Add freopen special-case tests: thread cancellation

Add tests of freopen adding or removing "c" (non-cancelling I/O) from
the mode string (so completing my planned tests of freopen with
different features used in the mode strings).  Note that it's in the
nature of the uncertain time at which cancellation might act (possibly
during freopen, possibly during subsequent reads) that these can leak
memory or file descriptors, so these do not include leak tests.

Tested for x86_64.
This commit is contained in:
Joseph Myers 2024-10-07 19:44:25 +00:00
parent e67f8e6dbd
commit 42c810c2cf
4 changed files with 164 additions and 0 deletions

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@ -224,10 +224,12 @@ tests := \
tst-freopen4 \
tst-freopen5 \
tst-freopen6 \
tst-freopen7 \
tst-freopen64-2 \
tst-freopen64-3 \
tst-freopen64-4 \
tst-freopen64-6 \
tst-freopen64-7 \
tst-fseek \
tst-fwrite \
tst-fwrite-memstrm \
@ -623,3 +625,6 @@ $(objpfx)tst-setvbuf1-cmp.out: tst-setvbuf1.expect $(objpfx)tst-setvbuf1.out
$(objpfx)tst-printf-round: $(libm)
$(objpfx)tst-scanf-round: $(libm)
$(objpfx)tst-freopen7: $(shared-thread-library)
$(objpfx)tst-freopen64-7: $(shared-thread-library)

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@ -0,0 +1,2 @@
#define FREOPEN freopen64
#include <tst-freopen7-main.c>

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@ -0,0 +1,155 @@
/* Test freopen cancellation handling.
Copyright (C) 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 <fcntl.h>
#include <mcheck.h>
#include <pthread.h>
#include <semaphore.h>
#include <stdio.h>
#include <stdlib.h>
#include <wchar.h>
#include <support/check.h>
#include <support/file_contents.h>
#include <support/support.h>
#include <support/temp_file.h>
#include <support/test-driver.h>
#include <support/xstdio.h>
#include <support/xthread.h>
#include <support/xunistd.h>
char *file1, *file2, *file3, *fifo;
sem_t sem;
void *
test_rc_to_r (void *p)
{
int ret;
FILE *fp, *fp2;
ret = sem_post (&sem);
TEST_VERIFY_EXIT (ret == 0);
fp = xfopen (file1, "rc");
for (int i = 0; i < 1000000; i++)
{
fgetc (fp);
fseek (fp, 0, SEEK_SET);
}
fp2 = xfopen (file3, "wc");
fputs ("rc_to_r got to freopen", fp2);
xfclose (fp2);
/* Cancellation should occur at some point from here onwards
(possibly leaking memory and file descriptors associated with the
FILE). */
fp = FREOPEN (file2, "r", fp);
TEST_VERIFY_EXIT (fp != NULL);
for (;;)
{
fgetc (fp);
fseek (fp, 0, SEEK_SET);
}
}
void *
test_r_to_rc (void *p)
{
int ret;
FILE *fp;
fp = xfopen (file1, "r");
fp = FREOPEN (fifo, "rc", fp);
TEST_VERIFY_EXIT (fp != NULL);
ret = sem_post (&sem);
TEST_VERIFY_EXIT (ret == 0);
/* No cancellation should occur for I/O on fifo. */
ret = fgetc (fp);
/* At this point, the other thread has called pthread_cancel and
then written a byte to the fifo, so this thread is cancelled at
the next cancellation point. */
TEST_VERIFY (ret == 'x');
xfclose (fp);
fp = xfopen (file3, "wc");
fputs ("r_to_rc got to fclose", fp);
xfclose (fp);
pthread_testcancel ();
FAIL_EXIT1 ("test_r_to_rc not cancelled\n");
}
int
do_test (void)
{
char *temp_dir = support_create_temp_directory ("tst-freopen-cancel");
file1 = xasprintf ("%s/file1", temp_dir);
support_write_file_string (file1, "file1");
add_temp_file (file1);
file2 = xasprintf ("%s/file2", temp_dir);
support_write_file_string (file2, "file2");
add_temp_file (file2);
file3 = xasprintf ("%s/file3", temp_dir);
support_write_file_string (file3, "file3");
add_temp_file (file3);
fifo = xasprintf ("%s/fifo", temp_dir);
xmkfifo (fifo, 0666);
add_temp_file (fifo);
int ret;
pthread_t thr;
void *retval;
/* Test changing to/from c (cancellation disabled). */
verbose_printf ("Testing rc -> r\n");
ret = sem_init (&sem, 0, 0);
TEST_VERIFY_EXIT (ret == 0);
thr = xpthread_create (NULL, test_rc_to_r, NULL);
ret = sem_wait (&sem);
TEST_VERIFY_EXIT (ret == 0);
xpthread_cancel (thr);
ret = pthread_join (thr, &retval);
TEST_COMPARE (ret, 0);
TEST_VERIFY (retval == PTHREAD_CANCELED);
TEST_OPEN_AND_COMPARE_FILE_STRING (file3, "rc_to_r got to freopen");
verbose_printf ("Testing r -> rc\n");
ret = sem_init (&sem, 0, 0);
TEST_VERIFY_EXIT (ret == 0);
thr = xpthread_create (NULL, test_r_to_rc, NULL);
FILE *fp = xfopen (fifo, "w");
ret = sem_wait (&sem);
TEST_VERIFY_EXIT (ret == 0);
/* This call happens while, or before, the other thread is waiting
to read a character from the fifo. It thus verifies that
cancellation does not occur from the fgetc call in that thread
(it should instead occur only in pthread_testcancel call),
because the expected string is only written to file3 after that
thread closes the fifo. */
xpthread_cancel (thr);
fputc ('x', fp);
xfclose (fp);
ret = pthread_join (thr, &retval);
TEST_COMPARE (ret, 0);
TEST_VERIFY (retval == PTHREAD_CANCELED);
TEST_OPEN_AND_COMPARE_FILE_STRING (file3, "r_to_rc got to fclose");
free (temp_dir);
free (file1);
free (file2);
free (file3);
return 0;
}
#include <support/test-driver.c>

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@ -0,0 +1,2 @@
#define FREOPEN freopen
#include <tst-freopen7-main.c>