_FAILURE, errno, "cannot allocate file name");

  mempcpy (mempcpy (name, tmpdir, tmpdirlen),

	   "/forkXXXXXX", sizeof ("/forkXXXXXX"));

  /* Open our test file.   */

  fd = mkstemp (name);

  if (fd == -1)

     error (EXIT_FAILURE, errno, "cannot open test file `%s'", name);

  /* Make sure it gets removed.  */

  unlink (name);

  /* Write some data.  */

  if (write (fd, testdata, strlen (testdata)) != strlen (testdata))

    error (EXIT_FAILURE, errno, "cannot write test data");

  /* Get the position in the stream.  */

  off = lseek (fd, 0, SEEK_CUR);

  if (off == (off_t) -1 || off != strlen (testdata))

    error (EXIT_FAILURE, errno, "wrong file position");

  /* Get the parent PID.  */

  ppid = getpid ();

  /* Now fork of the process.  */

  pid = fork ();

  if (pid == 0)

    {

      /* One little test first: the PID must have changed.  */

      if (getpid () == ppid)

	error (EXIT_FAILURE, 0, "child and parent have same PID");

      /* Test the `getppid' function.  */

      pid = getppid ();

      if (pid == (pid_t) -1 ? errno != ENOSYS : pid != ppid)

	error (EXIT_FAILURE, 0,

	       "getppid returned wrong PID (%ld, should be %ld)",

	       (long int) pid, (long int) ppid);

      /* This is the child.  First get the position of the descriptor.  */

      off = lseek (fd, 0, SEEK_CUR);

      if (off == (off_t) -1 || off != strlen (testdata))

	error (EXIT_FAILURE, errno, "wrong file position in child");

      /* Reset the position.  */

      if (lseek (fd, 0, SEEK_SET) != 0)

	error (EXIT_FAILURE, errno, "cannot reset position in child");

      /* Read the data.  */

      if (read (fd, buf, sizeof buf) != strlen (testdata))

	error (EXIT_FAILURE, errno, "cannot read data in child");

      /* Compare the data.  */

      if (memcmp (buf, testdata, strlen (testdata)) != 0)

	error (EXIT_FAILURE, 0, "data comparison failed in child");

      /* Reset position again.  */

      if (lseek (fd, 0, SEEK_SET) != 0)

	error (EXIT_FAILURE, errno, "cannot reset position again in child");

      /* Write new data.  */

      if (write (fd, testdata2, strlen (testdata2)) != strlen (testdata2))

	error (EXIT_FAILURE, errno, "cannot write new data in child");

      /* Close the file.  This must not remove it.  */

      close (fd);

      _exit (0);

    }

  else if (pid < 0)

    /* Something went wrong.  */

    error (EXIT_FAILURE, errno, "cannot fork");

  /* Wait for the child.  */

  if (waitpid (pid, &status, 0) != pid)

    error (EXIT_FAILURE, 0, "Oops, wrong test program terminated");

  if (WTERMSIG (status) != 0)

    error (EXIT_FAILURE, 0, "Child terminated incorrectly");

  status = WEXITSTATUS (status);

  if (status == 0)

    {

      /* Test whether the child wrote the right data.  First test the

	 position.  It must be the same as in the child.  */

      if (lseek (fd, 0, SEEK_CUR) != strlen (testdata2))

	error (EXIT_FAILURE, 0, "file position not changed");

      if (lseek (fd, 0, SEEK_SET) != 0)

	error (EXIT_FAILURE, errno, "cannot reset file position");

      if (read (fd, buf, sizeof buf) != strlen (testdata2))

	error (EXIT_FAILURE, errno, "cannot read new data");

      if (memcmp (buf, testdata2, strlen (testdata2)) != 0)

	error (EXIT_FAILURE, 0, "new data not read correctly");

    }

  return status;

}