rt/shm_open.c

   1 /* shm_open -- open a POSIX shared memory object.  Generic POSIX file version.
   2    Copyright (C) 2001-2021 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 <pthread.h>
  22 #include <shm-directory.h>
  23 #include <unistd.h>
  24
  25 /* Open shared memory object.  */
  26 int
  27 shm_open (const char *name, int oflag, mode_t mode)
  28 {
  29   struct shmdir_name dirname;
  30   if (__shm_get_name (&dirname, name, false) != 0)
  31     {
  32       __set_errno (EINVAL);
  33       return -1;
  34     }
  35
  36   oflag |= O_NOFOLLOW | O_CLOEXEC;
  37
  38   /* Disable asynchronous cancellation.  */
  39   int state;
  40   pthread_setcancelstate (PTHREAD_CANCEL_DISABLE, &state);
  41
  42   int fd = open (dirname.name, oflag, mode);
  43   if (fd == -1 && __glibc_unlikely (errno == EISDIR))
  44     /* It might be better to fold this error with EINVAL since
  45        directory names are just another example for unsuitable shared
  46        object names and the standard does not mention EISDIR.  */
  47     __set_errno (EINVAL);
  48
  49   pthread_setcancelstate (state, NULL);
  50
  51   return fd;
  52 }