Breakpad DWARF Parser: Improved DWARF-processing interface.

dwarf2reader::CompilationUnit is a simple and direct parser for DWARF
data, but its handler interface is not convenient to use. In
particular, the same handler object receives data about all DIEs
processed. One can't use distinct classes to separate the information
needed to handle different kinds of data.

This patch defines a new adapter type, dwarf2reader::DIEHandler, which
implements the existing DWARF parser's handler interface, given a
handler written to a more comfortable, object-orient interface. The
comments in dwarf2diehandler.h provide more detail.

a=jimblandy, r=ccoutant


git-svn-id: http://google-breakpad.googlecode.com/svn/trunk@495 4c0a9323-5329-0410-9bdc-e9ce6186880e

4 files changed, 1106 insertions, 0 deletions

diff --git a/src/common/dwarf/dwarf2diehandler.cc b/src/common/dwarf/dwarf2diehandler.cc
new file mode 100644
index 00000000..229a8284
--- /dev/null
+++ b/src/common/dwarf/dwarf2diehandler.cc
@@ -0,0 +1,183 @@
+// Copyright 2009 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.
+//     * Neither the name of Google Inc. nor the names of its
+// 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
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+// Implementation of dwarf2reader::DieDispatcher class.
+
+#include <cassert>
+
+#include "common/dwarf/dwarf2diehandler.h"
+
+namespace dwarf2reader {
+
+DIEDispatcher::~DIEDispatcher() {
+  while (!die_handlers_.empty()) {
+    HandlerStack &entry = die_handlers_.top();
+    if (entry.handler_ != root_handler_)
+      delete entry.handler_;
+    die_handlers_.pop();
+  }
+}
+
+bool DIEDispatcher::StartCompilationUnit(uint64 offset, uint8 address_size,
+                                         uint8 offset_size, uint64 cu_length,
+                                         uint8 dwarf_version) {
+  return root_handler_->StartCompilationUnit(offset, address_size,
+                                             offset_size, cu_length,
+                                             dwarf_version);
+}
+
+bool DIEDispatcher::StartDIE(uint64 offset, enum DwarfTag tag,
+                             const AttributeList& attrs) {
+  // The stack entry for the parent of this DIE, if there is one.
+  HandlerStack *parent = die_handlers_.empty() ? NULL : &die_handlers_.top();
+
+  // Does this call indicate that we're done receiving the parent's
+  // attributes' values?  If so, call its EndAttributes member function.
+  if (parent && parent->handler_ && !parent->reported_attributes_end_) {
+    parent->reported_attributes_end_ = true;
+    if (!parent->handler_->EndAttributes()) {
+      // Finish off this handler now. and edit *PARENT to indicate that
+      // we don't want to visit any of the children.
+      parent->handler_->Finish();
+      if (parent->handler_ != root_handler_)
+        delete parent->handler_;
+      parent->handler_ = NULL;
+      return false;
+    }
+  }
+
+  // Find a handler for this DIE.
+  DIEHandler *handler;
+  if (parent) {
+    if (parent->handler_)
+      // Ask the parent to find a handler.
+      handler = parent->handler_->FindChildHandler(offset, tag, attrs);
+    else
+      // No parent handler means we're not interested in any of our
+      // children.
+      handler = NULL;
+  } else {
+    // This is the root DIE.  For a non-root DIE, the parent's handler
+    // decides whether to visit it, but the root DIE has no parent
+    // handler, so we have a special method on the root DIE handler
+    // itself to decide.
+    if (root_handler_->StartRootDIE(offset, tag, attrs))
+      handler = root_handler_;
+    else
+      handler = NULL;
+  }
+
+  // Push a handler stack entry for this new handler. As an
+  // optimization, we don't push NULL-handler entries on top of other
+  // NULL-handler entries; we just let the oldest such entry stand for
+  // the whole subtree.
+  if (handler || !parent || parent->handler_) {
+    HandlerStack entry;
+    entry.offset_ = offset;
+    entry.handler_ = handler;
+    entry.reported_attributes_end_ = false;
+    die_handlers_.push(entry);
+  }
+
+  return handler != NULL;
+}
+
+void DIEDispatcher::EndDIE(uint64 offset) {
+  assert(!die_handlers_.empty());
+  HandlerStack *entry = &die_handlers_.top();
+  if (entry->handler_) {
+    // This entry had better be the handler for this DIE.
+    assert(entry->offset_ == offset);
+    // If a DIE has no children, this EndDIE call indicates that we're
+    // done receiving its attributes' values.
+    if (!entry->reported_attributes_end_)
+      entry->handler_->EndAttributes(); // Ignore return value: no children.
+    entry->handler_->Finish();
+    if (entry->handler_ != root_handler_)
+      delete entry->handler_;
+  } else {
+    // If this DIE is within a tree we're ignoring, then don't pop the
+    // handler stack: that entry stands for the whole tree.
+    if (entry->offset_ != offset)
+      return;
+  }
+  die_handlers_.pop();
+}
+
+void DIEDispatcher::ProcessAttributeUnsigned(uint64 offset,
+                                             enum DwarfAttribute attr,
+                                             enum DwarfForm form,
+                                             uint64 data) {
+  HandlerStack &current = die_handlers_.top();
+  // This had better be an attribute of the DIE we were meant to handle.
+  assert(offset == current.offset_);
+  current.handler_->ProcessAttributeUnsigned(attr, form, data);
+}
+
+void DIEDispatcher::ProcessAttributeSigned(uint64 offset,
+                                           enum DwarfAttribute attr,
+                                           enum DwarfForm form,
+                                           int64 data) {
+  HandlerStack &current = die_handlers_.top();
+  // This had better be an attribute of the DIE we were meant to handle.
+  assert(offset == current.offset_);
+  current.handler_->ProcessAttributeSigned(attr, form, data);
+}
+
+void DIEDispatcher::ProcessAttributeReference(uint64 offset,
+                                              enum DwarfAttribute attr,
+                                              enum DwarfForm form,
+                                              uint64 data) {
+  HandlerStack &current = die_handlers_.top();
+  // This had better be an attribute of the DIE we were meant to handle.
+  assert(offset == current.offset_);
+  current.handler_->ProcessAttributeReference(attr, form, data);
+}
+
+void DIEDispatcher::ProcessAttributeBuffer(uint64 offset,
+                                           enum DwarfAttribute attr,
+                                           enum DwarfForm form,
+                                           const char* data,
+                                           uint64 len) {
+  HandlerStack &current = die_handlers_.top();
+  // This had better be an attribute of the DIE we were meant to handle.
+  assert(offset == current.offset_);
+  current.handler_->ProcessAttributeBuffer(attr, form, data, len);
+}
+
+void DIEDispatcher::ProcessAttributeString(uint64 offset,
+                                           enum DwarfAttribute attr,
+                                           enum DwarfForm form,
+                                           const string& data) {
+  HandlerStack &current = die_handlers_.top();
+  // This had better be an attribute of the DIE we were meant to handle.
+  assert(offset == current.offset_);
+  current.handler_->ProcessAttributeString(attr, form, data);
+}
+
+} // namespace dwarf2reader
diff --git a/src/common/dwarf/dwarf2diehandler.h b/src/common/dwarf/dwarf2diehandler.h
new file mode 100644
index 00000000..6834193b
--- /dev/null
+++ b/src/common/dwarf/dwarf2diehandler.h
@@ -0,0 +1,345 @@
+// -*- mode: c++ -*-
+
+// Copyright 2009 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.
+//     * Neither the name of Google Inc. nor the names of its
+// 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
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+// dwarf2reader::CompilationUnit is a simple and direct parser for
+// DWARF data, but its handler interface is not convenient to use.  In
+// particular:
+//
+// - CompilationUnit calls Dwarf2Handler's member functions to report
+//   every attribute's value, regardless of what sort of DIE it is.
+//   As a result, the ProcessAttributeX functions end up looking like
+//   this:
+//
+//     switch (parent_die_tag) {
+//       case DW_TAG_x:
+//         switch (attribute_name) {
+//           case DW_AT_y:
+//             handle attribute y of DIE type x
+//           ...
+//         } break;
+//       ...
+//     } 
+//
+//   In C++ it's much nicer to use virtual function dispatch to find
+//   the right code for a given case than to switch on the DIE tag
+//   like this.
+//
+// - Processing different kinds of DIEs requires different sets of
+//   data: lexical block DIEs have start and end addresses, but struct
+//   type DIEs don't.  It would be nice to be able to have separate
+//   handler classes for separate kinds of DIEs, each with the members
+//   appropriate to its role, instead of having one handler class that
+//   needs to hold data for all every DIE type.
+//
+// - There should be a separate instance of the appropriate handler
+//   class for each DIE, instead of a single object with tables
+//   tracking all the dies in the compilation unit.
+//
+// - It's not convenient to take some action after all a DIE's
+//   attributes have been seen, but before visiting any of its
+//   children.  The only indication you have that a DIE's attribute
+//   list is complete is that you get either a StartDIE or an EndDIE
+//   call.
+//
+// - It's not convenient to make use of the tree structure of the
+//   DIEs.  Skipping all the children of a given die requires
+//   maintaining state and returning false from StartDIE until we get
+//   an EndDIE call with the appropriate offset.
+//
+// This interface tries to take care of all that.  (You're shocked, I'm sure.)
+//
+// Using the classes here, you provide an initial handler for the root
+// DIE of the compilation unit.  Each handler receives its DIE's
+// attributes, and provides fresh handler objects for children of
+// interest, if any.  The three classes are:
+//
+// - DIEHandler: the base class for your DIE-type-specific handler
+//   classes.
+//
+// - RootDIEHandler: derived from DIEHandler, the base class for your
+//   root DIE handler class.
+//
+// - DIEDispatcher: derived from Dwarf2Handler, an instance of this
+//   invokes your DIE-type-specific handler objects.
+//
+// In detail:
+//
+// - Define handler classes specialized for the DIE types you're
+//   interested in.  These handler classes must inherit from
+//   DIEHandler.  Thus:
+//
+//     class My_DW_TAG_X_Handler: public DIEHandler { ... };
+//     class My_DW_TAG_Y_Handler: public DIEHandler { ... };
+//
+//   DIEHandler subclasses needn't correspond exactly to single DIE
+//   types, as shown here; the point is that you can have several
+//   different classes appropriate to different kinds of DIEs.
+//
+// - In particular, define a handler class for the compilation
+//   unit's root DIE, that inherits from RootDIEHandler:
+//
+//     class My_DW_TAG_compile_unit_Handler: public RootDIEHandler { ... };
+//
+//   RootDIEHandler inherits from DIEHandler, adding a few additional
+//   member functions for examining the compilation unit as a whole,
+//   and other quirks of rootness.
+//
+// - Then, create a DIEDispatcher instance, passing it an instance of
+//   your root DIE handler class, and use that DIEDispatcher as the
+//   dwarf2reader::CompilationUnit's handler:
+//
+//     My_DW_TAG_compile_unit_Handler root_die_handler(...);
+//     DIEDispatcher die_dispatcher(&root_die_handler);
+//     CompilationUnit reader(sections, offset, bytereader, &die_dispatcher);
+//
+//   Here, 'die_dispatcher' acts as a shim between 'reader' and the
+//   various DIE-specific handlers you have defined.
+//
+// - When you call reader.Start(), die_dispatcher behaves as follows,
+//   starting with your root die handler and the compilation unit's
+//   root DIE:
+//
+//   - It calls the handler's ProcessAttributeX member functions for
+//     each of the DIE's attributes.
+//
+//   - It calls the handler's EndAttributes member function.  This
+//     should return true if any of the DIE's children should be
+//     visited, in which case:
+//
+//     - For each of the DIE's children, die_dispatcher calls the
+//       DIE's handler's FindChildHandler member function.  If that
+//       returns a pointer to a DIEHandler instance, then
+//       die_dispatcher uses that handler to process the child, using
+//       this procedure recursively.  Alternatively, if
+//       FindChildHandler returns NULL, die_dispatcher ignores that
+//       child and its descendants.
+// 
+//   - When die_dispatcher has finished processing all the DIE's
+//     children, it invokes the handler's Finish() member function,
+//     and destroys the handler.  (As a special case, it doesn't
+//     destroy the root DIE handler.)
+// 
+// This allows the code for handling a particular kind of DIE to be
+// gathered together in a single class, makes it easy to skip all the
+// children or individual children of a particular DIE, and provides
+// appropriate parental context for each die.
+
+#ifndef COMMON_DWARF_DWARF2DIEHANDLER_H__
+#define COMMON_DWARF_DWARF2DIEHANDLER_H__
+
+#include <stack>
+
+#include "common/dwarf/types.h"
+#include "common/dwarf/dwarf2enums.h"
+#include "common/dwarf/dwarf2reader.h"
+
+namespace dwarf2reader {
+
+// An base class for handlers for specific DIE types.  The series of
+// calls made on a DIE handler is as follows:
+//
+// - for each attribute of the DIE:
+//   - ProcessAttributeX()
+// - EndAttributes()
+// - if that returned true, then for each child:
+//   - FindChildHandler()
+//   - if that returns a non-NULL pointer to a new handler:
+//     - recurse, with the new handler and the child die
+// - Finish()
+// - destruction
+class DIEHandler {
+ public:
+  DIEHandler() { }
+  virtual ~DIEHandler() { }
+
+  // When we visit a DIE, we first use these member functions to
+  // report the DIE's attributes and their values.  These have the
+  // same restrictions as the corresponding member functions of
+  // dwarf2reader::Dwarf2Handler.
+  //
+  // The default definitions ignore the values they are passed.
+  virtual void ProcessAttributeUnsigned(enum DwarfAttribute attr,
+                                        enum DwarfForm form,
+                                        uint64 data) { }
+  virtual void ProcessAttributeSigned(enum DwarfAttribute attr,
+                                      enum DwarfForm form,
+                                      int64 data) { }
+  virtual void ProcessAttributeReference(enum DwarfAttribute attr,
+                                         enum DwarfForm form,
+                                         uint64 data) { }
+  virtual void ProcessAttributeBuffer(enum DwarfAttribute attr,
+                                      enum DwarfForm form,
+                                      const char* data,
+                                      uint64 len) { }
+  virtual void ProcessAttributeString(enum DwarfAttribute attr,
+                                      enum DwarfForm form,
+                                      const string& data) { }
+
+  // Once we have reported all the DIE's attributes' values, we call
+  // this member function.  If it returns false, we skip all the DIE's
+  // children.  If it returns true, we call FindChildHandler on each
+  // child.  If that returns a handler object, we use that to visit
+  // the child; otherwise, we skip the child.
+  //
+  // The default definition elects to ignore the DIE's children.
+  // You'll need to override this if you override FindChildHandler,
+  // but at least the default behavior isn't to pass the children to
+  // FindChildHandler, which then ignores them all.
+  virtual bool EndAttributes() { return false; }
+
+  // If EndAttributes returns true to indicate that some of the DIE's
+  // children might be of interest, then we apply this function to
+  // each of the DIE's children.  If it returns a handler object, then
+  // we use that to visit the child DIE.  If it returns NULL, we skip
+  // that child DIE (and all its descendants).
+  //
+  // OFFSET is the offset of the child; TAG indicates what kind of DIE
+  // it is; and ATTRS is the list of attributes the DIE will have, and
+  // their forms (their values are not provided).
+  //
+  // The default definition skips all children.
+  virtual DIEHandler *FindChildHandler(uint64 offset, enum DwarfTag tag,
+                                       const AttributeList &attrs) {
+    return NULL;
+  }
+
+  // When we are done processing a DIE, we call this member function.
+  // This happens after the EndAttributes call, all FindChildHandler
+  // calls (if any), and all operations on the children themselves (if
+  // any). We call Finish on every handler --- even if EndAttributes
+  // returns false.
+  virtual void Finish() { };
+};
+
+// A subclass of DIEHandler, with additional kludges for handling the
+// compilation unit's root die.
+class RootDIEHandler: public DIEHandler {
+ public:
+  RootDIEHandler() { }
+  virtual ~RootDIEHandler() { }
+
+  // We pass the values reported via Dwarf2Handler::StartCompilationUnit
+  // to this member function, and skip the entire compilation unit if it
+  // returns false.  So the root DIE handler is actually also
+  // responsible for handling the compilation unit metadata.
+  // The default definition always visits the compilation unit.
+  virtual bool StartCompilationUnit(uint64 offset, uint8 address_size,
+                                    uint8 offset_size, uint64 cu_length,
+                                    uint8 dwarf_version) { return true; }
+
+  // For the root DIE handler only, we pass the offset, tag and
+  // attributes of the compilation unit's root DIE.  This is the only
+  // way the root DIE handler can find the root DIE's tag.  If this
+  // function returns true, we will visit the root DIE using the usual
+  // DIEHandler methods; otherwise, we skip the entire compilation
+  // unit.
+  //
+  // The default definition elects to visit the root DIE.
+  virtual bool StartRootDIE(uint64 offset, enum DwarfTag tag,
+                            const AttributeList& attrs) { return true; }
+};
+
+class DIEDispatcher: public Dwarf2Handler {
+ public:
+  // Create a Dwarf2Handler which uses ROOT_HANDLER as the handler for
+  // the compilation unit's root die, as described for the DIEHandler
+  // class.
+  DIEDispatcher(RootDIEHandler *root_handler) : root_handler_(root_handler) { }
+  // Destroying a DIEDispatcher destroys all active handler objects
+  // except the root handler.
+  ~DIEDispatcher();
+  bool StartCompilationUnit(uint64 offset, uint8 address_size,
+                            uint8 offset_size, uint64 cu_length,
+                            uint8 dwarf_version);
+  bool StartDIE(uint64 offset, enum DwarfTag tag,
+                const AttributeList &attrs);
+  void ProcessAttributeUnsigned(uint64 offset,
+                                enum DwarfAttribute attr,
+                                enum DwarfForm form,
+                                uint64 data);
+  void ProcessAttributeSigned(uint64 offset,
+                              enum DwarfAttribute attr,
+                              enum DwarfForm form,
+                              int64 data);
+  void ProcessAttributeReference(uint64 offset,
+                                 enum DwarfAttribute attr,
+                                 enum DwarfForm form,
+                                 uint64 data);
+  void ProcessAttributeBuffer(uint64 offset,
+                              enum DwarfAttribute attr,
+                              enum DwarfForm form,
+                              const char* data,
+                              uint64 len);
+  void ProcessAttributeString(uint64 offset,
+                              enum DwarfAttribute attr,
+                              enum DwarfForm form,
+                              const string &data);
+  void EndDIE(uint64 offset);
+
+ private:
+
+  // The type of a handler stack entry.  This includes some fields
+  // which don't really need to be on the stack --- they could just be
+  // single data members of DIEDispatcher --- but putting them here
+  // makes it easier to see that the code is correct.
+  struct HandlerStack {
+    // The offset of the DIE for this handler stack entry.
+    uint64 offset_;
+
+    // The handler object interested in this DIE's attributes and
+    // children.  If NULL, we're not interested in either.
+    DIEHandler *handler_;
+
+    // Have we reported the end of this DIE's attributes to the handler?
+    bool reported_attributes_end_;
+  };
+
+  // Stack of DIE attribute handlers.  At StartDIE(D), the top of the
+  // stack is the handler of D's parent, whom we may ask for a handler
+  // for D itself.  At EndDIE(D), the top of the stack is D's handler.
+  // Special cases:
+  //
+  // - Before we've seen the compilation unit's root DIE, the stack is
+  //   empty; we'll call root_handler_'s special member functions, and
+  //   perhaps push root_handler_ on the stack to look at the root's
+  //   immediate children.
+  //
+  // - When we decide to ignore a subtree, we only push an entry on
+  //   the stack for the root of the tree being ignored, rather than
+  //   pushing lots of stack entries with handler_ set to NULL.
+  stack<HandlerStack> die_handlers_;
+
+  // The root handler.  We don't push it on die_handlers_ until we
+  // actually get the StartDIE call for the root.
+  RootDIEHandler *root_handler_;
+};
+
+} // namespace dwarf2reader
+#endif  // COMMON_DWARF_DWARF2DIEHANDLER_H__
diff --git a/src/common/dwarf/dwarf2diehandler_unittest.cc b/src/common/dwarf/dwarf2diehandler_unittest.cc
new file mode 100644
index 00000000..a440bd98
--- /dev/null
+++ b/src/common/dwarf/dwarf2diehandler_unittest.cc
@@ -0,0 +1,556 @@
+// -*- mode: c++ -*-
+
+// Copyright 2009 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.
+//     * Neither the name of Google Inc. nor the names of its
+// 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
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#include "breakpad_googletest_includes.h"
+
+#include "common/dwarf/dwarf2diehandler.h"
+
+using ::testing::_;
+using ::testing::ContainerEq;
+using ::testing::ElementsAreArray;
+using ::testing::Eq;
+using ::testing::InSequence;
+using ::testing::Return;
+using ::testing::Sequence;
+using ::testing::StrEq;
+
+using dwarf2reader::AttributeList;
+using dwarf2reader::DIEDispatcher;
+using dwarf2reader::DIEHandler;
+using dwarf2reader::DwarfAttribute;
+using dwarf2reader::DwarfForm;
+using dwarf2reader::DwarfTag;
+using dwarf2reader::RootDIEHandler;
+
+class MockDIEHandler: public DIEHandler {
+ public:
+  MOCK_METHOD3(ProcessAttributeUnsigned,
+               void(DwarfAttribute, DwarfForm, uint64));
+  MOCK_METHOD3(ProcessAttributeSigned,
+               void(DwarfAttribute, DwarfForm, int64));
+  MOCK_METHOD3(ProcessAttributeReference,
+               void(DwarfAttribute, DwarfForm, uint64));
+  MOCK_METHOD4(ProcessAttributeBuffer,
+               void(DwarfAttribute, DwarfForm, const char *, uint64));
+  MOCK_METHOD3(ProcessAttributeString,
+               void(DwarfAttribute, DwarfForm, const string &));
+  MOCK_METHOD0(EndAttributes, bool());
+  MOCK_METHOD3(FindChildHandler, DIEHandler *(uint64, DwarfTag,
+                                              const AttributeList &));
+  MOCK_METHOD0(Finish, void());
+};
+
+class MockRootDIEHandler: public RootDIEHandler {
+ public:
+  MOCK_METHOD3(ProcessAttributeUnsigned,
+               void(DwarfAttribute, DwarfForm, uint64));
+  MOCK_METHOD3(ProcessAttributeSigned,
+               void(DwarfAttribute, DwarfForm, int64));
+  MOCK_METHOD3(ProcessAttributeReference,
+               void(DwarfAttribute, DwarfForm, uint64));
+  MOCK_METHOD4(ProcessAttributeBuffer,
+               void(DwarfAttribute, DwarfForm, const char *, uint64));
+  MOCK_METHOD3(ProcessAttributeString,
+               void(DwarfAttribute, DwarfForm, const string &));
+  MOCK_METHOD0(EndAttributes, bool());
+  MOCK_METHOD3(FindChildHandler, DIEHandler *(uint64, DwarfTag,
+                                              const AttributeList &));
+  MOCK_METHOD0(Finish, void());
+  MOCK_METHOD5(StartCompilationUnit, bool(uint64, uint8, uint8, uint64, uint8));
+  MOCK_METHOD3(StartRootDIE, bool(uint64, DwarfTag, const AttributeList &));
+};
+
+// If the handler elects to skip the compilation unit, the dispatcher
+// should tell the reader so.
+TEST(Dwarf2DIEHandler, SkipCompilationUnit) {
+  Sequence s;
+  MockRootDIEHandler mock_root_handler;
+  DIEDispatcher die_dispatcher(&mock_root_handler);
+
+  EXPECT_CALL(mock_root_handler,
+              StartCompilationUnit(0x8d42aed77cfccf3eLL,
+                                   0x89, 0xdc,
+                                   0x2ecb4dc778a80f21LL,
+                                   0x66))
+      .InSequence(s)
+      .WillOnce(Return(false));
+
+  EXPECT_FALSE(die_dispatcher.StartCompilationUnit(0x8d42aed77cfccf3eLL,
+                                                   0x89, 0xdc,
+                                                   0x2ecb4dc778a80f21LL,
+                                                   0x66));
+}
+
+// If the handler elects to skip the root DIE, the dispatcher should
+// tell the reader so.
+TEST(Dwarf2DIEHandler, SkipRootDIE) {
+  Sequence s;
+  MockRootDIEHandler mock_root_handler;
+  DIEDispatcher die_dispatcher(&mock_root_handler);
+
+  AttributeList mock_attribute_list;
+  mock_attribute_list.push_back(make_pair(dwarf2reader::DW_AT_name,
+                                          dwarf2reader::DW_FORM_string));
+
+  EXPECT_CALL(mock_root_handler,
+              StartCompilationUnit(0xde8994029fc8b999LL, 0xf4, 0x02,
+                                   0xb00febffa76e2b2bLL, 0x5c))
+      .InSequence(s)
+      .WillOnce(Return(true));
+  EXPECT_CALL(mock_root_handler,
+              StartRootDIE(0x7d08242b4b510cf2LL, (DwarfTag) 0xb4f98da6,
+                           ContainerEq(mock_attribute_list)))
+      .InSequence(s)
+      .WillOnce(Return(false));
+
+  EXPECT_TRUE(die_dispatcher.StartCompilationUnit(0xde8994029fc8b999LL, 
+                                                  0xf4, 0x02,
+                                                  0xb00febffa76e2b2bLL, 0x5c));
+  EXPECT_FALSE(die_dispatcher.StartDIE(0x7d08242b4b510cf2LL,
+                                       (DwarfTag) 0xb4f98da6,
+                                       mock_attribute_list));
+  die_dispatcher.EndDIE(0x7d08242b4b510cf2LL);
+}
+
+// If the handler elects to skip the root DIE's children, the
+// dispatcher should tell the reader so --- and avoid deleting the
+// root handler.
+TEST(Dwarf2DIEHandler, SkipRootDIEChildren) {
+  MockRootDIEHandler mock_root_handler;
+  DIEDispatcher die_dispatcher(&mock_root_handler);
+
+  AttributeList mock_attribute_list;
+
+  {
+    InSequence s;
+
+    EXPECT_CALL(mock_root_handler,
+                StartCompilationUnit(0x15d6897480cc65a7LL, 0x26, 0xa0,
+                                     0x09f8bf0767f91675LL, 0xdb))
+      .WillOnce(Return(true));
+    EXPECT_CALL(mock_root_handler,
+                StartRootDIE(0x7d08242b4b510cf2LL, (DwarfTag) 0xb4f98da6,
+                             ContainerEq(mock_attribute_list)))
+      .WillOnce(Return(true));
+    // Please don't tell me about my children.
+    EXPECT_CALL(mock_root_handler, EndAttributes())
+      .WillOnce(Return(false));
+    EXPECT_CALL(mock_root_handler, Finish())
+      .WillOnce(Return());
+  }
+
+  EXPECT_TRUE(die_dispatcher.StartCompilationUnit(0x15d6897480cc65a7LL,
+                                                  0x26, 0xa0,
+                                                  0x09f8bf0767f91675LL, 0xdb));
+  EXPECT_TRUE(die_dispatcher.StartDIE(0x7d08242b4b510cf2LL,
+                                      (DwarfTag) 0xb4f98da6,
+                                      mock_attribute_list));
+  EXPECT_FALSE(die_dispatcher.StartDIE(0x435150ceedccda18LL,
+                                       (DwarfTag) 0xc3a17bba,
+                                       mock_attribute_list));
+  die_dispatcher.EndDIE(0x435150ceedccda18LL);
+  die_dispatcher.EndDIE(0x7d08242b4b510cf2LL);
+}
+
+// The dispatcher should pass attribute values through to the die
+// handler accurately.
+TEST(Dwarf2DIEHandler, PassAttributeValues) {
+  MockRootDIEHandler mock_root_handler;
+  DIEDispatcher die_dispatcher(&mock_root_handler);
+
+  AttributeList mock_attribute_list;
+  mock_attribute_list.push_back(make_pair(dwarf2reader::DW_AT_name,
+                                          dwarf2reader::DW_FORM_string));
+  const char buffer[10] = { 0x24, 0x24, 0x35, 0x9a, 0xca,
+                            0xcf, 0xa8, 0x84, 0xa7, 0x18 };
+  string str = "\xc8\x26\x2e\x0d\xa4\x9c\x37\xd6\xfb\x1d";
+
+  // Set expectations.
+  {
+    InSequence s;
+
+    // We'll like the compilation unit header.
+    EXPECT_CALL(mock_root_handler,
+                StartCompilationUnit(0x8d42aed77cfccf3eLL, 0x89, 0xdc,
+                                     0x2ecb4dc778a80f21LL, 0x66))
+      .WillOnce(Return(true));
+
+    // We'll like the root DIE.
+    EXPECT_CALL(mock_root_handler,
+                StartRootDIE(0xe2222da01e29f2a9LL, (DwarfTag) 0x9829445c,
+                             ContainerEq(mock_attribute_list)))
+      .WillOnce(Return(true));
+
+    // Expect some attribute values.
+    EXPECT_CALL(mock_root_handler,
+                ProcessAttributeUnsigned((DwarfAttribute) 0x1cc0bfed,
+                                         (DwarfForm) 0x424f1468,
+                                         0xa592571997facda1ULL))
+      .WillOnce(Return());
+    EXPECT_CALL(mock_root_handler,
+                ProcessAttributeSigned((DwarfAttribute) 0x43694dc9,
+                                       (DwarfForm) 0xf6f78901L,
+                                       0x92602a4e3bf1f446LL))
+      .WillOnce(Return());
+    EXPECT_CALL(mock_root_handler,
+                ProcessAttributeReference((DwarfAttribute) 0x4033e8cL,
+                                          (DwarfForm) 0xf66fbe0bL,
+                                          0x50fddef44734fdecULL))
+      .WillOnce(Return());
+    EXPECT_CALL(mock_root_handler,
+                ProcessAttributeBuffer((DwarfAttribute) 0x25d7e0af,
+                                       (DwarfForm) 0xe99a539a,
+                                       buffer, sizeof(buffer)))
+      .WillOnce(Return());
+    EXPECT_CALL(mock_root_handler,
+                ProcessAttributeString((DwarfAttribute) 0x310ed065,
+                                       (DwarfForm) 0x15762fec,
+                                       StrEq(str)))
+      .WillOnce(Return());
+    EXPECT_CALL(mock_root_handler, EndAttributes())
+      .WillOnce(Return(true));
+    EXPECT_CALL(mock_root_handler, FindChildHandler(_, _, _))
+      .Times(0);
+    EXPECT_CALL(mock_root_handler, Finish())
+      .WillOnce(Return());
+  }
+
+  // Drive the dispatcher.
+
+  // Report the CU header.
+  EXPECT_TRUE(die_dispatcher.StartCompilationUnit(0x8d42aed77cfccf3eLL,
+                                                  0x89, 0xdc,
+                                                  0x2ecb4dc778a80f21LL,
+                                                  0x66));
+  // Report the root DIE.
+  EXPECT_TRUE(die_dispatcher.StartDIE(0xe2222da01e29f2a9LL,
+                                      (DwarfTag) 0x9829445c,
+                                      mock_attribute_list));
+
+  // Report some attribute values.
+  die_dispatcher.ProcessAttributeUnsigned(0xe2222da01e29f2a9LL,
+                                          (DwarfAttribute) 0x1cc0bfed,
+                                          (DwarfForm) 0x424f1468,
+                                          0xa592571997facda1ULL);
+  die_dispatcher.ProcessAttributeSigned(0xe2222da01e29f2a9LL,
+                                        (DwarfAttribute) 0x43694dc9,
+                                        (DwarfForm) 0xf6f78901,
+                                        0x92602a4e3bf1f446LL);
+  die_dispatcher.ProcessAttributeReference(0xe2222da01e29f2a9LL,
+                                           (DwarfAttribute) 0x4033e8c,
+                                           (DwarfForm) 0xf66fbe0b,
+                                           0x50fddef44734fdecULL);
+  die_dispatcher.ProcessAttributeBuffer(0xe2222da01e29f2a9LL,
+                                        (DwarfAttribute) 0x25d7e0af,
+                                        (DwarfForm) 0xe99a539a,
+                                        buffer, sizeof(buffer));
+  die_dispatcher.ProcessAttributeString(0xe2222da01e29f2a9LL,
+                                        (DwarfAttribute) 0x310ed065,
+                                        (DwarfForm) 0x15762fec,
+                                        str);
+
+  // Finish the root DIE (and thus the CU).
+  die_dispatcher.EndDIE(0xe2222da01e29f2a9LL);
+}
+
+TEST(Dwarf2DIEHandler, FindAndSkipChildren) {
+  MockRootDIEHandler mock_root_handler;
+  MockDIEHandler *mock_child1_handler = new(MockDIEHandler);
+  MockDIEHandler *mock_child3_handler = new(MockDIEHandler);
+  DIEDispatcher die_dispatcher(&mock_root_handler);
+
+  AttributeList root_attribute_list;
+  root_attribute_list.push_back(make_pair((DwarfAttribute) 0xb01185df,
+                                          (DwarfForm) 0xbc97cee8));
+  AttributeList child1_attribute_list;
+  child1_attribute_list.push_back(make_pair((DwarfAttribute) 0x41014e43,
+                                            (DwarfForm) 0x63155f4c));
+  AttributeList grandchild1_attribute_list;
+  grandchild1_attribute_list.push_back(make_pair((DwarfAttribute) 0xf72f823c,
+                                                 (DwarfForm) 0x0ff6a201));
+  AttributeList greatgrandchild1_attribute_list;
+  greatgrandchild1_attribute_list
+    .push_back(make_pair((DwarfAttribute) 0xbe66e5f0, (DwarfForm) 0xb4b24ff7));
+  AttributeList child2_attribute_list;
+  child1_attribute_list.push_back(make_pair((DwarfAttribute) 0xf22df14c,
+                                            (DwarfForm) 0x20676e7d));
+  AttributeList child3_attribute_list;
+  child3_attribute_list.push_back(make_pair((DwarfAttribute) 0xe8bf1201,
+                                            (DwarfForm) 0x53a5b7a8));
+
+  {
+    InSequence s;
+
+    // We'll like the compilation unit header.
+    EXPECT_CALL(mock_root_handler,
+                StartCompilationUnit(0x9ec1e6d05e434a0eLL, 0xeb, 0x21,
+                                     0x47dd3c764275a216LL, 0xa5))
+      .WillOnce(Return(true));
+
+    // Root DIE.
+    {
+      EXPECT_CALL(mock_root_handler,
+                  StartRootDIE(0x15f0e06bdfe3c372LL, (DwarfTag) 0xf5d60c59,
+                               ContainerEq(root_attribute_list)))
+        .WillOnce(Return(true));
+      EXPECT_CALL(mock_root_handler,
+                  ProcessAttributeSigned((DwarfAttribute) 0xf779a642,
+                                         (DwarfForm) 0x2cb63027,
+                                         0x18e744661769d08fLL))
+        .WillOnce(Return());
+      EXPECT_CALL(mock_root_handler, EndAttributes())
+        .WillOnce(Return(true));
+
+      // First child DIE.
+      EXPECT_CALL(mock_root_handler,
+                  FindChildHandler(0x149f644f8116fe8cLL,
+                                   (DwarfTag) 0xac2cbd8c,
+                                   ContainerEq(child1_attribute_list)))
+        .WillOnce(Return(mock_child1_handler));
+      {
+        EXPECT_CALL(*mock_child1_handler,
+                    ProcessAttributeSigned((DwarfAttribute) 0xa6fd6f65,
+                                           (DwarfForm) 0xe4f64c41,
+                                           0x1b04e5444a55fe67LL))
+          .WillOnce(Return());
+        EXPECT_CALL(*mock_child1_handler, EndAttributes())
+          .WillOnce(Return(false));
+        // Skip first grandchild DIE and first great-grandchild DIE.
+        EXPECT_CALL(*mock_child1_handler, Finish())
+          .WillOnce(Return());
+      }
+
+      // Second child DIE.  Root handler will decline to return a handler
+      // for this child.
+      EXPECT_CALL(mock_root_handler,
+                  FindChildHandler(0x97412be24875de9dLL,
+                                   (DwarfTag) 0x505a068b,
+                                   ContainerEq(child2_attribute_list)))
+        .WillOnce(Return((DIEHandler *) NULL));
+
+      // Third child DIE.
+      EXPECT_CALL(mock_root_handler,
+                  FindChildHandler(0x753c964c8ab538aeLL,
+                                   (DwarfTag) 0x8c22970e,
+                                   ContainerEq(child3_attribute_list)))
+        .WillOnce(Return(mock_child3_handler));
+      {
+        EXPECT_CALL(*mock_child3_handler,
+                    ProcessAttributeSigned((DwarfAttribute) 0x4e2b7cfb,
+                                           (DwarfForm) 0x610b7ae1,
+                                           0x3ea5c609d7d7560fLL))
+          .WillOnce(Return());
+        EXPECT_CALL(*mock_child3_handler, EndAttributes())
+          .WillOnce(Return(true));
+        EXPECT_CALL(*mock_child3_handler, Finish())
+          .WillOnce(Return());
+      }
+
+      EXPECT_CALL(mock_root_handler, Finish())
+        .WillOnce(Return());
+    }
+  }
+
+    
+  // Drive the dispatcher.
+
+  // Report the CU header.
+  EXPECT_TRUE(die_dispatcher
+              .StartCompilationUnit(0x9ec1e6d05e434a0eLL, 0xeb, 0x21,
+                                    0x47dd3c764275a216LL, 0xa5));
+  // Report the root DIE.
+  {
+    EXPECT_TRUE(die_dispatcher.StartDIE(0x15f0e06bdfe3c372LL,
+                                        (DwarfTag) 0xf5d60c59,
+                                        root_attribute_list));
+    die_dispatcher.ProcessAttributeSigned(0x15f0e06bdfe3c372LL,
+                                          (DwarfAttribute) 0xf779a642,
+                                          (DwarfForm) 0x2cb63027,
+                                          0x18e744661769d08fLL);
+
+    // First child DIE.
+    {
+      EXPECT_TRUE(die_dispatcher.StartDIE(0x149f644f8116fe8cLL,
+                                          (DwarfTag) 0xac2cbd8c,
+                                          child1_attribute_list));
+      die_dispatcher.ProcessAttributeSigned(0x149f644f8116fe8cLL,
+                                            (DwarfAttribute) 0xa6fd6f65,
+                                            (DwarfForm) 0xe4f64c41,
+                                            0x1b04e5444a55fe67LL);
+
+      // First grandchild DIE.  Will be skipped.
+      {
+        EXPECT_FALSE(die_dispatcher.StartDIE(0xd68de1ee0bd29419LL,
+                                            (DwarfTag) 0x22f05a15,
+                                            grandchild1_attribute_list));
+        // First great-grandchild DIE.  Will be skipped without being
+        // mentioned to any handler.
+        {
+          EXPECT_FALSE(die_dispatcher
+                       .StartDIE(0xb3076285d25cac25LL,
+                                 (DwarfTag) 0xcff4061b,
+                                 greatgrandchild1_attribute_list));
+          die_dispatcher.EndDIE(0xb3076285d25cac25LL);          
+        }
+        die_dispatcher.EndDIE(0xd68de1ee0bd29419LL);
+      }
+      die_dispatcher.EndDIE(0x149f644f8116fe8cLL);
+    }
+
+    // Second child DIE.  Root handler will decline to find a handler for it.
+    {
+      EXPECT_FALSE(die_dispatcher.StartDIE(0x97412be24875de9dLL,
+                                           (DwarfTag) 0x505a068b,
+                                           child2_attribute_list));
+      die_dispatcher.EndDIE(0x97412be24875de9dLL);
+    }
+    
+    // Third child DIE.
+    {
+      EXPECT_TRUE(die_dispatcher.StartDIE(0x753c964c8ab538aeLL,
+                                          (DwarfTag) 0x8c22970e,
+                                          child3_attribute_list));
+      die_dispatcher.ProcessAttributeSigned(0x753c964c8ab538aeLL,
+                                            (DwarfAttribute) 0x4e2b7cfb,
+                                            (DwarfForm) 0x610b7ae1,
+                                            0x3ea5c609d7d7560fLL);
+      die_dispatcher.EndDIE(0x753c964c8ab538aeLL);
+    }
+    
+    // Finish the root DIE (and thus the CU).
+    die_dispatcher.EndDIE(0x15f0e06bdfe3c372LL);
+  }
+}
+
+// The DIEDispatcher destructor is supposed to delete all handlers on
+// the stack, except for the root.
+TEST(Dwarf2DIEHandler, FreeHandlersOnStack) {
+  MockRootDIEHandler mock_root_handler;
+  MockDIEHandler *mock_child_handler = new(MockDIEHandler);
+  MockDIEHandler *mock_grandchild_handler = new(MockDIEHandler);
+  AttributeList empty_attribute_list;
+
+  {
+    InSequence s;
+
+    // We'll like the compilation unit header.
+    EXPECT_CALL(mock_root_handler,
+                StartCompilationUnit(0x87b41ba8381cd71cLL, 0xff, 0x89,
+                                     0x76d392ff393ddda2LL, 0xbf))
+      .WillOnce(Return(true));
+
+    // Root DIE.
+    {
+      EXPECT_CALL(mock_root_handler,
+                  StartRootDIE(0xbf13b761691ddc91LL, (DwarfTag) 0x98980361,
+                               ContainerEq(empty_attribute_list)))
+        .WillOnce(Return(true));
+      EXPECT_CALL(mock_root_handler, EndAttributes())
+        .WillOnce(Return(true));
+      
+      // Child DIE.
+      EXPECT_CALL(mock_root_handler,
+                  FindChildHandler(0x058f09240c5fc8c9LL,
+                                   (DwarfTag) 0x898bf0d0,
+                                   ContainerEq(empty_attribute_list)))
+        .WillOnce(Return(mock_child_handler));
+      {
+        EXPECT_CALL(*mock_child_handler, EndAttributes())
+          .WillOnce(Return(true));
+
+        // Grandchild DIE.
+        EXPECT_CALL(*mock_child_handler,
+                    FindChildHandler(0x32dc00c9945dc0c8LL,
+                                     (DwarfTag) 0x2802d007,
+                                     ContainerEq(empty_attribute_list)))
+          .WillOnce(Return(mock_grandchild_handler));
+        {
+          EXPECT_CALL(*mock_grandchild_handler,
+                      ProcessAttributeSigned((DwarfAttribute) 0x4e2b7cfb,
+                                             (DwarfForm) 0x610b7ae1,
+                                             0x3ea5c609d7d7560fLL))
+            .WillOnce(Return());
+
+          // At this point, we abandon the traversal, so none of the
+          // usual stuff should get called.
+          EXPECT_CALL(*mock_grandchild_handler, EndAttributes())
+            .Times(0);
+          EXPECT_CALL(*mock_grandchild_handler, Finish())
+            .Times(0);
+        }
+
+        EXPECT_CALL(*mock_child_handler, Finish())
+          .Times(0);
+      }
+
+      EXPECT_CALL(mock_root_handler, Finish())
+        .Times(0);
+    }
+  }
+
+  // The dispatcher.
+  DIEDispatcher die_dispatcher(&mock_root_handler);
+  
+  // Report the CU header.
+  EXPECT_TRUE(die_dispatcher
+              .StartCompilationUnit(0x87b41ba8381cd71cLL, 0xff, 0x89,
+                                    0x76d392ff393ddda2LL, 0xbf));
+  // Report the root DIE.
+  {
+    EXPECT_TRUE(die_dispatcher.StartDIE(0xbf13b761691ddc91LL,
+                                        (DwarfTag) 0x98980361,
+                                        empty_attribute_list));
+
+    // Child DIE.
+    {
+      EXPECT_TRUE(die_dispatcher.StartDIE(0x058f09240c5fc8c9LL,
+                                          (DwarfTag) 0x898bf0d0,
+                                          empty_attribute_list));
+
+      // Grandchild DIE.
+      {
+        EXPECT_TRUE(die_dispatcher.StartDIE(0x32dc00c9945dc0c8LL,
+                                            (DwarfTag) 0x2802d007,
+                                            empty_attribute_list));
+        die_dispatcher.ProcessAttributeSigned(0x32dc00c9945dc0c8LL,
+                                              (DwarfAttribute) 0x4e2b7cfb,
+                                              (DwarfForm) 0x610b7ae1,
+                                              0x3ea5c609d7d7560fLL);
+
+        // Stop the traversal abruptly, so that there will still be
+        // handlers on the stack when the dispatcher is destructed.
+
+        // No EndDIE call...
+      }
+      // No EndDIE call...
+    }
+    // No EndDIE call...
+  }
+}
diff --git a/src/tools/linux/dump_syms/Makefile b/src/tools/linux/dump_syms/Makefile
index 78a1a1ab..b944f3cf 100644
--- a/src/tools/linux/dump_syms/Makefile
+++ b/src/tools/linux/dump_syms/Makefile
@@ -77,6 +77,7 @@ dump_syms:					\
 	dump_stabs.o				\
 	dump_syms.o				\
 	dump_symbols.o				\
+	dwarf2diehandler.o			\
 	file_id.o				\
 	module.o				\
 	stabs_reader.o				\
@@ -97,6 +98,10 @@ COVERAGE_SOURCES += module.cc
 stabs_reader.o: stabs_reader.cc
 COVERAGE_SOURCES += stabs_reader.cc
 
+VPATH += $(SRC)/common/dwarf
+dwarf2diehandler.o: dwarf2diehandler.cc
+COVERAGE_SOURCES += dwarf2diehandler.cc
+
 
 
 ### Google C++ Testing Framework.
@@ -180,6 +185,23 @@ clean::
 	rm -f dump_stabs_unittest
 
 
+### Unit tests for dwarf2reader::DwarfDIEDispatcher.
+check: check-dwarf2diehandler_unittest
+check-dwarf2diehandler_unittest: dwarf2diehandler_unittest
+dwarf2diehandler_unittest:			\
+	gmock-all.o				\
+	gtest-all.o				\
+	gtest_main.o				\
+	dwarf2diehandler.o			\
+	$(empty)
+CPP_EXECUTABLES += dwarf2diehandler_unittest
+dwarf2diehandler_unittest.o: dwarf2diehandler_unittest.cc
+dwarf2diehandler_unittest.o: override CPPFLAGS += $(GTEST_CPPFLAGS) \
+						  $(GMOCK_CPPFLAGS)
+clean::
+	rm -f dwarf2diehandler_unittest
+
+
 ### Generic compilation rules.
 
 # Link C++ executables using the C++ compiler; see CPP_EXECUTABLES above.