2 files changed, 228 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
diff --git a/security/sandbox/chromium-shim/base/files/file_util.h b/security/sandbox/chromium-shim/base/files/file_util.h
new file mode 100644
index 0000000000..bd6ce0c0a8
--- /dev/null
+++ b/security/sandbox/chromium-shim/base/files/file_util.h
@@ -0,0 +1,11 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+// This is a cut down version of Chromium source file base/files/file_util.h
+// This is included in base/memory/shared_memory.h, but it only actually
+// requires the include for base/files/file_path.h.
+
+#include "base/files/file_path.h"