The Tor Browser / file revision

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

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

 // found in the LICENSE file.

 // 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/containers/hash_tables.h"

 #include "base/strings/string16.h"

 #include "base/strings/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[];

   // arraysize(kSeparators).

   static const size_t kSeparatorsLength;

   // 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 true if the patch ends with a path separator character.

   bool EndsWithSeparator() const WARN_UNUSED_RESULT;

   // Returns a copy of this FilePath that ends with a trailing separator. If

   // the input path is empty, an empty FilePath will be returned.

   FilePath AsEndingWithSeparator() const WARN_UNUSED_RESULT;

   // 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;

   // Similar to AsUTF8Unsafe, but returns UTF-16 instead.

   string16 AsUTF16Unsafe() 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);

   // Similar to FromUTF8Unsafe, but accepts UTF-16 instead.

   static FilePath FromUTF16Unsafe(const string16& utf16);

   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_