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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.
47 lines
1.5 KiB
C
47 lines
1.5 KiB
C
/* Determine directory for shm/sem files. Generic POSIX version.
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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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#include <unistd.h>
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#if _POSIX_MAPPED_FILES
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#include <alloc_buffer.h>
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#include <shm-directory.h>
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#include <string.h>
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int
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__shm_get_name (struct shmdir_name *result, const char *name, bool sem_prefix)
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{
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while (name[0] == '/')
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++name;
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size_t namelen = strlen (name);
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struct alloc_buffer buffer
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= alloc_buffer_create (result->name, sizeof (result->name));
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alloc_buffer_copy_bytes (&buffer, SHMDIR, strlen (SHMDIR));
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if (sem_prefix)
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alloc_buffer_copy_bytes (&buffer, "sem.", strlen ("sem."));
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alloc_buffer_copy_bytes (&buffer, name, namelen + 1);
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if (namelen == 0 || memchr (name, '/', namelen) != NULL
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|| alloc_buffer_has_failed (&buffer))
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return -1;
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return 0;
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}
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#endif
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