1/*
2 * Copyright (C) 2017 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17#ifndef IDMAP_H_
18#define IDMAP_H_
19
20#include <memory>
21#include <string>
22#include <unordered_map>
23
24#include "android-base/macros.h"
25
26#include "androidfw/StringPiece.h"
27
28namespace android {
29
30struct Idmap_header;
31struct IdmapEntry_header;
32
33// Represents a loaded/parsed IDMAP for a Runtime Resource Overlay (RRO).
34// An RRO and its target APK have different resource IDs assigned to their resources. Overlaying
35// a resource is done by resource name. An IDMAP is a generated mapping between the resource IDs
36// of the RRO and the target APK for each resource with the same name.
37// A LoadedIdmap can be set alongside the overlay's LoadedArsc to allow the overlay ApkAssets to
38// masquerade as the target ApkAssets resources.
39class LoadedIdmap {
40 public:
41  // Loads an IDMAP from a chunk of memory. Returns nullptr if the IDMAP data was malformed.
42  static std::unique_ptr<const LoadedIdmap> Load(const StringPiece& idmap_data);
43
44  // Performs a lookup of the expected entry ID for the given IDMAP entry header.
45  // Returns true if the mapping exists and fills `output_entry_id` with the result.
46  static bool Lookup(const IdmapEntry_header* header, uint16_t input_entry_id,
47                     uint16_t* output_entry_id);
48
49  // Returns the package ID for which this overlay should apply.
50  uint8_t TargetPackageId() const;
51
52  // Returns the path to the RRO (Runtime Resource Overlay) APK for which this IDMAP was generated.
53  inline const std::string& OverlayApkPath() const {
54    return overlay_apk_path_;
55  }
56
57  // Returns the mapping of target entry ID to overlay entry ID for the given target type.
58  const IdmapEntry_header* GetEntryMapForType(uint8_t type_id) const;
59
60 protected:
61  // Exposed as protected so that tests can subclass and mock this class out.
62  LoadedIdmap() = default;
63
64  const Idmap_header* header_ = nullptr;
65  std::string overlay_apk_path_;
66  std::unordered_map<uint8_t, const IdmapEntry_header*> type_map_;
67
68 private:
69  DISALLOW_COPY_AND_ASSIGN(LoadedIdmap);
70
71  explicit LoadedIdmap(const Idmap_header* header);
72};
73
74}  // namespace android
75
76#endif  // IDMAP_H_
77