rt/shm_open.c

   1 /* shm_open -- open a POSIX shared memory object.  Generic POSIX file version.
   2    Copyright (C) 2001-2023 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <https://www.gnu.org/licenses/>.  */
  18
  19 #include <errno.h>
  20 #include <fcntl.h>
  21 #include <not-cancel.h>
  22 #include <pthread.h>
  23 #include <shlib-compat.h>
  24 #include <shm-directory.h>
  25 #include <unistd.h>
  26 #include <sys/mman.h>
  27
  28 /* Open shared memory object.  */
  29 int
  30 __shm_open (const char *name, int oflag, mode_t mode)
  31 {
  32   struct shmdir_name dirname;
  33   if (__shm_get_name (&dirname, name, false) != 0)
  34     {
  35       __set_errno (EINVAL);
  36       return -1;
  37     }
  38
  39   oflag |= O_NOFOLLOW | O_CLOEXEC;
  40 #if defined (SHM_ANON) && defined (O_TMPFILE)
  41   if (name == SHM_ANON)
  42     oflag |= O_TMPFILE;
  43 #endif
  44
  45   int fd = __open64_nocancel (dirname.name, oflag, mode);
  46   if (fd == -1 && __glibc_unlikely (errno == EISDIR))
  47     /* It might be better to fold this error with EINVAL since
  48        directory names are just another example for unsuitable shared
  49        object names and the standard does not mention EISDIR.  */
  50     __set_errno (EINVAL);
  51
  52   return fd;
  53 }
  54 versioned_symbol (libc, __shm_open, shm_open, GLIBC_2_34);
  55
  56 #if OTHER_SHLIB_COMPAT (librt, GLIBC_2_2, GLIBC_2_34)
  57 compat_symbol (libc, __shm_open, shm_open, GLIBC_2_2);
  58 #endif