diff options
Diffstat (limited to 'security/sandbox/chromium-shim/base/files/file_path.cpp')
| -rw-r--r-- | security/sandbox/chromium-shim/base/files/file_path.cpp | 217 |
1 files changed, 217 insertions, 0 deletions
diff --git a/security/sandbox/chromium-shim/base/files/file_path.cpp b/security/sandbox/chromium-shim/base/files/file_path.cpp new file mode 100644 index 0000000000..bcbfecab99 --- /dev/null +++ b/security/sandbox/chromium-shim/base/files/file_path.cpp @@ -0,0 +1,217 @@ +// 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. + +// This is a partial implementation of Chromium's source file +// base/file/file_path.cc. + +#include "base/files/file_path.h" + +namespace base { + +using StringType = FilePath::StringType; +using StringPieceType = FilePath::StringPieceType; + +namespace { + +const FilePath::CharType kStringTerminator = FILE_PATH_LITERAL('\0'); + +// If this FilePath contains a drive letter specification, returns the +// position of the last character of the drive letter specification, +// otherwise returns npos. This can only be true on Windows, when a pathname +// begins with a letter followed by a colon. On other platforms, this always +// returns npos. +StringPieceType::size_type FindDriveLetter(StringPieceType path) { +#if defined(FILE_PATH_USES_DRIVE_LETTERS) + // This is dependent on an ASCII-based character set, but that's a + // reasonable assumption. iswalpha can be too inclusive here. + if (path.length() >= 2 && path[1] == L':' && + ((path[0] >= L'A' && path[0] <= L'Z') || + (path[0] >= L'a' && path[0] <= L'z'))) { + return 1; + } +#endif // FILE_PATH_USES_DRIVE_LETTERS + return StringType::npos; +} + +bool IsPathAbsolute(StringPieceType path) { +#if defined(FILE_PATH_USES_DRIVE_LETTERS) + StringType::size_type letter = FindDriveLetter(path); + if (letter != StringType::npos) { + // Look for a separator right after the drive specification. + return path.length() > letter + 1 && + FilePath::IsSeparator(path[letter + 1]); + } + // Look for a pair of leading separators. + return path.length() > 1 && + FilePath::IsSeparator(path[0]) && FilePath::IsSeparator(path[1]); +#else // FILE_PATH_USES_DRIVE_LETTERS + // Look for a separator in the first position. + return path.length() > 0 && FilePath::IsSeparator(path[0]); +#endif // FILE_PATH_USES_DRIVE_LETTERS +} + +} // namespace + +FilePath::FilePath() = default; + +FilePath::FilePath(const FilePath& that) = default; +FilePath::FilePath(FilePath&& that) noexcept = default; + +FilePath::FilePath(StringPieceType path) : path_(path) { + StringType::size_type nul_pos = path_.find(kStringTerminator); + if (nul_pos != StringType::npos) + path_.erase(nul_pos, StringType::npos); +} + +FilePath::~FilePath() = default; + +FilePath& FilePath::operator=(const FilePath& that) = default; + +FilePath& FilePath::operator=(FilePath&& that) = default; + +// static +bool FilePath::IsSeparator(CharType character) { + for (size_t i = 0; i < kSeparatorsLength - 1; ++i) { + if (character == kSeparators[i]) { + return true; + } + } + + return false; +} + +// libgen's dirname and basename aren't guaranteed to be thread-safe and aren't +// guaranteed to not modify their input strings, and in fact are implemented +// differently in this regard on different platforms. Don't use them, but +// adhere to their behavior. +FilePath FilePath::DirName() const { + FilePath new_path(path_); + new_path.StripTrailingSeparatorsInternal(); + + // The drive letter, if any, always needs to remain in the output. If there + // is no drive letter, as will always be the case on platforms which do not + // support drive letters, letter will be npos, or -1, so the comparisons and + // resizes below using letter will still be valid. + StringType::size_type letter = FindDriveLetter(new_path.path_); + + StringType::size_type last_separator = + new_path.path_.find_last_of(kSeparators, StringType::npos, + kSeparatorsLength - 1); + if (last_separator == StringType::npos) { + // path_ is in the current directory. + new_path.path_.resize(letter + 1); + } else if (last_separator == letter + 1) { + // path_ is in the root directory. + new_path.path_.resize(letter + 2); + } else if (last_separator == letter + 2 && + IsSeparator(new_path.path_[letter + 1])) { + // path_ is in "//" (possibly with a drive letter); leave the double + // separator intact indicating alternate root. + new_path.path_.resize(letter + 3); + } else if (last_separator != 0) { + // path_ is somewhere else, trim the basename. + new_path.path_.resize(last_separator); + } + + new_path.StripTrailingSeparatorsInternal(); + if (!new_path.path_.length()) + new_path.path_ = kCurrentDirectory; + + return new_path; +} + +FilePath FilePath::BaseName() const { + FilePath new_path(path_); + new_path.StripTrailingSeparatorsInternal(); + + // The drive letter, if any, is always stripped. + StringType::size_type letter = FindDriveLetter(new_path.path_); + if (letter != StringType::npos) { + new_path.path_.erase(0, letter + 1); + } + + // Keep everything after the final separator, but if the pathname is only + // one character and it's a separator, leave it alone. + StringType::size_type last_separator = + new_path.path_.find_last_of(kSeparators, StringType::npos, + kSeparatorsLength - 1); + if (last_separator != StringType::npos && + last_separator < new_path.path_.length() - 1) { + new_path.path_.erase(0, last_separator + 1); + } + + return new_path; +} + +FilePath FilePath::Append(StringPieceType component) const { + StringPieceType appended = component; + StringType without_nuls; + + StringType::size_type nul_pos = component.find(kStringTerminator); + if (nul_pos != StringPieceType::npos) { + without_nuls = StringType(component.substr(0, nul_pos)); + appended = StringPieceType(without_nuls); + } + + DCHECK(!IsPathAbsolute(appended)); + + if (path_.compare(kCurrentDirectory) == 0 && !appended.empty()) { + // Append normally doesn't do any normalization, but as a special case, + // when appending to kCurrentDirectory, just return a new path for the + // component argument. Appending component to kCurrentDirectory would + // serve no purpose other than needlessly lengthening the path, and + // it's likely in practice to wind up with FilePath objects containing + // only kCurrentDirectory when calling DirName on a single relative path + // component. + return FilePath(appended); + } + + FilePath new_path(path_); + new_path.StripTrailingSeparatorsInternal(); + + // Don't append a separator if the path is empty (indicating the current + // directory) or if the path component is empty (indicating nothing to + // append). + if (!appended.empty() && !new_path.path_.empty()) { + // Don't append a separator if the path still ends with a trailing + // separator after stripping (indicating the root directory). + if (!IsSeparator(new_path.path_.back())) { + // Don't append a separator if the path is just a drive letter. + if (FindDriveLetter(new_path.path_) + 1 != new_path.path_.length()) { + new_path.path_.append(1, kSeparators[0]); + } + } + } + + new_path.path_.append(appended.data(), appended.size()); + return new_path; +} + +FilePath FilePath::Append(const FilePath& component) const { + return Append(component.value()); +} + +void FilePath::StripTrailingSeparatorsInternal() { + // If there is no drive letter, start will be 1, which will prevent stripping + // the leading separator if there is only one separator. If there is a drive + // letter, start will be set appropriately to prevent stripping the first + // separator following the drive letter, if a separator immediately follows + // the drive letter. + StringType::size_type start = FindDriveLetter(path_) + 2; + + StringType::size_type last_stripped = StringType::npos; + for (StringType::size_type pos = path_.length(); + pos > start && IsSeparator(path_[pos - 1]); + --pos) { + // If the string only has two separators and they're at the beginning, + // don't strip them, unless the string began with more than two separators. + if (pos != start + 1 || last_stripped == start + 2 || + !IsSeparator(path_[start - 1])) { + path_.resize(pos - 1); + last_stripped = pos; + } + } +} + +} // namespace base |