Revert "Revert "Revert "Revert "Add BacktraceOffline for offline backtracing.""""

This reverts commit 94ece83270deca76c69f5755f8c0ff5c859341fd.

Change-Id: Ie06465c89a5fc115517130f9f2904cc855973155
diff --git a/libbacktrace/BacktraceOffline.h b/libbacktrace/BacktraceOffline.h
new file mode 100644
index 0000000..42f826d
--- /dev/null
+++ b/libbacktrace/BacktraceOffline.h
@@ -0,0 +1,105 @@
+/*
+ * Copyright (C) 2015 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.
+ */
+
+#ifndef _LIBBACKTRACE_UNWIND_OFFLINE_H
+#define _LIBBACKTRACE_UNWIND_OFFLINE_H
+
+#include <libunwind.h>
+#include <stdint.h>
+#include <sys/types.h>
+#include <ucontext.h>
+
+#include <unordered_map>
+#include <unordered_set>
+
+#include <backtrace/Backtrace.h>
+
+struct Space {
+  uint64_t start;
+  uint64_t end;
+  const uint8_t* data;
+
+  Space() {
+    Clear();
+  }
+
+  void Clear();
+  size_t Read(uint64_t addr, uint8_t* buffer, size_t size);
+};
+
+struct DebugFrameInfo {
+  bool is_eh_frame;
+  struct EhFrame {
+    uint64_t eh_frame_hdr_vaddr;
+    uint64_t eh_frame_vaddr;
+    uint64_t fde_table_offset_in_eh_frame_hdr;
+    std::vector<uint8_t> eh_frame_hdr_data;
+    std::vector<uint8_t> eh_frame_data;
+    struct ProgramHeader {
+      uint64_t vaddr;
+      uint64_t file_offset;
+      uint64_t file_size;
+    };
+    std::vector<ProgramHeader> program_headers;
+  } eh_frame;
+};
+
+class BacktraceOffline : public Backtrace {
+ public:
+  BacktraceOffline(pid_t pid, pid_t tid, BacktraceMap* map, const backtrace_stackinfo_t& stack,
+                   bool cache_file)
+      : Backtrace(pid, tid, map),
+        cache_file_(cache_file),
+        context_(nullptr),
+        last_debug_frame_(nullptr) {
+    stack_space_.start = stack.start;
+    stack_space_.end = stack.end;
+    stack_space_.data = stack.data;
+  }
+
+  virtual ~BacktraceOffline() {
+    if (last_debug_frame_ != nullptr) {
+      delete last_debug_frame_;
+    }
+  }
+
+  bool Unwind(size_t num_ignore_frames, ucontext_t* context) override;
+
+  bool ReadWord(uintptr_t ptr, word_t* out_value) override;
+
+  size_t Read(uintptr_t addr, uint8_t* buffer, size_t bytes) override;
+
+  bool FindProcInfo(unw_addr_space_t addr_space, uint64_t ip, unw_proc_info_t* proc_info,
+                    int need_unwind_info);
+
+  bool ReadReg(size_t reg_index, uint64_t* value);
+
+ protected:
+  std::string GetFunctionNameRaw(uintptr_t pc, uintptr_t* offset) override;
+  DebugFrameInfo* GetDebugFrameInFile(const std::string& filename);
+
+  static std::unordered_map<std::string, std::unique_ptr<DebugFrameInfo>> debug_frames_;
+  static std::unordered_set<std::string> debug_frame_missing_files_;
+
+  bool cache_file_;
+  ucontext_t* context_;
+  Space eh_frame_hdr_space_;
+  Space eh_frame_space_;
+  Space stack_space_;
+  DebugFrameInfo* last_debug_frame_;
+};
+
+#endif  // _LIBBACKTRACE_BACKTRACE_OFFLINE_H