Initial implementation of x86 stackwalker (#9). r=bryner

git-svn-id: http://google-breakpad.googlecode.com/svn/trunk@12 4c0a9323-5329-0410-9bdc-e9ce6186880e

src/processor/stackwalker.h

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+// Copyright (C) 2006 Google Inc.
+//
+// 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.
+
+// stackwalker.cc: 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 "google/stack_frame.h"
+#include "processor/memory_region.h"
+
+
+namespace google_airbag {
+
+
+class MinidumpModuleList;
+
+
+class Stackwalker {
+  public:
+    virtual ~Stackwalker() {}
+
+    // Produces a vector of StackFrames by calling GetContextFrame and
+    // GetCallerFrame, and populating the returned frames with module
+    // offset and name information if possible.  The caller takes ownership
+    // of the StackFrames object and is responsible for freeing it.
+    StackFrames* Walk();
+
+  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.
+    Stackwalker(MemoryRegion* memory, MinidumpModuleList* modules);
+
+    // The stack memory to walk.  Subclasses will require this region to
+    // get information from the stack.
+    MemoryRegion*       memory_;
+
+  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.  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) = 0;
+
+    // A list of modules, for populating each StackFrame's module information.
+    // This field is optional and may be NULL.
+    MinidumpModuleList* modules_;
+};
+
+
+} // namespace google_airbag
+
+
+#endif // PROCESSOR_STACKWALKER_H__