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glibc/posix/tst-fork.c
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/* Tests for fork. | |
Copyright (C) 2000-2016 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; | |
} |