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a979b72747
This adds a special SHM_ANON value that can be passed into shm_open () in place of a name. When called in this way, shm_open () will create a new anonymous shared memory file. The file will be created in the same way that other shared memory files are created (i.e., under /dev/shm/), except that it is not given a name and therefore cannot be reached from the file system, nor by other calls to shm_open (). This is accomplished by utilizing O_TMPFILE. This is intended to be compatible with FreeBSD's API of the same name. Signed-off-by: Sergey Bugaev <bugaevc@gmail.com> Message-Id: <20230130125216.6254-4-bugaevc@gmail.com>
59 lines
1.9 KiB
C
59 lines
1.9 KiB
C
/* shm_open -- open a POSIX shared memory object. Generic POSIX file version.
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Copyright (C) 2001-2023 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 <not-cancel.h>
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#include <pthread.h>
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#include <shlib-compat.h>
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#include <shm-directory.h>
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#include <unistd.h>
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#include <sys/mman.h>
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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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struct shmdir_name dirname;
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if (__shm_get_name (&dirname, name, false) != 0)
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{
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__set_errno (EINVAL);
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return -1;
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}
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oflag |= O_NOFOLLOW | O_CLOEXEC;
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#if defined (SHM_ANON) && defined (O_TMPFILE)
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if (name == SHM_ANON)
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oflag |= O_TMPFILE;
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#endif
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int fd = __open64_nocancel (dirname.name, oflag, mode);
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if (fd == -1 && __glibc_unlikely (errno == EISDIR))
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/* It might be better to fold this error with EINVAL since
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directory names are just another example for unsuitable shared
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object names and the standard does not mention EISDIR. */
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__set_errno (EINVAL);
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return fd;
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}
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versioned_symbol (libc, __shm_open, shm_open, GLIBC_2_34);
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#if OTHER_SHLIB_COMPAT (librt, GLIBC_2_2, GLIBC_2_34)
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compat_symbol (libc, __shm_open, shm_open, GLIBC_2_2);
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#endif
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