| /* Header for directory for shm/sem files. |
| Copyright (C) 2014-2018 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 |
| <http://www.gnu.org/licenses/>. */ |
| |
| #ifndef _SHM_DIRECTORY_H |
| |
| #include <errno.h> |
| #include <limits.h> |
| #include <stdbool.h> |
| #include <stdlib.h> |
| #include <string.h> |
| |
| extern const char *__shm_directory (size_t *len); |
| |
| /* This defines local variables SHM_DIR and SHM_DIRLEN, giving the |
| directory prefix (with trailing slash) and length (not including '\0' |
| terminator) of the directory used for shm files. If that cannot be |
| determined, it sets errno to ENOSYS and returns RETVAL_FOR_INVALID. |
| |
| This uses the local variable NAME as an lvalue, and increments it past |
| any leading slashes. It then defines the local variable NAMELEN, giving |
| strlen (NAME) + 1. If NAME is invalid, it sets errno to |
| ERRNO_FOR_INVALID and returns RETVAL_FOR_INVALID. Finally, it defines |
| the local variable SHM_NAME, giving the absolute file name of the shm |
| file corresponding to NAME. PREFIX is a string constant used as a |
| prefix on NAME. */ |
| |
| #define SHM_GET_NAME(errno_for_invalid, retval_for_invalid, prefix) \ |
| size_t shm_dirlen; \ |
| const char *shm_dir = __shm_directory (&shm_dirlen); \ |
| /* If we don't know what directory to use, there is nothing we can do. */ \ |
| if (__glibc_unlikely (shm_dir == NULL)) \ |
| { \ |
| __set_errno (ENOSYS); \ |
| return retval_for_invalid; \ |
| } \ |
| /* Construct the filename. */ \ |
| while (name[0] == '/') \ |
| ++name; \ |
| size_t namelen = strlen (name) + 1; \ |
| /* Validate the filename. */ \ |
| if (namelen == 1 || namelen >= NAME_MAX || strchr (name, '/') != NULL) \ |
| { \ |
| __set_errno (errno_for_invalid); \ |
| return retval_for_invalid; \ |
| } \ |
| char *shm_name = __alloca (shm_dirlen + sizeof prefix - 1 + namelen); \ |
| __mempcpy (__mempcpy (__mempcpy (shm_name, shm_dir, shm_dirlen), \ |
| prefix, sizeof prefix - 1), \ |
| name, namelen) |
| |
| #endif /* shm-directory.h */ |