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Diffstat (limited to 'base/files/file_path.h')
| -rw-r--r-- | base/files/file_path.h | 442 |
1 files changed, 442 insertions, 0 deletions
diff --git a/base/files/file_path.h b/base/files/file_path.h new file mode 100644 index 0000000..2e0009d --- /dev/null +++ b/base/files/file_path.h @@ -0,0 +1,442 @@ +// 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. + +// FilePath is a container for pathnames stored in a platform's native string +// type, providing containers for manipulation in according with the +// platform's conventions for pathnames. It supports the following path +// types: +// +// POSIX Windows +// --------------- ---------------------------------- +// Fundamental type char[] wchar_t[] +// Encoding unspecified* UTF-16 +// Separator / \, tolerant of / +// Drive letters no case-insensitive A-Z followed by : +// Alternate root // (surprise!) \\, for UNC paths +// +// * The encoding need not be specified on POSIX systems, although some +// POSIX-compliant systems do specify an encoding. Mac OS X uses UTF-8. +// Chrome OS also uses UTF-8. +// Linux does not specify an encoding, but in practice, the locale's +// character set may be used. +// +// For more arcane bits of path trivia, see below. +// +// FilePath objects are intended to be used anywhere paths are. An +// application may pass FilePath objects around internally, masking the +// underlying differences between systems, only differing in implementation +// where interfacing directly with the system. For example, a single +// OpenFile(const FilePath &) function may be made available, allowing all +// callers to operate without regard to the underlying implementation. On +// POSIX-like platforms, OpenFile might wrap fopen, and on Windows, it might +// wrap _wfopen_s, perhaps both by calling file_path.value().c_str(). This +// allows each platform to pass pathnames around without requiring conversions +// between encodings, which has an impact on performance, but more imporantly, +// has an impact on correctness on platforms that do not have well-defined +// encodings for pathnames. +// +// Several methods are available to perform common operations on a FilePath +// object, such as determining the parent directory (DirName), isolating the +// final path component (BaseName), and appending a relative pathname string +// to an existing FilePath object (Append). These methods are highly +// recommended over attempting to split and concatenate strings directly. +// These methods are based purely on string manipulation and knowledge of +// platform-specific pathname conventions, and do not consult the filesystem +// at all, making them safe to use without fear of blocking on I/O operations. +// These methods do not function as mutators but instead return distinct +// instances of FilePath objects, and are therefore safe to use on const +// objects. The objects themselves are safe to share between threads. +// +// To aid in initialization of FilePath objects from string literals, a +// FILE_PATH_LITERAL macro is provided, which accounts for the difference +// between char[]-based pathnames on POSIX systems and wchar_t[]-based +// pathnames on Windows. +// +// Paths can't contain NULs as a precaution agaist premature truncation. +// +// Because a FilePath object should not be instantiated at the global scope, +// instead, use a FilePath::CharType[] and initialize it with +// FILE_PATH_LITERAL. At runtime, a FilePath object can be created from the +// character array. Example: +// +// | const FilePath::CharType kLogFileName[] = FILE_PATH_LITERAL("log.txt"); +// | +// | void Function() { +// | FilePath log_file_path(kLogFileName); +// | [...] +// | } +// +// WARNING: FilePaths should ALWAYS be displayed with LTR directionality, even +// when the UI language is RTL. This means you always need to pass filepaths +// through base::i18n::WrapPathWithLTRFormatting() before displaying it in the +// RTL UI. +// +// This is a very common source of bugs, please try to keep this in mind. +// +// ARCANE BITS OF PATH TRIVIA +// +// - A double leading slash is actually part of the POSIX standard. Systems +// are allowed to treat // as an alternate root, as Windows does for UNC +// (network share) paths. Most POSIX systems don't do anything special +// with two leading slashes, but FilePath handles this case properly +// in case it ever comes across such a system. FilePath needs this support +// for Windows UNC paths, anyway. +// References: +// The Open Group Base Specifications Issue 7, sections 3.266 ("Pathname") +// and 4.12 ("Pathname Resolution"), available at: +// http://www.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap03.html#tag_03_266 +// http://www.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap04.html#tag_04_12 +// +// - Windows treats c:\\ the same way it treats \\. This was intended to +// allow older applications that require drive letters to support UNC paths +// like \\server\share\path, by permitting c:\\server\share\path as an +// equivalent. Since the OS treats these paths specially, FilePath needs +// to do the same. Since Windows can use either / or \ as the separator, +// FilePath treats c://, c:\\, //, and \\ all equivalently. +// Reference: +// The Old New Thing, "Why is a drive letter permitted in front of UNC +// paths (sometimes)?", available at: +// http://blogs.msdn.com/oldnewthing/archive/2005/11/22/495740.aspx + +#ifndef BASE_FILES_FILE_PATH_H_ +#define BASE_FILES_FILE_PATH_H_ + +#include <stddef.h> +#include <string> +#include <vector> + +#include "base/base_export.h" +#include "base/compiler_specific.h" +#include "base/hash_tables.h" +#include "base/string16.h" +#include "base/string_piece.h" // For implicit conversions. +#include "build/build_config.h" + +// Windows-style drive letter support and pathname separator characters can be +// enabled and disabled independently, to aid testing. These #defines are +// here so that the same setting can be used in both the implementation and +// in the unit test. +#if defined(OS_WIN) +#define FILE_PATH_USES_DRIVE_LETTERS +#define FILE_PATH_USES_WIN_SEPARATORS +#endif // OS_WIN + +class Pickle; +class PickleIterator; + +namespace base { + +// An abstraction to isolate users from the differences between native +// pathnames on different platforms. +class BASE_EXPORT FilePath { + public: +#if defined(OS_POSIX) + // On most platforms, native pathnames are char arrays, and the encoding + // may or may not be specified. On Mac OS X, native pathnames are encoded + // in UTF-8. + typedef std::string StringType; +#elif defined(OS_WIN) + // On Windows, for Unicode-aware applications, native pathnames are wchar_t + // arrays encoded in UTF-16. + typedef std::wstring StringType; +#endif // OS_WIN + + typedef StringType::value_type CharType; + + // Null-terminated array of separators used to separate components in + // hierarchical paths. Each character in this array is a valid separator, + // but kSeparators[0] is treated as the canonical separator and will be used + // when composing pathnames. + static const CharType kSeparators[]; + + // A special path component meaning "this directory." + static const CharType kCurrentDirectory[]; + + // A special path component meaning "the parent directory." + static const CharType kParentDirectory[]; + + // The character used to identify a file extension. + static const CharType kExtensionSeparator; + + FilePath(); + FilePath(const FilePath& that); + explicit FilePath(const StringType& path); + ~FilePath(); + FilePath& operator=(const FilePath& that); + + bool operator==(const FilePath& that) const; + + bool operator!=(const FilePath& that) const; + + // Required for some STL containers and operations + bool operator<(const FilePath& that) const { + return path_ < that.path_; + } + + const StringType& value() const { return path_; } + + bool empty() const { return path_.empty(); } + + void clear() { path_.clear(); } + + // Returns true if |character| is in kSeparators. + static bool IsSeparator(CharType character); + + // Returns a vector of all of the components of the provided path. It is + // equivalent to calling DirName().value() on the path's root component, + // and BaseName().value() on each child component. + void GetComponents(std::vector<FilePath::StringType>* components) const; + + // Returns true if this FilePath is a strict parent of the |child|. Absolute + // and relative paths are accepted i.e. is /foo parent to /foo/bar and + // is foo parent to foo/bar. Does not convert paths to absolute, follow + // symlinks or directory navigation (e.g. ".."). A path is *NOT* its own + // parent. + bool IsParent(const FilePath& child) const; + + // If IsParent(child) holds, appends to path (if non-NULL) the + // relative path to child and returns true. For example, if parent + // holds "/Users/johndoe/Library/Application Support", child holds + // "/Users/johndoe/Library/Application Support/Google/Chrome/Default", and + // *path holds "/Users/johndoe/Library/Caches", then after + // parent.AppendRelativePath(child, path) is called *path will hold + // "/Users/johndoe/Library/Caches/Google/Chrome/Default". Otherwise, + // returns false. + bool AppendRelativePath(const FilePath& child, FilePath* path) const; + + // Returns a FilePath corresponding to the directory containing the path + // named by this object, stripping away the file component. If this object + // only contains one component, returns a FilePath identifying + // kCurrentDirectory. If this object already refers to the root directory, + // returns a FilePath identifying the root directory. + FilePath DirName() const WARN_UNUSED_RESULT; + + // Returns a FilePath corresponding to the last path component of this + // object, either a file or a directory. If this object already refers to + // the root directory, returns a FilePath identifying the root directory; + // this is the only situation in which BaseName will return an absolute path. + FilePath BaseName() const WARN_UNUSED_RESULT; + + // Returns ".jpg" for path "C:\pics\jojo.jpg", or an empty string if + // the file has no extension. If non-empty, Extension() will always start + // with precisely one ".". The following code should always work regardless + // of the value of path. + // new_path = path.RemoveExtension().value().append(path.Extension()); + // ASSERT(new_path == path.value()); + // NOTE: this is different from the original file_util implementation which + // returned the extension without a leading "." ("jpg" instead of ".jpg") + StringType Extension() const; + + // Returns "C:\pics\jojo" for path "C:\pics\jojo.jpg" + // NOTE: this is slightly different from the similar file_util implementation + // which returned simply 'jojo'. + FilePath RemoveExtension() const WARN_UNUSED_RESULT; + + // Inserts |suffix| after the file name portion of |path| but before the + // extension. Returns "" if BaseName() == "." or "..". + // Examples: + // path == "C:\pics\jojo.jpg" suffix == " (1)", returns "C:\pics\jojo (1).jpg" + // path == "jojo.jpg" suffix == " (1)", returns "jojo (1).jpg" + // path == "C:\pics\jojo" suffix == " (1)", returns "C:\pics\jojo (1)" + // path == "C:\pics.old\jojo" suffix == " (1)", returns "C:\pics.old\jojo (1)" + FilePath InsertBeforeExtension( + const StringType& suffix) const WARN_UNUSED_RESULT; + FilePath InsertBeforeExtensionASCII( + const base::StringPiece& suffix) const WARN_UNUSED_RESULT; + + // Adds |extension| to |file_name|. Returns the current FilePath if + // |extension| is empty. Returns "" if BaseName() == "." or "..". + FilePath AddExtension( + const StringType& extension) const WARN_UNUSED_RESULT; + + // Replaces the extension of |file_name| with |extension|. If |file_name| + // does not have an extension, then |extension| is added. If |extension| is + // empty, then the extension is removed from |file_name|. + // Returns "" if BaseName() == "." or "..". + FilePath ReplaceExtension( + const StringType& extension) const WARN_UNUSED_RESULT; + + // Returns true if the file path matches the specified extension. The test is + // case insensitive. Don't forget the leading period if appropriate. + bool MatchesExtension(const StringType& extension) const; + + // Returns a FilePath by appending a separator and the supplied path + // component to this object's path. Append takes care to avoid adding + // excessive separators if this object's path already ends with a separator. + // If this object's path is kCurrentDirectory, a new FilePath corresponding + // only to |component| is returned. |component| must be a relative path; + // it is an error to pass an absolute path. + FilePath Append(const StringType& component) const WARN_UNUSED_RESULT; + FilePath Append(const FilePath& component) const WARN_UNUSED_RESULT; + + // Although Windows StringType is std::wstring, since the encoding it uses for + // paths is well defined, it can handle ASCII path components as well. + // Mac uses UTF8, and since ASCII is a subset of that, it works there as well. + // On Linux, although it can use any 8-bit encoding for paths, we assume that + // ASCII is a valid subset, regardless of the encoding, since many operating + // system paths will always be ASCII. + FilePath AppendASCII(const base::StringPiece& component) + const WARN_UNUSED_RESULT; + + // Returns true if this FilePath contains an absolute path. On Windows, an + // absolute path begins with either a drive letter specification followed by + // a separator character, or with two separator characters. On POSIX + // platforms, an absolute path begins with a separator character. + bool IsAbsolute() const; + + // Returns a copy of this FilePath that does not end with a trailing + // separator. + FilePath StripTrailingSeparators() const WARN_UNUSED_RESULT; + + // Returns true if this FilePath contains any attempt to reference a parent + // directory (i.e. has a path component that is ".." + bool ReferencesParent() const; + + // Return a Unicode human-readable version of this path. + // Warning: you can *not*, in general, go from a display name back to a real + // path. Only use this when displaying paths to users, not just when you + // want to stuff a string16 into some other API. + string16 LossyDisplayName() const; + + // Return the path as ASCII, or the empty string if the path is not ASCII. + // This should only be used for cases where the FilePath is representing a + // known-ASCII filename. + std::string MaybeAsASCII() const; + + // Return the path as UTF-8. + // + // This function is *unsafe* as there is no way to tell what encoding is + // used in file names on POSIX systems other than Mac and Chrome OS, + // although UTF-8 is practically used everywhere these days. To mitigate + // the encoding issue, this function internally calls + // SysNativeMBToWide() on POSIX systems other than Mac and Chrome OS, + // per assumption that the current locale's encoding is used in file + // names, but this isn't a perfect solution. + // + // Once it becomes safe to to stop caring about non-UTF-8 file names, + // the SysNativeMBToWide() hack will be removed from the code, along + // with "Unsafe" in the function name. + std::string AsUTF8Unsafe() const; + + // Older Chromium code assumes that paths are always wstrings. + // This function converts wstrings to FilePaths, and is + // useful to smooth porting that old code to the FilePath API. + // It has "Hack" its name so people feel bad about using it. + // http://code.google.com/p/chromium/issues/detail?id=24672 + // + // If you are trying to be a good citizen and remove these, ask yourself: + // - Am I interacting with other Chrome code that deals with files? Then + // try to convert the API into using FilePath. + // - Am I interacting with OS-native calls? Then use value() to get at an + // OS-native string format. + // - Am I using well-known file names, like "config.ini"? Then use the + // ASCII functions (we require paths to always be supersets of ASCII). + // - Am I displaying a string to the user in some UI? Then use the + // LossyDisplayName() function, but keep in mind that you can't + // ever use the result of that again as a path. + static FilePath FromWStringHack(const std::wstring& wstring); + + // Returns a FilePath object from a path name in UTF-8. This function + // should only be used for cases where you are sure that the input + // string is UTF-8. + // + // Like AsUTF8Unsafe(), this function is unsafe. This function + // internally calls SysWideToNativeMB() on POSIX systems other than Mac + // and Chrome OS, to mitigate the encoding issue. See the comment at + // AsUTF8Unsafe() for details. + static FilePath FromUTF8Unsafe(const std::string& utf8); + + void WriteToPickle(Pickle* pickle) const; + bool ReadFromPickle(PickleIterator* iter); + + // Normalize all path separators to backslash on Windows + // (if FILE_PATH_USES_WIN_SEPARATORS is true), or do nothing on POSIX systems. + FilePath NormalizePathSeparators() const; + + // Compare two strings in the same way the file system does. + // Note that these always ignore case, even on file systems that are case- + // sensitive. If case-sensitive comparison is ever needed, add corresponding + // methods here. + // The methods are written as a static method so that they can also be used + // on parts of a file path, e.g., just the extension. + // CompareIgnoreCase() returns -1, 0 or 1 for less-than, equal-to and + // greater-than respectively. + static int CompareIgnoreCase(const StringType& string1, + const StringType& string2); + static bool CompareEqualIgnoreCase(const StringType& string1, + const StringType& string2) { + return CompareIgnoreCase(string1, string2) == 0; + } + static bool CompareLessIgnoreCase(const StringType& string1, + const StringType& string2) { + return CompareIgnoreCase(string1, string2) < 0; + } + +#if defined(OS_MACOSX) + // Returns the string in the special canonical decomposed form as defined for + // HFS, which is close to, but not quite, decomposition form D. See + // http://developer.apple.com/mac/library/technotes/tn/tn1150.html#UnicodeSubtleties + // for further comments. + // Returns the epmty string if the conversion failed. + static StringType GetHFSDecomposedForm(const FilePath::StringType& 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(const StringType& string1, + const StringType& string2); +#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_; +}; + +} // namespace base + +// This is required by googletest to print a readable output on test failures. +BASE_EXPORT extern void PrintTo(const base::FilePath& path, std::ostream* out); + +// Macros for string literal initialization of FilePath::CharType[], and for +// using a FilePath::CharType[] in a printf-style format string. +#if defined(OS_POSIX) +#define FILE_PATH_LITERAL(x) x +#define PRFilePath "s" +#define PRFilePathLiteral "%s" +#elif defined(OS_WIN) +#define FILE_PATH_LITERAL(x) L ## x +#define PRFilePath "ls" +#define PRFilePathLiteral L"%ls" +#endif // OS_WIN + +// Provide a hash function so that hash_sets and maps can contain FilePath +// objects. +namespace BASE_HASH_NAMESPACE { +#if defined(COMPILER_GCC) + +template<> +struct hash<base::FilePath> { + size_t operator()(const base::FilePath& f) const { + return hash<base::FilePath::StringType>()(f.value()); + } +}; + +#elif defined(COMPILER_MSVC) + +inline size_t hash_value(const base::FilePath& f) { + return hash_value(f.value()); +} + +#endif // COMPILER + +} // namespace BASE_HASH_NAMESPACE + +#endif // BASE_FILES_FILE_PATH_H_ |