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e9fed2438a
Previously, glibc would pick an arbitrary tmpfs file system from /proc/mounts if /dev/shm was not available. This could lead to an unsuitable file system being picked for the backing storage for shm_open, sem_open, and related functions. This patch introduces a new function, __shm_get_name, which builds the file name under the appropriate (now hard-coded) directory. It is called from the various shm_* and sem_* function. Unlike the SHM_GET_NAME macro it replaces, the callers handle the return values and errno updates. shm-directory.c is moved directly into the posix subdirectory because it can be implemented directly using POSIX functionality. It resides in libc because it is needed by both librt and nptl/htl. In the sem_open implementation, tmpfname is initialized directly from a string constant. This happens to remove one alloca call. Checked on x86_64-linux-gnu.
42 lines
1.5 KiB
C
42 lines
1.5 KiB
C
/* Header for directory for shm/sem files.
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Copyright (C) 2014-2021 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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#ifndef _SHM_DIRECTORY_H
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#include <limits.h>
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#include <paths.h>
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#include <stdbool.h>
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/* The directory that contains shared POSIX objects. */
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#define SHMDIR _PATH_DEV "shm/"
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struct shmdir_name
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{
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/* The combined prefix/name. The sizeof includes the terminating
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NUL byte. 4 bytes are needed for the optional "sem." prefix. */
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char name[sizeof (SHMDIR) + 4 + NAME_MAX];
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};
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/* Sets RESULT->name to the constructed name and returns 0 on success,
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or -1 on failure. Includes the "sem." prefix in the name if
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SEM_PREFIX is true. */
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int __shm_get_name (struct shmdir_name *result, const char *name,
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bool sem_prefix);
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#endif /* shm-directory.h */
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