blob: 26bf011d1f1f743e67f07eae7e57972b9b11204d [file] [log] [blame]
// 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[] char16_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 char16_t[]-based
// pathnames on Windows.
// As a precaution against premature truncation, paths can't contain NULs.
// 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.
// - 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 3.267 ("Pathname")
// and 4.12 ("Pathname Resolution"), available at:
// - 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:
#include <stddef.h>
#include <iosfwd>
#include <string>
#include <string_view>
#include <vector>
#include "base/compiler_specific.h"
#include "util/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)
#endif // OS_WIN
// To print path names portably use PRIsFP (based on PRIuS and friends from
// C99 and format_macros.h) like this:
// base::StringPrintf("Path is %" PRIsFP ".\n", PATH_CSTR(path);
#if defined(OS_WIN)
#define PRIsFP "ls"
#define PATH_CSTR(x) reinterpret_cast<const wchar_t*>(x.value().c_str())
#elif defined(OS_POSIX) || defined(OS_FUCHSIA)
#define PRIsFP "s"
#define PATH_CSTR(x) (x.value().c_str())
#endif // OS_WIN
namespace base {
class Pickle;
class PickleIterator;
// An abstraction to isolate users from the differences between native
// pathnames on different platforms.
class FilePath {
#if defined(OS_WIN)
// On Windows, for Unicode-aware applications, native pathnames are char16_t
// arrays encoded in UTF-16.
typedef std::u16string StringType;
#elif defined(OS_POSIX) || defined(OS_FUCHSIA)
// 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;
#endif // OS_WIN
using CharType = StringType::value_type;
using StringViewType = std::basic_string_view<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[];
// std::size(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(const FilePath& that);
explicit FilePath(StringViewType path);
FilePath& operator=(const FilePath& that);
// Constructs FilePath with the contents of |that|, which is left in valid but
// unspecified state.
FilePath(FilePath&& that) noexcept;
// Replaces the contents with those of |that|, which is left in valid but
// unspecified state.
FilePath& operator=(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.
// To make sure this is lossless so we can differentiate absolute and
// relative paths, the root slash will be included even though no other
// slashes will be. The precise behavior is:
// Posix: "/foo/bar" -> [ "/", "foo", "bar" ]
// Windows: "C:\foo\bar" -> [ "C:", "\\", "foo", "bar" ]
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. Please note that this
// doesn't resolve directory navigation, e.g. the result for "../a" is "..".
[[nodiscard]] FilePath DirName() const;
// 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.
[[nodiscard]] FilePath BaseName() const;
// 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. For common double-extensions like .tar.gz and
// .user.js, this method returns the combined extension. For a single
// component, use FinalExtension().
// 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")
[[nodiscard]] StringType Extension() const;
// Returns the path's file extension, as in Extension(), but will
// never return a double extension.
// TODO(davidben): Check all our extension-sensitive code to see if
// we can rename this to Extension() and the other to something like
// LongExtension(), defaulting to short extensions and leaving the
// long "extensions" to logic like base::GetUniquePathNumber().
[[nodiscard]] StringType FinalExtension() 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'.
[[nodiscard]] FilePath RemoveExtension() const;
// Removes the path's file extension, as in RemoveExtension(), but
// ignores double extensions.
[[nodiscard]] FilePath RemoveFinalExtension() const;
// 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)"
[[nodiscard]] FilePath InsertBeforeExtension(StringViewType suffix) const;
[[nodiscard]] FilePath InsertBeforeExtensionASCII(
std::string_view suffix) const;
// Adds |extension| to |file_name|. Returns the current FilePath if
// |extension| is empty. Returns "" if BaseName() == "." or "..".
[[nodiscard]] FilePath AddExtension(StringViewType extension) const;
// 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 "..".
[[nodiscard]] FilePath ReplaceExtension(StringViewType 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.
[[nodiscard]] FilePath Append(StringViewType component) const;
[[nodiscard]] FilePath Append(const FilePath& component) const;
// Although Windows StringType is std::u16string, 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.
[[nodiscard]] FilePath AppendASCII(std::string_view component) const;
// 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.
[[nodiscard]] bool EndsWithSeparator() const;
// Returns a copy of this FilePath that ends with a trailing separator. If
// the input path is empty, an empty FilePath will be returned.
[[nodiscard]] FilePath AsEndingWithSeparator() const;
// Returns a copy of this FilePath that does not end with a trailing
// separator.
[[nodiscard]] FilePath StripTrailingSeparators() const;
// Returns true if this FilePath contains an attempt to reference a parent
// directory (e.g. 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 std::u16string into some other API.
std::u16string 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 8-bit. On Linux this isn't guaranteed to be UTF-8.
std::string As8Bit() const;
// 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;
// Normalize all path separattors to given type on Windows
// (if FILE_PATH_USES_WIN_SEPARATORS is true), or do nothing on POSIX systems.
FilePath NormalizePathSeparatorsTo(CharType separator) const;
// 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
// Macros for string literal initialization of FilePath::CharType[].
#if defined(OS_WIN)
#define FILE_PATH_LITERAL(x) u##x
#elif defined(OS_POSIX) || defined(OS_FUCHSIA)
#define FILE_PATH_LITERAL(x) x
#endif // OS_WIN
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