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 // PLATFORM_FILE_(OPEN|CREATE).* are mutually exclusive. You should specify
  32 // exactly one of the five (possibly combining with other flags) when opening
  33 // or creating a file.
  34 enum PlatformFileFlags {
  35   PLATFORM_FILE_OPEN = 1,             // Opens a file, only if it exists.
  36   PLATFORM_FILE_CREATE = 2,           // Creates a new file, only if it does not
  37                                       // already exist.
  38   PLATFORM_FILE_OPEN_ALWAYS = 4,      // May create a new file.
  39   PLATFORM_FILE_CREATE_ALWAYS = 8,    // May overwrite an old file.
  40   PLATFORM_FILE_OPEN_TRUNCATED = 16,  // Opens a file and truncates it, only if
  41                                       // it exists.
  42   PLATFORM_FILE_READ = 32,
  43   PLATFORM_FILE_WRITE = 64,
  44   PLATFORM_FILE_EXCLUSIVE_READ = 128,  // EXCLUSIVE is opposite of Windows SHARE
  45   PLATFORM_FILE_EXCLUSIVE_WRITE = 256,
  46   PLATFORM_FILE_ASYNC = 512,
  47   PLATFORM_FILE_TEMPORARY = 1024,       // Used on Windows only
  48   PLATFORM_FILE_HIDDEN = 2048,          // Used on Windows only
  49   PLATFORM_FILE_DELETE_ON_CLOSE = 4096,
  50
  51   PLATFORM_FILE_WRITE_ATTRIBUTES = 8192,  // Used on Windows only
  52   PLATFORM_FILE_ENUMERATE = 16384,  // May enumerate directory
  53
  54   PLATFORM_FILE_SHARE_DELETE = 32768,  // Used on Windows only
  55 };
  56
  57 // PLATFORM_FILE_ERROR_ACCESS_DENIED is returned when a call fails because of
  58 // a filesystem restriction. PLATFORM_FILE_ERROR_SECURITY is returned when a
  59 // browser policy doesn't allow the operation to be executed.
  60 enum PlatformFileError {
  61   PLATFORM_FILE_OK = 0,
  62   PLATFORM_FILE_ERROR_FAILED = -1,
  63   PLATFORM_FILE_ERROR_IN_USE = -2,
  64   PLATFORM_FILE_ERROR_EXISTS = -3,
  65   PLATFORM_FILE_ERROR_NOT_FOUND = -4,
  66   PLATFORM_FILE_ERROR_ACCESS_DENIED = -5,
  67   PLATFORM_FILE_ERROR_TOO_MANY_OPENED = -6,
  68   PLATFORM_FILE_ERROR_NO_MEMORY = -7,
  69   PLATFORM_FILE_ERROR_NO_SPACE = -8,
  70   PLATFORM_FILE_ERROR_NOT_A_DIRECTORY = -9,
  71   PLATFORM_FILE_ERROR_INVALID_OPERATION = -10,
  72   PLATFORM_FILE_ERROR_SECURITY = -11,
  73   PLATFORM_FILE_ERROR_ABORT = -12,
  74   PLATFORM_FILE_ERROR_NOT_A_FILE = -13,
  75   PLATFORM_FILE_ERROR_NOT_EMPTY = -14,
  76   PLATFORM_FILE_ERROR_INVALID_URL = -15,
  77 };
  78
  79 // Used to hold information about a given file.
  80 // If you add more fields to this structure (platform-specific fields are OK),
  81 // make sure to update all functions that use it in file_util_{win|posix}.cc
  82 // too, and the ParamTraits<base::PlatformFileInfo> implementation in
  83 // chrome/common/common_param_traits.cc.
  84 struct BASE_API PlatformFileInfo {
  85   PlatformFileInfo();
  86   ~PlatformFileInfo();
  87
  88   // The size of the file in bytes.  Undefined when is_directory is true.
  89   int64 size;
  90
  91   // True if the file corresponds to a directory.
  92   bool is_directory;
  93
  94   // True if the file corresponds to a symbolic link.
  95   bool is_symbolic_link;
  96
  97   // The last modified time of a file.
  98   base::Time last_modified;
  99
 100   // The last accessed time of a file.
 101   base::Time last_accessed;
 102
 103   // The creation time of a file.
 104   base::Time creation_time;
 105 };
 106
 107 // Creates or opens the given file. If |created| is provided, it will be set to
 108 // true if a new file was created [or an old one truncated to zero length to
 109 // simulate a new file, which can happen with PLATFORM_FILE_CREATE_ALWAYS], and
 110 // false otherwise.  |error_code| can be NULL.
 111 BASE_API PlatformFile CreatePlatformFile(const FilePath& name,
 112                                          int flags,
 113                                          bool* created,
 114                                          PlatformFileError* error_code);
 115
 116 // Closes a file handle. Returns |true| on success and |false| otherwise.
 117 BASE_API bool ClosePlatformFile(PlatformFile file);
 118
 119 // Reads the given number of bytes (or until EOF is reached) starting with the
 120 // given offset. Returns the number of bytes read, or -1 on error.
 121 BASE_API int ReadPlatformFile(PlatformFile file, int64 offset,
 122                               char* data, int size);
 123
 124 // Writes the given buffer into the file at the given offset, overwritting any
 125 // data that was previously there. Returns the number of bytes written, or -1
 126 // on error.
 127 BASE_API int WritePlatformFile(PlatformFile file, int64 offset,
 128                                const char* data, int size);
 129
 130 // Truncates the given file to the given length. If |length| is greater than
 131 // the current size of the file, the file is extended with zeros. If the file
 132 // doesn't exist, |false| is returned.
 133 BASE_API bool TruncatePlatformFile(PlatformFile file, int64 length);
 134
 135 // Flushes the buffers of the given file.
 136 BASE_API bool FlushPlatformFile(PlatformFile file);
 137
 138 // Touches the given file.
 139 BASE_API bool TouchPlatformFile(PlatformFile file, const Time& last_access_time,
 140                                 const Time& last_modified_time);
 141
 142 // Returns some information for the given file.
 143 BASE_API bool GetPlatformFileInfo(PlatformFile file, PlatformFileInfo* info);
 144
 145 // Use this class to pass ownership of a PlatformFile to a receiver that may or
 146 // may not want to accept it.  This class does not own the storage for the
 147 // PlatformFile.
 148 //
 149 // EXAMPLE:
 150 //
 151 //  void MaybeProcessFile(PassPlatformFile pass_file) {
 152 //    if (...) {
 153 //      PlatformFile file = pass_file.ReleaseValue();
 154 //      // Now, we are responsible for closing |file|.
 155 //    }
 156 //  }
 157 //
 158 //  void OpenAndMaybeProcessFile(const FilePath& path) {
 159 //    PlatformFile file = CreatePlatformFile(path, ...);
 160 //    MaybeProcessFile(PassPlatformFile(&file));
 161 //    if (file != kInvalidPlatformFileValue)
 162 //      ClosePlatformFile(file);
 163 //  }
 164 //
 165 class BASE_API PassPlatformFile {
 166  public:
 167   explicit PassPlatformFile(PlatformFile* value) : value_(value) {
 168   }
 169
 170   // Called to retrieve the PlatformFile stored in this object.  The caller
 171   // gains ownership of the PlatformFile and is now responsible for closing it.
 172   // Any subsequent calls to this method will return an invalid PlatformFile.
 173   PlatformFile ReleaseValue() {
 174     PlatformFile temp = *value_;
 175     *value_ = kInvalidPlatformFileValue;
 176     return temp;
 177   }
 178
 179  private:
 180   PlatformFile* value_;
 181 };
 182
 183 }  // namespace base
 184
 185 #endif  // BASE_PLATFORM_FILE_H_