ceph/src/common/safe_io.h

   1 // -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
   2 // vim: ts=8 sw=2 smarttab
   3 /*
   4  * Ceph - scalable distributed file system
   5  *
   6  * Copyright (C) 2011 New Dream Network
   7  *
   8  * This is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU Lesser General Public
  10  * License version 2.1, as published by the Free Software
  11  * Foundation.  See file COPYING.
  12  *
  13  */
  14
  15 #ifndef CEPH_SAFE_IO
  16 #define CEPH_SAFE_IO
  17
  18 #include "common/compiler_extensions.h"
  19 #include <sys/types.h>
  20
  21 #ifdef __cplusplus
  22 extern "C" {
  23 #endif
  24
  25   /*
  26    * Safe functions wrapping the raw read() and write() libc functions.
  27    * These retry on EINTR, and on error return -errno instead of returning
  28    * -1 and setting errno).
  29    */
  30   ssize_t safe_read(int fd, void *buf, size_t count)
  31       WARN_UNUSED_RESULT;
  32   ssize_t safe_write(int fd, const void *buf, size_t count)
  33       WARN_UNUSED_RESULT;
  34   ssize_t safe_pread(int fd, void *buf, size_t count, off_t offset)
  35       WARN_UNUSED_RESULT;
  36   ssize_t safe_pwrite(int fd, const void *buf, size_t count, off_t offset)
  37       WARN_UNUSED_RESULT;
  38 #ifdef CEPH_HAVE_SPLICE
  39   /*
  40    * Similar to the above (non-exact version) and below (exact version).
  41    * See splice(2) for parameter descriptions.
  42    */
  43   ssize_t safe_splice(int fd_in, off_t *off_in, int fd_out, off_t *off_out,
  44                       size_t len, unsigned int flags)
  45     WARN_UNUSED_RESULT;
  46   ssize_t safe_splice_exact(int fd_in, off_t *off_in, int fd_out,
  47                             off_t *off_out, size_t len, unsigned int flags)
  48     WARN_UNUSED_RESULT;
  49 #endif
  50
  51   /*
  52    * Same as the above functions, but return -EDOM unless exactly the requested
  53    * number of bytes can be read.
  54    */
  55   ssize_t safe_read_exact(int fd, void *buf, size_t count)
  56       WARN_UNUSED_RESULT;
  57   ssize_t safe_pread_exact(int fd, void *buf, size_t count, off_t offset)
  58       WARN_UNUSED_RESULT;
  59
  60
  61   /*
  62    * Safe functions to read and write an entire file.
  63    */
  64   int safe_write_file(const char *base, const char *file,
  65                         const char *val, size_t vallen);
  66   int safe_read_file(const char *base, const char *file,
  67                        char *val, size_t vallen);
  68
  69 #ifdef __cplusplus
  70 }
  71 #endif
  72
  73 #endif