The Tor Browser: security/sandbox/chromium/base/files/file

security/sandbox/chromium/base/files/file_path.h@b8a032363ba2 (annotated)

security/sandbox/chromium/base/files/file_path.h

Thu, 22 Jan 2015 13:21:57 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Thu, 22 Jan 2015 13:21:57 +0100
branch: TOR_BUG_9701
changeset 15: b8a032363ba2
permissions: -rw-r--r--

Incorporate requested changes from Mozilla in review:
https://bugzilla.mozilla.org/show_bug.cgi?id=1123480#c6

 // 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_

The Tor Browser / annotate

security/sandbox/chromium/base/files/file_path.h@b8a032363ba2 (annotated)

security/sandbox/chromium/base/files/file_path.h