base/platform_file.h

   1 // Copyright (c) 2012 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
   8 #include "build/build_config.h"
   9 #if defined(OS_WIN)
  10 #include <windows.h>
  11 #endif
  12
  13 #include <string>
  14
  15 #include "base/base_export.h"
  16 #include "base/basictypes.h"
  17 #include "base/file_path.h"
  18 #include "base/time.h"
  19
  20 namespace base {
  21
  22 #if defined(OS_WIN)
  23 typedef HANDLE PlatformFile;
  24 const PlatformFile kInvalidPlatformFileValue = INVALID_HANDLE_VALUE;
  25 #elif defined(OS_POSIX)
  26 typedef int PlatformFile;
  27 const PlatformFile kInvalidPlatformFileValue = -1;
  28 #endif
  29
  30 // PLATFORM_FILE_(OPEN|CREATE).* are mutually exclusive. You should specify
  31 // exactly one of the five (possibly combining with other flags) when opening
  32 // or creating a file.
  33 enum PlatformFileFlags {
  34   PLATFORM_FILE_OPEN = 1 << 0,             // Opens a file, only if it exists.
  35   PLATFORM_FILE_CREATE = 1 << 1,           // Creates a new file, only if it
  36                                            // does not already exist.
  37   PLATFORM_FILE_OPEN_ALWAYS = 1 << 2,      // May create a new file.
  38   PLATFORM_FILE_CREATE_ALWAYS = 1 << 3,    // May overwrite an old file.
  39   PLATFORM_FILE_OPEN_TRUNCATED = 1 << 4,   // Opens a file and truncates it,
  40                                            // only if it exists.
  41   PLATFORM_FILE_READ = 1 << 5,
  42   PLATFORM_FILE_WRITE = 1 << 6,
  43   PLATFORM_FILE_EXCLUSIVE_READ = 1 << 7,   // EXCLUSIVE is opposite of Windows
  44                                            // SHARE
  45   PLATFORM_FILE_EXCLUSIVE_WRITE = 1 << 8,
  46   PLATFORM_FILE_ASYNC = 1 << 9,
  47   PLATFORM_FILE_TEMPORARY = 1 << 10,       // Used on Windows only
  48   PLATFORM_FILE_HIDDEN = 1 << 11,          // Used on Windows only
  49   PLATFORM_FILE_DELETE_ON_CLOSE = 1 << 12,
  50
  51   PLATFORM_FILE_WRITE_ATTRIBUTES = 1 << 13,  // Used on Windows only
  52   PLATFORM_FILE_ENUMERATE = 1 << 14,         // May enumerate directory
  53
  54   PLATFORM_FILE_SHARE_DELETE = 1 << 15,      // Used on Windows only
  55
  56   PLATFORM_FILE_TERMINAL_DEVICE = 1 << 16,   // Serial port flags
  57 };
  58
  59 // PLATFORM_FILE_ERROR_ACCESS_DENIED is returned when a call fails because of
  60 // a filesystem restriction. PLATFORM_FILE_ERROR_SECURITY is returned when a
  61 // browser policy doesn't allow the operation to be executed.
  62 enum PlatformFileError {
  63   PLATFORM_FILE_OK = 0,
  64   PLATFORM_FILE_ERROR_FAILED = -1,
  65   PLATFORM_FILE_ERROR_IN_USE = -2,
  66   PLATFORM_FILE_ERROR_EXISTS = -3,
  67   PLATFORM_FILE_ERROR_NOT_FOUND = -4,
  68   PLATFORM_FILE_ERROR_ACCESS_DENIED = -5,
  69   PLATFORM_FILE_ERROR_TOO_MANY_OPENED = -6,
  70   PLATFORM_FILE_ERROR_NO_MEMORY = -7,
  71   PLATFORM_FILE_ERROR_NO_SPACE = -8,
  72   PLATFORM_FILE_ERROR_NOT_A_DIRECTORY = -9,
  73   PLATFORM_FILE_ERROR_INVALID_OPERATION = -10,
  74   PLATFORM_FILE_ERROR_SECURITY = -11,
  75   PLATFORM_FILE_ERROR_ABORT = -12,
  76   PLATFORM_FILE_ERROR_NOT_A_FILE = -13,
  77   PLATFORM_FILE_ERROR_NOT_EMPTY = -14,
  78   PLATFORM_FILE_ERROR_INVALID_URL = -15,
  79 };
  80
  81 // Used to hold information about a given file.
  82 // If you add more fields to this structure (platform-specific fields are OK),
  83 // make sure to update all functions that use it in file_util_{win|posix}.cc
  84 // too, and the ParamTraits<base::PlatformFileInfo> implementation in
  85 // chrome/common/common_param_traits.cc.
  86 struct BASE_EXPORT PlatformFileInfo {
  87   PlatformFileInfo();
  88   ~PlatformFileInfo();
  89
  90   // The size of the file in bytes.  Undefined when is_directory is true.
  91   int64 size;
  92
  93   // True if the file corresponds to a directory.
  94   bool is_directory;
  95
  96   // True if the file corresponds to a symbolic link.
  97   bool is_symbolic_link;
  98
  99   // The last modified time of a file.
 100   base::Time last_modified;
 101
 102   // The last accessed time of a file.
 103   base::Time last_accessed;
 104
 105   // The creation time of a file.
 106   base::Time creation_time;
 107 };
 108
 109 // Creates or opens the given file. If |created| is provided, it will be set to
 110 // true if a new file was created [or an old one truncated to zero length to
 111 // simulate a new file, which can happen with PLATFORM_FILE_CREATE_ALWAYS], and
 112 // false otherwise.  |error_code| can be NULL.
 113 BASE_EXPORT PlatformFile CreatePlatformFile(const FilePath& name,
 114                                             int flags,
 115                                             bool* created,
 116                                             PlatformFileError* error_code);
 117
 118 // Closes a file handle. Returns |true| on success and |false| otherwise.
 119 BASE_EXPORT bool ClosePlatformFile(PlatformFile file);
 120
 121 // Reads the given number of bytes (or until EOF is reached) starting with the
 122 // given offset. Returns the number of bytes read, or -1 on error. Note that
 123 // this function makes a best effort to read all data on all platforms, so it is
 124 // not intended for stream oriented files but instead for cases when the normal
 125 // expectation is that actually |size| bytes are read unless there is an error.
 126 BASE_EXPORT int ReadPlatformFile(PlatformFile file, int64 offset,
 127                                  char* data, int size);
 128
 129 // Same as above but without seek.
 130 BASE_EXPORT int ReadPlatformFileAtCurrentPos(PlatformFile file,
 131                                              char* data, int size);
 132
 133 // Reads the given number of bytes (or until EOF is reached) starting with the
 134 // given offset, but does not make any effort to read all data on all platforms.
 135 // Returns the number of bytes read, or -1 on error.
 136 BASE_EXPORT int ReadPlatformFileNoBestEffort(PlatformFile file, int64 offset,
 137                                              char* data, int size);
 138
 139 // Writes the given buffer into the file at the given offset, overwritting any
 140 // data that was previously there. Returns the number of bytes written, or -1
 141 // on error. Note that this function makes a best effort to write all data on
 142 // all platforms.
 143 BASE_EXPORT int WritePlatformFile(PlatformFile file, int64 offset,
 144                                   const char* data, int size);
 145
 146 // Save as above but without seek.
 147 BASE_EXPORT int WritePlatformFileAtCurrentPos(PlatformFile file,
 148                                               const char* data, int size);
 149
 150 // Truncates the given file to the given length. If |length| is greater than
 151 // the current size of the file, the file is extended with zeros. If the file
 152 // doesn't exist, |false| is returned.
 153 BASE_EXPORT bool TruncatePlatformFile(PlatformFile file, int64 length);
 154
 155 // Flushes the buffers of the given file.
 156 BASE_EXPORT bool FlushPlatformFile(PlatformFile file);
 157
 158 // Touches the given file.
 159 BASE_EXPORT bool TouchPlatformFile(PlatformFile file,
 160                                    const Time& last_access_time,
 161                                    const Time& last_modified_time);
 162
 163 // Returns some information for the given file.
 164 BASE_EXPORT bool GetPlatformFileInfo(PlatformFile file, PlatformFileInfo* info);
 165
 166 // Use this class to pass ownership of a PlatformFile to a receiver that may or
 167 // may not want to accept it.  This class does not own the storage for the
 168 // PlatformFile.
 169 //
 170 // EXAMPLE:
 171 //
 172 //  void MaybeProcessFile(PassPlatformFile pass_file) {
 173 //    if (...) {
 174 //      PlatformFile file = pass_file.ReleaseValue();
 175 //      // Now, we are responsible for closing |file|.
 176 //    }
 177 //  }
 178 //
 179 //  void OpenAndMaybeProcessFile(const FilePath& path) {
 180 //    PlatformFile file = CreatePlatformFile(path, ...);
 181 //    MaybeProcessFile(PassPlatformFile(&file));
 182 //    if (file != kInvalidPlatformFileValue)
 183 //      ClosePlatformFile(file);
 184 //  }
 185 //
 186 class BASE_EXPORT PassPlatformFile {
 187  public:
 188   explicit PassPlatformFile(PlatformFile* value) : value_(value) {
 189   }
 190
 191   // Called to retrieve the PlatformFile stored in this object.  The caller
 192   // gains ownership of the PlatformFile and is now responsible for closing it.
 193   // Any subsequent calls to this method will return an invalid PlatformFile.
 194   PlatformFile ReleaseValue() {
 195     PlatformFile temp = *value_;
 196     *value_ = kInvalidPlatformFileValue;
 197     return temp;
 198   }
 199
 200  private:
 201   PlatformFile* value_;
 202 };
 203
 204 }  // namespace base
 205
 206 #endif  // BASE_PLATFORM_FILE_H_