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67 lines
2.8 KiB
C
67 lines
2.8 KiB
C
/* Header for directory for shm/sem files.
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Copyright (C) 2014-2016 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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<http://www.gnu.org/licenses/>. */
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#ifndef _SHM_DIRECTORY_H
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#include <errno.h>
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#include <limits.h>
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#include <stdbool.h>
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#include <stdlib.h>
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#include <string.h>
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extern const char *__shm_directory (size_t *len);
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/* This defines local variables SHM_DIR and SHM_DIRLEN, giving the
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directory prefix (with trailing slash) and length (not including '\0'
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terminator) of the directory used for shm files. If that cannot be
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determined, it sets errno to ENOSYS and returns RETVAL_FOR_INVALID.
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This uses the local variable NAME as an lvalue, and increments it past
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any leading slashes. It then defines the local variable NAMELEN, giving
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strlen (NAME) + 1. If NAME is invalid, it sets errno to
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ERRNO_FOR_INVALID and returns RETVAL_FOR_INVALID. Finally, it defines
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the local variable SHM_NAME, giving the absolute file name of the shm
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file corresponding to NAME. PREFIX is a string constant used as a
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prefix on NAME. */
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#define SHM_GET_NAME(errno_for_invalid, retval_for_invalid, prefix) \
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size_t shm_dirlen; \
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const char *shm_dir = __shm_directory (&shm_dirlen); \
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/* If we don't know what directory to use, there is nothing we can do. */ \
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if (__glibc_unlikely (shm_dir == NULL)) \
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{ \
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__set_errno (ENOSYS); \
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return retval_for_invalid; \
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} \
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/* Construct the filename. */ \
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while (name[0] == '/') \
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++name; \
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size_t namelen = strlen (name) + 1; \
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/* Validate the filename. */ \
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if (namelen == 1 || namelen >= NAME_MAX || strchr (name, '/') != NULL) \
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{ \
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__set_errno (errno_for_invalid); \
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return retval_for_invalid; \
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} \
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char *shm_name = __alloca (shm_dirlen + sizeof prefix - 1 + namelen); \
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__mempcpy (__mempcpy (__mempcpy (shm_name, shm_dir, shm_dirlen), \
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prefix, sizeof prefix - 1), \
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name, namelen)
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#endif /* shm-directory.h */
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