// Copyright (c) 2006, Google Inc.
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//
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// stackwalker.h: Generic stackwalker.
//
// The Stackwalker class is an abstract base class providing common generic
// methods that apply to stacks from all systems.  Specific implementations
// will extend this class by providing GetContextFrame and GetCallerFrame
// methods to fill in system-specific data in a StackFrame structure.
// Stackwalker assembles these StackFrame strucutres into a vector of
// StackFrames.
//
// Author: Mark Mentovai


#ifndef PROCESSOR_STACKWALKER_H__
#define PROCESSOR_STACKWALKER_H__

#include <vector>

#include "google/stack_frame.h"
#include "processor/memory_region.h"
#include "processor/stack_frame_info.h"

namespace google_airbag {

class MinidumpContext;
class MinidumpModuleList;
class SymbolSupplier;


class Stackwalker {
 public:
  virtual ~Stackwalker() {}

  // Fills the given vector of StackFrames by calling GetContextFrame and
  // GetCallerFrame, and populating the returned frames with all available
  // data.
  void Walk(StackFrames *frames);

  // Returns a new concrete subclass suitable for the CPU that a stack was
  // generated on, according to the CPU type indicated by the context
  // argument.  If no suitable concrete subclass exists, returns NULL.
  static Stackwalker* StackwalkerForCPU(MinidumpContext *context,
                                        MemoryRegion *memory,
                                        MinidumpModuleList *modules,
                                        SymbolSupplier *supplier);

 protected:
  // memory identifies a MemoryRegion that provides the stack memory
  // for the stack to walk.  modules, if non-NULL, is a MinidumpModuleList
  // that is used to look up which code module each stack frame is
  // associated with.  supplier is an optional caller-supplied SymbolSupplier
  // implementation.  If supplier is NULL, source line info will not be
  // resolved.
  Stackwalker(MemoryRegion *memory,
              MinidumpModuleList *modules,
              SymbolSupplier *supplier);

  // The stack memory to walk.  Subclasses will require this region to
  // get information from the stack.
  MemoryRegion *memory_;

  // Additional debugging information for each stack frame.  This vector
  // parallels the StackFrames vector.  Subclasses may use this information
  // to walk the stack.
  std::vector<StackFrameInfo> stack_frame_info_;

 private:
  // Obtains the context frame, the innermost called procedure in a stack
  // trace.  Returns false on failure.
  virtual bool GetContextFrame(StackFrame *frame) = 0;

  // Obtains a caller frame.  Each call to GetCallerFrame should return the
  // frame that called the last frame returned by GetContextFrame or
  // GetCallerFrame.  To aid this purpose, walked_frames contains the
  // StackFrames vector of frames that have already been walked.
  // GetCallerFrame should return false on failure or when there are no more
  // caller frames (when the end of the stack has been reached).
  virtual bool GetCallerFrame(StackFrame *frame,
                              const StackFrames *walked_frames) = 0;

  // A list of modules, for populating each StackFrame's module information.
  // This field is optional and may be NULL.
  MinidumpModuleList *modules_;

  // The optional SymbolSupplier for resolving source line info.
  SymbolSupplier *supplier_;
};


} // namespace google_airbag


#endif // PROCESSOR_STACKWALKER_H__