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// Copyright (c) 2012 The Chromium Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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#ifndef BASE_FILES_FILE_H_
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#define BASE_FILES_FILE_H_
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#include "build/build_config.h"
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#include "base/base_export.h"
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#include "base/basictypes.h"
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#include "base/move.h"
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#include "base/time/time.h"
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#include "base/win/scoped_handle.h"
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typedef HANDLE PlatformFile;
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#elif defined(OS_POSIX)
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typedef int PlatformFile;
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// Thin wrapper around an OS-level file.
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// Note that this class does not provide any support for asynchronous IO, other
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// than the ability to create asynchronous handles on Windows.
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// Note about const: this class does not attempt to determine if the underlying
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// file system object is affected by a particular method in order to consider
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// that method const or not. Only methods that deal with member variables in an
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// obvious non-modifying way are marked as const. Any method that forward calls
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// to the OS is not considered const, even if there is no apparent change to
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class BASE_EXPORT File {
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MOVE_ONLY_TYPE_FOR_CPP_03(File, RValue)
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// FLAG_(OPEN|CREATE).* are mutually exclusive. You should specify exactly one
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// of the five (possibly combining with other flags) when opening or creating
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// FLAG_(WRITE|APPEND) are mutually exclusive. This is so that APPEND behavior
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// will be consistent with O_APPEND on POSIX.
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// FLAG_EXCLUSIVE_(READ|WRITE) only grant exclusive access to the file on
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// creation on POSIX; for existing files, consider using Lock().
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FLAG_OPEN = 1 << 0, // Opens a file, only if it exists.
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FLAG_CREATE = 1 << 1, // Creates a new file, only if it does not
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FLAG_OPEN_ALWAYS = 1 << 2, // May create a new file.
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FLAG_CREATE_ALWAYS = 1 << 3, // May overwrite an old file.
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FLAG_OPEN_TRUNCATED = 1 << 4, // Opens a file and truncates it, only if it
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FLAG_EXCLUSIVE_READ = 1 << 8, // EXCLUSIVE is opposite of Windows SHARE.
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FLAG_EXCLUSIVE_WRITE = 1 << 9,
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FLAG_TEMPORARY = 1 << 11, // Used on Windows only.
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FLAG_HIDDEN = 1 << 12, // Used on Windows only.
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FLAG_DELETE_ON_CLOSE = 1 << 13,
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FLAG_WRITE_ATTRIBUTES = 1 << 14, // Used on Windows only.
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FLAG_SHARE_DELETE = 1 << 15, // Used on Windows only.
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FLAG_TERMINAL_DEVICE = 1 << 16, // Serial port flags.
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FLAG_BACKUP_SEMANTICS = 1 << 17, // Used on Windows only.
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FLAG_EXECUTE = 1 << 18, // Used on Windows only.
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// This enum has been recorded in multiple histograms. If the order of the
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// fields needs to change, please ensure that those histograms are obsolete or
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// have been moved to a different enum.
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// FILE_ERROR_ACCESS_DENIED is returned when a call fails because of a
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// filesystem restriction. FILE_ERROR_SECURITY is returned when a browser
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// policy doesn't allow the operation to be executed.
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FILE_ERROR_FAILED = -1,
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FILE_ERROR_IN_USE = -2,
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FILE_ERROR_EXISTS = -3,
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FILE_ERROR_NOT_FOUND = -4,
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FILE_ERROR_ACCESS_DENIED = -5,
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FILE_ERROR_TOO_MANY_OPENED = -6,
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FILE_ERROR_NO_MEMORY = -7,
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FILE_ERROR_NO_SPACE = -8,
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FILE_ERROR_NOT_A_DIRECTORY = -9,
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FILE_ERROR_INVALID_OPERATION = -10,
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FILE_ERROR_SECURITY = -11,
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FILE_ERROR_ABORT = -12,
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FILE_ERROR_NOT_A_FILE = -13,
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FILE_ERROR_NOT_EMPTY = -14,
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FILE_ERROR_INVALID_URL = -15,
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// Put new entries here and increment FILE_ERROR_MAX.
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// This explicit mapping matches both FILE_ on Windows and SEEK_ on Linux.
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// Used to hold information about a given file.
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// If you add more fields to this structure (platform-specific fields are OK),
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// make sure to update all functions that use it in file_util_{win|posix}.cc
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// too, and the ParamTraits<base::PlatformFileInfo> implementation in
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// chrome/common/common_param_traits.cc.
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struct BASE_EXPORT Info {
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// The size of the file in bytes. Undefined when is_directory is true.
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// True if the file corresponds to a directory.
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// True if the file corresponds to a symbolic link.
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bool is_symbolic_link;
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// The last modified time of a file.
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base::Time last_modified;
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// The last accessed time of a file.
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base::Time last_accessed;
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// The creation time of a file.
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base::Time creation_time;
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// Creates or opens the given file. This will fail with 'access denied' if the
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// |name| contains path traversal ('..') components.
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File(const FilePath& name, uint32 flags);
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// Takes ownership of |platform_file|.
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explicit File(PlatformFile platform_file);
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// Move constructor for C++03 move emulation of this type.
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// Move operator= for C++03 move emulation of this type.
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File& operator=(RValue other);
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// Creates or opens the given file.
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void Initialize(const FilePath& name, uint32 flags);
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// Creates or opens the given file, allowing paths with traversal ('..')
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// components. Use only with extreme care.
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void InitializeUnsafe(const FilePath& name, uint32 flags);
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bool IsValid() const;
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// Returns true if a new file was created (or an old one truncated to zero
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// length to simulate a new file, which can happen with
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// FLAG_CREATE_ALWAYS), and false otherwise.
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bool created() const { return created_; }
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// Returns the OS result of opening this file. Note that the way to verify
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// the success of the operation is to use IsValid(), not this method:
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// File file(name, flags);
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// if (!file.IsValid())
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Error error_details() const { return error_details_; }
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PlatformFile GetPlatformFile() const { return file_; }
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PlatformFile TakePlatformFile();
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// Destroying this object closes the file automatically.
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// Changes current position in the file to an |offset| relative to an origin
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// defined by |whence|. Returns the resultant current position in the file
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// (relative to the start) or -1 in case of error.
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int64 Seek(Whence whence, int64 offset);
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// Reads the given number of bytes (or until EOF is reached) starting with the
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// given offset. Returns the number of bytes read, or -1 on error. Note that
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// this function makes a best effort to read all data on all platforms, so it
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// is not intended for stream oriented files but instead for cases when the
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// normal expectation is that actually |size| bytes are read unless there is
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int Read(int64 offset, char* data, int size);
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// Same as above but without seek.
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int ReadAtCurrentPos(char* data, int size);
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// Reads the given number of bytes (or until EOF is reached) starting with the
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// given offset, but does not make any effort to read all data on all
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// platforms. Returns the number of bytes read, or -1 on error.
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int ReadNoBestEffort(int64 offset, char* data, int size);
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// Same as above but without seek.
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int ReadAtCurrentPosNoBestEffort(char* data, int size);
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// Writes the given buffer into the file at the given offset, overwritting any
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// data that was previously there. Returns the number of bytes written, or -1
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// on error. Note that this function makes a best effort to write all data on
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// Ignores the offset and writes to the end of the file if the file was opened
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int Write(int64 offset, const char* data, int size);
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// Save as above but without seek.
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int WriteAtCurrentPos(const char* data, int size);
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// Save as above but does not make any effort to write all data on all
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// platforms. Returns the number of bytes written, or -1 on error.
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int WriteAtCurrentPosNoBestEffort(const char* data, int size);
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// Returns the current size of this file, or a negative number on failure.
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// Truncates the file to the given length. If |length| is greater than the
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// current size of the file, the file is extended with zeros. If the file
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// doesn't exist, |false| is returned.
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bool SetLength(int64 length);
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// Flushes the buffers.
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// Updates the file times.
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bool SetTimes(Time last_access_time, Time last_modified_time);
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// Returns some basic information for the given file.
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bool GetInfo(Info* info);
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// Attempts to take an exclusive write lock on the file. Returns immediately
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// (i.e. does not wait for another process to unlock the file). If the lock
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// was obtained, the result will be FILE_OK. A lock only guarantees
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// that other processes may not also take a lock on the same file with the
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// same API - it may still be opened, renamed, unlinked, etc.
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// * Locks are held by processes, but not inherited by child processes.
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// * Locks are released by the OS on file close or process termination.
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// * Locks are reliable only on local filesystems.
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// * Duplicated file handles may also write to locked files.
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// Windows-specific semantics:
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// * Locks are mandatory for read/write APIs, advisory for mapping APIs.
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// * Within a process, locking the same file (by the same or new handle)
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// POSIX-specific semantics:
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// * Locks are advisory only.
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// * Within a process, locking the same file (by the same or new handle)
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// * Closing any descriptor on a given file releases the lock.
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// Unlock a file previously locked.
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static Error OSErrorToFileError(DWORD last_error);
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#elif defined(OS_POSIX)
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static Error OSErrorToFileError(int saved_errno);
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void SetPlatformFile(PlatformFile file);
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win::ScopedHandle file_;
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#elif defined(OS_POSIX)
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Error error_details_;
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#endif // BASE_FILES_FILE_H_