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/* Tests for fork.
Copyright (C) 2000-2024 Free Software Foundation, Inc.
This file is part of the GNU C Library.
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
<https://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;
}
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