Fix memory leak of DexFile handle after release

The DexFile handle is allocated from heap in OpenFromFd/OpenFromMemory.
After releasing the unique_ptr, the DexFile handle itself is no longer
managed by the smart pointer. However, the DexFile handle is not freed
in the constructor of DexFileFromFile/DexFileFromMemory.

This change uses get() method to get the DexFile pointer while allowing
it to be managed by smart pointer so that it can be freed after method
end.

Added new unit tests to detect leaks.

Bug: 151966190

Test: Unwinding can still retrieve dex frame information during crash.
Test: Ran new unit tests before change and verified they fail, ran them
Test: after the change and verified they don't fail.

Signed-off-by: Yong Li <yongl0722@gmail.com>
Change-Id: I0627e1e255eb6644aba51e940c1a79ff78d568d7
(cherry picked from commit 489c3a8b356a7a3ae235afec5e1e954f90301622)
diff --git a/libunwindstack/DexFile.cpp b/libunwindstack/DexFile.cpp
index dff7a8b..bf63abf 100644
--- a/libunwindstack/DexFile.cpp
+++ b/libunwindstack/DexFile.cpp
@@ -89,7 +89,7 @@
     return nullptr;
   }
 
-  return std::unique_ptr<DexFileFromFile>(new DexFileFromFile(std::move(*art_dex_file.release())));
+  return std::unique_ptr<DexFileFromFile>(new DexFileFromFile(art_dex_file));
 }
 
 std::unique_ptr<DexFileFromMemory> DexFileFromMemory::Create(uint64_t dex_file_offset_in_memory,
@@ -108,7 +108,7 @@
 
     if (art_dex_file != nullptr) {
       return std::unique_ptr<DexFileFromMemory>(
-          new DexFileFromMemory(std::move(*art_dex_file.release()), std::move(backing_memory)));
+          new DexFileFromMemory(art_dex_file, std::move(backing_memory)));
     }
 
     if (!error_msg.empty()) {
diff --git a/libunwindstack/DexFile.h b/libunwindstack/DexFile.h
index ca658e6..4e8369f 100644
--- a/libunwindstack/DexFile.h
+++ b/libunwindstack/DexFile.h
@@ -39,7 +39,8 @@
                                          MapInfo* info);
 
  protected:
-  DexFile(art_api::dex::DexFile&& art_dex_file) : art_api::dex::DexFile(std::move(art_dex_file)) {}
+  DexFile(std::unique_ptr<art_api::dex::DexFile>& art_dex_file)
+      : art_api::dex::DexFile(art_dex_file) {}
 };
 
 class DexFileFromFile : public DexFile {
@@ -48,7 +49,7 @@
                                                  const std::string& file);
 
  private:
-  DexFileFromFile(art_api::dex::DexFile&& art_dex_file) : DexFile(std::move(art_dex_file)) {}
+  DexFileFromFile(std::unique_ptr<art_api::dex::DexFile>& art_dex_file) : DexFile(art_dex_file) {}
 };
 
 class DexFileFromMemory : public DexFile {
@@ -57,8 +58,9 @@
                                                    Memory* memory, const std::string& name);
 
  private:
-  DexFileFromMemory(art_api::dex::DexFile&& art_dex_file, std::vector<uint8_t>&& memory)
-      : DexFile(std::move(art_dex_file)), memory_(std::move(memory)) {}
+  DexFileFromMemory(std::unique_ptr<art_api::dex::DexFile>& art_dex_file,
+                    std::vector<uint8_t>&& memory)
+      : DexFile(art_dex_file), memory_(std::move(memory)) {}
 
   std::vector<uint8_t> memory_;
 };
diff --git a/libunwindstack/tests/DexFileTest.cpp b/libunwindstack/tests/DexFileTest.cpp
index 1b54da6..dc935a3 100644
--- a/libunwindstack/tests/DexFileTest.cpp
+++ b/libunwindstack/tests/DexFileTest.cpp
@@ -14,6 +14,7 @@
  * limitations under the License.
  */
 
+#include <malloc.h>
 #include <stdint.h>
 #include <sys/types.h>
 #include <unistd.h>
@@ -72,6 +73,37 @@
   EXPECT_TRUE(DexFileFromFile::Create(0x100, tf.path) != nullptr);
 }
 
+static constexpr size_t kNumLeakLoops = 5000;
+static constexpr size_t kMaxAllowedLeakBytes = 1024;
+
+static void CheckForLeak(size_t loop, size_t* first_allocated_bytes, size_t* last_allocated_bytes) {
+  size_t allocated_bytes = mallinfo().uordblks;
+  if (*first_allocated_bytes == 0) {
+    *first_allocated_bytes = allocated_bytes;
+  } else if (*last_allocated_bytes > *first_allocated_bytes) {
+    // Check that the total memory did not increase too much over the first loop.
+    ASSERT_LE(*last_allocated_bytes - *first_allocated_bytes, kMaxAllowedLeakBytes)
+        << "Failed in loop " << loop << " first_allocated_bytes " << *first_allocated_bytes
+        << " last_allocated_bytes " << *last_allocated_bytes;
+  }
+  *last_allocated_bytes = allocated_bytes;
+}
+
+TEST(DexFileTest, from_file_no_leak) {
+  TemporaryFile tf;
+  ASSERT_TRUE(tf.fd != -1);
+
+  ASSERT_EQ(sizeof(kDexData),
+            static_cast<size_t>(TEMP_FAILURE_RETRY(write(tf.fd, kDexData, sizeof(kDexData)))));
+
+  size_t first_allocated_bytes = 0;
+  size_t last_allocated_bytes = 0;
+  for (size_t i = 0; i < kNumLeakLoops; i++) {
+    EXPECT_TRUE(DexFileFromFile::Create(0, tf.path) != nullptr);
+    ASSERT_NO_FATAL_FAILURE(CheckForLeak(i, &first_allocated_bytes, &last_allocated_bytes));
+  }
+}
+
 TEST(DexFileTest, from_memory_fail_too_small_for_header) {
   MemoryFake memory;
 
@@ -96,6 +128,19 @@
   EXPECT_TRUE(DexFileFromMemory::Create(0x1000, &memory, "") != nullptr);
 }
 
+TEST(DexFileTest, from_memory_no_leak) {
+  MemoryFake memory;
+
+  memory.SetMemory(0x1000, kDexData, sizeof(kDexData));
+
+  size_t first_allocated_bytes = 0;
+  size_t last_allocated_bytes = 0;
+  for (size_t i = 0; i < kNumLeakLoops; i++) {
+    EXPECT_TRUE(DexFileFromMemory::Create(0x1000, &memory, "") != nullptr);
+    ASSERT_NO_FATAL_FAILURE(CheckForLeak(i, &first_allocated_bytes, &last_allocated_bytes));
+  }
+}
+
 TEST(DexFileTest, create_using_file) {
   TemporaryFile tf;
   ASSERT_TRUE(tf.fd != -1);