From 78e21c5df674e037d06e86c5d4cb95818c8f6b8c Mon Sep 17 00:00:00 2001 From: Roland McGrath Date: Thu, 11 Dec 2014 14:15:51 -0800 Subject: Refactor shm_{open,unlink} code to separate Linux-specific directory choice from POSIX-generic code. --- sysdeps/posix/shm-directory.h | 63 +++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 63 insertions(+) create mode 100644 sysdeps/posix/shm-directory.h (limited to 'sysdeps/posix/shm-directory.h') diff --git a/sysdeps/posix/shm-directory.h b/sysdeps/posix/shm-directory.h new file mode 100644 index 0000000000..1c4d965b28 --- /dev/null +++ b/sysdeps/posix/shm-directory.h @@ -0,0 +1,63 @@ +/* Header for directory for shm/sem files. + Copyright (C) 2014 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 + . */ + +#ifndef _SHM_DIRECTORY_H + +#include +#include +#include +#include +#include + +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. */ + +#define SHM_GET_NAME(errno_for_invalid, retval_for_invalid) \ + 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 + namelen); \ + __mempcpy (__mempcpy (shm_name, shm_dir, shm_dirlen), name, namelen) + +#endif /* shm-directory.h */ -- cgit 1.4.1