Allow adding extra memory regions to minidump on linux/windows

A=Bill McCloskey <wmccloskey@mozilla.com>, ted, original patch from https://bugzilla.mozilla.org/show_bug.cgi?id=662646
R=mark at https://breakpad.appspot.com/450002/

git-svn-id: http://google-breakpad.googlecode.com/svn/trunk@1041 4c0a9323-5329-0410-9bdc-e9ce6186880e

3 files changed, 178 insertions, 18 deletions

diff --git a/src/client/windows/handler/exception_handler.cc b/src/client/windows/handler/exception_handler.cc
index 6e5b724a..4b0c2917 100644
--- a/src/client/windows/handler/exception_handler.cc
+++ b/src/client/windows/handler/exception_handler.cc
@@ -46,9 +46,8 @@ static const int kExceptionHandlerThreadInitialStackSize = 64 * 1024;
 
 // This is passed as the context to the MinidumpWriteDump callback.
 typedef struct {
-  ULONG64 memory_base;
-  ULONG memory_size;
-  bool finished;
+  AppMemoryList::const_iterator iter;
+  AppMemoryList::const_iterator end;
 } MinidumpCallbackContext;
 
 vector<ExceptionHandler*>* ExceptionHandler::handler_stack_ = NULL;
@@ -220,6 +219,12 @@ void ExceptionHandler::Initialize(const wstring& dump_path,
     set_dump_path(dump_path);
   }
 
+  // Reserve one element for the instruction memory
+  AppMemory instruction_memory;
+  instruction_memory.ptr = NULL;
+  instruction_memory.length = 0;
+  app_memory_info_.push_back(instruction_memory);
+
   // There is a race condition here. If the first instance has not yet
   // initialized the critical section, the second (and later) instances may
   // try to use uninitialized critical section object. The feature of multiple
@@ -795,9 +800,6 @@ bool ExceptionHandler::WriteMinidumpWithException(
           ++user_streams.UserStreamCount;
         }
 
-        MINIDUMP_CALLBACK_INFORMATION callback;
-        MinidumpCallbackContext context;
-        MINIDUMP_CALLBACK_INFORMATION* callback_pointer = NULL;
         // Older versions of DbgHelp.dll don't correctly put the memory around
         // the faulting instruction pointer into the minidump. This
         // callback will ensure that it gets included.
@@ -822,23 +824,34 @@ bool ExceptionHandler::WriteMinidumpWithException(
             // pointer, but settle for whatever's available up to the
             // boundaries of the memory region.
             const ULONG64 kIPMemorySize = 256;
-            context.memory_base =
+            ULONG64 base =
               (std::max)(reinterpret_cast<ULONG64>(info.BaseAddress),
                        instruction_pointer - (kIPMemorySize / 2));
             ULONG64 end_of_range =
               (std::min)(instruction_pointer + (kIPMemorySize / 2),
                        reinterpret_cast<ULONG64>(info.BaseAddress)
                        + info.RegionSize);
-            context.memory_size =
-                static_cast<ULONG>(end_of_range - context.memory_base);
+            ULONG size = static_cast<ULONG>(end_of_range - base);
 
-            context.finished = false;
-            callback.CallbackRoutine = MinidumpWriteDumpCallback;
-            callback.CallbackParam = reinterpret_cast<void*>(&context);
-            callback_pointer = &callback;
+            AppMemory& elt = app_memory_info_.front();
+            elt.ptr = base;
+            elt.length = size;
           }
         }
 
+        MinidumpCallbackContext context;
+        context.iter = app_memory_info_.begin();
+        context.end = app_memory_info_.end();
+
+        // Skip the reserved element if there was no instruction memory
+        if (context.iter->ptr == 0) {
+          context.iter++;
+        }
+
+        MINIDUMP_CALLBACK_INFORMATION callback;
+        callback.CallbackRoutine = MinidumpWriteDumpCallback;
+        callback.CallbackParam = reinterpret_cast<void*>(&context);
+
         // The explicit comparison to TRUE avoids a warning (C4800).
         success = (minidump_write_dump_(GetCurrentProcess(),
                                         GetCurrentProcessId(),
@@ -846,7 +859,7 @@ bool ExceptionHandler::WriteMinidumpWithException(
                                         dump_type_,
                                         exinfo ? &except_info : NULL,
                                         &user_streams,
-                                        callback_pointer) == TRUE);
+                                        &callback) == TRUE);
 
         CloseHandle(dump_file);
       }
@@ -874,13 +887,13 @@ BOOL CALLBACK ExceptionHandler::MinidumpWriteDumpCallback(
   case MemoryCallback: {
     MinidumpCallbackContext* callback_context =
         reinterpret_cast<MinidumpCallbackContext*>(context);
-    if (callback_context->finished)
+    if (callback_context->iter == callback_context->end)
       return FALSE;
 
     // Include the specified memory region.
-    callback_output->MemoryBase = callback_context->memory_base;
-    callback_output->MemorySize = callback_context->memory_size;
-    callback_context->finished = true;
+    callback_output->MemoryBase = callback_context->iter->ptr;
+    callback_output->MemorySize = callback_context->iter->length;
+    callback_context->iter++;
     return TRUE;
   }
     
@@ -924,4 +937,26 @@ void ExceptionHandler::UpdateNextID() {
   next_minidump_path_c_ = next_minidump_path_.c_str();
 }
 
+void ExceptionHandler::RegisterAppMemory(void* ptr, size_t length) {
+  AppMemoryList::iterator iter =
+    std::find(app_memory_info_.begin(), app_memory_info_.end(), ptr);
+  if (iter != app_memory_info_.end()) {
+    // Don't allow registering the same pointer twice.
+    return;
+  }
+
+  AppMemory app_memory;
+  app_memory.ptr = reinterpret_cast<ULONG64>(ptr);
+  app_memory.length = static_cast<ULONG>(length);
+  app_memory_info_.push_back(app_memory);
+}
+
+void ExceptionHandler::UnregisterAppMemory(void* ptr) {
+  AppMemoryList::iterator iter =
+    std::find(app_memory_info_.begin(), app_memory_info_.end(), ptr);
+  if (iter != app_memory_info_.end()) {
+    app_memory_info_.erase(iter);
+  }
+}
+
 }  // namespace google_breakpad
diff --git a/src/client/windows/handler/exception_handler.h b/src/client/windows/handler/exception_handler.h
index 09f5177c..b7f1f949 100644
--- a/src/client/windows/handler/exception_handler.h
+++ b/src/client/windows/handler/exception_handler.h
@@ -65,6 +65,7 @@
 // Disable exception handler warnings.
 #pragma warning( disable : 4530 )
 
+#include <list>
 #include <string>
 #include <vector>
 
@@ -78,6 +79,22 @@ namespace google_breakpad {
 using std::vector;
 using std::wstring;
 
+// These entries store a list of memory regions that the client wants included
+// in the minidump.
+struct AppMemory {
+  ULONG64 ptr;
+  ULONG length;
+
+  bool operator==(const struct AppMemory& other) const {
+    return ptr == other.ptr;
+  }
+
+  bool operator==(const void* other) const {
+    return ptr == reinterpret_cast<ULONG64>(other);
+  }
+};
+typedef std::list<AppMemory> AppMemoryList;
+
 class ExceptionHandler {
  public:
   // A callback function to run before Breakpad performs any substantial
@@ -219,6 +236,11 @@ class ExceptionHandler {
   // Returns whether out-of-process dump generation is used or not.
   bool IsOutOfProcess() const { return crash_generation_client_.get() != NULL; }
 
+  // Calling RegisterAppMemory(p, len) causes len bytes starting
+  // at address p to be copied to the minidump when a crash happens.
+  void RegisterAppMemory(void* ptr, size_t length);
+  void UnregisterAppMemory(void* ptr);
+
  private:
   friend class AutoExceptionHandler;
 
@@ -404,6 +426,10 @@ class ExceptionHandler {
   // to not interfere with debuggers.
   bool handle_debug_exceptions_;
 
+  // Callers can request additional memory regions to be included in
+  // the dump.
+  AppMemoryList app_memory_info_;
+
   // A stack of ExceptionHandler objects that have installed unhandled
   // exception filters.  This vector is used by HandleException to determine
   // which ExceptionHandler object to route an exception to.  When an
diff --git a/src/client/windows/unittests/exception_handler_test.cc b/src/client/windows/unittests/exception_handler_test.cc
index 74d9a9be..9851998e 100644
--- a/src/client/windows/unittests/exception_handler_test.cc
+++ b/src/client/windows/unittests/exception_handler_test.cc
@@ -374,4 +374,103 @@ TEST_F(ExceptionHandlerTest, WriteMinidumpTest) {
   //TODO(ted): more comprehensive tests...
 }
 
+// Test that an additional memory region can be included in the minidump.
+TEST_F(ExceptionHandlerTest, AdditionalMemory) {
+  SYSTEM_INFO si;
+  GetSystemInfo(&si);
+  const u_int32_t kMemorySize = si.dwPageSize;
+
+  // Get some heap memory.
+  u_int8_t* memory = new u_int8_t[kMemorySize];
+  const uintptr_t kMemoryAddress = reinterpret_cast<uintptr_t>(memory);
+  ASSERT_TRUE(memory);
+
+  // Stick some data into the memory so the contents can be verified.
+  for (u_int32_t i = 0; i < kMemorySize; ++i) {
+    memory[i] = i % 255;
+  }
+
+  ExceptionHandler handler(temp_path_,
+                           NULL,
+                           DumpCallback,
+                           NULL,
+                           ExceptionHandler::HANDLER_ALL);
+
+  // Add the memory region to the list of memory to be included.
+  handler.RegisterAppMemory(memory, kMemorySize);
+  ASSERT_TRUE(handler.WriteMinidump());
+  ASSERT_FALSE(dump_file.empty());
+
+  string minidump_filename;
+  ASSERT_TRUE(WindowsStringUtils::safe_wcstombs(dump_file,
+                                                &minidump_filename));
+
+  // Read the minidump. Ensure that the memory region is present
+  Minidump minidump(minidump_filename);
+  ASSERT_TRUE(minidump.Read());
+
+  MinidumpMemoryList* dump_memory_list = minidump.GetMemoryList();
+  ASSERT_TRUE(dump_memory_list);
+  const MinidumpMemoryRegion* region =
+    dump_memory_list->GetMemoryRegionForAddress(kMemoryAddress);
+  ASSERT_TRUE(region);
+
+  EXPECT_EQ(kMemoryAddress, region->GetBase());
+  EXPECT_EQ(kMemorySize, region->GetSize());
+
+  // Verify memory contents.
+  EXPECT_EQ(0, memcmp(region->GetMemory(), memory, kMemorySize));
+
+  delete[] memory;
+}
+
+// Test that a memory region that was previously registered
+// can be unregistered.
+TEST_F(ExceptionHandlerTest, AdditionalMemoryRemove) {
+  SYSTEM_INFO si;
+  GetSystemInfo(&si);
+  const u_int32_t kMemorySize = si.dwPageSize;
+
+  // Get some heap memory.
+  u_int8_t* memory = new u_int8_t[kMemorySize];
+  const uintptr_t kMemoryAddress = reinterpret_cast<uintptr_t>(memory);
+  ASSERT_TRUE(memory);
+
+  // Stick some data into the memory so the contents can be verified.
+  for (u_int32_t i = 0; i < kMemorySize; ++i) {
+    memory[i] = i % 255;
+  }
+
+  ExceptionHandler handler(temp_path_,
+                           NULL,
+                           DumpCallback,
+                           NULL,
+                           ExceptionHandler::HANDLER_ALL);
+
+  // Add the memory region to the list of memory to be included.
+  handler.RegisterAppMemory(memory, kMemorySize);
+
+  // ...and then remove it
+  handler.UnregisterAppMemory(memory);
+
+  ASSERT_TRUE(handler.WriteMinidump());
+  ASSERT_FALSE(dump_file.empty());
+
+  string minidump_filename;
+  ASSERT_TRUE(WindowsStringUtils::safe_wcstombs(dump_file,
+                                                &minidump_filename));
+
+  // Read the minidump. Ensure that the memory region is not present.
+  Minidump minidump(minidump_filename);
+  ASSERT_TRUE(minidump.Read());
+
+  MinidumpMemoryList* dump_memory_list = minidump.GetMemoryList();
+  ASSERT_TRUE(dump_memory_list);
+  const MinidumpMemoryRegion* region =
+    dump_memory_list->GetMemoryRegionForAddress(kMemoryAddress);
+  EXPECT_FALSE(region);
+
+  delete[] memory;
+}
+
 }  // namespace