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

9 files changed, 443 insertions, 36 deletions

diff --git a/src/client/linux/handler/exception_handler.cc b/src/client/linux/handler/exception_handler.cc
index 490b6eb9..6f0b8de4 100644
--- a/src/client/linux/handler/exception_handler.cc
+++ b/src/client/linux/handler/exception_handler.cc
@@ -495,13 +495,15 @@ bool ExceptionHandler::DoDump(pid_t crashing_process, const void* context,
                                           crashing_process,
                                           context,
                                           context_size,
-                                          mapping_list_);
+                                          mapping_list_,
+                                          app_memory_list_);
   }
   return google_breakpad::WriteMinidump(minidump_descriptor_.path(),
                                         crashing_process,
                                         context,
                                         context_size,
-                                        mapping_list_);
+                                        mapping_list_,
+                                        app_memory_list_);
 }
 
 // static
@@ -562,4 +564,26 @@ void ExceptionHandler::AddMappingInfo(const string& name,
   mapping_list_.push_back(mapping);
 }
 
+void ExceptionHandler::RegisterAppMemory(void* ptr, size_t length) {
+  AppMemoryList::iterator iter =
+    std::find(app_memory_list_.begin(), app_memory_list_.end(), ptr);
+  if (iter != app_memory_list_.end()) {
+    // Don't allow registering the same pointer twice.
+    return;
+  }
+
+  AppMemory app_memory;
+  app_memory.ptr = ptr;
+  app_memory.length = length;
+  app_memory_list_.push_back(app_memory);
+}
+
+void ExceptionHandler::UnregisterAppMemory(void* ptr) {
+  AppMemoryList::iterator iter =
+    std::find(app_memory_list_.begin(), app_memory_list_.end(), ptr);
+  if (iter != app_memory_list_.end()) {
+    app_memory_list_.erase(iter);
+  }
+}
+
 }  // namespace google_breakpad
diff --git a/src/client/linux/handler/exception_handler.h b/src/client/linux/handler/exception_handler.h
index 95817424..68953adf 100644
--- a/src/client/linux/handler/exception_handler.h
+++ b/src/client/linux/handler/exception_handler.h
@@ -193,6 +193,13 @@ class ExceptionHandler {
                       size_t mapping_size,
                       size_t file_offset);
 
+  // Register a block of memory of length bytes starting at address ptr
+  // to be copied to the minidump when a crash happens.
+  void RegisterAppMemory(void* ptr, size_t length);
+
+  // Unregister a block of memory that was registered with RegisterAppMemory.
+  void UnregisterAppMemory(void* ptr);
+
   // Force signal handling for the specified signal.
   bool SimulateSignalDelivery(int sig);
  private:
@@ -238,6 +245,10 @@ class ExceptionHandler {
   // Callers can add extra info about mappings for cases where the
   // dumper code cannot extract enough information from /proc/<pid>/maps.
   MappingList mapping_list_;
+
+  // Callers can request additional memory regions to be included in
+  // the dump.
+  AppMemoryList app_memory_list_;
 };
 
 }  // namespace google_breakpad
diff --git a/src/client/linux/handler/exception_handler_unittest.cc b/src/client/linux/handler/exception_handler_unittest.cc
index 6de9b8d4..341d2fb0 100644
--- a/src/client/linux/handler/exception_handler_unittest.cc
+++ b/src/client/linux/handler/exception_handler_unittest.cc
@@ -939,6 +939,85 @@ TEST(ExceptionHandlerTest, GenerateMultipleDumpsWithPath) {
   ASSERT_TRUE(minidump2.Read());
   unlink(minidump_2.path());
 
-  // We expect 2 distinct files.
+  // 2 distinct files should be produced.
   ASSERT_STRNE(minidump_1_path.c_str(), minidump_2_path.c_str());
 }
+
+// Test that an additional memory region can be added to the minidump.
+TEST(ExceptionHandlerTest, AdditionalMemory) {
+  const u_int32_t kMemorySize = sysconf(_SC_PAGESIZE);
+
+  // 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;
+  }
+
+  AutoTempDir temp_dir;
+  ExceptionHandler handler(
+      MinidumpDescriptor(temp_dir.path()), NULL, NULL, NULL, true, -1);
+
+  // Add the memory region to the list of memory to be included.
+  handler.RegisterAppMemory(memory, kMemorySize);
+  handler.WriteMinidump();
+
+  const MinidumpDescriptor& minidump_desc = handler.minidump_descriptor();
+
+  // Read the minidump. Ensure that the memory region is present
+  Minidump minidump(minidump_desc.path());
+  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(ExceptionHandlerTest, AdditionalMemoryRemove) {
+  const u_int32_t kMemorySize = sysconf(_SC_PAGESIZE);
+
+  // 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);
+
+  AutoTempDir temp_dir;
+  ExceptionHandler handler(
+      MinidumpDescriptor(temp_dir.path()), NULL, NULL, NULL, true, -1);
+
+  // Add the memory region to the list of memory to be included.
+  handler.RegisterAppMemory(memory, kMemorySize);
+
+  // ...and then remove it
+  handler.UnregisterAppMemory(memory);
+  handler.WriteMinidump();
+
+  const MinidumpDescriptor& minidump_desc = handler.minidump_descriptor();
+
+  // Read the minidump. Ensure that the memory region is not present.
+  Minidump minidump(minidump_desc.path());
+  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;
+}
diff --git a/src/client/linux/minidump_writer/minidump_writer.cc b/src/client/linux/minidump_writer/minidump_writer.cc
index eb2e6d64..b081b298 100644
--- a/src/client/linux/minidump_writer/minidump_writer.cc
+++ b/src/client/linux/minidump_writer/minidump_writer.cc
@@ -76,6 +76,7 @@
 
 namespace {
 
+using google_breakpad::AppMemoryList;
 using google_breakpad::ExceptionHandler;
 using google_breakpad::LineReader;
 using google_breakpad::LinuxDumper;
@@ -381,6 +382,7 @@ class MinidumpWriter {
                  int minidump_fd,
                  const ExceptionHandler::CrashContext* context,
                  const MappingList& mappings,
+                 const AppMemoryList& appmem,
                  LinuxDumper* dumper)
       : fd_(minidump_fd),
         path_(minidump_path),
@@ -393,7 +395,8 @@ class MinidumpWriter {
 #endif
         dumper_(dumper),
         memory_blocks_(dumper_->allocator()),
-        mapping_list_(mappings) {
+        mapping_list_(mappings),
+        app_memory_list_(appmem) {
     // Assert there should be either a valid fd or a valid path, not both.
     assert(fd_ != -1 || minidump_path);
     assert(fd_ == -1 || !minidump_path);
@@ -480,6 +483,9 @@ class MinidumpWriter {
       return false;
     dir.CopyIndex(dir_index++, &dirent);
 
+    if (!WriteAppMemory())
+      return false;
+
     if (!WriteMemoryListStream(&dirent))
       return false;
     dir.CopyIndex(dir_index++, &dirent);
@@ -781,6 +787,30 @@ class MinidumpWriter {
     return true;
   }
 
+  // Write application-provided memory regions.
+  bool WriteAppMemory() {
+    for (AppMemoryList::const_iterator iter = app_memory_list_.begin();
+         iter != app_memory_list_.end();
+         ++iter) {
+      uint8_t* data_copy =
+        reinterpret_cast<uint8_t*>(dumper_->allocator()->Alloc(iter->length));
+      dumper_->CopyFromProcess(data_copy, GetCrashThread(), iter->ptr,
+                               iter->length);
+
+      UntypedMDRVA memory(&minidump_writer_);
+      if (!memory.Allocate(iter->length)) {
+        return false;
+      }
+      memory.Copy(data_copy, iter->length);
+      MDMemoryDescriptor desc;
+      desc.start_of_memory_range = reinterpret_cast<uintptr_t>(iter->ptr);
+      desc.memory = memory.location();
+      memory_blocks_.push_back(desc);
+    }
+
+    return true;
+  }
+
   static bool ShouldIncludeMapping(const MappingInfo& mapping) {
     if (mapping.name[0] == 0 ||  // only want modules with filenames.
         mapping.offset ||  // only want to include one mapping per shared lib.
@@ -1361,6 +1391,9 @@ class MinidumpWriter {
   wasteful_vector<MDMemoryDescriptor> memory_blocks_;
   // Additional information about some mappings provided by the caller.
   const MappingList& mapping_list_;
+  // Additional memory regions to be included in the dump,
+  // provided by the caller.
+  const AppMemoryList& app_memory_list_;
 };
 
 
@@ -1368,7 +1401,8 @@ bool WriteMinidumpImpl(const char* minidump_path,
                        int minidump_fd,
                        pid_t crashing_process,
                        const void* blob, size_t blob_size,
-                       const MappingList& mappings) {
+                       const MappingList& mappings,
+                       const AppMemoryList& appmem) {
   if (blob_size != sizeof(ExceptionHandler::CrashContext))
     return false;
   const ExceptionHandler::CrashContext* context =
@@ -1378,7 +1412,8 @@ bool WriteMinidumpImpl(const char* minidump_path,
       reinterpret_cast<uintptr_t>(context->siginfo.si_addr));
   dumper.set_crash_signal(context->siginfo.si_signo);
   dumper.set_crash_thread(context->tid);
-  MinidumpWriter writer(minidump_path, minidump_fd, context, mappings, &dumper);
+  MinidumpWriter writer(minidump_path, minidump_fd, context, mappings,
+                        appmem, &dumper);
   if (!writer.Init())
     return false;
   return writer.Dump();
@@ -1391,33 +1426,36 @@ namespace google_breakpad {
 bool WriteMinidump(const char* minidump_path, pid_t crashing_process,
                    const void* blob, size_t blob_size) {
   return WriteMinidumpImpl(minidump_path, -1, crashing_process, blob, blob_size,
-                           MappingList());
+                           MappingList(), AppMemoryList());
 }
 
 bool WriteMinidump(int minidump_fd, pid_t crashing_process,
                    const void* blob, size_t blob_size) {
   return WriteMinidumpImpl(NULL, minidump_fd, crashing_process, blob, blob_size,
-                           MappingList());
+                           MappingList(), AppMemoryList());
 }
 
 bool WriteMinidump(const char* minidump_path, pid_t crashing_process,
                    const void* blob, size_t blob_size,
-                   const MappingList& mappings) {
+                   const MappingList& mappings,
+                   const AppMemoryList& appmem) {
   return WriteMinidumpImpl(minidump_path, -1, crashing_process, blob, blob_size,
-                           mappings);
+                           mappings, appmem);
 }
 
 bool WriteMinidump(int minidump_fd, pid_t crashing_process,
                    const void* blob, size_t blob_size,
-                   const MappingList& mappings) {
+                   const MappingList& mappings,
+                   const AppMemoryList& appmem) {
   return WriteMinidumpImpl(NULL, minidump_fd, crashing_process, blob, blob_size,
-                           mappings);
+                           mappings, appmem);
 }
 
 bool WriteMinidump(const char* filename,
                    const MappingList& mappings,
+                   const AppMemoryList& appmem,
                    LinuxDumper* dumper) {
-  MinidumpWriter writer(filename, -1, NULL, mappings, dumper);
+  MinidumpWriter writer(filename, -1, NULL, mappings, appmem, dumper);
   if (!writer.Init())
     return false;
   return writer.Dump();
diff --git a/src/client/linux/minidump_writer/minidump_writer.h b/src/client/linux/minidump_writer/minidump_writer.h
index 14da94b6..1370d938 100644
--- a/src/client/linux/minidump_writer/minidump_writer.h
+++ b/src/client/linux/minidump_writer/minidump_writer.h
@@ -51,6 +51,22 @@ struct MappingEntry {
 // A list of <MappingInfo, GUID>
 typedef std::list<MappingEntry> MappingList;
 
+// These entries store a list of memory regions that the client wants included
+// in the minidump.
+struct AppMemory {
+  void* ptr;
+  size_t length;
+
+  bool operator==(const struct AppMemory& other) const {
+    return ptr == other.ptr;
+  }
+
+  bool operator==(const void* other) const {
+    return ptr == other;
+  }
+};
+typedef std::list<AppMemory> AppMemoryList;
+
 // Writes a minidump to the filesystem. These functions do not malloc nor use
 // libc functions which may. Thus, it can be used in contexts where the state
 // of the heap may be corrupt.
@@ -67,16 +83,20 @@ bool WriteMinidump(const char* minidump_path, pid_t crashing_process,
 bool WriteMinidump(int minidump_fd, pid_t crashing_process,
                    const void* blob, size_t blob_size);
 
-// These overloads also allow passing a list of known mappings.
+// These overloads also allow passing a list of known mappings and
+// a list of additional memory regions to be included in the minidump.
 bool WriteMinidump(const char* minidump_path, pid_t crashing_process,
                    const void* blob, size_t blob_size,
-                   const MappingList& mappings);
+                   const MappingList& mappings,
+                   const AppMemoryList& appdata);
 bool WriteMinidump(int minidump_fd, pid_t crashing_process,
                    const void* blob, size_t blob_size,
-                   const MappingList& mappings);
+                   const MappingList& mappings,
+                   const AppMemoryList& appdata);
 
 bool WriteMinidump(const char* filename,
                    const MappingList& mappings,
+                   const AppMemoryList& appdata,
                    LinuxDumper* dumper);
 
 }  // namespace google_breakpad
diff --git a/src/client/linux/minidump_writer/minidump_writer_unittest.cc b/src/client/linux/minidump_writer/minidump_writer_unittest.cc
index 7558bee4..0a6b07d1 100644
--- a/src/client/linux/minidump_writer/minidump_writer_unittest.cc
+++ b/src/client/linux/minidump_writer/minidump_writer_unittest.cc
@@ -32,6 +32,7 @@
 #include <sys/stat.h>
 #include <sys/syscall.h>
 #include <sys/types.h>
+#include <ucontext.h>
 #include <unistd.h>
 
 #include <string>
@@ -184,12 +185,13 @@ TEST(MinidumpWriterTest, MappingInfo) {
   strcpy(info.name, kMemoryName);
 
   MappingList mappings;
+  AppMemoryList memory_list;
   MappingEntry mapping;
   mapping.first = info;
   memcpy(mapping.second, kModuleGUID, sizeof(MDGUID));
   mappings.push_back(mapping);
   ASSERT_TRUE(WriteMinidump(templ.c_str(), child, &context, sizeof(context),
-                            mappings));
+                            mappings, memory_list));
 
   // Read the minidump. Load the module list, and ensure that
   // the mmap'ed |memory| is listed with the given module name
@@ -288,12 +290,13 @@ TEST(MinidumpWriterTest, MappingInfoContained) {
   strcpy(info.name, kMemoryName);
 
   MappingList mappings;
+  AppMemoryList memory_list;
   MappingEntry mapping;
   mapping.first = info;
   memcpy(mapping.second, kModuleGUID, sizeof(MDGUID));
   mappings.push_back(mapping);
   ASSERT_TRUE(WriteMinidump(dumpfile.c_str(), child, &context, sizeof(context),
-                            mappings));
+                            mappings, memory_list));
 
   // Read the minidump. Load the module list, and ensure that
   // the mmap'ed |memory| is listed with the given module name
@@ -410,3 +413,75 @@ TEST(MinidumpWriterTest, DeletedBinary) {
   module_identifier += "0";
   EXPECT_EQ(module_identifier, module->debug_identifier());
 }
+
+// Test that an additional memory region can be added to the minidump.
+TEST(MinidumpWriterTest, AdditionalMemory) {
+  int fds[2];
+  ASSERT_NE(-1, pipe(fds));
+
+  // These are defined here so the parent can use them to check the
+  // data from the minidump afterwards.
+  const u_int32_t kMemorySize = sysconf(_SC_PAGESIZE);
+
+  // 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;
+  }
+
+  const pid_t child = fork();
+  if (child == 0) {
+    close(fds[1]);
+    char b;
+    HANDLE_EINTR(read(fds[0], &b, sizeof(b)));
+    close(fds[0]);
+    syscall(__NR_exit);
+  }
+  close(fds[0]);
+
+  ExceptionHandler::CrashContext context;
+
+  // This needs a valid context for minidump writing to work, but getting
+  // a useful one from the child is too much work, so just use one from
+  // the parent since the child is just a forked copy anyway.
+  ASSERT_EQ(0, getcontext(&context.context));
+  context.tid = child;
+
+  AutoTempDir temp_dir;
+  string templ = temp_dir.path() + "/minidump-writer-unittest";
+  unlink(templ.c_str());
+
+  MappingList mappings;
+  AppMemoryList memory_list;
+
+  // Add the memory region to the list of memory to be included.
+  AppMemory app_memory;
+  app_memory.ptr = memory;
+  app_memory.length = kMemorySize;
+  memory_list.push_back(app_memory);
+  ASSERT_TRUE(WriteMinidump(templ.c_str(), child, &context, sizeof(context),
+                            mappings, memory_list));
+
+  // Read the minidump. Ensure that the memory region is present
+  Minidump minidump(templ.c_str());
+  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;
+  close(fds[1]);
+}
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