linux: Require /dev/shm as the shared memory file system

[thirdparty/glibc.git] / posix / shm-directory.c

/* Determine directory for shm/sem files.  Generic POSIX version.
   Copyright (C) 2014-2021 Free Software Foundation, Inc.
   This file is part of the GNU C Library.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with the GNU C Library; if not, see
   <https://www.gnu.org/licenses/>.  */

#include <unistd.h>

#if _POSIX_MAPPED_FILES

#include <alloc_buffer.h>
#include <shm-directory.h>
#include <string.h>

int
__shm_get_name (struct shmdir_name *result, const char *name, bool sem_prefix)
{
  while (name[0] == '/')
    ++name;
  size_t namelen = strlen (name);

  struct alloc_buffer buffer
    = alloc_buffer_create (result->name, sizeof (result->name));
  alloc_buffer_copy_bytes (&buffer, SHMDIR, strlen (SHMDIR));
  if (sem_prefix)
    alloc_buffer_copy_bytes (&buffer, "sem.", strlen ("sem."));
  alloc_buffer_copy_bytes (&buffer, name, namelen + 1);
  if (namelen == 0 || memchr (name, '/', namelen) != NULL
      || alloc_buffer_has_failed (&buffer))
    return -1;
  return 0;
}

#endif