src/extensions/common/extension_resource.cc

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "extensions/common/extension_resource.h"
   6
   7 #include "base/files/file_util.h"
   8 #include "base/logging.h"
   9 #include "base/threading/thread_restrictions.h"
  10
  11 namespace extensions {
  12
  13 ExtensionResource::ExtensionResource() : follow_symlinks_anywhere_(false) {
  14 }
  15
  16 ExtensionResource::ExtensionResource(const std::string& extension_id,
  17                                      const base::FilePath& extension_root,
  18                                      const base::FilePath& relative_path)
  19     : extension_id_(extension_id),
  20       extension_root_(extension_root),
  21       relative_path_(relative_path),
  22       follow_symlinks_anywhere_(false) {
  23 }
  24
  25 ExtensionResource::~ExtensionResource() {}
  26
  27 void ExtensionResource::set_follow_symlinks_anywhere() {
  28   follow_symlinks_anywhere_ = true;
  29 }
  30
  31 const base::FilePath& ExtensionResource::GetFilePath() const {
  32   if (extension_root_.empty() || relative_path_.empty()) {
  33     DCHECK(full_resource_path_.empty());
  34     return full_resource_path_;
  35   }
  36
  37   // We've already checked, just return last value.
  38   if (!full_resource_path_.empty())
  39     return full_resource_path_;
  40
  41   full_resource_path_ = GetFilePath(
  42       extension_root_, relative_path_,
  43       follow_symlinks_anywhere_ ?
  44           FOLLOW_SYMLINKS_ANYWHERE : SYMLINKS_MUST_RESOLVE_WITHIN_ROOT);
  45   return full_resource_path_;
  46 }
  47
  48 // static
  49 base::FilePath ExtensionResource::GetFilePath(
  50     const base::FilePath& extension_root,
  51     const base::FilePath& relative_path,
  52     SymlinkPolicy symlink_policy) {
  53   // We need to resolve the parent references in the extension_root
  54   // path on its own because IsParent doesn't like parent references.
  55   base::FilePath clean_extension_root(
  56       base::MakeAbsoluteFilePath(extension_root));
  57   if (clean_extension_root.empty())
  58     return base::FilePath();
  59
  60   base::FilePath full_path = clean_extension_root.Append(relative_path);
  61
  62   // If we are allowing the file to be a symlink outside of the root, then the
  63   // path before resolving the symlink must still be within it.
  64   if (symlink_policy == FOLLOW_SYMLINKS_ANYWHERE) {
  65     std::vector<base::FilePath::StringType> components;
  66     relative_path.GetComponents(&components);
  67     int depth = 0;
  68
  69     for (std::vector<base::FilePath::StringType>::const_iterator
  70          i = components.begin(); i != components.end(); i++) {
  71       if (*i == base::FilePath::kParentDirectory) {
  72         depth--;
  73       } else if (*i != base::FilePath::kCurrentDirectory) {
  74         depth++;
  75       }
  76       if (depth < 0) {
  77         return base::FilePath();
  78       }
  79     }
  80   }
  81
  82   // We must resolve the absolute path of the combined path when
  83   // the relative path contains references to a parent folder (i.e., '..').
  84   // We also check if the path exists because the posix version of
  85   // MakeAbsoluteFilePath will fail if the path doesn't exist, and we want the
  86   // same behavior on Windows... So until the posix and Windows version of
  87   // MakeAbsoluteFilePath are unified, we need an extra call to PathExists,
  88   // unfortunately.
  89   // TODO(mad): Fix this once MakeAbsoluteFilePath is unified.
  90   full_path = base::MakeAbsoluteFilePath(full_path);
  91   if (base::PathExists(full_path) &&
  92       (symlink_policy == FOLLOW_SYMLINKS_ANYWHERE ||
  93        clean_extension_root.IsParent(full_path))) {
  94     return full_path;
  95   }
  96
  97   return base::FilePath();
  98 }
  99
 100 // Unit-testing helpers.
 101 base::FilePath::StringType ExtensionResource::NormalizeSeperators(
 102     const base::FilePath::StringType& path) const {
 103 #if defined(FILE_PATH_USES_WIN_SEPARATORS)
 104   base::FilePath::StringType win_path = path;
 105   for (size_t i = 0; i < win_path.length(); i++) {
 106     if (base::FilePath::IsSeparator(win_path[i]))
 107       win_path[i] = base::FilePath::kSeparators[0];
 108   }
 109   return win_path;
 110 #else
 111   return path;
 112 #endif  // FILE_PATH_USES_WIN_SEPARATORS
 113 }
 114
 115 bool ExtensionResource::ComparePathWithDefault(
 116     const base::FilePath& path) const {
 117   // Make sure we have a cached value to test against...
 118   if (full_resource_path_.empty())
 119     GetFilePath();
 120   if (NormalizeSeperators(path.value()) ==
 121     NormalizeSeperators(full_resource_path_.value())) {
 122     return true;
 123   } else {
 124     return false;
 125   }
 126 }
 127
 128 }  // namespace extensions