Keeping track of modules without symbols during crash report processing.

http://breakpad.appspot.com/534002/



git-svn-id: http://google-breakpad.googlecode.com/svn/trunk@1126 4c0a9323-5329-0410-9bdc-e9ce6186880e

10 files changed, 230 insertions, 49 deletions

diff --git a/src/google_breakpad/processor/process_state.h b/src/google_breakpad/processor/process_state.h
index 780cb548..d234ebbf 100644
--- a/src/google_breakpad/processor/process_state.h
+++ b/src/google_breakpad/processor/process_state.h
@@ -106,6 +106,9 @@ class ProcessState {
   }
   const SystemInfo* system_info() const { return &system_info_; }
   const CodeModules* modules() const { return modules_; }
+  const vector<const CodeModule*>* modules_without_symbols() const {
+    return &modules_without_symbols_;
+  }
   ExploitabilityRating exploitability() const { return exploitability_; }
 
  private:
@@ -158,6 +161,9 @@ class ProcessState {
   // ProcessState.
   const CodeModules *modules_;
 
+  // The modules that didn't have symbols when the report was processed.
+  vector<const CodeModule*> modules_without_symbols_;
+
   // The exploitability rating as determined by the exploitability
   // engine. When the exploitability engine is not enabled this
   // defaults to EXPLOITABILITY_NONE.
diff --git a/src/google_breakpad/processor/stackwalker.h b/src/google_breakpad/processor/stackwalker.h
index 9e678e3c..f09291fe 100644
--- a/src/google_breakpad/processor/stackwalker.h
+++ b/src/google_breakpad/processor/stackwalker.h
@@ -43,6 +43,7 @@
 
 #include <set>
 #include <string>
+#include <vector>
 
 #include "common/using_std_string.h"
 #include "google_breakpad/common/breakpad_types.h"
@@ -57,6 +58,7 @@ class MinidumpContext;
 class StackFrameSymbolizer;
 
 using std::set;
+using std::vector;
 
 class Stackwalker {
  public:
@@ -66,7 +68,15 @@ class Stackwalker {
   // 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);
+  // Upon return, modules_without_symbols will be populated with pointers to
+  // the code modules (CodeModule*) that DON'T have symbols.
+  // modules_without_symbols DOES NOT take ownership of the code modules.
+  // The lifetime of these code modules is the same as the lifetime of the
+  // CodeModules passed to the StackWalker constructor (which currently
+  // happens to be the lifetime of the Breakpad's ProcessingState object).
+  // There is a check for duplicate modules so no duplicates are expected.
+  bool Walk(CallStack* stack,
+            vector<const CodeModule*>* modules_without_symbols);
 
   // Returns a new concrete subclass suitable for the CPU that a stack was
   // generated on, according to the CPU type indicated by the context
diff --git a/src/processor/minidump_processor.cc b/src/processor/minidump_processor.cc
index 059d8849..08682780 100644
--- a/src/processor/minidump_processor.cc
+++ b/src/processor/minidump_processor.cc
@@ -227,9 +227,10 @@ ProcessResult MinidumpProcessor::Process(
 
     scoped_ptr<CallStack> stack(new CallStack());
     if (stackwalker.get()) {
-      if (!stackwalker->Walk(stack.get())) {
-        BPLOG(INFO) << "Stackwalker interrupt (missing symbols?) at " <<
-          thread_string;
+      if (!stackwalker->Walk(stack.get(),
+                             &process_state->modules_without_symbols_)) {
+        BPLOG(INFO) << "Stackwalker interrupt (missing symbols?) at "
+                    << thread_string;
         interrupted = true;
       }
     } else {
diff --git a/src/processor/minidump_stackwalk.cc b/src/processor/minidump_stackwalk.cc
index 7b930e46..6bf78ac1 100644
--- a/src/processor/minidump_stackwalk.cc
+++ b/src/processor/minidump_stackwalk.cc
@@ -333,7 +333,51 @@ static void PrintStackMachineReadable(int thread_num, const CallStack *stack) {
   }
 }
 
-static void PrintModules(const CodeModules *modules) {
+// ContainsModule checks whether a given |module| is in the vector
+// |modules_without_symbols|.
+static bool ContainsModule(
+    const vector<const CodeModule*> *modules,
+    const CodeModule *module) {
+  assert(modules);
+  assert(module);
+  vector<const CodeModule*>::const_iterator iter;
+  for (iter = modules->begin(); iter != modules->end(); ++iter) {
+    if (module->debug_file().compare((*iter)->debug_file()) == 0 &&
+        module->debug_identifier().compare((*iter)->debug_identifier()) == 0) {
+      return true;
+    }
+  }
+  return false;
+}
+
+// PrintModule prints a single |module| to stdout.
+// |modules_without_symbols| should contain the list of modules that were
+// confirmed to be missing their symbols during the stack walk.
+static void PrintModule(
+    const CodeModule *module,
+    const vector<const CodeModule*> *modules_without_symbols,
+    uint64_t main_address) {
+  string missing_symbols;
+  if (ContainsModule(modules_without_symbols, module)) {
+    missing_symbols = "  (WARNING: No symbols, " +
+        PathnameStripper::File(module->debug_file()) + ", " +
+        module->debug_identifier() + ")";
+  }
+  uint64_t base_address = module->base_address();
+  printf("0x%08" PRIx64 " - 0x%08" PRIx64 "  %s  %s%s%s\n",
+         base_address, base_address + module->size() - 1,
+         PathnameStripper::File(module->code_file()).c_str(),
+         module->version().empty() ? "???" : module->version().c_str(),
+         main_address != 0 && base_address == main_address ? "  (main)" : "",
+         missing_symbols.c_str());
+}
+
+// PrintModules prints the list of all loaded |modules| to stdout.
+// |modules_without_symbols| should contain the list of modules that were
+// confirmed to be missing their symbols during the stack walk.
+static void PrintModules(
+    const CodeModules *modules,
+    const vector<const CodeModule*> *modules_without_symbols) {
   if (!modules)
     return;
 
@@ -351,13 +395,7 @@ static void PrintModules(const CodeModules *modules) {
        module_sequence < module_count;
        ++module_sequence) {
     const CodeModule *module = modules->GetModuleAtSequence(module_sequence);
-    uint64_t base_address = module->base_address();
-    printf("0x%08" PRIx64 " - 0x%08" PRIx64 "  %s  %s%s\n",
-           base_address, base_address + module->size() - 1,
-           PathnameStripper::File(module->code_file()).c_str(),
-           module->version().empty() ? "???" : module->version().c_str(),
-           main_module != NULL && base_address == main_address ?
-               "  (main)" : "");
+    PrintModule(module, modules_without_symbols, main_address);
   }
 }
 
@@ -449,7 +487,8 @@ static void PrintProcessState(const ProcessState& process_state) {
     }
   }
 
-  PrintModules(process_state.modules());
+  PrintModules(process_state.modules(),
+               process_state.modules_without_symbols());
 }
 
 static void PrintProcessStateMachineReadable(const ProcessState& process_state)
diff --git a/src/processor/process_state.cc b/src/processor/process_state.cc
index 1d970bad..6c3a6567 100644
--- a/src/processor/process_state.cc
+++ b/src/processor/process_state.cc
@@ -57,6 +57,9 @@ void ProcessState::Clear() {
   }
   threads_.clear();
   system_info_.Clear();
+  // modules_without_symbols_ DOES NOT owns the underlying CodeModule pointers.
+  // Just clear the vector.
+  modules_without_symbols_.clear();
   delete modules_;
   modules_ = NULL;
 }
diff --git a/src/processor/stackwalker.cc b/src/processor/stackwalker.cc
index c1b290e6..a92d71b8 100644
--- a/src/processor/stackwalker.cc
+++ b/src/processor/stackwalker.cc
@@ -70,11 +70,16 @@ Stackwalker::Stackwalker(const SystemInfo* system_info,
 }
 
 
-bool Stackwalker::Walk(CallStack* stack) {
+bool Stackwalker::Walk(CallStack* stack,
+                       vector<const CodeModule*>* modules_without_symbols) {
   BPLOG_IF(ERROR, !stack) << "Stackwalker::Walk requires |stack|";
   assert(stack);
   stack->Clear();
 
+  BPLOG_IF(ERROR, !modules_without_symbols) << "Stackwalker::Walk requires "
+                                            << "|modules_without_symbols|";
+  assert(modules_without_symbols);
+
   // Begin with the context frame, and keep getting callers until there are
   // no more.
 
@@ -95,6 +100,27 @@ bool Stackwalker::Walk(CallStack* stack) {
       return false;
     }
 
+    // Keep track of modules that have no symbols.
+    if (symbolizer_result == StackFrameSymbolizer::kError &&
+        frame->module != NULL) {
+      bool found = false;
+      vector<const CodeModule*>::iterator iter;
+      for (iter = modules_without_symbols->begin();
+           iter != modules_without_symbols->end();
+           ++iter) {
+        if (*iter == frame->module) {
+          found = true;
+          break;
+        }
+      }
+      if (!found) {
+        BPLOG(INFO) << "Couldn't load symbols for: "
+                    << frame->module->debug_file() << "|"
+                    << frame->module->debug_identifier();
+        modules_without_symbols->push_back(frame->module);
+      }
+    }
+
     // Add the frame to the call stack.  Relinquish the ownership claim
     // over the frame, because the stack now owns it.
     stack->frames_.push_back(frame.release());
diff --git a/src/processor/stackwalker_amd64_unittest.cc b/src/processor/stackwalker_amd64_unittest.cc
index a726e8ac..8faf09ab 100644
--- a/src/processor/stackwalker_amd64_unittest.cc
+++ b/src/processor/stackwalker_amd64_unittest.cc
@@ -41,6 +41,7 @@
 #include "google_breakpad/common/minidump_format.h"
 #include "google_breakpad/processor/basic_source_line_resolver.h"
 #include "google_breakpad/processor/call_stack.h"
+#include "google_breakpad/processor/code_module.h"
 #include "google_breakpad/processor/source_line_resolver_interface.h"
 #include "google_breakpad/processor/stack_frame_cpu.h"
 #include "processor/stackwalker_unittest_utils.h"
@@ -48,6 +49,7 @@
 
 using google_breakpad::BasicSourceLineResolver;
 using google_breakpad::CallStack;
+using google_breakpad::CodeModule;
 using google_breakpad::StackFrameSymbolizer;
 using google_breakpad::StackFrame;
 using google_breakpad::StackFrameAMD64;
@@ -143,7 +145,10 @@ TEST_F(SanityCheck, NoResolver) {
   StackwalkerAMD64 walker(&system_info, &raw_context, &stack_region, &modules,
                           &frame_symbolizer);
   // This should succeed even without a resolver or supplier.
-  ASSERT_TRUE(walker.Walk(&call_stack));
+  vector<const CodeModule*> modules_without_symbols;
+  ASSERT_TRUE(walker.Walk(&call_stack, &modules_without_symbols));
+  ASSERT_EQ(1U, modules_without_symbols.size());
+  ASSERT_EQ("module1", modules_without_symbols[0]->debug_file());
   frames = call_stack.frames();
   ASSERT_GE(1U, frames->size());
   StackFrameAMD64 *frame = static_cast<StackFrameAMD64 *>(frames->at(0));
@@ -163,7 +168,10 @@ TEST_F(GetContextFrame, Simple) {
   StackFrameSymbolizer frame_symbolizer(&supplier, &resolver);
   StackwalkerAMD64 walker(&system_info, &raw_context, &stack_region, &modules,
                           &frame_symbolizer);
-  ASSERT_TRUE(walker.Walk(&call_stack));
+  vector<const CodeModule*> modules_without_symbols;
+  ASSERT_TRUE(walker.Walk(&call_stack, &modules_without_symbols));
+  ASSERT_EQ(1U, modules_without_symbols.size());
+  ASSERT_EQ("module1", modules_without_symbols[0]->debug_file());
   frames = call_stack.frames();
   ASSERT_GE(1U, frames->size());
   StackFrameAMD64 *frame = static_cast<StackFrameAMD64 *>(frames->at(0));
@@ -181,7 +189,10 @@ TEST_F(GetContextFrame, NoStackMemory) {
   StackFrameSymbolizer frame_symbolizer(&supplier, &resolver);
   StackwalkerAMD64 walker(&system_info, &raw_context, NULL, &modules,
                           &frame_symbolizer);
-  ASSERT_TRUE(walker.Walk(&call_stack));
+  vector<const CodeModule*> modules_without_symbols;
+  ASSERT_TRUE(walker.Walk(&call_stack, &modules_without_symbols));
+  ASSERT_EQ(1U, modules_without_symbols.size());
+  ASSERT_EQ("module1", modules_without_symbols[0]->debug_file());
   frames = call_stack.frames();
   ASSERT_GE(1U, frames->size());
   StackFrameAMD64 *frame = static_cast<StackFrameAMD64 *>(frames->at(0));
@@ -236,7 +247,11 @@ TEST_F(GetCallerFrame, ScanWithoutSymbols) {
   StackFrameSymbolizer frame_symbolizer(&supplier, &resolver);
   StackwalkerAMD64 walker(&system_info, &raw_context, &stack_region, &modules,
                           &frame_symbolizer);
-  ASSERT_TRUE(walker.Walk(&call_stack));
+  vector<const CodeModule*> modules_without_symbols;
+  ASSERT_TRUE(walker.Walk(&call_stack, &modules_without_symbols));
+  ASSERT_EQ(2U, modules_without_symbols.size());
+  ASSERT_EQ("module1", modules_without_symbols[0]->debug_file());
+  ASSERT_EQ("module2", modules_without_symbols[1]->debug_file());
   frames = call_stack.frames();
   ASSERT_EQ(3U, frames->size());
 
@@ -304,7 +319,9 @@ TEST_F(GetCallerFrame, ScanWithFunctionSymbols) {
   StackFrameSymbolizer frame_symbolizer(&supplier, &resolver);
   StackwalkerAMD64 walker(&system_info, &raw_context, &stack_region, &modules,
                           &frame_symbolizer);
-  ASSERT_TRUE(walker.Walk(&call_stack));
+  vector<const CodeModule*> modules_without_symbols;
+  ASSERT_TRUE(walker.Walk(&call_stack, &modules_without_symbols));
+  ASSERT_EQ(0U, modules_without_symbols.size());
   frames = call_stack.frames();
   ASSERT_EQ(2U, frames->size());
 
@@ -369,7 +386,9 @@ TEST_F(GetCallerFrame, CallerPushedRBP) {
   StackFrameSymbolizer frame_symbolizer(&supplier, &resolver);
   StackwalkerAMD64 walker(&system_info, &raw_context, &stack_region, &modules,
                           &frame_symbolizer);
-  ASSERT_TRUE(walker.Walk(&call_stack));
+  vector<const CodeModule*> modules_without_symbols;
+  ASSERT_TRUE(walker.Walk(&call_stack, &modules_without_symbols));
+  ASSERT_EQ(0U, modules_without_symbols.size());
   frames = call_stack.frames();
   ASSERT_EQ(2U, frames->size());
 
@@ -445,7 +464,9 @@ struct CFIFixture: public StackwalkerAMD64Fixture {
     StackFrameSymbolizer frame_symbolizer(&supplier, &resolver);
     StackwalkerAMD64 walker(&system_info, &raw_context, &stack_region, &modules,
                             &frame_symbolizer);
-    ASSERT_TRUE(walker.Walk(&call_stack));
+    vector<const CodeModule*> modules_without_symbols;
+    ASSERT_TRUE(walker.Walk(&call_stack, &modules_without_symbols));
+    ASSERT_EQ(0U, modules_without_symbols.size());
     frames = call_stack.frames();
     ASSERT_EQ(2U, frames->size());
 
diff --git a/src/processor/stackwalker_arm_unittest.cc b/src/processor/stackwalker_arm_unittest.cc
index f1d18bb7..588b5c5f 100644
--- a/src/processor/stackwalker_arm_unittest.cc
+++ b/src/processor/stackwalker_arm_unittest.cc
@@ -41,6 +41,7 @@
 #include "google_breakpad/common/minidump_format.h"
 #include "google_breakpad/processor/basic_source_line_resolver.h"
 #include "google_breakpad/processor/call_stack.h"
+#include "google_breakpad/processor/code_module.h"
 #include "google_breakpad/processor/source_line_resolver_interface.h"
 #include "google_breakpad/processor/stack_frame_cpu.h"
 #include "processor/stackwalker_unittest_utils.h"
@@ -49,6 +50,7 @@
 
 using google_breakpad::BasicSourceLineResolver;
 using google_breakpad::CallStack;
+using google_breakpad::CodeModule;
 using google_breakpad::StackFrameSymbolizer;
 using google_breakpad::StackFrame;
 using google_breakpad::StackFrameARM;
@@ -139,7 +141,9 @@ TEST_F(SanityCheck, NoResolver) {
   StackwalkerARM walker(&system_info, &raw_context, -1, &stack_region, &modules,
                         &frame_symbolizer);
   // This should succeed even without a resolver or supplier.
-  ASSERT_TRUE(walker.Walk(&call_stack));
+  vector<const CodeModule*> modules_without_symbols;
+  ASSERT_TRUE(walker.Walk(&call_stack, &modules_without_symbols));
+  ASSERT_EQ(0U, modules_without_symbols.size());
   frames = call_stack.frames();
   ASSERT_EQ(1U, frames->size());
   StackFrameARM *frame = static_cast<StackFrameARM *>(frames->at(0));
@@ -157,7 +161,9 @@ TEST_F(GetContextFrame, Simple) {
   StackFrameSymbolizer frame_symbolizer(&supplier, &resolver);
   StackwalkerARM walker(&system_info, &raw_context, -1, &stack_region, &modules,
                         &frame_symbolizer);
-  ASSERT_TRUE(walker.Walk(&call_stack));
+  vector<const CodeModule*> modules_without_symbols;
+  ASSERT_TRUE(walker.Walk(&call_stack, &modules_without_symbols));
+  ASSERT_EQ(0U, modules_without_symbols.size());
   frames = call_stack.frames();
   ASSERT_EQ(1U, frames->size());
   StackFrameARM *frame = static_cast<StackFrameARM *>(frames->at(0));
@@ -172,7 +178,9 @@ TEST_F(GetContextFrame, NoStackMemory) {
   StackFrameSymbolizer frame_symbolizer(&supplier, &resolver);
   StackwalkerARM walker(&system_info, &raw_context, -1, NULL, &modules,
                         &frame_symbolizer);
-  ASSERT_TRUE(walker.Walk(&call_stack));
+  vector<const CodeModule*> modules_without_symbols;
+  ASSERT_TRUE(walker.Walk(&call_stack, &modules_without_symbols));
+  ASSERT_EQ(0U, modules_without_symbols.size());
   frames = call_stack.frames();
   ASSERT_EQ(1U, frames->size());
   StackFrameARM *frame = static_cast<StackFrameARM *>(frames->at(0));
@@ -220,7 +228,11 @@ TEST_F(GetCallerFrame, ScanWithoutSymbols) {
   StackFrameSymbolizer frame_symbolizer(&supplier, &resolver);
   StackwalkerARM walker(&system_info, &raw_context, -1, &stack_region, &modules,
                         &frame_symbolizer);
-  ASSERT_TRUE(walker.Walk(&call_stack));
+  vector<const CodeModule*> modules_without_symbols;
+  ASSERT_TRUE(walker.Walk(&call_stack, &modules_without_symbols));
+  ASSERT_EQ(2U, modules_without_symbols.size());
+  ASSERT_EQ("module1", modules_without_symbols[0]->debug_file());
+  ASSERT_EQ("module2", modules_without_symbols[1]->debug_file());
   frames = call_stack.frames();
   ASSERT_EQ(3U, frames->size());
 
@@ -284,7 +296,9 @@ TEST_F(GetCallerFrame, ScanWithFunctionSymbols) {
   StackFrameSymbolizer frame_symbolizer(&supplier, &resolver);
   StackwalkerARM walker(&system_info, &raw_context, -1, &stack_region, &modules,
                         &frame_symbolizer);
-  ASSERT_TRUE(walker.Walk(&call_stack));
+  vector<const CodeModule*> modules_without_symbols;
+  ASSERT_TRUE(walker.Walk(&call_stack, &modules_without_symbols));
+  ASSERT_EQ(0U, modules_without_symbols.size());
   frames = call_stack.frames();
   ASSERT_EQ(2U, frames->size());
 
@@ -345,7 +359,11 @@ TEST_F(GetCallerFrame, ScanFirstFrame) {
   StackFrameSymbolizer frame_symbolizer(&supplier, &resolver);
   StackwalkerARM walker(&system_info, &raw_context, -1, &stack_region, &modules,
                         &frame_symbolizer);
-  ASSERT_TRUE(walker.Walk(&call_stack));
+  vector<const CodeModule*> modules_without_symbols;
+  ASSERT_TRUE(walker.Walk(&call_stack, &modules_without_symbols));
+  ASSERT_EQ(2U, modules_without_symbols.size());
+  ASSERT_EQ("module1", modules_without_symbols[0]->debug_file());
+  ASSERT_EQ("module2", modules_without_symbols[1]->debug_file());
   frames = call_stack.frames();
   ASSERT_EQ(2U, frames->size());
 
@@ -453,7 +471,9 @@ struct CFIFixture: public StackwalkerARMFixture {
     StackwalkerARM walker(&system_info, &raw_context, -1, &stack_region,
                           &modules, &frame_symbolizer);
     walker.SetContextFrameValidity(context_frame_validity);
-    ASSERT_TRUE(walker.Walk(&call_stack));
+    vector<const CodeModule*> modules_without_symbols;
+    ASSERT_TRUE(walker.Walk(&call_stack, &modules_without_symbols));
+    ASSERT_EQ(0U, modules_without_symbols.size());
     frames = call_stack.frames();
     ASSERT_EQ(2U, frames->size());
 
@@ -645,7 +665,9 @@ TEST_F(CFI, RejectBackwards) {
   StackFrameSymbolizer frame_symbolizer(&supplier, &resolver);
   StackwalkerARM walker(&system_info, &raw_context, -1, &stack_region, &modules,
                         &frame_symbolizer);
-  ASSERT_TRUE(walker.Walk(&call_stack));
+  vector<const CodeModule*> modules_without_symbols;
+  ASSERT_TRUE(walker.Walk(&call_stack, &modules_without_symbols));
+  ASSERT_EQ(0U, modules_without_symbols.size());
   frames = call_stack.frames();
   ASSERT_EQ(1U, frames->size());
 }
@@ -657,7 +679,9 @@ TEST_F(CFI, RejectBadExpressions) {
   StackFrameSymbolizer frame_symbolizer(&supplier, &resolver);
   StackwalkerARM walker(&system_info, &raw_context, -1, &stack_region, &modules,
                         &frame_symbolizer);
-  ASSERT_TRUE(walker.Walk(&call_stack));
+  vector<const CodeModule*> modules_without_symbols;
+  ASSERT_TRUE(walker.Walk(&call_stack, &modules_without_symbols));
+  ASSERT_EQ(0U, modules_without_symbols.size());
   frames = call_stack.frames();
   ASSERT_EQ(1U, frames->size());
 }
@@ -715,7 +739,11 @@ TEST_F(GetFramesByFramePointer, OnlyFramePointer) {
   StackwalkerARM walker(&system_info, &raw_context, MD_CONTEXT_ARM_REG_IOS_FP,
                         &stack_region, &modules, &frame_symbolizer);
 
-  ASSERT_TRUE(walker.Walk(&call_stack));
+  vector<const CodeModule*> modules_without_symbols;
+  ASSERT_TRUE(walker.Walk(&call_stack, &modules_without_symbols));
+  ASSERT_EQ(2U, modules_without_symbols.size());
+  ASSERT_EQ("module1", modules_without_symbols[0]->debug_file());
+  ASSERT_EQ("module2", modules_without_symbols[1]->debug_file());
   frames = call_stack.frames();
   ASSERT_EQ(3U, frames->size());
 
@@ -805,7 +833,10 @@ TEST_F(GetFramesByFramePointer, FramePointerAndCFI) {
   StackwalkerARM walker(&system_info, &raw_context, MD_CONTEXT_ARM_REG_IOS_FP,
                         &stack_region, &modules, &frame_symbolizer);
 
-  ASSERT_TRUE(walker.Walk(&call_stack));
+  vector<const CodeModule*> modules_without_symbols;
+  ASSERT_TRUE(walker.Walk(&call_stack, &modules_without_symbols));
+  ASSERT_EQ(1U, modules_without_symbols.size());
+  ASSERT_EQ("module2", modules_without_symbols[0]->debug_file());
   frames = call_stack.frames();
   ASSERT_EQ(3U, frames->size());
 
diff --git a/src/processor/stackwalker_selftest.cc b/src/processor/stackwalker_selftest.cc
index 99644d7a..75d47582 100644
--- a/src/processor/stackwalker_selftest.cc
+++ b/src/processor/stackwalker_selftest.cc
@@ -69,12 +69,14 @@
 #include "google_breakpad/common/minidump_format.h"
 #include "google_breakpad/processor/basic_source_line_resolver.h"
 #include "google_breakpad/processor/call_stack.h"
+#include "google_breakpad/processor/code_module.h"
 #include "google_breakpad/processor/memory_region.h"
 #include "google_breakpad/processor/stack_frame.h"
 #include "google_breakpad/processor/stack_frame_cpu.h"
 
 using google_breakpad::BasicSourceLineResolver;
 using google_breakpad::CallStack;
+using google_breakpad::CodeModule;
 using google_breakpad::MemoryRegion;
 using google_breakpad::scoped_ptr;
 using google_breakpad::StackFrame;
@@ -337,7 +339,8 @@ static unsigned int CountCallerFrames() {
 #endif  // __i386__ || __ppc__ || __sparc__
 
   CallStack stack;
-  stackwalker.Walk(&stack);
+  vector<const CodeModule*> modules_without_symbols;
+  stackwalker.Walk(&stack, &modules_without_symbols);
 
 #ifdef PRINT_STACKS
   printf("\n");
diff --git a/src/processor/stackwalker_x86_unittest.cc b/src/processor/stackwalker_x86_unittest.cc
index 841ad0d8..caf899e6 100644
--- a/src/processor/stackwalker_x86_unittest.cc
+++ b/src/processor/stackwalker_x86_unittest.cc
@@ -40,6 +40,7 @@
 #include "google_breakpad/common/minidump_format.h"
 #include "google_breakpad/processor/basic_source_line_resolver.h"
 #include "google_breakpad/processor/call_stack.h"
+#include "google_breakpad/processor/code_module.h"
 #include "google_breakpad/processor/source_line_resolver_interface.h"
 #include "google_breakpad/processor/stack_frame_cpu.h"
 #include "processor/stackwalker_unittest_utils.h"
@@ -48,6 +49,7 @@
 
 using google_breakpad::BasicSourceLineResolver;
 using google_breakpad::CallStack;
+using google_breakpad::CodeModule;
 using google_breakpad::StackFrameSymbolizer;
 using google_breakpad::StackFrame;
 using google_breakpad::StackFrameX86;
@@ -153,7 +155,10 @@ TEST_F(SanityCheck, NoResolver) {
   StackwalkerX86 walker(&system_info, &raw_context, &stack_region, &modules,
                         &frame_symbolizer);
   // This should succeed, even without a resolver or supplier.
-  ASSERT_TRUE(walker.Walk(&call_stack));
+  vector<const CodeModule*> modules_without_symbols;
+  ASSERT_TRUE(walker.Walk(&call_stack, &modules_without_symbols));
+  ASSERT_EQ(1U, modules_without_symbols.size());
+  ASSERT_EQ("module1", modules_without_symbols[0]->debug_file());
   frames = call_stack.frames();
   StackFrameX86 *frame = static_cast<StackFrameX86 *>(frames->at(0));
   // Check that the values from the original raw context made it
@@ -173,7 +178,10 @@ TEST_F(GetContextFrame, Simple) {
   StackFrameSymbolizer frame_symbolizer(&supplier, &resolver);
   StackwalkerX86 walker(&system_info, &raw_context, &stack_region, &modules,
                         &frame_symbolizer);
-  ASSERT_TRUE(walker.Walk(&call_stack));
+  vector<const CodeModule*> modules_without_symbols;
+  ASSERT_TRUE(walker.Walk(&call_stack, &modules_without_symbols));
+  ASSERT_EQ(1U, modules_without_symbols.size());
+  ASSERT_EQ("module1", modules_without_symbols[0]->debug_file());
   frames = call_stack.frames();
   StackFrameX86 *frame = static_cast<StackFrameX86 *>(frames->at(0));
   // Check that the values from the original raw context made it
@@ -190,7 +198,10 @@ TEST_F(GetContextFrame, NoStackMemory) {
   StackFrameSymbolizer frame_symbolizer(&supplier, &resolver);
   StackwalkerX86 walker(&system_info, &raw_context, NULL, &modules,
                         &frame_symbolizer);
-  ASSERT_TRUE(walker.Walk(&call_stack));
+  vector<const CodeModule*> modules_without_symbols;
+  ASSERT_TRUE(walker.Walk(&call_stack, &modules_without_symbols));
+  ASSERT_EQ(1U, modules_without_symbols.size());
+  ASSERT_EQ("module1", modules_without_symbols[0]->debug_file());
   frames = call_stack.frames();
   StackFrameX86 *frame = static_cast<StackFrameX86 *>(frames->at(0));
   // Check that the values from the original raw context made it
@@ -223,7 +234,10 @@ TEST_F(GetCallerFrame, Traditional) {
   StackFrameSymbolizer frame_symbolizer(&supplier, &resolver);
   StackwalkerX86 walker(&system_info, &raw_context, &stack_region, &modules,
                         &frame_symbolizer);
-  ASSERT_TRUE(walker.Walk(&call_stack));
+  vector<const CodeModule*> modules_without_symbols;
+  ASSERT_TRUE(walker.Walk(&call_stack, &modules_without_symbols));
+  ASSERT_EQ(1U, modules_without_symbols.size());
+  ASSERT_EQ("module1", modules_without_symbols[0]->debug_file());
   frames = call_stack.frames();
   ASSERT_EQ(2U, frames->size());
 
@@ -279,7 +293,10 @@ TEST_F(GetCallerFrame, TraditionalScan) {
   StackFrameSymbolizer frame_symbolizer(&supplier, &resolver);
   StackwalkerX86 walker(&system_info, &raw_context, &stack_region, &modules,
                         &frame_symbolizer);
-  ASSERT_TRUE(walker.Walk(&call_stack));
+  vector<const CodeModule*> modules_without_symbols;
+  ASSERT_TRUE(walker.Walk(&call_stack, &modules_without_symbols));
+  ASSERT_EQ(1U, modules_without_symbols.size());
+  ASSERT_EQ("module1", modules_without_symbols[0]->debug_file());
   frames = call_stack.frames();
   ASSERT_EQ(2U, frames->size());
 
@@ -341,7 +358,10 @@ TEST_F(GetCallerFrame, TraditionalScanLongWay) {
   StackFrameSymbolizer frame_symbolizer(&supplier, &resolver);
   StackwalkerX86 walker(&system_info, &raw_context, &stack_region, &modules,
                         &frame_symbolizer);
-  ASSERT_TRUE(walker.Walk(&call_stack));
+  vector<const CodeModule*> modules_without_symbols;
+  ASSERT_TRUE(walker.Walk(&call_stack, &modules_without_symbols));
+  ASSERT_EQ(1U, modules_without_symbols.size());
+  ASSERT_EQ("module1", modules_without_symbols[0]->debug_file());
   frames = call_stack.frames();
   ASSERT_EQ(2U, frames->size());
 
@@ -413,7 +433,9 @@ TEST_F(GetCallerFrame, WindowsFrameData) {
   StackFrameSymbolizer frame_symbolizer(&supplier, &resolver);
   StackwalkerX86 walker(&system_info, &raw_context, &stack_region, &modules,
                         &frame_symbolizer);
-  ASSERT_TRUE(walker.Walk(&call_stack));
+  vector<const CodeModule*> modules_without_symbols;
+  ASSERT_TRUE(walker.Walk(&call_stack, &modules_without_symbols));
+  ASSERT_EQ(0U, modules_without_symbols.size());
   frames = call_stack.frames();
   ASSERT_EQ(2U, frames->size());
 
@@ -485,7 +507,10 @@ TEST_F(GetCallerFrame, WindowsFrameDataAligned) {
   StackFrameSymbolizer frame_symbolizer(&supplier, &resolver);
   StackwalkerX86 walker(&system_info, &raw_context, &stack_region, &modules,
                         &frame_symbolizer);
-  ASSERT_TRUE(walker.Walk(&call_stack));
+  vector<const CodeModule*> modules_without_symbols;
+  ASSERT_TRUE(walker.Walk(&call_stack, &modules_without_symbols));
+  ASSERT_EQ(1U, modules_without_symbols.size());
+  ASSERT_EQ("module2", modules_without_symbols[0]->debug_file());
   frames = call_stack.frames();
   ASSERT_EQ(2U, frames->size());
 
@@ -568,7 +593,9 @@ TEST_F(GetCallerFrame, WindowsFrameDataParameterSize) {
   StackFrameSymbolizer frame_symbolizer(&supplier, &resolver);
   StackwalkerX86 walker(&system_info, &raw_context, &stack_region, &modules,
                         &frame_symbolizer);
-  ASSERT_TRUE(walker.Walk(&call_stack));
+  vector<const CodeModule*> modules_without_symbols;
+  ASSERT_TRUE(walker.Walk(&call_stack, &modules_without_symbols));
+  ASSERT_EQ(0U, modules_without_symbols.size());
   frames = call_stack.frames();
   ASSERT_EQ(3U, frames->size());
 
@@ -663,7 +690,9 @@ TEST_F(GetCallerFrame, WindowsFrameDataScan) {
   StackFrameSymbolizer frame_symbolizer(&supplier, &resolver);
   StackwalkerX86 walker(&system_info, &raw_context, &stack_region, &modules,
                         &frame_symbolizer);
-  ASSERT_TRUE(walker.Walk(&call_stack));
+  vector<const CodeModule*> modules_without_symbols;
+  ASSERT_TRUE(walker.Walk(&call_stack, &modules_without_symbols));
+  ASSERT_EQ(0U, modules_without_symbols.size());
   frames = call_stack.frames();
   ASSERT_EQ(2U, frames->size());
 
@@ -747,7 +776,9 @@ TEST_F(GetCallerFrame, WindowsFrameDataBadEIPScan) {
   StackFrameSymbolizer frame_symbolizer(&supplier, &resolver);
   StackwalkerX86 walker(&system_info, &raw_context, &stack_region, &modules,
                         &frame_symbolizer);
-  ASSERT_TRUE(walker.Walk(&call_stack));
+  vector<const CodeModule*> modules_without_symbols;
+  ASSERT_TRUE(walker.Walk(&call_stack, &modules_without_symbols));
+  ASSERT_EQ(0U, modules_without_symbols.size());
   frames = call_stack.frames();
   ASSERT_EQ(2U, frames->size());
 
@@ -815,7 +846,9 @@ TEST_F(GetCallerFrame, WindowsFPOUnchangedEBP) {
   StackFrameSymbolizer frame_symbolizer(&supplier, &resolver);
   StackwalkerX86 walker(&system_info, &raw_context, &stack_region, &modules,
                         &frame_symbolizer);
-  ASSERT_TRUE(walker.Walk(&call_stack));
+  vector<const CodeModule*> modules_without_symbols;
+  ASSERT_TRUE(walker.Walk(&call_stack, &modules_without_symbols));
+  ASSERT_EQ(0U, modules_without_symbols.size());
   frames = call_stack.frames();
   ASSERT_EQ(2U, frames->size());
 
@@ -892,7 +925,9 @@ TEST_F(GetCallerFrame, WindowsFPOUsedEBP) {
   StackFrameSymbolizer frame_symbolizer(&supplier, &resolver);
   StackwalkerX86 walker(&system_info, &raw_context, &stack_region, &modules,
                         &frame_symbolizer);
-  ASSERT_TRUE(walker.Walk(&call_stack));
+  vector<const CodeModule*> modules_without_symbols;
+  ASSERT_TRUE(walker.Walk(&call_stack, &modules_without_symbols));
+  ASSERT_EQ(0U, modules_without_symbols.size());
   frames = call_stack.frames();
   ASSERT_EQ(2U, frames->size());
 
@@ -1030,7 +1065,9 @@ TEST_F(GetCallerFrame, WindowsFPOSystemCall) {
   StackFrameSymbolizer frame_symbolizer(&supplier, &resolver);
   StackwalkerX86 walker(&system_info, &raw_context, &stack_region, &modules,
                         &frame_symbolizer);
-  ASSERT_TRUE(walker.Walk(&call_stack));
+  vector<const CodeModule*> modules_without_symbols;
+  ASSERT_TRUE(walker.Walk(&call_stack, &modules_without_symbols));
+  ASSERT_EQ(0U, modules_without_symbols.size());
   frames = call_stack.frames();
 
   ASSERT_EQ(4U, frames->size());
@@ -1238,7 +1275,9 @@ TEST_F(GetCallerFrame, ReturnAddressIsNotInKnownModule) {
   StackFrameSymbolizer frame_symbolizer(&supplier, &resolver);
   StackwalkerX86 walker(&system_info, &raw_context, &stack_region,
                         &local_modules, &frame_symbolizer);
-  ASSERT_TRUE(walker.Walk(&call_stack));
+  vector<const CodeModule*> modules_without_symbols;
+  ASSERT_TRUE(walker.Walk(&call_stack, &modules_without_symbols));
+  ASSERT_EQ(0U, modules_without_symbols.size());
   frames = call_stack.frames();
 
   ASSERT_EQ(3U, frames->size());
@@ -1365,7 +1404,9 @@ struct CFIFixture: public StackwalkerX86Fixture {
     StackFrameSymbolizer frame_symbolizer(&supplier, &resolver);
     StackwalkerX86 walker(&system_info, &raw_context, &stack_region, &modules,
                           &frame_symbolizer);
-    ASSERT_TRUE(walker.Walk(&call_stack));
+    vector<const CodeModule*> modules_without_symbols;
+    ASSERT_TRUE(walker.Walk(&call_stack, &modules_without_symbols));
+    ASSERT_EQ(0U, modules_without_symbols.size());
     frames = call_stack.frames();
     ASSERT_EQ(2U, frames->size());