// Copyright (c) 2010 Google Inc.
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
//     * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
//     * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
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// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

// 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 CallStack.
//
// Author: Mark Mentovai


#ifndef GOOGLE_BREAKPAD_PROCESSOR_STACKWALKER_H__
#define GOOGLE_BREAKPAD_PROCESSOR_STACKWALKER_H__

#include <set>
#include <string>
#include "google_breakpad/common/breakpad_types.h"
#include "google_breakpad/processor/code_modules.h"
#include "google_breakpad/processor/memory_region.h"

namespace google_breakpad {

class CallStack;
class MinidumpContext;
class SourceLineResolverInterface;
struct StackFrame;
class SymbolSupplier;
struct SystemInfo;

using std::set;


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

  // Populates the given CallStack by calling GetContextFrame and
  // GetCallerFrame.  The frames are further processed to fill all available
  // data.  Returns true if the stackwalk completed, or false if it was
  // interrupted by SymbolSupplier::GetSymbolFile().
  bool Walk(CallStack *stack);

  // 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(const SystemInfo *system_info,
                                        MinidumpContext *context,
                                        MemoryRegion *memory,
                                        const CodeModules *modules,
                                        SymbolSupplier *supplier,
                                        SourceLineResolverInterface *resolver);

  static void set_max_frames(u_int32_t max_frames) { max_frames_ = max_frames; }
  static u_int32_t max_frames() { return max_frames_; }

 protected:
  // system_info identifies the operating system, NULL or empty if unknown.
  // memory identifies a MemoryRegion that provides the stack memory
  // for the stack to walk.  modules, if non-NULL, is a CodeModules
  // object 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.  resolver is an instance of SourceLineResolverInterface
  // (see source_line_resolver_interface.h and basic_source_line_resolver.h).
  // If resolver is NULL, source line info will not be resolved.
  Stackwalker(const SystemInfo *system_info,
              MemoryRegion *memory,
              const CodeModules *modules,
              SymbolSupplier *supplier,
              SourceLineResolverInterface *resolver);

  // This can be used to filter out potential return addresses when
  // the stack walker resorts to stack scanning.
  // Returns true if any of:
  // * This address is within a loaded module, but we don't have symbols
  //   for that module.
  // * This address is within a loaded module for which we have symbols,
  //   and falls inside a function in that module.
  // Returns false otherwise.
  bool InstructionAddressSeemsValid(u_int64_t address);

  // 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 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 ip_found to the value contained at that
  // location in memory.
  template<typename InstructionType>
  bool ScanForReturnAddress(InstructionType location_start,
                            InstructionType *location_found,
                            InstructionType *ip_found) {
    const int kRASearchWords = 30;
    for (InstructionType location = location_start;
         location <= location_start + kRASearchWords * sizeof(InstructionType);
         location += sizeof(InstructionType)) {
      InstructionType ip;
      if (!memory_->GetMemoryAtAddress(location, &ip))
        break;

      if (modules_ && modules_->GetModuleForAddress(ip) &&
          InstructionAddressSeemsValid(ip)) {

        *ip_found = ip;
        *location_found = location;
        return true;
      }
    }
    // nothing found
    return false;
  }

  // Information about the system that produced the minidump.  Subclasses
  // and the SymbolSupplier may find this information useful.
  const SystemInfo *system_info_;

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

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

 protected:
  // The SourceLineResolver implementation.
  SourceLineResolverInterface *resolver_;

 private:
  // Obtains the context frame, the innermost called procedure in a stack
  // trace.  Returns NULL on failure.  GetContextFrame allocates a new
  // StackFrame (or StackFrame subclass), ownership of which is taken by
  // the caller.
  virtual StackFrame* GetContextFrame() = 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, stack contains the CallStack
  // made of frames that have already been walked.  GetCallerFrame should
  // return NULL on failure or when there are no more caller frames (when
  // the end of the stack has been reached).  GetCallerFrame allocates a new
  // StackFrame (or StackFrame subclass), ownership of which is taken by
  // the caller.
  virtual StackFrame* GetCallerFrame(const CallStack *stack) = 0;

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

  // A list of modules that we haven't found symbols for.  We track
  // this in order to avoid repeatedly looking them up again within
  // one minidump.
  set<std::string> no_symbol_modules_;

  // The maximum number of frames Stackwalker will walk through.
  // This defaults to 1024 to prevent infinite loops.
  static u_int32_t max_frames_;
};


}  // namespace google_breakpad


#endif  // GOOGLE_BREAKPAD_PROCESSOR_STACKWALKER_H__
