Base: Move platform_file.* to files/base_file.*

base/files/base_file.h

 // 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_
+#ifndef BASE_FILES_BASE_FILE_H_
+#define BASE_FILES_BASE_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/move.h"
 #include "base/time/time.h"
 
+#if defined(OS_WIN)
+#include "base/win/scoped_handle.h"
+#endif
+
 namespace base {
 
-// PLATFORM_FILE_(OPEN|CREATE).* are mutually exclusive. You should specify
+// BASE_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
+// BASE_FILE_(WRITE|APPEND) are mutually exclusive. This is so that APPEND
 // behavior will be consistent with O_APPEND on POSIX.
-// PLATFORM_FILE_EXCLUSIVE_(READ|WRITE) only grant exclusive access to the file
+// BASE_FILE_EXCLUSIVE_(READ|WRITE) only grant exclusive access to the file
 // on creation on POSIX; for existing files, consider using LockPlatformFile().
-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
+enum BaseFileFlags {

[brettw, 2013/11/26 23:04:49]

Can these be in the BaseFile class? If I was doing this from scratch, I'd use
names like BaseFile::FLAG_OPEN.

[rvargas (doing something else), 2013/11/26 23:45:53]

Sure... I assume you are talking only about the enums.

+  BASE_FILE_OPEN = 1 << 0,             // Opens a file, only if it exists.
+  BASE_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,
+  BASE_FILE_OPEN_ALWAYS = 1 << 2,      // May create a new file.
+  BASE_FILE_CREATE_ALWAYS = 1 << 3,    // May overwrite an old file.
+  BASE_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
+  BASE_FILE_READ = 1 << 5,
+  BASE_FILE_WRITE = 1 << 6,
+  BASE_FILE_APPEND = 1 << 7,
+  BASE_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,
+  BASE_FILE_EXCLUSIVE_WRITE = 1 << 9,
+  BASE_FILE_ASYNC = 1 << 10,
+  BASE_FILE_TEMPORARY = 1 << 11,       // Used on Windows only
+  BASE_FILE_HIDDEN = 1 << 12,          // Used on Windows only
+  BASE_FILE_DELETE_ON_CLOSE = 1 << 13,
 
-  PLATFORM_FILE_WRITE_ATTRIBUTES = 1 << 14,  // Used on Windows only
+  BASE_FILE_WRITE_ATTRIBUTES = 1 << 14,  // Used on Windows only
 
-  PLATFORM_FILE_SHARE_DELETE = 1 << 15,      // Used on Windows only
+  BASE_FILE_SHARE_DELETE = 1 << 15,      // Used on Windows only
 
-  PLATFORM_FILE_TERMINAL_DEVICE = 1 << 16,   // Serial port flags
-  PLATFORM_FILE_BACKUP_SEMANTICS = 1 << 17,  // Used on Windows only
+  BASE_FILE_TERMINAL_DEVICE = 1 << 16,   // Serial port flags
+  BASE_FILE_BACKUP_SEMANTICS = 1 << 17,  // Used on Windows only
 
-  PLATFORM_FILE_EXECUTE = 1 << 18,           // Used on Windows only
+  BASE_FILE_EXECUTE = 1 << 18,           // Used on Windows only
 };
 
 // This enum has been recorded in multiple histograms. If the order of the
 // fields needs to change, please ensure that those histograms are obsolete or
 // have been moved to a different enum.
 //
-// PLATFORM_FILE_ERROR_ACCESS_DENIED is returned when a call fails because of
-// a filesystem restriction. PLATFORM_FILE_ERROR_SECURITY is returned when a
+// BASE_FILE_ERROR_ACCESS_DENIED is returned when a call fails because of
+// a filesystem restriction. BASE_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
+enum BaseFileError {
+  BASE_FILE_OK = 0,
+  BASE_FILE_ERROR_FAILED = -1,
+  BASE_FILE_ERROR_IN_USE = -2,
+  BASE_FILE_ERROR_EXISTS = -3,
+  BASE_FILE_ERROR_NOT_FOUND = -4,
+  BASE_FILE_ERROR_ACCESS_DENIED = -5,
+  BASE_FILE_ERROR_TOO_MANY_OPENED = -6,
+  BASE_FILE_ERROR_NO_MEMORY = -7,
+  BASE_FILE_ERROR_NO_SPACE = -8,
+  BASE_FILE_ERROR_NOT_A_DIRECTORY = -9,
+  BASE_FILE_ERROR_INVALID_OPERATION = -10,
+  BASE_FILE_ERROR_SECURITY = -11,
+  BASE_FILE_ERROR_ABORT = -12,
+  BASE_FILE_ERROR_NOT_A_FILE = -13,
+  BASE_FILE_ERROR_NOT_EMPTY = -14,
+  BASE_FILE_ERROR_INVALID_URL = -15,
+  BASE_FILE_ERROR_IO = -16,
+  // Put new entries here and increment BASE_FILE_ERROR_MAX.
+  BASE_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
+enum BaseFileWhence {
+  BASE_FILE_FROM_BEGIN   = 0,
+  BASE_FILE_FROM_CURRENT = 1,
+  BASE_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();
+struct BASE_EXPORT BaseFileInfo {
+  BaseFileInfo();
+  ~BaseFileInfo();
 
   // 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;
-BASE_EXPORT PlatformFileError LastErrorToPlatformFileError(DWORD last_error);
+BASE_EXPORT BaseFileError ErrorToBaseFileError(DWORD last_error);
 #elif defined(OS_POSIX)
 typedef int PlatformFile;
-const PlatformFile kInvalidPlatformFileValue = -1;
-BASE_EXPORT PlatformFileError ErrnoToPlatformFileError(int saved_errno);
+BASE_EXPORT BaseFileError ErrorToBaseFileError(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);
+// Thin wrapper around an OS-level file.
+// Note that this class does not provide any support for asynchronous IO, other
+// than the ability to create asynchronous handles on Windows.
+class BASE_EXPORT BaseFile {
+  MOVE_ONLY_TYPE_FOR_CPP_03(BaseFile, RValue)
 
-// 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);
+ public:
+  BaseFile();
 
-BASE_EXPORT FILE* FdopenPlatformFile(PlatformFile file, const char* mode);
+  // Creates or opens the given file. This will fail with 'access denied' if the
+  // |name| contains path traversal ('..') components.
+  BaseFile(const FilePath& name, int flags);
 
-// Closes a file handle. Returns |true| on success and |false| otherwise.
-BASE_EXPORT bool ClosePlatformFile(PlatformFile file);
+  // Takes ownership of |platform_file|.
+  explicit BaseFile(PlatformFile platform_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);
+  // Move constructor for C++03 move emulation of this type.
+  BaseFile(RValue other);
 
-// 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);
+  ~BaseFile();
 
-// Same as above but without seek.
-BASE_EXPORT int ReadPlatformFileAtCurrentPos(PlatformFile file,
-                                             char* data, int size);
+  // Move operator= for C++03 move emulation of this type.
+  BaseFile& operator=(RValue other);
 
-// 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);
+  // Creates or opens the given file, allowing paths with traversal ('..')
+  // components. Use only with extreme care.
+  void CreateBaseFileUnsafe(const FilePath& name, int flags);
 
-// Same as above but without seek.
-BASE_EXPORT int ReadPlatformFileCurPosNoBestEffort(PlatformFile file,
-                                                   char* data, int size);
+  bool IsValid() const;
 
-// 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);
+  // Returns true if a new file was created (or an old one truncated to zero
+  // length to simulate a new file, which can happen with
+  // BASE_FILE_CREATE_ALWAYS), and false otherwise.
+  bool created() const { return created_; }
 
-// Save as above but without seek.
-BASE_EXPORT int WritePlatformFileAtCurrentPos(PlatformFile file,
-                                              const char* data, int size);
+  // Returns the OS result of opening this file.
+  BaseFileError error() const { return error_; }
 
-// 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);
+  PlatformFile GetPlatformFile() const { return file_; }
+  PlatformFile TakePlatformFile();
 
-// 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);
+  // Destroying this object closes the file automatically.
+  void Close();
 
-// Flushes the buffers of the given file.
-BASE_EXPORT bool FlushPlatformFile(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.
+  int64 Seek(BaseFileWhence whence, int64 offset);
 
-// Touches the given file.
-BASE_EXPORT bool TouchPlatformFile(PlatformFile file,
-                                   const Time& last_access_time,
-                                   const Time& last_modified_time);
+  // 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.
+  int Read(int64 offset, char* data, int size);
 
-// Returns some information for the given file.
-BASE_EXPORT bool GetPlatformFileInfo(PlatformFile file, PlatformFileInfo* info);
+  // Same as above but without seek.
+  int ReadAtCurrentPos(char* data, int size);
 
-// Attempts to take an exclusive write lock on the file. Returns immediately
-// (i.e. does not wait for another process to unlock the file). If the lock
-// was obtained, the result will be PLATFORM_FILE_OK. A lock only guarantees
-// that other processes may not also take a lock on the same file with the
-// same API - it may still be opened, renamed, unlinked, etc.
-//
-// Common semantics:
-//  * Locks are held by processes, but not inherited by child processes.
-//  * Locks are released by the OS on file handle close or process termination.
-//  * Locks are reliable only on local filesystems.
-//  * Duplicated file handles may also write to locked files.
-// Windows-specific semantics:
-//  * Locks are mandatory for read/write APIs, advisory for mapping APIs.
-//  * Within a process, locking the same file (by the same or new handle)
-//    will fail.
-// POSIX-specific semantics:
-//  * Locks are advisory only.
-//  * Within a process, locking the same file (by the same or new handle)
-//    will succeed.
-//  * Closing any descriptor on a given file releases the lock.
-BASE_EXPORT PlatformFileError LockPlatformFile(PlatformFile file);
+  // 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.
+  int ReadNoBestEffort(int64 offset, char* data, int size);
 
-// Unlock a file previously locked with LockPlatformFile.
-BASE_EXPORT PlatformFileError UnlockPlatformFile(PlatformFile file);
+  // Same as above but without seek.
+  int ReadAtCurrentPosNoBestEffort(char* data, int size);
 
-// 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) {
-  }
+  // 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 BASE_FILE_APPEND.
+  int Write(int64 offset, const char* data, int size);
 
-  // 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;
-  }
+  // Save as above but without seek.
+  int WriteAtCurrentPos(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.
+  int WriteAtCurrentPosNoBestEffort(const char* data, int size);
+
+  // Truncates the 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.
+  bool Truncate(int64 length);
+
+  // Flushes the buffers.
+  bool Flush();
+
+  // Updates the file times.
+  bool SetTime(Time last_access_time, Time last_modified_time);
+
+  // Returns some basic information for the given file.
+  bool GetInfo(BaseFileInfo* info);
+
+  // Attempts to take an exclusive write lock on the file. Returns immediately
+  // (i.e. does not wait for another process to unlock the file). If the lock
+  // was obtained, the result will be BASE_FILE_OK. A lock only guarantees
+  // that other processes may not also take a lock on the same file with the
+  // same API - it may still be opened, renamed, unlinked, etc.
+  //
+  // Common semantics:
+  //  * Locks are held by processes, but not inherited by child processes.
+  //  * Locks are released by the OS on file close or process termination.
+  //  * Locks are reliable only on local filesystems.
+  //  * Duplicated file handles may also write to locked files.
+  // Windows-specific semantics:
+  //  * Locks are mandatory for read/write APIs, advisory for mapping APIs.
+  //  * Within a process, locking the same file (by the same or new handle)
+  //    will fail.
+  // POSIX-specific semantics:
+  //  * Locks are advisory only.
+  //  * Within a process, locking the same file (by the same or new handle)
+  //    will succeed.
+  //  * Closing any descriptor on a given file releases the lock.
+  BaseFileError Lock();
+
+  // Unlock a file previously locked.
+  BaseFileError Unlock();
 
  private:
-  PlatformFile* value_;
+  void SetPlatformFile(PlatformFile file);
+
+#if defined(OS_WIN)
+  win::ScopedHandle file_;
+#elif defined(OS_POSIX)
+  PlatformFile file_;
+#endif
+
+  BaseFileError error_;
+  bool created_;
+  bool async_;
 };
 
 }  // namespace base
 
-#endif  // BASE_PLATFORM_FILE_H_
+#endif  // BASE_FILES_BASE_FILE_H_