485 lines
22 KiB
C++
485 lines
22 KiB
C++
// 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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// FilePath is a container for pathnames stored in a platform's native string
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// type, providing containers for manipulation in according with the
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// platform's conventions for pathnames. It supports the following path
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// types:
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//
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// POSIX Windows
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// --------------- ----------------------------------
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// Fundamental type char[] wchar_t[]
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// Encoding unspecified* UTF-16
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// Separator / \, tolerant of /
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// Drive letters no case-insensitive A-Z followed by :
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// Alternate root // (surprise!) \\, for UNC paths
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//
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// * The encoding need not be specified on POSIX systems, although some
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// POSIX-compliant systems do specify an encoding. Mac OS X uses UTF-8.
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// Chrome OS also uses UTF-8.
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// Linux does not specify an encoding, but in practice, the locale's
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// character set may be used.
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//
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// For more arcane bits of path trivia, see below.
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//
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// FilePath objects are intended to be used anywhere paths are. An
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// application may pass FilePath objects around internally, masking the
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// underlying differences between systems, only differing in implementation
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// where interfacing directly with the system. For example, a single
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// OpenFile(const FilePath &) function may be made available, allowing all
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// callers to operate without regard to the underlying implementation. On
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// POSIX-like platforms, OpenFile might wrap fopen, and on Windows, it might
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// wrap _wfopen_s, perhaps both by calling file_path.value().c_str(). This
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// allows each platform to pass pathnames around without requiring conversions
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// between encodings, which has an impact on performance, but more imporantly,
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// has an impact on correctness on platforms that do not have well-defined
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// encodings for pathnames.
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//
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// Several methods are available to perform common operations on a FilePath
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// object, such as determining the parent directory (DirName), isolating the
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// final path component (BaseName), and appending a relative pathname string
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// to an existing FilePath object (Append). These methods are highly
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// recommended over attempting to split and concatenate strings directly.
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// These methods are based purely on string manipulation and knowledge of
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// platform-specific pathname conventions, and do not consult the filesystem
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// at all, making them safe to use without fear of blocking on I/O operations.
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// These methods do not function as mutators but instead return distinct
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// instances of FilePath objects, and are therefore safe to use on const
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// objects. The objects themselves are safe to share between threads.
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//
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// To aid in initialization of FilePath objects from string literals, a
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// FILE_PATH_LITERAL macro is provided, which accounts for the difference
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// between char[]-based pathnames on POSIX systems and wchar_t[]-based
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// pathnames on Windows.
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//
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// As a precaution against premature truncation, paths can't contain NULs.
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//
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// Because a FilePath object should not be instantiated at the global scope,
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// instead, use a FilePath::CharType[] and initialize it with
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// FILE_PATH_LITERAL. At runtime, a FilePath object can be created from the
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// character array. Example:
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//
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// | const FilePath::CharType kLogFileName[] = FILE_PATH_LITERAL("log.txt");
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// |
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// | void Function() {
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// | FilePath log_file_path(kLogFileName);
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// | [...]
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// | }
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//
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// WARNING: FilePaths should ALWAYS be displayed with LTR directionality, even
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// when the UI language is RTL. This means you always need to pass filepaths
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// through base::i18n::WrapPathWithLTRFormatting() before displaying it in the
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// RTL UI.
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//
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// This is a very common source of bugs, please try to keep this in mind.
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//
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// ARCANE BITS OF PATH TRIVIA
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//
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// - A double leading slash is actually part of the POSIX standard. Systems
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// are allowed to treat // as an alternate root, as Windows does for UNC
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// (network share) paths. Most POSIX systems don't do anything special
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// with two leading slashes, but FilePath handles this case properly
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// in case it ever comes across such a system. FilePath needs this support
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// for Windows UNC paths, anyway.
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// References:
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// The Open Group Base Specifications Issue 7, sections 3.267 ("Pathname")
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// and 4.12 ("Pathname Resolution"), available at:
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// http://www.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap03.html#tag_03_267
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// http://www.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap04.html#tag_04_12
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//
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// - Windows treats c:\\ the same way it treats \\. This was intended to
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// allow older applications that require drive letters to support UNC paths
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// like \\server\share\path, by permitting c:\\server\share\path as an
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// equivalent. Since the OS treats these paths specially, FilePath needs
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// to do the same. Since Windows can use either / or \ as the separator,
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// FilePath treats c://, c:\\, //, and \\ all equivalently.
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// Reference:
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// The Old New Thing, "Why is a drive letter permitted in front of UNC
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// paths (sometimes)?", available at:
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// http://blogs.msdn.com/oldnewthing/archive/2005/11/22/495740.aspx
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#ifndef BASE_FILES_FILE_PATH_H_
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#define BASE_FILES_FILE_PATH_H_
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#include <stddef.h>
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#include <functional>
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#include <iosfwd>
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#include <string>
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#include <vector>
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#include "base/base_export.h"
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#include "base/compiler_specific.h"
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#include "base/stl_util.h"
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#include "base/strings/string16.h"
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#include "base/strings/string_piece.h"
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#include "build/build_config.h"
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// Windows-style drive letter support and pathname separator characters can be
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// enabled and disabled independently, to aid testing. These #defines are
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// here so that the same setting can be used in both the implementation and
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// in the unit test.
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#if defined(OS_WIN)
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#define FILE_PATH_USES_DRIVE_LETTERS
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#define FILE_PATH_USES_WIN_SEPARATORS
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#endif // OS_WIN
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// To print path names portably use PRFilePath (based on PRIuS and friends from
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// C99 and format_macros.h) like this:
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// base::StringPrintf("Path is %" PRFilePath ".\n", path.value().c_str());
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#if defined(OS_WIN)
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#define PRFilePath "ls"
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#elif defined(OS_POSIX) || defined(OS_FUCHSIA)
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#define PRFilePath "s"
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#endif // OS_WIN
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// Macros for string literal initialization of FilePath::CharType[].
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#if defined(OS_WIN)
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#define FILE_PATH_LITERAL(x) L##x
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#elif defined(OS_POSIX) || defined(OS_FUCHSIA)
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#define FILE_PATH_LITERAL(x) x
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#endif // OS_WIN
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namespace base {
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class Pickle;
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class PickleIterator;
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// An abstraction to isolate users from the differences between native
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// pathnames on different platforms.
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class BASE_EXPORT FilePath {
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public:
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#if defined(OS_WIN)
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// On Windows, for Unicode-aware applications, native pathnames are wchar_t
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// arrays encoded in UTF-16.
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typedef std::wstring StringType;
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#elif defined(OS_POSIX) || defined(OS_FUCHSIA)
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// On most platforms, native pathnames are char arrays, and the encoding
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// may or may not be specified. On Mac OS X, native pathnames are encoded
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// in UTF-8.
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typedef std::string StringType;
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#endif // OS_WIN
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typedef BasicStringPiece<StringType> StringPieceType;
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typedef StringType::value_type CharType;
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// Null-terminated array of separators used to separate components in
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// hierarchical paths. Each character in this array is a valid separator,
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// but kSeparators[0] is treated as the canonical separator and will be used
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// when composing pathnames.
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static const CharType kSeparators[];
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// base::size(kSeparators).
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static const size_t kSeparatorsLength;
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// A special path component meaning "this directory."
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static const CharType kCurrentDirectory[];
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// A special path component meaning "the parent directory."
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static const CharType kParentDirectory[];
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// The character used to identify a file extension.
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static const CharType kExtensionSeparator;
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FilePath();
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FilePath(const FilePath& that);
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explicit FilePath(StringPieceType path);
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~FilePath();
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FilePath& operator=(const FilePath& that);
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// Constructs FilePath with the contents of |that|, which is left in valid but
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// unspecified state.
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FilePath(FilePath&& that) noexcept;
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// Replaces the contents with those of |that|, which is left in valid but
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// unspecified state.
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FilePath& operator=(FilePath&& that);
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bool operator==(const FilePath& that) const;
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bool operator!=(const FilePath& that) const;
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// Required for some STL containers and operations
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bool operator<(const FilePath& that) const {
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return path_ < that.path_;
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}
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const StringType& value() const { return path_; }
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bool empty() const { return path_.empty(); }
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void clear() { path_.clear(); }
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// Returns true if |character| is in kSeparators.
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static bool IsSeparator(CharType character);
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// Returns a vector of all of the components of the provided path. It is
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// equivalent to calling DirName().value() on the path's root component,
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// and BaseName().value() on each child component.
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//
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// To make sure this is lossless so we can differentiate absolute and
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// relative paths, the root slash will be included even though no other
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// slashes will be. The precise behavior is:
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//
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// Posix: "/foo/bar" -> [ "/", "foo", "bar" ]
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// Windows: "C:\foo\bar" -> [ "C:", "\\", "foo", "bar" ]
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void GetComponents(std::vector<FilePath::StringType>* components) const;
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// Returns true if this FilePath is a parent or ancestor of the |child|.
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// Absolute and relative paths are accepted i.e. /foo is a parent to /foo/bar,
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// and foo is a parent to foo/bar. Any ancestor is considered a parent i.e. /a
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// is a parent to both /a/b and /a/b/c. Does not convert paths to absolute,
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// follow symlinks or directory navigation (e.g. ".."). A path is *NOT* its
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// own parent.
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bool IsParent(const FilePath& child) const;
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// If IsParent(child) holds, appends to path (if non-NULL) the
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// relative path to child and returns true. For example, if parent
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// holds "/Users/johndoe/Library/Application Support", child holds
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// "/Users/johndoe/Library/Application Support/Google/Chrome/Default", and
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// *path holds "/Users/johndoe/Library/Caches", then after
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// parent.AppendRelativePath(child, path) is called *path will hold
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// "/Users/johndoe/Library/Caches/Google/Chrome/Default". Otherwise,
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// returns false.
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bool AppendRelativePath(const FilePath& child, FilePath* path) const;
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// Returns a FilePath corresponding to the directory containing the path
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// named by this object, stripping away the file component. If this object
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// only contains one component, returns a FilePath identifying
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// kCurrentDirectory. If this object already refers to the root directory,
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// returns a FilePath identifying the root directory. Please note that this
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// doesn't resolve directory navigation, e.g. the result for "../a" is "..".
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FilePath DirName() const WARN_UNUSED_RESULT;
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// Returns a FilePath corresponding to the last path component of this
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// object, either a file or a directory. If this object already refers to
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// the root directory, returns a FilePath identifying the root directory;
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// this is the only situation in which BaseName will return an absolute path.
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FilePath BaseName() const WARN_UNUSED_RESULT;
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// Returns ".jpg" for path "C:\pics\jojo.jpg", or an empty string if
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// the file has no extension. If non-empty, Extension() will always start
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// with precisely one ".". The following code should always work regardless
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// of the value of path. For common double-extensions like .tar.gz and
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// .user.js, this method returns the combined extension. For a single
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// component, use FinalExtension().
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// new_path = path.RemoveExtension().value().append(path.Extension());
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// ASSERT(new_path == path.value());
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// NOTE: this is different from the original file_util implementation which
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// returned the extension without a leading "." ("jpg" instead of ".jpg")
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StringType Extension() const WARN_UNUSED_RESULT;
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// Returns the path's file extension, as in Extension(), but will
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// never return a double extension.
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//
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// TODO(davidben): Check all our extension-sensitive code to see if
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// we can rename this to Extension() and the other to something like
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// LongExtension(), defaulting to short extensions and leaving the
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// long "extensions" to logic like base::GetUniquePathNumber().
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StringType FinalExtension() const WARN_UNUSED_RESULT;
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// Returns "C:\pics\jojo" for path "C:\pics\jojo.jpg"
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// NOTE: this is slightly different from the similar file_util implementation
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// which returned simply 'jojo'.
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FilePath RemoveExtension() const WARN_UNUSED_RESULT;
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// Removes the path's file extension, as in RemoveExtension(), but
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// ignores double extensions.
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FilePath RemoveFinalExtension() const WARN_UNUSED_RESULT;
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// Inserts |suffix| after the file name portion of |path| but before the
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// extension. Returns "" if BaseName() == "." or "..".
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// Examples:
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// path == "C:\pics\jojo.jpg" suffix == " (1)", returns "C:\pics\jojo (1).jpg"
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// path == "jojo.jpg" suffix == " (1)", returns "jojo (1).jpg"
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// path == "C:\pics\jojo" suffix == " (1)", returns "C:\pics\jojo (1)"
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// path == "C:\pics.old\jojo" suffix == " (1)", returns "C:\pics.old\jojo (1)"
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FilePath InsertBeforeExtension(
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StringPieceType suffix) const WARN_UNUSED_RESULT;
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FilePath InsertBeforeExtensionASCII(
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StringPiece suffix) const WARN_UNUSED_RESULT;
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// Adds |extension| to |file_name|. Returns the current FilePath if
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// |extension| is empty. Returns "" if BaseName() == "." or "..".
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FilePath AddExtension(StringPieceType extension) const WARN_UNUSED_RESULT;
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// Like above, but takes the extension as an ASCII string. See AppendASCII for
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// details on how this is handled.
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FilePath AddExtensionASCII(StringPiece extension) const WARN_UNUSED_RESULT;
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// Replaces the extension of |file_name| with |extension|. If |file_name|
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// does not have an extension, then |extension| is added. If |extension| is
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// empty, then the extension is removed from |file_name|.
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// Returns "" if BaseName() == "." or "..".
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FilePath ReplaceExtension(StringPieceType extension) const WARN_UNUSED_RESULT;
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// Returns true if the file path matches the specified extension. The test is
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// case insensitive. Don't forget the leading period if appropriate.
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bool MatchesExtension(StringPieceType extension) const;
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// Returns a FilePath by appending a separator and the supplied path
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// component to this object's path. Append takes care to avoid adding
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// excessive separators if this object's path already ends with a separator.
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// If this object's path is kCurrentDirectory, a new FilePath corresponding
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// only to |component| is returned. |component| must be a relative path;
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// it is an error to pass an absolute path.
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FilePath Append(StringPieceType component) const WARN_UNUSED_RESULT;
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FilePath Append(const FilePath& component) const WARN_UNUSED_RESULT;
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// Although Windows StringType is std::wstring, since the encoding it uses for
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// paths is well defined, it can handle ASCII path components as well.
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// Mac uses UTF8, and since ASCII is a subset of that, it works there as well.
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// On Linux, although it can use any 8-bit encoding for paths, we assume that
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// ASCII is a valid subset, regardless of the encoding, since many operating
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// system paths will always be ASCII.
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FilePath AppendASCII(StringPiece component) const WARN_UNUSED_RESULT;
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// Returns true if this FilePath contains an absolute path. On Windows, an
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// absolute path begins with either a drive letter specification followed by
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// a separator character, or with two separator characters. On POSIX
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// platforms, an absolute path begins with a separator character.
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bool IsAbsolute() const;
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// Returns true if the patch ends with a path separator character.
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bool EndsWithSeparator() const WARN_UNUSED_RESULT;
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// Returns a copy of this FilePath that ends with a trailing separator. If
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// the input path is empty, an empty FilePath will be returned.
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FilePath AsEndingWithSeparator() const WARN_UNUSED_RESULT;
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// Returns a copy of this FilePath that does not end with a trailing
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// separator.
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FilePath StripTrailingSeparators() const WARN_UNUSED_RESULT;
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// Returns true if this FilePath contains an attempt to reference a parent
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// directory (e.g. has a path component that is "..").
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bool ReferencesParent() const;
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// Return a Unicode human-readable version of this path.
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// Warning: you can *not*, in general, go from a display name back to a real
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// path. Only use this when displaying paths to users, not just when you
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// want to stuff a string16 into some other API.
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string16 LossyDisplayName() const;
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// Return the path as ASCII, or the empty string if the path is not ASCII.
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// This should only be used for cases where the FilePath is representing a
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// known-ASCII filename.
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std::string MaybeAsASCII() const;
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// Return the path as UTF-8.
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//
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// This function is *unsafe* as there is no way to tell what encoding is
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// used in file names on POSIX systems other than Mac and Chrome OS,
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// although UTF-8 is practically used everywhere these days. To mitigate
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// the encoding issue, this function internally calls
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// SysNativeMBToWide() on POSIX systems other than Mac and Chrome OS,
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// per assumption that the current locale's encoding is used in file
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// names, but this isn't a perfect solution.
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//
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// Once it becomes safe to to stop caring about non-UTF-8 file names,
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// the SysNativeMBToWide() hack will be removed from the code, along
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// with "Unsafe" in the function name.
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std::string AsUTF8Unsafe() const;
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// Similar to AsUTF8Unsafe, but returns UTF-16 instead.
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string16 AsUTF16Unsafe() const;
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// Returns a FilePath object from a path name in UTF-8. This function
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// should only be used for cases where you are sure that the input
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// string is UTF-8.
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//
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// Like AsUTF8Unsafe(), this function is unsafe. This function
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// internally calls SysWideToNativeMB() on POSIX systems other than Mac
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// and Chrome OS, to mitigate the encoding issue. See the comment at
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// AsUTF8Unsafe() for details.
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static FilePath FromUTF8Unsafe(StringPiece utf8);
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// Similar to FromUTF8Unsafe, but accepts UTF-16 instead.
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static FilePath FromUTF16Unsafe(StringPiece16 utf16);
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void WriteToPickle(Pickle* pickle) const;
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bool ReadFromPickle(PickleIterator* iter);
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// Normalize all path separators to backslash on Windows
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// (if FILE_PATH_USES_WIN_SEPARATORS is true), or do nothing on POSIX systems.
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FilePath NormalizePathSeparators() const;
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// Normalize all path separattors to given type on Windows
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// (if FILE_PATH_USES_WIN_SEPARATORS is true), or do nothing on POSIX systems.
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FilePath NormalizePathSeparatorsTo(CharType separator) const;
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// Compare two strings in the same way the file system does.
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// Note that these always ignore case, even on file systems that are case-
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// sensitive. If case-sensitive comparison is ever needed, add corresponding
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// methods here.
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// The methods are written as a static method so that they can also be used
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// on parts of a file path, e.g., just the extension.
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// CompareIgnoreCase() returns -1, 0 or 1 for less-than, equal-to and
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// greater-than respectively.
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static int CompareIgnoreCase(StringPieceType string1,
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StringPieceType string2);
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static bool CompareEqualIgnoreCase(StringPieceType string1,
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StringPieceType string2) {
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return CompareIgnoreCase(string1, string2) == 0;
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}
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static bool CompareLessIgnoreCase(StringPieceType string1,
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StringPieceType string2) {
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return CompareIgnoreCase(string1, string2) < 0;
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}
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#if defined(OS_MACOSX)
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// Returns the string in the special canonical decomposed form as defined for
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// HFS, which is close to, but not quite, decomposition form D. See
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// http://developer.apple.com/mac/library/technotes/tn/tn1150.html#UnicodeSubtleties
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// for further comments.
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// Returns the epmty string if the conversion failed.
|
|
static StringType GetHFSDecomposedForm(StringPieceType string);
|
|
|
|
// Special UTF-8 version of FastUnicodeCompare. Cf:
|
|
// http://developer.apple.com/mac/library/technotes/tn/tn1150.html#StringComparisonAlgorithm
|
|
// IMPORTANT: The input strings must be in the special HFS decomposed form!
|
|
// (cf. above GetHFSDecomposedForm method)
|
|
static int HFSFastUnicodeCompare(StringPieceType string1,
|
|
StringPieceType string2);
|
|
#endif
|
|
|
|
#if defined(OS_ANDROID)
|
|
// On android, file selection dialog can return a file with content uri
|
|
// scheme(starting with content://). Content uri needs to be opened with
|
|
// ContentResolver to guarantee that the app has appropriate permissions
|
|
// to access it.
|
|
// Returns true if the path is a content uri, or false otherwise.
|
|
bool IsContentUri() const;
|
|
#endif
|
|
|
|
private:
|
|
// Remove trailing separators from this object. If the path is absolute, it
|
|
// will never be stripped any more than to refer to the absolute root
|
|
// directory, so "////" will become "/", not "". A leading pair of
|
|
// separators is never stripped, to support alternate roots. This is used to
|
|
// support UNC paths on Windows.
|
|
void StripTrailingSeparatorsInternal();
|
|
|
|
StringType path_;
|
|
};
|
|
|
|
BASE_EXPORT std::ostream& operator<<(std::ostream& out,
|
|
const FilePath& file_path);
|
|
|
|
} // namespace base
|
|
|
|
namespace std {
|
|
|
|
template <>
|
|
struct hash<base::FilePath> {
|
|
typedef base::FilePath argument_type;
|
|
typedef std::size_t result_type;
|
|
result_type operator()(argument_type const& f) const {
|
|
return hash<base::FilePath::StringType>()(f.value());
|
|
}
|
|
};
|
|
|
|
} // namespace std
|
|
|
|
#endif // BASE_FILES_FILE_PATH_H_
|