The Tor Browser / file revision

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.

 // Use of this source code is governed by a BSD-style license that can be

 // found in the LICENSE file.

 #ifndef BASE_PLATFORM_FILE_H_

 #define BASE_PLATFORM_FILE_H_

 #include "build/build_config.h"

 #if defined(OS_WIN)

 #include <windows.h>

 #endif

 #include <string>

 #include "base/base_export.h"

 #include "base/basictypes.h"

 #include "base/files/file_path.h"

 #include "base/time/time.h"

 namespace base {

 // PLATFORM_FILE_(OPEN|CREATE).* are mutually exclusive. You should specify

 // exactly one of the five (possibly combining with other flags) when opening

 // or creating a file.

 // PLATFORM_FILE_(WRITE|APPEND) are mutually exclusive. This is so that APPEND

 // behavior will be consistent with O_APPEND on POSIX.

 enum PlatformFileFlags {

   PLATFORM_FILE_OPEN = 1 << 0,             // Opens a file, only if it exists.

   PLATFORM_FILE_CREATE = 1 << 1,           // Creates a new file, only if it

                                            // does not already exist.

   PLATFORM_FILE_OPEN_ALWAYS = 1 << 2,      // May create a new file.

   PLATFORM_FILE_CREATE_ALWAYS = 1 << 3,    // May overwrite an old file.

   PLATFORM_FILE_OPEN_TRUNCATED = 1 << 4,   // Opens a file and truncates it,

                                            // only if it exists.

   PLATFORM_FILE_READ = 1 << 5,

   PLATFORM_FILE_WRITE = 1 << 6,

   PLATFORM_FILE_APPEND = 1 << 7,

   PLATFORM_FILE_EXCLUSIVE_READ = 1 << 8,   // EXCLUSIVE is opposite of Windows

                                            // SHARE

   PLATFORM_FILE_EXCLUSIVE_WRITE = 1 << 9,

   PLATFORM_FILE_ASYNC = 1 << 10,

   PLATFORM_FILE_TEMPORARY = 1 << 11,       // Used on Windows only

   PLATFORM_FILE_HIDDEN = 1 << 12,          // Used on Windows only

   PLATFORM_FILE_DELETE_ON_CLOSE = 1 << 13,

   PLATFORM_FILE_WRITE_ATTRIBUTES = 1 << 14,  // Used on Windows only

   PLATFORM_FILE_ENUMERATE = 1 << 15,         // May enumerate directory

   PLATFORM_FILE_SHARE_DELETE = 1 << 16,      // Used on Windows only

   PLATFORM_FILE_TERMINAL_DEVICE = 1 << 17,   // Serial port flags

   PLATFORM_FILE_BACKUP_SEMANTICS = 1 << 18,  // Used on Windows only

   PLATFORM_FILE_EXECUTE = 1 << 19,           // Used on Windows only

 };

 // PLATFORM_FILE_ERROR_ACCESS_DENIED is returned when a call fails because of

 // a filesystem restriction. PLATFORM_FILE_ERROR_SECURITY is returned when a

 // browser policy doesn't allow the operation to be executed.

 enum PlatformFileError {

   PLATFORM_FILE_OK = 0,

   PLATFORM_FILE_ERROR_FAILED = -1,

   PLATFORM_FILE_ERROR_IN_USE = -2,

   PLATFORM_FILE_ERROR_EXISTS = -3,

   PLATFORM_FILE_ERROR_NOT_FOUND = -4,

   PLATFORM_FILE_ERROR_ACCESS_DENIED = -5,

   PLATFORM_FILE_ERROR_TOO_MANY_OPENED = -6,

   PLATFORM_FILE_ERROR_NO_MEMORY = -7,

   PLATFORM_FILE_ERROR_NO_SPACE = -8,

   PLATFORM_FILE_ERROR_NOT_A_DIRECTORY = -9,

   PLATFORM_FILE_ERROR_INVALID_OPERATION = -10,

   PLATFORM_FILE_ERROR_SECURITY = -11,

   PLATFORM_FILE_ERROR_ABORT = -12,

   PLATFORM_FILE_ERROR_NOT_A_FILE = -13,

   PLATFORM_FILE_ERROR_NOT_EMPTY = -14,

   PLATFORM_FILE_ERROR_INVALID_URL = -15,

   PLATFORM_FILE_ERROR_IO = -16,

   // Put new entries here and increment PLATFORM_FILE_ERROR_MAX.

   PLATFORM_FILE_ERROR_MAX = -17

 };

 // This explicit mapping matches both FILE_ on Windows and SEEK_ on Linux.

 enum PlatformFileWhence {

   PLATFORM_FILE_FROM_BEGIN   = 0,

   PLATFORM_FILE_FROM_CURRENT = 1,

   PLATFORM_FILE_FROM_END     = 2

 };

 // Used to hold information about a given file.

 // If you add more fields to this structure (platform-specific fields are OK),

 // make sure to update all functions that use it in file_util_{win|posix}.cc

 // too, and the ParamTraits<base::PlatformFileInfo> implementation in

 // chrome/common/common_param_traits.cc.

 struct BASE_EXPORT PlatformFileInfo {

   PlatformFileInfo();

   ~PlatformFileInfo();

   // The size of the file in bytes.  Undefined when is_directory is true.

   int64 size;

   // True if the file corresponds to a directory.

   bool is_directory;

   // True if the file corresponds to a symbolic link.

   bool is_symbolic_link;

   // The last modified time of a file.

   base::Time last_modified;

   // The last accessed time of a file.

   base::Time last_accessed;

   // The creation time of a file.

   base::Time creation_time;

 };

 #if defined(OS_WIN)

 typedef HANDLE PlatformFile;

 const PlatformFile kInvalidPlatformFileValue = INVALID_HANDLE_VALUE;

 PlatformFileError LastErrorToPlatformFileError(DWORD saved_errno);

 #elif defined(OS_POSIX)

 typedef int PlatformFile;

 const PlatformFile kInvalidPlatformFileValue = -1;

 PlatformFileError ErrnoToPlatformFileError(int saved_errno);

 #endif

 // Creates or opens the given file. If |created| is provided, it will be set to

 // true if a new file was created [or an old one truncated to zero length to

 // simulate a new file, which can happen with PLATFORM_FILE_CREATE_ALWAYS], and

 // false otherwise.  |error| can be NULL.

 //

 // This function fails with 'access denied' if the |name| contains path

 // traversal ('..') components.

 BASE_EXPORT PlatformFile CreatePlatformFile(const FilePath& name,

                                             int flags,

                                             bool* created,

                                             PlatformFileError* error);

 // Same as CreatePlatformFile but allows paths with traversal (like \..\)

 // components. Use only with extreme care.

 BASE_EXPORT PlatformFile CreatePlatformFileUnsafe(const FilePath& name,

                                                   int flags,

                                                   bool* created,

                                                   PlatformFileError* error);

 BASE_EXPORT FILE* FdopenPlatformFile(PlatformFile file, const char* mode);

 // Closes a file handle. Returns |true| on success and |false| otherwise.

 BASE_EXPORT bool ClosePlatformFile(PlatformFile file);

 // Changes current position in the file to an |offset| relative to an origin

 // defined by |whence|. Returns the resultant current position in the file

 // (relative to the start) or -1 in case of error.

 BASE_EXPORT int64 SeekPlatformFile(PlatformFile file,

                                    PlatformFileWhence whence,

                                    int64 offset);

 // Reads the given number of bytes (or until EOF is reached) starting with the

 // given offset. Returns the number of bytes read, or -1 on error. Note that

 // this function makes a best effort to read all data on all platforms, so it is

 // not intended for stream oriented files but instead for cases when the normal

 // expectation is that actually |size| bytes are read unless there is an error.

 BASE_EXPORT int ReadPlatformFile(PlatformFile file, int64 offset,

                                  char* data, int size);

 // Same as above but without seek.

 BASE_EXPORT int ReadPlatformFileAtCurrentPos(PlatformFile file,

                                              char* data, int size);

 // Reads the given number of bytes (or until EOF is reached) starting with the

 // given offset, but does not make any effort to read all data on all platforms.

 // Returns the number of bytes read, or -1 on error.

 BASE_EXPORT int ReadPlatformFileNoBestEffort(PlatformFile file, int64 offset,

                                              char* data, int size);

 // Same as above but without seek.

 BASE_EXPORT int ReadPlatformFileCurPosNoBestEffort(PlatformFile file,

                                                    char* data, int size);

 // Writes the given buffer into the file at the given offset, overwritting any

 // data that was previously there. Returns the number of bytes written, or -1

 // on error. Note that this function makes a best effort to write all data on

 // all platforms.

 // Ignores the offset and writes to the end of the file if the file was opened

 // with PLATFORM_FILE_APPEND.

 BASE_EXPORT int WritePlatformFile(PlatformFile file, int64 offset,

                                   const char* data, int size);

 // Save as above but without seek.

 BASE_EXPORT int WritePlatformFileAtCurrentPos(PlatformFile file,

                                               const char* data, int size);

 // Save as above but does not make any effort to write all data on all

 // platforms. Returns the number of bytes written, or -1 on error.

 BASE_EXPORT int WritePlatformFileCurPosNoBestEffort(PlatformFile file,

                                                     const char* data, int size);

 // Truncates the given file to the given length. If |length| is greater than

 // the current size of the file, the file is extended with zeros. If the file

 // doesn't exist, |false| is returned.

 BASE_EXPORT bool TruncatePlatformFile(PlatformFile file, int64 length);

 // Flushes the buffers of the given file.

 BASE_EXPORT bool FlushPlatformFile(PlatformFile file);

 // Touches the given file.

 BASE_EXPORT bool TouchPlatformFile(PlatformFile file,

                                    const Time& last_access_time,

                                    const Time& last_modified_time);

 // Returns some information for the given file.

 BASE_EXPORT bool GetPlatformFileInfo(PlatformFile file, PlatformFileInfo* info);

 // Use this class to pass ownership of a PlatformFile to a receiver that may or

 // may not want to accept it.  This class does not own the storage for the

 // PlatformFile.

 //

 // EXAMPLE:

 //

 //  void MaybeProcessFile(PassPlatformFile pass_file) {

 //    if (...) {

 //      PlatformFile file = pass_file.ReleaseValue();

 //      // Now, we are responsible for closing |file|.

 //    }

 //  }

 //

 //  void OpenAndMaybeProcessFile(const FilePath& path) {

 //    PlatformFile file = CreatePlatformFile(path, ...);

 //    MaybeProcessFile(PassPlatformFile(&file));

 //    if (file != kInvalidPlatformFileValue)

 //      ClosePlatformFile(file);

 //  }

 //

 class BASE_EXPORT PassPlatformFile {

  public:

   explicit PassPlatformFile(PlatformFile* value) : value_(value) {

   }

   // Called to retrieve the PlatformFile stored in this object.  The caller

   // gains ownership of the PlatformFile and is now responsible for closing it.

   // Any subsequent calls to this method will return an invalid PlatformFile.

   PlatformFile ReleaseValue() {

     PlatformFile temp = *value_;

     *value_ = kInvalidPlatformFileValue;

     return temp;

   }

  private:

   PlatformFile* value_;

 };

 }  // namespace base

 #endif  // BASE_PLATFORM_FILE_H_