1 files changed, 81 insertions, 0 deletions
diff --git a/libs/androidfw/ChunkIterator.cpp b/libs/androidfw/ChunkIterator.cpp
new file mode 100644
index 000000000000..747aa4ad20e6
--- /dev/null
+++ b/libs/androidfw/ChunkIterator.cpp
@@ -0,0 +1,81 @@
+/*
+ * Copyright (C) 2016 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "Chunk.h"
+
+#include "android-base/logging.h"
+
+namespace android {
+
+Chunk ChunkIterator::Next() {
+  CHECK(len_ != 0) << "called Next() after last chunk";
+
+  const ResChunk_header* this_chunk = next_chunk_;
+
+  // We've already checked the values of this_chunk, so safely increment.
+  next_chunk_ = reinterpret_cast<const ResChunk_header*>(
+      reinterpret_cast<const uint8_t*>(this_chunk) + dtohl(this_chunk->size));
+  len_ -= dtohl(this_chunk->size);
+
+  if (len_ != 0) {
+    // Prepare the next chunk.
+    VerifyNextChunk();
+  }
+  return Chunk(this_chunk);
+}
+
+// Returns false if there was an error.
+bool ChunkIterator::VerifyNextChunk() {
+  const uintptr_t header_start = reinterpret_cast<uintptr_t>(next_chunk_);
+
+  // This data must be 4-byte aligned, since we directly
+  // access 32-bit words, which must be aligned on
+  // certain architectures.
+  if (header_start & 0x03) {
+    last_error_ = "header not aligned on 4-byte boundary";
+    return false;
+  }
+
+  if (len_ < sizeof(ResChunk_header)) {
+    last_error_ = "not enough space for header";
+    return false;
+  }
+
+  const size_t header_size = dtohs(next_chunk_->headerSize);
+  const size_t size = dtohl(next_chunk_->size);
+  if (header_size < sizeof(ResChunk_header)) {
+    last_error_ = "header size too small";
+    return false;
+  }
+
+  if (header_size > size) {
+    last_error_ = "header size is larger than entire chunk";
+    return false;
+  }
+
+  if (size > len_) {
+    last_error_ = "chunk size is bigger than given data";
+    return false;
+  }
+
+  if ((size | header_size) & 0x03) {
+    last_error_ = "header sizes are not aligned on 4-byte boundary";
+    return false;
+  }
+  return true;
+}
+
+}  // namespace android