Add a MemoryOfflineBuffer object.

Use this for offline stack data so that it's not necessary to
copy any data around.

Add unit tests for the new object.

Bug: 77258731
Bug: 74354410

Test: Ran libunwindstack/libbacktrace unit tests.
Change-Id: I9b0f25d9520c96e64aedef5f295423c60ddb3488

1 files changed, 97 insertions, 0 deletions

diff --git a/libunwindstack/tests/MemoryOfflineBufferTest.cpp b/libunwindstack/tests/MemoryOfflineBufferTest.cpp
new file mode 100644
index 000000000..f022884cb
--- /dev/null
+++ b/libunwindstack/tests/MemoryOfflineBufferTest.cpp
@@ -0,0 +1,97 @@
+/*
+ * 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 <vector>
+
+#include <gtest/gtest.h>
+
+#include <unwindstack/Memory.h>
+
+#include "LogFake.h"
+
+namespace unwindstack {
+
+class MemoryOfflineBufferTest : public ::testing::Test {
+ protected:
+  void SetUp() override {
+    ResetLogs();
+    memory_.reset(new MemoryOfflineBuffer(buffer_.data(), kStart, kEnd));
+  }
+
+  static void SetUpTestCase() {
+    buffer_.resize(kLength);
+    for (size_t i = 0; i < kLength; i++) {
+      buffer_[i] = i % 189;
+    }
+  }
+
+  std::unique_ptr<MemoryOfflineBuffer> memory_;
+
+  static constexpr size_t kLength = 0x2000;
+  static constexpr uint64_t kStart = 0x1000;
+  static constexpr uint64_t kEnd = kStart + kLength;
+  static std::vector<uint8_t> buffer_;
+};
+
+std::vector<uint8_t> MemoryOfflineBufferTest::buffer_;
+
+static void VerifyBuffer(uint8_t* buffer, size_t start_value, size_t length) {
+  for (size_t i = 0; i < length; i++) {
+    ASSERT_EQ((start_value + i) % 189, buffer[i]) << "Failed at byte " << i;
+  }
+}
+
+TEST_F(MemoryOfflineBufferTest, read_out_of_bounds) {
+  std::vector<uint8_t> buffer(1024);
+  ASSERT_FALSE(memory_->ReadFully(0, buffer.data(), 1));
+  ASSERT_FALSE(memory_->ReadFully(0xfff, buffer.data(), 1));
+  ASSERT_FALSE(memory_->ReadFully(0xfff, buffer.data(), 2));
+  ASSERT_FALSE(memory_->ReadFully(0x3000, buffer.data(), 1));
+  ASSERT_FALSE(memory_->ReadFully(0x3001, buffer.data(), 1));
+}
+
+TEST_F(MemoryOfflineBufferTest, read) {
+  std::vector<uint8_t> buffer(1024);
+  ASSERT_TRUE(memory_->ReadFully(kStart, buffer.data(), 10));
+  ASSERT_NO_FATAL_FAILURE(VerifyBuffer(buffer.data(), 0, 10));
+
+  ASSERT_TRUE(memory_->ReadFully(kStart + 555, buffer.data(), 40));
+  ASSERT_NO_FATAL_FAILURE(VerifyBuffer(buffer.data(), 555, 40));
+
+  ASSERT_TRUE(memory_->ReadFully(kStart + kLength - 105, buffer.data(), 105));
+  ASSERT_NO_FATAL_FAILURE(VerifyBuffer(buffer.data(), kLength - 105, 105));
+}
+
+TEST_F(MemoryOfflineBufferTest, read_past_end) {
+  std::vector<uint8_t> buffer(1024);
+  ASSERT_EQ(100U, memory_->Read(kStart + kLength - 100, buffer.data(), buffer.size()));
+  VerifyBuffer(buffer.data(), kLength - 100, 100);
+}
+
+TEST_F(MemoryOfflineBufferTest, read_after_reset) {
+  std::vector<uint8_t> buffer(1024);
+  ASSERT_TRUE(memory_->ReadFully(kStart, buffer.data(), 100));
+  ASSERT_NO_FATAL_FAILURE(VerifyBuffer(buffer.data(), 0, 100));
+
+  memory_->Reset(&buffer_[10], 0x12000, 0x13000);
+  ASSERT_TRUE(memory_->ReadFully(0x12000, buffer.data(), 100));
+  ASSERT_NO_FATAL_FAILURE(VerifyBuffer(buffer.data(), 10, 100));
+
+  ASSERT_EQ(50U, memory_->Read(0x13000 - 50, buffer.data(), buffer.size()));
+  ASSERT_NO_FATAL_FAILURE(VerifyBuffer(buffer.data(), 0x1000 - 50 + 10, 50));
+}
+
+}  // namespace unwindstack