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86 lines
2.2 KiB
C
86 lines
2.2 KiB
C
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/* shm_open -- open a POSIX shared memory object. Generic POSIX file version.
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Copyright (C) 2001 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 Library General Public License as
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published by the Free Software Foundation; either version 2 of the
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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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Library General Public License for more details.
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You should have received a copy of the GNU Library General Public
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License along with the GNU C Library; see the file COPYING.LIB. If not,
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write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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Boston, MA 02111-1307, USA. */
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#include <unistd.h>
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#if ! _POSIX_MAPPED_FILES
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#include <sysdeps/generic/shm_open.c>
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#else
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#include <errno.h>
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#include <sys/mman.h>
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#include <fcntl.h>
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#include <string.h>
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#include <stdlib.h>
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#include <paths.h>
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#define SHMDIR (_PATH_VARRUN "shm/")
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/* Open shared memory object. */
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int
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shm_open (const char *name, int oflag, mode_t mode)
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{
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size_t namelen;
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char *fname;
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int fd;
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/* Construct the filename. */
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while (name[0] == '/')
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++name;
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if (name[0] == '\0')
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{
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/* The name "/" is not supported. */
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__set_errno (EINVAL);
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return -1;
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}
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namelen = strlen (name);
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fname = (char *) __alloca (sizeof SHMDIR - 1 + namelen + 1);
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__mempcpy (__mempcpy (fname, SHMDIR, sizeof SHMDIR - 1),
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name, namelen + 1);
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fd = open (name, oflag, mode);
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if (fd != -1)
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{
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/* We got a descriptor. Now set the FD_CLOEXEC bit. */
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int flags = fcntl (fd, F_GETFD, 0);
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if (__builtin_expect (flags, 0) != -1)
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{
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flags |= FD_CLOEXEC;
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flags = fcntl (fd, F_SETFD, flags);
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}
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if (flags == -1)
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{
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/* Something went wrong. We cannot return the descriptor. */
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int save_errno = errno;
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close (fd);
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fd = -1;
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__set_errno (save_errno);
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}
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}
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return fd;
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}
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#endif
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