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f6233ab412
The O_PATH-based fchmodat emulation will rely on the fact that closing an O_PATH descriptor never releases POSIX advisory locks, so this commit adds a test case for this behavior.
101 lines
2.8 KiB
C
101 lines
2.8 KiB
C
/* Test that closing O_PATH descriptors does not release POSIX advisory locks.
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Copyright (C) 2020 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<https://www.gnu.org/licenses/>. */
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#include <errno.h>
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#include <fcntl.h>
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#include <stdbool.h>
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#include <stdlib.h>
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#include <support/check.h>
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#include <support/namespace.h>
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#include <support/support.h>
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#include <support/temp_file.h>
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#include <support/xunistd.h>
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/* The subprocess writes the errno value of the lock operation
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here. */
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static int *shared_errno;
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/* The path of the temporary file which is locked. */
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static char *path;
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/* Try to obtain an exclusive lock on the file at path. */
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static void
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subprocess (void *closure)
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{
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int fd = xopen (path, O_RDWR, 0);
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struct flock64 lock = { .l_type = F_WRLCK, };
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int ret = fcntl64 (fd, F_SETLK, &lock);
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if (ret == 0)
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*shared_errno = 0;
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else
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*shared_errno = errno;
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xclose (fd);
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}
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/* Return true if the file at path is currently locked, false if
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not. */
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static bool
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probe_lock (void)
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{
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*shared_errno = -1;
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support_isolate_in_subprocess (subprocess, NULL);
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if (*shared_errno == 0)
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/* Lock was aquired by the subprocess, so this process has not
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locked it. */
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return false;
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else
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{
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/* POSIX allows both EACCES and EAGAIN. Linux use EACCES. */
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TEST_COMPARE (*shared_errno, EAGAIN);
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return true;
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}
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}
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static int
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do_test (void)
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{
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shared_errno = support_shared_allocate (sizeof (*shared_errno));
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int fd = create_temp_file ("tst-o_path-locks-", &path);
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/* The file is not locked initially. */
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TEST_VERIFY (!probe_lock ());
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struct flock64 lock = { .l_type = F_WRLCK, };
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TEST_COMPARE (fcntl64 (fd, F_SETLK, &lock), 0);
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/* The lock has been acquired. */
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TEST_VERIFY (probe_lock ());
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/* Closing the same file via a different descriptor releases the
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lock. */
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xclose (xopen (path, O_RDONLY, 0));
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TEST_VERIFY (!probe_lock ());
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/* But not if it is an O_PATH descriptor. */
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TEST_COMPARE (fcntl64 (fd, F_SETLK, &lock), 0);
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xclose (xopen (path, O_PATH, 0));
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TEST_VERIFY (probe_lock ());
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xclose (fd);
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free (path);
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support_shared_free (shared_errno);
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return 0;
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}
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#include <support/test-driver.c>
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