base/platform_file.h

   1 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef BASE_PLATFORM_FILE_H_
   6 #define BASE_PLATFORM_FILE_H_
   7 #pragma once
   8
   9 #include "build/build_config.h"
  10 #if defined(OS_WIN)
  11 #include <windows.h>
  12 #endif
  13
  14 #include <string>
  15
  16 #include "base/base_api.h"
  17 #include "base/basictypes.h"
  18 #include "base/file_path.h"
  19 #include "base/time.h"
  20
  21 namespace base {
  22
  23 #if defined(OS_WIN)
  24 typedef HANDLE PlatformFile;
  25 const PlatformFile kInvalidPlatformFileValue = INVALID_HANDLE_VALUE;
  26 #elif defined(OS_POSIX)
  27 typedef int PlatformFile;
  28 const PlatformFile kInvalidPlatformFileValue = -1;
  29 #endif
  30
  31 enum PlatformFileFlags {
  32   PLATFORM_FILE_OPEN = 1,
  33   PLATFORM_FILE_CREATE = 2,
  34   PLATFORM_FILE_OPEN_ALWAYS = 4,    // May create a new file.
  35   PLATFORM_FILE_CREATE_ALWAYS = 8,  // May overwrite an old file.
  36   PLATFORM_FILE_READ = 16,
  37   PLATFORM_FILE_WRITE = 32,
  38   PLATFORM_FILE_EXCLUSIVE_READ = 64,  // EXCLUSIVE is opposite of Windows SHARE
  39   PLATFORM_FILE_EXCLUSIVE_WRITE = 128,
  40   PLATFORM_FILE_ASYNC = 256,
  41   PLATFORM_FILE_TEMPORARY = 512,        // Used on Windows only
  42   PLATFORM_FILE_HIDDEN = 1024,          // Used on Windows only
  43   PLATFORM_FILE_DELETE_ON_CLOSE = 2048,
  44   PLATFORM_FILE_TRUNCATE = 4096,
  45   PLATFORM_FILE_WRITE_ATTRIBUTES = 8192,  // Used on Windows only
  46   PLATFORM_FILE_ENUMERATE = 16384,  // May enumerate directory
  47 };
  48
  49 // PLATFORM_FILE_ERROR_ACCESS_DENIED is returned when a call fails because of
  50 // a filesystem restriction. PLATFORM_FILE_ERROR_SECURITY is returned when a
  51 // browser policy doesn't allow the operation to be executed.
  52 enum PlatformFileError {
  53   PLATFORM_FILE_OK = 0,
  54   PLATFORM_FILE_ERROR_FAILED = -1,
  55   PLATFORM_FILE_ERROR_IN_USE = -2,
  56   PLATFORM_FILE_ERROR_EXISTS = -3,
  57   PLATFORM_FILE_ERROR_NOT_FOUND = -4,
  58   PLATFORM_FILE_ERROR_ACCESS_DENIED = -5,
  59   PLATFORM_FILE_ERROR_TOO_MANY_OPENED = -6,
  60   PLATFORM_FILE_ERROR_NO_MEMORY = -7,
  61   PLATFORM_FILE_ERROR_NO_SPACE = -8,
  62   PLATFORM_FILE_ERROR_NOT_A_DIRECTORY = -9,
  63   PLATFORM_FILE_ERROR_INVALID_OPERATION = -10,
  64   PLATFORM_FILE_ERROR_SECURITY = -11,
  65   PLATFORM_FILE_ERROR_ABORT = -12,
  66   PLATFORM_FILE_ERROR_NOT_A_FILE = -13,
  67   PLATFORM_FILE_ERROR_NOT_EMPTY = -14,
  68 };
  69
  70 // Used to hold information about a given file.
  71 // If you add more fields to this structure (platform-specific fields are OK),
  72 // make sure to update all functions that use it in file_util_{win|posix}.cc
  73 // too, and the ParamTraits<base::PlatformFileInfo> implementation in
  74 // chrome/common/common_param_traits.cc.
  75 struct BASE_API PlatformFileInfo {
  76   PlatformFileInfo();
  77   ~PlatformFileInfo();
  78
  79   // The size of the file in bytes.  Undefined when is_directory is true.
  80   int64 size;
  81
  82   // True if the file corresponds to a directory.
  83   bool is_directory;
  84
  85   // True if the file corresponds to a symbolic link.
  86   bool is_symbolic_link;
  87
  88   // The last modified time of a file.
  89   base::Time last_modified;
  90
  91   // The last accessed time of a file.
  92   base::Time last_accessed;
  93
  94   // The creation time of a file.
  95   base::Time creation_time;
  96 };
  97
  98 // Creates or opens the given file. If PLATFORM_FILE_OPEN_ALWAYS is used, and
  99 // |created| is provided, |created| will be set to true if the file was created
 100 // or to false in case the file was just opened. |error_code| can be NULL.
 101 BASE_API PlatformFile CreatePlatformFile(const FilePath& name,
 102                                          int flags,
 103                                          bool* created,
 104                                          PlatformFileError* error_code);
 105
 106 // Closes a file handle. Returns |true| on success and |false| otherwise.
 107 BASE_API bool ClosePlatformFile(PlatformFile file);
 108
 109 // Reads the given number of bytes (or until EOF is reached) starting with the
 110 // given offset. Returns the number of bytes read, or -1 on error.
 111 BASE_API int ReadPlatformFile(PlatformFile file, int64 offset,
 112                               char* data, int size);
 113
 114 // Writes the given buffer into the file at the given offset, overwritting any
 115 // data that was previously there. Returns the number of bytes written, or -1
 116 // on error.
 117 BASE_API int WritePlatformFile(PlatformFile file, int64 offset,
 118                                const char* data, int size);
 119
 120 // Truncates the given file to the given length. If |length| is greater than
 121 // the current size of the file, the file is extended with zeros. If the file
 122 // doesn't exist, |false| is returned.
 123 BASE_API bool TruncatePlatformFile(PlatformFile file, int64 length);
 124
 125 // Flushes the buffers of the given file.
 126 BASE_API bool FlushPlatformFile(PlatformFile file);
 127
 128 // Touches the given file.
 129 BASE_API bool TouchPlatformFile(PlatformFile file, const Time& last_access_time,
 130                                 const Time& last_modified_time);
 131
 132 // Returns some information for the given file.
 133 BASE_API bool GetPlatformFileInfo(PlatformFile file, PlatformFileInfo* info);
 134
 135 // Use this class to pass ownership of a PlatformFile to a receiver that may or
 136 // may not want to accept it.  This class does not own the storage for the
 137 // PlatformFile.
 138 //
 139 // EXAMPLE:
 140 //
 141 //  void MaybeProcessFile(PassPlatformFile pass_file) {
 142 //    if (...) {
 143 //      PlatformFile file = pass_file.ReleaseValue();
 144 //      // Now, we are responsible for closing |file|.
 145 //    }
 146 //  }
 147 //
 148 //  void OpenAndMaybeProcessFile(const FilePath& path) {
 149 //    PlatformFile file = CreatePlatformFile(path, ...);
 150 //    MaybeProcessFile(PassPlatformFile(&file));
 151 //    if (file != kInvalidPlatformFileValue)
 152 //      ClosePlatformFile(file);
 153 //  }
 154 //
 155 class BASE_API PassPlatformFile {
 156  public:
 157   explicit PassPlatformFile(PlatformFile* value) : value_(value) {
 158   }
 159
 160   // Called to retrieve the PlatformFile stored in this object.  The caller
 161   // gains ownership of the PlatformFile and is now responsible for closing it.
 162   // Any subsequent calls to this method will return an invalid PlatformFile.
 163   PlatformFile ReleaseValue() {
 164     PlatformFile temp = *value_;
 165     *value_ = kInvalidPlatformFileValue;
 166     return temp;
 167   }
 168
 169  private:
 170   PlatformFile* value_;
 171 };
 172
 173 }  // namespace base
 174
 175 #endif  // BASE_PLATFORM_FILE_H_