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, 15 insertions, 0 deletions

diff --git a/libunwindstack/include/unwindstack/Memory.h b/libunwindstack/include/unwindstack/Memory.h
index 19bce04..c0c07f4 100644
--- a/libunwindstack/include/unwindstack/Memory.h
+++ b/libunwindstack/include/unwindstack/Memory.h
@@ -151,6 +151,21 @@ class MemoryOffline : public Memory {
   std::unique_ptr<MemoryRange> memory_;
 };
 
+class MemoryOfflineBuffer : public Memory {
+ public:
+  MemoryOfflineBuffer(const uint8_t* data, uint64_t start, uint64_t end);
+  virtual ~MemoryOfflineBuffer() = default;
+
+  void Reset(const uint8_t* data, uint64_t start, uint64_t end);
+
+  size_t Read(uint64_t addr, void* dst, size_t size) override;
+
+ private:
+  const uint8_t* data_;
+  uint64_t start_;
+  uint64_t end_;
+};
+
 class MemoryOfflineParts : public Memory {
  public:
   MemoryOfflineParts() = default;