Add extra frame when dex_pc is non-zero.

Use the art dex file library to read the dex data.

Add unit tests for the UnwindDexFile code.

Bug: 72070049

Test: All unit tests continue to pass.
Test: Dumped the backtrace of the 137-cfi test while running in interpreter
Test: mode and verified that the stack trace is correct. Did this on host
Test: and for arm/arm64.

Change-Id: Ia6f343318c5dd6968a954015a7d59fdf101575b0
diff --git a/libbacktrace/UnwindDexFile.cpp b/libbacktrace/UnwindDexFile.cpp
new file mode 100644
index 0000000..5780fbb
--- /dev/null
+++ b/libbacktrace/UnwindDexFile.cpp
@@ -0,0 +1,162 @@
+/*
+ * Copyright (C) 2018 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 <stdint.h>
+#include <sys/mman.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+#include <memory>
+
+#include <android-base/unique_fd.h>
+
+#include <dex/code_item_accessors-no_art-inl.h>
+#include <dex/compact_dex_file.h>
+#include <dex/dex_file-inl.h>
+#include <dex/dex_file_loader.h>
+#include <dex/standard_dex_file.h>
+
+#include <unwindstack/MapInfo.h>
+#include <unwindstack/Memory.h>
+
+#include "UnwindDexFile.h"
+
+UnwindDexFile* UnwindDexFile::Create(uint64_t dex_file_offset_in_memory,
+                                     unwindstack::Memory* memory, unwindstack::MapInfo* info) {
+  if (!info->name.empty()) {
+    std::unique_ptr<UnwindDexFileFromFile> dex_file(new UnwindDexFileFromFile);
+    if (dex_file->Open(dex_file_offset_in_memory - info->start + info->offset, info->name)) {
+      return dex_file.release();
+    }
+  }
+
+  std::unique_ptr<UnwindDexFileFromMemory> dex_file(new UnwindDexFileFromMemory);
+  if (dex_file->Open(dex_file_offset_in_memory, memory)) {
+    return dex_file.release();
+  }
+  return nullptr;
+}
+
+void UnwindDexFile::GetMethodInformation(uint64_t dex_offset, std::string* method_name,
+                                         uint64_t* method_offset) {
+  if (dex_file_ == nullptr) {
+    return;
+  }
+
+  for (uint32_t i = 0; i < dex_file_->NumClassDefs(); ++i) {
+    const art::DexFile::ClassDef& class_def = dex_file_->GetClassDef(i);
+    const uint8_t* class_data = dex_file_->GetClassData(class_def);
+    if (class_data == nullptr) {
+      continue;
+    }
+    for (art::ClassDataItemIterator it(*dex_file_.get(), class_data); it.HasNext(); it.Next()) {
+      if (!it.IsAtMethod()) {
+        continue;
+      }
+      const art::DexFile::CodeItem* code_item = it.GetMethodCodeItem();
+      if (code_item == nullptr) {
+        continue;
+      }
+      art::CodeItemInstructionAccessor code(*dex_file_.get(), code_item);
+      if (!code.HasCodeItem()) {
+        continue;
+      }
+
+      uint64_t offset = reinterpret_cast<const uint8_t*>(code.Insns()) - dex_file_->Begin();
+      size_t size = code.InsnsSizeInCodeUnits() * sizeof(uint16_t);
+      if (offset <= dex_offset && dex_offset < offset + size) {
+        *method_name = dex_file_->PrettyMethod(it.GetMemberIndex(), false);
+        *method_offset = dex_offset - offset;
+        return;
+      }
+    }
+  }
+}
+
+UnwindDexFileFromFile::~UnwindDexFileFromFile() {
+  if (size_ != 0) {
+    munmap(mapped_memory_, size_);
+  }
+}
+
+bool UnwindDexFileFromFile::Open(uint64_t dex_file_offset_in_file, const std::string& file) {
+  android::base::unique_fd fd(TEMP_FAILURE_RETRY(open(file.c_str(), O_RDONLY | O_CLOEXEC)));
+  if (fd == -1) {
+    return false;
+  }
+  struct stat buf;
+  if (fstat(fd, &buf) == -1) {
+    return false;
+  }
+  uint64_t length;
+  if (buf.st_size < 0 ||
+      __builtin_add_overflow(dex_file_offset_in_file, sizeof(art::DexFile::Header), &length) ||
+      static_cast<uint64_t>(buf.st_size) < length) {
+    return false;
+  }
+
+  mapped_memory_ = mmap(nullptr, buf.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
+  if (mapped_memory_ == MAP_FAILED) {
+    return false;
+  }
+  size_ = buf.st_size;
+
+  uint8_t* memory = reinterpret_cast<uint8_t*>(mapped_memory_);
+
+  art::DexFile::Header* header =
+      reinterpret_cast<art::DexFile::Header*>(&memory[dex_file_offset_in_file]);
+  if (!art::StandardDexFile::IsMagicValid(header->magic_) &&
+      !art::CompactDexFile::IsMagicValid(header->magic_)) {
+    return false;
+  }
+
+  if (__builtin_add_overflow(dex_file_offset_in_file, header->file_size_, &length) ||
+      static_cast<uint64_t>(buf.st_size) < length) {
+    return false;
+  }
+
+  art::DexFileLoader loader;
+  std::string error_msg;
+  auto dex = loader.Open(&memory[dex_file_offset_in_file], header->file_size_, "", 0, nullptr,
+                         false, false, &error_msg);
+  dex_file_.reset(dex.release());
+  return dex_file_ != nullptr;
+}
+
+bool UnwindDexFileFromMemory::Open(uint64_t dex_file_offset_in_memory, unwindstack::Memory* memory) {
+  art::DexFile::Header header;
+  if (!memory->ReadFully(dex_file_offset_in_memory, &header, sizeof(header))) {
+    return false;
+  }
+
+  if (!art::StandardDexFile::IsMagicValid(header.magic_) &&
+      !art::CompactDexFile::IsMagicValid(header.magic_)) {
+    return false;
+  }
+
+  memory_.resize(header.file_size_);
+  if (!memory->ReadFully(dex_file_offset_in_memory, memory_.data(), header.file_size_)) {
+    return false;
+  }
+
+  art::DexFileLoader loader;
+  std::string error_msg;
+  auto dex =
+      loader.Open(memory_.data(), header.file_size_, "", 0, nullptr, false, false, &error_msg);
+  dex_file_.reset(dex.release());
+  return dex_file_ != nullptr;
+}