cutils/fs.h

   1 /*
   2  * Copyright (C) 2012 The Android Open Source Project
   3  *
   4  * Licensed under the Apache License, Version 2.0 (the "License");
   5  * you may not use this file except in compliance with the License.
   6  * You may obtain a copy of the License at
   7  *
   8  *      http://www.apache.org/licenses/LICENSE-2.0
   9  *
  10  * Unless required by applicable law or agreed to in writing, software
  11  * distributed under the License is distributed on an "AS IS" BASIS,
  12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  13  * See the License for the specific language governing permissions and
  14  * limitations under the License.
  15  */
  16
  17 #ifndef __CUTILS_FS_H
  18 #define __CUTILS_FS_H
  19
  20 #include <sys/types.h>
  21
  22 /*
  23  * TEMP_FAILURE_RETRY is defined by some, but not all, versions of
  24  * <unistd.h>. (Alas, it is not as standard as we'd hoped!) So, if it's
  25  * not already defined, then define it here.
  26  */
  27 #ifndef TEMP_FAILURE_RETRY
  28 /* Used to retry syscalls that can return EINTR. */
  29 #define TEMP_FAILURE_RETRY(exp) ({         \
  30     typeof (exp) _rc;                      \
  31     do {                                   \
  32         _rc = (exp);                       \
  33     } while (_rc == -1 && errno == EINTR); \
  34     _rc; })
  35 #endif
  36
  37 #ifdef __cplusplus
  38 extern "C" {
  39 #endif
  40
  41 /*
  42  * Ensure that directory exists with given mode and owners.
  43  */
  44 extern int fs_prepare_dir(const char* path, mode_t mode, uid_t uid, gid_t gid);
  45
  46 /*
  47  * Read single plaintext integer from given file, correctly handling files
  48  * partially written with fs_write_atomic_int().
  49  */
  50 extern int fs_read_atomic_int(const char* path, int* value);
  51
  52 /*
  53  * Write single plaintext integer to given file, creating backup while
  54  * in progress.
  55  */
  56 extern int fs_write_atomic_int(const char* path, int value);
  57
  58 #ifdef __cplusplus
  59 }
  60 #endif
  61
  62 #endif /* __CUTILS_FS_H */