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/files/file_path.h" 18 #include "base/time/time.h" 19 20 namespace base { 21 22 // *************************************************************************** 23 // ***** Don't use anything from this file anymore. It is being removed! 24 // ***** Use base/files/base_file.h instead 25 // *************************************************************************** 26 27 // PLATFORM_FILE_(OPEN|CREATE).* are mutually exclusive. You should specify 28 // exactly one of the five (possibly combining with other flags) when opening 29 // or creating a file. 30 // PLATFORM_FILE_(WRITE|APPEND) are mutually exclusive. This is so that APPEND 31 // behavior will be consistent with O_APPEND on POSIX. 32 // PLATFORM_FILE_EXCLUSIVE_(READ|WRITE) only grant exclusive access to the file 33 // on creation on POSIX; for existing files, consider using LockPlatformFile(). 34 enum PlatformFileFlags { 35 PLATFORM_FILE_OPEN = 1 << 0, // Opens a file, only if it exists. 36 PLATFORM_FILE_CREATE = 1 << 1, // Creates a new file, only if it 37 // does not already exist. 38 PLATFORM_FILE_OPEN_ALWAYS = 1 << 2, // May create a new file. 39 PLATFORM_FILE_CREATE_ALWAYS = 1 << 3, // May overwrite an old file. 40 PLATFORM_FILE_OPEN_TRUNCATED = 1 << 4, // Opens a file and truncates it, 41 // only if it exists. 42 PLATFORM_FILE_READ = 1 << 5, 43 PLATFORM_FILE_WRITE = 1 << 6, 44 PLATFORM_FILE_APPEND = 1 << 7, 45 PLATFORM_FILE_EXCLUSIVE_READ = 1 << 8, // EXCLUSIVE is opposite of Windows 46 // SHARE 47 PLATFORM_FILE_EXCLUSIVE_WRITE = 1 << 9, 48 PLATFORM_FILE_ASYNC = 1 << 10, 49 PLATFORM_FILE_TEMPORARY = 1 << 11, // Used on Windows only 50 PLATFORM_FILE_HIDDEN = 1 << 12, // Used on Windows only 51 PLATFORM_FILE_DELETE_ON_CLOSE = 1 << 13, 52 53 PLATFORM_FILE_WRITE_ATTRIBUTES = 1 << 14, // Used on Windows only 54 55 PLATFORM_FILE_SHARE_DELETE = 1 << 15, // Used on Windows only 56 57 PLATFORM_FILE_TERMINAL_DEVICE = 1 << 16, // Serial port flags 58 PLATFORM_FILE_BACKUP_SEMANTICS = 1 << 17, // Used on Windows only 59 60 PLATFORM_FILE_EXECUTE = 1 << 18, // Used on Windows only 61 }; 62 63 // This enum has been recorded in multiple histograms. If the order of the 64 // fields needs to change, please ensure that those histograms are obsolete or 65 // have been moved to a different enum. 66 // 67 // PLATFORM_FILE_ERROR_ACCESS_DENIED is returned when a call fails because of 68 // a filesystem restriction. PLATFORM_FILE_ERROR_SECURITY is returned when a 69 // browser policy doesn't allow the operation to be executed. 70 enum PlatformFileError { 71 PLATFORM_FILE_OK = 0, 72 PLATFORM_FILE_ERROR_FAILED = -1, 73 PLATFORM_FILE_ERROR_IN_USE = -2, 74 PLATFORM_FILE_ERROR_EXISTS = -3, 75 PLATFORM_FILE_ERROR_NOT_FOUND = -4, 76 PLATFORM_FILE_ERROR_ACCESS_DENIED = -5, 77 PLATFORM_FILE_ERROR_TOO_MANY_OPENED = -6, 78 PLATFORM_FILE_ERROR_NO_MEMORY = -7, 79 PLATFORM_FILE_ERROR_NO_SPACE = -8, 80 PLATFORM_FILE_ERROR_NOT_A_DIRECTORY = -9, 81 PLATFORM_FILE_ERROR_INVALID_OPERATION = -10, 82 PLATFORM_FILE_ERROR_SECURITY = -11, 83 PLATFORM_FILE_ERROR_ABORT = -12, 84 PLATFORM_FILE_ERROR_NOT_A_FILE = -13, 85 PLATFORM_FILE_ERROR_NOT_EMPTY = -14, 86 PLATFORM_FILE_ERROR_INVALID_URL = -15, 87 PLATFORM_FILE_ERROR_IO = -16, 88 // Put new entries here and increment PLATFORM_FILE_ERROR_MAX. 89 PLATFORM_FILE_ERROR_MAX = -17 90 }; 91 92 // This explicit mapping matches both FILE_ on Windows and SEEK_ on Linux. 93 enum PlatformFileWhence { 94 PLATFORM_FILE_FROM_BEGIN = 0, 95 PLATFORM_FILE_FROM_CURRENT = 1, 96 PLATFORM_FILE_FROM_END = 2 97 }; 98 99 // Used to hold information about a given file. 100 // If you add more fields to this structure (platform-specific fields are OK), 101 // make sure to update all functions that use it in file_util_{win|posix}.cc 102 // too, and the ParamTraits<base::PlatformFileInfo> implementation in 103 // chrome/common/common_param_traits.cc. 104 struct BASE_EXPORT PlatformFileInfo { 105 PlatformFileInfo(); 106 ~PlatformFileInfo(); 107 108 // The size of the file in bytes. Undefined when is_directory is true. 109 int64 size; 110 111 // True if the file corresponds to a directory. 112 bool is_directory; 113 114 // True if the file corresponds to a symbolic link. 115 bool is_symbolic_link; 116 117 // The last modified time of a file. 118 base::Time last_modified; 119 120 // The last accessed time of a file. 121 base::Time last_accessed; 122 123 // The creation time of a file. 124 base::Time creation_time; 125 }; 126 127 #if defined(OS_WIN) 128 typedef HANDLE PlatformFile; 129 const PlatformFile kInvalidPlatformFileValue = INVALID_HANDLE_VALUE; 130 BASE_EXPORT PlatformFileError LastErrorToPlatformFileError(DWORD last_error); 131 #elif defined(OS_POSIX) 132 typedef int PlatformFile; 133 const PlatformFile kInvalidPlatformFileValue = -1; 134 BASE_EXPORT PlatformFileError ErrnoToPlatformFileError(int saved_errno); 135 #endif 136 137 // Creates or opens the given file. If |created| is provided, it will be set to 138 // true if a new file was created [or an old one truncated to zero length to 139 // simulate a new file, which can happen with PLATFORM_FILE_CREATE_ALWAYS], and 140 // false otherwise. |error| can be NULL. 141 // 142 // This function fails with 'access denied' if the |name| contains path 143 // traversal ('..') components. 144 BASE_EXPORT PlatformFile CreatePlatformFile(const FilePath& name, 145 int flags, 146 bool* created, 147 PlatformFileError* error); 148 149 // Same as CreatePlatformFile but allows paths with traversal (like \..\) 150 // components. Use only with extreme care. 151 BASE_EXPORT PlatformFile CreatePlatformFileUnsafe(const FilePath& name, 152 int flags, 153 bool* created, 154 PlatformFileError* error); 155 156 BASE_EXPORT FILE* FdopenPlatformFile(PlatformFile file, const char* mode); 157 158 // Closes a file handle. Returns |true| on success and |false| otherwise. 159 BASE_EXPORT bool ClosePlatformFile(PlatformFile file); 160 161 // Changes current position in the file to an |offset| relative to an origin 162 // defined by |whence|. Returns the resultant current position in the file 163 // (relative to the start) or -1 in case of error. 164 BASE_EXPORT int64 SeekPlatformFile(PlatformFile file, 165 PlatformFileWhence whence, 166 int64 offset); 167 168 // Reads the given number of bytes (or until EOF is reached) starting with the 169 // given offset. Returns the number of bytes read, or -1 on error. Note that 170 // this function makes a best effort to read all data on all platforms, so it is 171 // not intended for stream oriented files but instead for cases when the normal 172 // expectation is that actually |size| bytes are read unless there is an error. 173 BASE_EXPORT int ReadPlatformFile(PlatformFile file, int64 offset, 174 char* data, int size); 175 176 // Same as above but without seek. 177 BASE_EXPORT int ReadPlatformFileAtCurrentPos(PlatformFile file, 178 char* data, int size); 179 180 // Reads the given number of bytes (or until EOF is reached) starting with the 181 // given offset, but does not make any effort to read all data on all platforms. 182 // Returns the number of bytes read, or -1 on error. 183 BASE_EXPORT int ReadPlatformFileNoBestEffort(PlatformFile file, int64 offset, 184 char* data, int size); 185 186 // Same as above but without seek. 187 BASE_EXPORT int ReadPlatformFileCurPosNoBestEffort(PlatformFile file, 188 char* data, int size); 189 190 // Writes the given buffer into the file at the given offset, overwritting any 191 // data that was previously there. Returns the number of bytes written, or -1 192 // on error. Note that this function makes a best effort to write all data on 193 // all platforms. 194 // Ignores the offset and writes to the end of the file if the file was opened 195 // with PLATFORM_FILE_APPEND. 196 BASE_EXPORT int WritePlatformFile(PlatformFile file, int64 offset, 197 const char* data, int size); 198 199 // Save as above but without seek. 200 BASE_EXPORT int WritePlatformFileAtCurrentPos(PlatformFile file, 201 const char* data, int size); 202 203 // Save as above but does not make any effort to write all data on all 204 // platforms. Returns the number of bytes written, or -1 on error. 205 BASE_EXPORT int WritePlatformFileCurPosNoBestEffort(PlatformFile file, 206 const char* data, int size); 207 208 // Truncates the given file to the given length. If |length| is greater than 209 // the current size of the file, the file is extended with zeros. If the file 210 // doesn't exist, |false| is returned. 211 BASE_EXPORT bool TruncatePlatformFile(PlatformFile file, int64 length); 212 213 // Flushes the buffers of the given file. 214 BASE_EXPORT bool FlushPlatformFile(PlatformFile file); 215 216 // Touches the given file. 217 BASE_EXPORT bool TouchPlatformFile(PlatformFile file, 218 const Time& last_access_time, 219 const Time& last_modified_time); 220 221 // Returns some information for the given file. 222 BASE_EXPORT bool GetPlatformFileInfo(PlatformFile file, PlatformFileInfo* info); 223 224 // Attempts to take an exclusive write lock on the file. Returns immediately 225 // (i.e. does not wait for another process to unlock the file). If the lock 226 // was obtained, the result will be PLATFORM_FILE_OK. A lock only guarantees 227 // that other processes may not also take a lock on the same file with the 228 // same API - it may still be opened, renamed, unlinked, etc. 229 // 230 // Common semantics: 231 // * Locks are held by processes, but not inherited by child processes. 232 // * Locks are released by the OS on file handle close or process termination. 233 // * Locks are reliable only on local filesystems. 234 // * Duplicated file handles may also write to locked files. 235 // Windows-specific semantics: 236 // * Locks are mandatory for read/write APIs, advisory for mapping APIs. 237 // * Within a process, locking the same file (by the same or new handle) 238 // will fail. 239 // POSIX-specific semantics: 240 // * Locks are advisory only. 241 // * Within a process, locking the same file (by the same or new handle) 242 // will succeed. 243 // * Closing any descriptor on a given file releases the lock. 244 BASE_EXPORT PlatformFileError LockPlatformFile(PlatformFile file); 245 246 // Unlock a file previously locked with LockPlatformFile. 247 BASE_EXPORT PlatformFileError UnlockPlatformFile(PlatformFile file); 248 249 // Use this class to pass ownership of a PlatformFile to a receiver that may or 250 // may not want to accept it. This class does not own the storage for the 251 // PlatformFile. 252 // 253 // EXAMPLE: 254 // 255 // void MaybeProcessFile(PassPlatformFile pass_file) { 256 // if (...) { 257 // PlatformFile file = pass_file.ReleaseValue(); 258 // // Now, we are responsible for closing |file|. 259 // } 260 // } 261 // 262 // void OpenAndMaybeProcessFile(const FilePath& path) { 263 // PlatformFile file = CreatePlatformFile(path, ...); 264 // MaybeProcessFile(PassPlatformFile(&file)); 265 // if (file != kInvalidPlatformFileValue) 266 // ClosePlatformFile(file); 267 // } 268 // 269 class BASE_EXPORT PassPlatformFile { 270 public: 271 explicit PassPlatformFile(PlatformFile* value) : value_(value) { 272 } 273 274 // Called to retrieve the PlatformFile stored in this object. The caller 275 // gains ownership of the PlatformFile and is now responsible for closing it. 276 // Any subsequent calls to this method will return an invalid PlatformFile. 277 PlatformFile ReleaseValue() { 278 PlatformFile temp = *value_; 279 *value_ = kInvalidPlatformFileValue; 280 return temp; 281 } 282 283 private: 284 PlatformFile* value_; 285 }; 286 287 } // namespace base 288 289 #endif // BASE_PLATFORM_FILE_H_ 290
