1/*
2 * Copyright (C) 2014 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#include <androidfw/TypeWrappers.h>
18
19namespace android {
20
21TypeVariant::iterator& TypeVariant::iterator::operator++() {
22    mIndex++;
23    if (mIndex > dtohl(mTypeVariant->data->entryCount)) {
24        mIndex = dtohl(mTypeVariant->data->entryCount);
25    }
26    return *this;
27}
28
29const ResTable_entry* TypeVariant::iterator::operator*() const {
30    const ResTable_type* type = mTypeVariant->data;
31    const uint32_t entryCount = dtohl(type->entryCount);
32    if (mIndex >= entryCount) {
33        return NULL;
34    }
35
36    const uintptr_t containerEnd = reinterpret_cast<uintptr_t>(type)
37            + dtohl(type->header.size);
38    const uint32_t* const entryIndices = reinterpret_cast<const uint32_t*>(
39            reinterpret_cast<uintptr_t>(type) + dtohs(type->header.headerSize));
40    if (reinterpret_cast<uintptr_t>(entryIndices) + (sizeof(uint32_t) * entryCount) > containerEnd) {
41        ALOGE("Type's entry indices extend beyond its boundaries");
42        return NULL;
43    }
44
45    const uint32_t entryOffset = dtohl(entryIndices[mIndex]);
46    if (entryOffset == ResTable_type::NO_ENTRY) {
47        return NULL;
48    }
49
50    if ((entryOffset & 0x3) != 0) {
51        ALOGE("Index %u points to entry with unaligned offset 0x%08x", mIndex, entryOffset);
52        return NULL;
53    }
54
55    const ResTable_entry* entry = reinterpret_cast<const ResTable_entry*>(
56            reinterpret_cast<uintptr_t>(type) + dtohl(type->entriesStart) + entryOffset);
57    if (reinterpret_cast<uintptr_t>(entry) > containerEnd - sizeof(*entry)) {
58        ALOGE("Entry offset at index %u points outside the Type's boundaries", mIndex);
59        return NULL;
60    } else if (reinterpret_cast<uintptr_t>(entry) + dtohs(entry->size) > containerEnd) {
61        ALOGE("Entry at index %u extends beyond Type's boundaries", mIndex);
62        return NULL;
63    } else if (dtohs(entry->size) < sizeof(*entry)) {
64        ALOGE("Entry at index %u is too small (%u)", mIndex, dtohs(entry->size));
65        return NULL;
66    }
67    return entry;
68}
69
70} // namespace android
71