// -*- mode: c++ -*- 

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// stackwalker_x86.h: x86-specific stackwalker.
//
// Provides stack frames given x86 register context and a memory region
// corresponding to an x86 stack.
//
// Author: Mark Mentovai


#ifndef PROCESSOR_STACKWALKER_X86_H__
#define PROCESSOR_STACKWALKER_X86_H__


#include "google_breakpad/common/breakpad_types.h"
#include "google_breakpad/common/minidump_format.h"
#include "google_breakpad/processor/stackwalker.h"
#include "google_breakpad/processor/stack_frame_cpu.h"

namespace google_breakpad {

class CodeModules;


class StackwalkerX86 : public Stackwalker {
 public:
  // context is an x86 context object that gives access to x86-specific
  // register state corresponding to the innermost called frame to be
  // included in the stack.  The other arguments are passed directly through
  // to the base Stackwalker constructor.
  StackwalkerX86(const SystemInfo *system_info,
                 const MDRawContextX86 *context,
                 MemoryRegion *memory,
                 const CodeModules *modules,
                 SymbolSupplier *supplier,
                 SourceLineResolverInterface *resolver);

 private:
  // Implementation of Stackwalker, using x86 context (%ebp, %esp, %eip) and
  // stack conventions (saved %ebp at [%ebp], saved %eip at 4[%ebp], or
  // alternate conventions as guided by any WindowsFrameInfo available for the
  // code in question.).
  virtual StackFrame *GetContextFrame();
  virtual StackFrame *GetCallerFrame(const CallStack *stack);

  // Use windows_frame_info (derived from STACK WIN and FUNC records)
  // to construct the frame that called frames.back(). The caller
  // takes ownership of the returned frame. Return NULL on failure.
  StackFrameX86 *GetCallerByWindowsFrameInfo(
      const vector<StackFrame*> &frames,
      WindowsFrameInfo *windows_frame_info);

  // Assuming a traditional frame layout --- where the caller's %ebp
  // has been pushed just after the return address and the callee's
  // %ebp points to the saved %ebp --- construct the frame that called
  // frames.back(). The caller takes ownership of the returned frame.
  // Return NULL on failure.
  StackFrameX86 *GetCallerByEBPAtBase(const vector<StackFrame*> &frames);

  // Scan the stack starting at location_start, looking for an address
  // that looks like a valid instruction pointer. Addresses must
  // 1) be contained in the current stack memory
  // 2) pass the checks in Stackwalker::InstructionAddressSeemsValid
  //
  // Returns true if a valid-looking instruction pointer was found.
  // When returning true, sets location_found to the address at which
  // the value was found, and eip_found to the value contained at that
  // location in memory.
  bool ScanForReturnAddress(u_int32_t location_start,
                            u_int32_t *location_found,
                            u_int32_t *eip_found);

  // Stores the CPU context corresponding to the innermost stack frame to
  // be returned by GetContextFrame.
  const MDRawContextX86 *context_;
};


}  // namespace google_breakpad


#endif  // PROCESSOR_STACKWALKER_X86_H__