mirror of
https://sourceware.org/git/glibc.git
synced 2024-12-26 20:51:11 +00:00
c32c868ab8
Austin Group issue 62 [1] dropped the async-signal-safe requirement for fork and provided a async-signal-safe _Fork replacement that does not run the atfork handlers. It will be included in the next POSIX standard. It allow to close a long standing issue to make fork AS-safe (BZ#4737). As indicated on the bug, besides the internal lock for the atfork handlers itself; there is no guarantee that the handlers itself will not introduce more AS-safe issues. The idea is synchronize fork with the required internal locks to allow children in multithread processes to use mostly of standard function (even though POSIX states only AS-safe function should be used). On signal handles, _Fork should be used intead and only AS-safe functions should be used. For testing, the new tst-_Fork only check basic usage. I also added a new tst-mallocfork3 which uses the same strategy to check for deadlock of tst-mallocfork2 but using threads instead of subprocesses (and it does deadlock if it replaces _Fork with fork). [1] https://austingroupbugs.net/view.php?id=62
155 lines
3.7 KiB
C
155 lines
3.7 KiB
C
/* Basic tests for _Fork.
|
|
Copyright (C) 2021 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 <array_length.h>
|
|
#include <stdlib.h>
|
|
#include <string.h>
|
|
#include <pthread.h>
|
|
#include <stdbool.h>
|
|
#include <support/check.h>
|
|
#include <support/xsignal.h>
|
|
#include <support/temp_file.h>
|
|
#include <support/xunistd.h>
|
|
#include <support/xthread.h>
|
|
|
|
/* For single-thread, _Fork behaves like fork. */
|
|
static int
|
|
singlethread_test (void)
|
|
{
|
|
const char testdata1[] = "abcdefghijklmnopqrtuvwxz";
|
|
enum { testdatalen1 = array_length (testdata1) };
|
|
const char testdata2[] = "01234567890";
|
|
enum { testdatalen2 = array_length (testdata2) };
|
|
|
|
pid_t ppid = getpid ();
|
|
|
|
int tempfd = create_temp_file ("tst-_Fork", NULL);
|
|
|
|
/* Check if the opened file is shared between process by read and write
|
|
some data on parent and child processes. */
|
|
xwrite (tempfd, testdata1, testdatalen1);
|
|
off_t off = xlseek (tempfd, 0, SEEK_CUR);
|
|
TEST_COMPARE (off, testdatalen1);
|
|
|
|
pid_t pid = _Fork ();
|
|
TEST_VERIFY_EXIT (pid != -1);
|
|
if (pid == 0)
|
|
{
|
|
TEST_VERIFY_EXIT (getpid () != ppid);
|
|
TEST_COMPARE (getppid(), ppid);
|
|
|
|
TEST_COMPARE (xlseek (tempfd, 0, SEEK_CUR), testdatalen1);
|
|
|
|
xlseek (tempfd, 0, SEEK_SET);
|
|
char buf[testdatalen1];
|
|
TEST_COMPARE (read (tempfd, buf, sizeof (buf)), testdatalen1);
|
|
TEST_COMPARE_BLOB (buf, testdatalen1, testdata1, testdatalen1);
|
|
|
|
xlseek (tempfd, 0, SEEK_SET);
|
|
xwrite (tempfd, testdata2, testdatalen2);
|
|
|
|
xclose (tempfd);
|
|
|
|
_exit (EXIT_SUCCESS);
|
|
}
|
|
|
|
int status;
|
|
xwaitpid (pid, &status, 0);
|
|
TEST_VERIFY (WIFEXITED (status));
|
|
TEST_COMPARE (WEXITSTATUS (status), EXIT_SUCCESS);
|
|
|
|
TEST_COMPARE (xlseek (tempfd, 0, SEEK_CUR), testdatalen2);
|
|
|
|
xlseek (tempfd, 0, SEEK_SET);
|
|
char buf[testdatalen2];
|
|
TEST_COMPARE (read (tempfd, buf, sizeof (buf)), testdatalen2);
|
|
|
|
TEST_COMPARE_BLOB (buf, testdatalen2, testdata2, testdatalen2);
|
|
|
|
return 0;
|
|
}
|
|
|
|
|
|
static volatile sig_atomic_t sigusr1_handler_ran;
|
|
#define SIG_PID_EXIT_CODE 20
|
|
|
|
static bool atfork_prepare_var;
|
|
static bool atfork_parent_var;
|
|
static bool atfork_child_var;
|
|
|
|
static void
|
|
atfork_prepare (void)
|
|
{
|
|
atfork_prepare_var = true;
|
|
}
|
|
|
|
static void
|
|
atfork_parent (void)
|
|
{
|
|
atfork_parent_var = true;
|
|
}
|
|
|
|
static void
|
|
atfork_child (void)
|
|
{
|
|
atfork_child_var = true;
|
|
}
|
|
|
|
/* Different than fork, _Fork does not execute any pthread_atfork
|
|
handlers. */
|
|
static int
|
|
singlethread_atfork_test (void)
|
|
{
|
|
pthread_atfork (atfork_prepare, atfork_parent, atfork_child);
|
|
singlethread_test ();
|
|
TEST_VERIFY (!atfork_prepare_var);
|
|
TEST_VERIFY (!atfork_parent_var);
|
|
TEST_VERIFY (!atfork_child_var);
|
|
|
|
return 0;
|
|
}
|
|
|
|
static void *
|
|
mt_atfork_test (void *args)
|
|
{
|
|
singlethread_atfork_test ();
|
|
|
|
return NULL;
|
|
}
|
|
|
|
static int
|
|
multithread_atfork_test (void)
|
|
{
|
|
pthread_t thr = xpthread_create (NULL, mt_atfork_test, NULL);
|
|
xpthread_join (thr);
|
|
|
|
return 0;
|
|
}
|
|
|
|
|
|
static int
|
|
do_test (void)
|
|
{
|
|
singlethread_atfork_test ();
|
|
multithread_atfork_test ();
|
|
|
|
return 0;
|
|
}
|
|
|
|
#include <support/test-driver.c>
|