Allow generating minidumps from live processes on Windows.

R=mark at https://breakpad.appspot.com/115002/

git-svn-id: http://google-breakpad.googlecode.com/svn/trunk@1042 4c0a9323-5329-0410-9bdc-e9ce6186880e

2 files changed, 215 insertions, 110 deletions

diff --git a/src/client/windows/handler/exception_handler.cc b/src/client/windows/handler/exception_handler.cc
index 4b0c2917..eb778191 100644
--- a/src/client/windows/handler/exception_handler.cc
+++ b/src/client/windows/handler/exception_handler.cc
@@ -738,6 +738,62 @@ bool ExceptionHandler::WriteMinidump(const wstring &dump_path,
   return handler.WriteMinidump();
 }
 
+// static
+bool ExceptionHandler::WriteMinidumpForChild(HANDLE child,
+                                             DWORD child_blamed_thread,
+                                             const wstring& dump_path,
+                                             MinidumpCallback callback,
+                                             void* callback_context) {
+  EXCEPTION_RECORD ex;
+  CONTEXT ctx;
+  EXCEPTION_POINTERS exinfo = { NULL, NULL };
+  DWORD last_suspend_count = -1;
+  HANDLE child_thread_handle = OpenThread(THREAD_GET_CONTEXT |
+                                          THREAD_QUERY_INFORMATION |
+                                          THREAD_SUSPEND_RESUME,
+                                          FALSE,
+                                          child_blamed_thread);
+  // This thread may have died already, so not opening the handle is a
+  // non-fatal error.
+  if (child_thread_handle != NULL) {
+    last_suspend_count = SuspendThread(child_thread_handle);
+    if (last_suspend_count >= 0) {
+      ctx.ContextFlags = CONTEXT_ALL;
+      if (GetThreadContext(child_thread_handle, &ctx)) {
+        memset(&ex, 0, sizeof(ex));
+        ex.ExceptionCode = EXCEPTION_BREAKPOINT;
+#if defined(_M_IX86)
+        ex.ExceptionAddress = reinterpret_cast<PVOID>(ctx.Eip);
+#elif defined(_M_X64)
+        ex.ExceptionAddress = reinterpret_cast<PVOID>(ctx.Rip);
+#endif
+        exinfo.ExceptionRecord = &ex;
+        exinfo.ContextRecord = &ctx;
+      }
+    }
+  }
+
+  ExceptionHandler handler(dump_path, NULL, callback, callback_context,
+                           HANDLER_NONE);
+  bool success = handler.WriteMinidumpWithExceptionForProcess(
+      child_blamed_thread,
+      exinfo.ExceptionRecord ? &exinfo : NULL,
+      NULL, child, false);
+
+  if (last_suspend_count >= 0) {
+    ResumeThread(child_thread_handle);
+  }
+
+  CloseHandle(child_thread_handle);
+
+  if (callback) {
+    success = callback(handler.dump_path_c_, handler.next_minidump_id_c_,
+                       callback_context, NULL, NULL, success);
+  }
+
+  return success;
+}
+
 bool ExceptionHandler::WriteMinidumpWithException(
     DWORD requesting_thread_id,
     EXCEPTION_POINTERS* exinfo,
@@ -756,114 +812,11 @@ bool ExceptionHandler::WriteMinidumpWithException(
   if (IsOutOfProcess()) {
     success = crash_generation_client_->RequestDump(exinfo, assertion);
   } else {
-    if (minidump_write_dump_) {
-      HANDLE dump_file = CreateFile(next_minidump_path_c_,
-                                    GENERIC_WRITE,
-                                    0,  // no sharing
-                                    NULL,
-                                    CREATE_NEW,  // fail if exists
-                                    FILE_ATTRIBUTE_NORMAL,
-                                    NULL);
-      if (dump_file != INVALID_HANDLE_VALUE) {
-        MINIDUMP_EXCEPTION_INFORMATION except_info;
-        except_info.ThreadId = requesting_thread_id;
-        except_info.ExceptionPointers = exinfo;
-        except_info.ClientPointers = FALSE;
-
-        // Add an MDRawBreakpadInfo stream to the minidump, to provide
-        // additional information about the exception handler to the Breakpad
-        // processor. The information will help the processor determine which
-        // threads are relevant.  The Breakpad processor does not require this
-        // information but can function better with Breakpad-generated dumps
-        // when it is present. The native debugger is not harmed by the
-        // presence of this information.
-        MDRawBreakpadInfo breakpad_info;
-        breakpad_info.validity = MD_BREAKPAD_INFO_VALID_DUMP_THREAD_ID |
-                               MD_BREAKPAD_INFO_VALID_REQUESTING_THREAD_ID;
-        breakpad_info.dump_thread_id = GetCurrentThreadId();
-        breakpad_info.requesting_thread_id = requesting_thread_id;
-
-        // Leave room in user_stream_array for a possible assertion info stream.
-        MINIDUMP_USER_STREAM user_stream_array[2];
-        user_stream_array[0].Type = MD_BREAKPAD_INFO_STREAM;
-        user_stream_array[0].BufferSize = sizeof(breakpad_info);
-        user_stream_array[0].Buffer = &breakpad_info;
-
-        MINIDUMP_USER_STREAM_INFORMATION user_streams;
-        user_streams.UserStreamCount = 1;
-        user_streams.UserStreamArray = user_stream_array;
-
-        if (assertion) {
-          user_stream_array[1].Type = MD_ASSERTION_INFO_STREAM;
-          user_stream_array[1].BufferSize = sizeof(MDRawAssertionInfo);
-          user_stream_array[1].Buffer = assertion;
-          ++user_streams.UserStreamCount;
-        }
-
-        // 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.
-        if (exinfo) {
-          // Find a memory region of 256 bytes centered on the
-          // faulting instruction pointer.
-          const ULONG64 instruction_pointer = 
-#if defined(_M_IX86)
-            exinfo->ContextRecord->Eip;
-#elif defined(_M_AMD64)
-            exinfo->ContextRecord->Rip;
-#else
-#error Unsupported platform
-#endif
-
-          MEMORY_BASIC_INFORMATION info;
-          if (VirtualQuery(reinterpret_cast<LPCVOID>(instruction_pointer),
-                           &info,
-                           sizeof(MEMORY_BASIC_INFORMATION)) != 0 &&
-              info.State == MEM_COMMIT) {
-            // Attempt to get 128 bytes before and after the instruction
-            // pointer, but settle for whatever's available up to the
-            // boundaries of the memory region.
-            const ULONG64 kIPMemorySize = 256;
-            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);
-            ULONG size = static_cast<ULONG>(end_of_range - base);
-
-            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(),
-                                        dump_file,
-                                        dump_type_,
-                                        exinfo ? &except_info : NULL,
-                                        &user_streams,
-                                        &callback) == TRUE);
-
-        CloseHandle(dump_file);
-      }
-    }
+    success = WriteMinidumpWithExceptionForProcess(requesting_thread_id,
+                                                   exinfo,
+                                                   assertion,
+                                                   GetCurrentProcess(),
+                                                   true);
   }
 
   if (callback_) {
@@ -917,6 +870,132 @@ BOOL CALLBACK ExceptionHandler::MinidumpWriteDumpCallback(
   return FALSE;
 }
 
+bool ExceptionHandler::WriteMinidumpWithExceptionForProcess(
+    DWORD requesting_thread_id,
+    EXCEPTION_POINTERS* exinfo,
+    MDRawAssertionInfo* assertion,
+    HANDLE process,
+    bool write_requester_stream) {
+  bool success = false;
+  if (minidump_write_dump_) {
+    HANDLE dump_file = CreateFile(next_minidump_path_c_,
+                                  GENERIC_WRITE,
+                                  0,  // no sharing
+                                  NULL,
+                                  CREATE_NEW,  // fail if exists
+                                  FILE_ATTRIBUTE_NORMAL,
+                                  NULL);
+    if (dump_file != INVALID_HANDLE_VALUE) {
+      MINIDUMP_EXCEPTION_INFORMATION except_info;
+      except_info.ThreadId = requesting_thread_id;
+      except_info.ExceptionPointers = exinfo;
+      except_info.ClientPointers = FALSE;
+
+      // Leave room in user_stream_array for possible breakpad and
+      // assertion info streams.
+      MINIDUMP_USER_STREAM user_stream_array[2];
+      MINIDUMP_USER_STREAM_INFORMATION user_streams;
+      user_streams.UserStreamCount = 0;
+      user_streams.UserStreamArray = user_stream_array;
+
+      if (write_requester_stream) {
+        // Add an MDRawBreakpadInfo stream to the minidump, to provide
+        // additional information about the exception handler to the Breakpad
+        // processor. The information will help the processor determine which
+        // threads are relevant.  The Breakpad processor does not require this
+        // information but can function better with Breakpad-generated dumps
+        // when it is present. The native debugger is not harmed by the
+        // presence of this information.
+        MDRawBreakpadInfo breakpad_info;
+        breakpad_info.validity = MD_BREAKPAD_INFO_VALID_DUMP_THREAD_ID |
+                                 MD_BREAKPAD_INFO_VALID_REQUESTING_THREAD_ID;
+        breakpad_info.dump_thread_id = GetCurrentThreadId();
+        breakpad_info.requesting_thread_id = requesting_thread_id;
+
+        int index = user_streams.UserStreamCount;
+        user_stream_array[index].Type = MD_BREAKPAD_INFO_STREAM;
+        user_stream_array[index].BufferSize = sizeof(breakpad_info);
+        user_stream_array[index].Buffer = &breakpad_info;
+        ++user_streams.UserStreamCount;
+      }
+
+      if (assertion) {
+        int index = user_streams.UserStreamCount;
+        user_stream_array[index].Type = MD_ASSERTION_INFO_STREAM;
+        user_stream_array[index].BufferSize = sizeof(MDRawAssertionInfo);
+        user_stream_array[index].Buffer = assertion;
+        ++user_streams.UserStreamCount;
+      }
+
+      // 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.
+      if (exinfo) {
+        // Find a memory region of 256 bytes centered on the
+        // faulting instruction pointer.
+        const ULONG64 instruction_pointer =
+#if defined(_M_IX86)
+          exinfo->ContextRecord->Eip;
+#elif defined(_M_AMD64)
+        exinfo->ContextRecord->Rip;
+#else
+#error Unsupported platform
+#endif
+
+        MEMORY_BASIC_INFORMATION info;
+        if (VirtualQueryEx(process,
+                           reinterpret_cast<LPCVOID>(instruction_pointer),
+                           &info,
+                           sizeof(MEMORY_BASIC_INFORMATION)) != 0 &&
+            info.State == MEM_COMMIT) {
+          // Attempt to get 128 bytes before and after the instruction
+          // pointer, but settle for whatever's available up to the
+          // boundaries of the memory region.
+          const ULONG64 kIPMemorySize = 256;
+          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);
+          ULONG size = static_cast<ULONG>(end_of_range - base);
+
+          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_(process,
+                                      GetCurrentProcessId(),
+                                      dump_file,
+                                      dump_type_,
+                                      exinfo ? &except_info : NULL,
+                                      &user_streams,
+                                      &callback) == TRUE);
+
+      CloseHandle(dump_file);
+    }
+  }
+
+  return success;
+}
+
 void ExceptionHandler::UpdateNextID() {
   assert(uuid_create_);
   UUID id = {0};
diff --git a/src/client/windows/handler/exception_handler.h b/src/client/windows/handler/exception_handler.h
index b7f1f949..c1945e1e 100644
--- a/src/client/windows/handler/exception_handler.h
+++ b/src/client/windows/handler/exception_handler.h
@@ -221,6 +221,17 @@ class ExceptionHandler {
   static bool WriteMinidump(const wstring &dump_path,
                             MinidumpCallback callback, void* callback_context);
 
+  // Write a minidump of |child| immediately.  This can be used to
+  // capture the execution state of |child| independently of a crash.
+  // Pass a meaningful |child_blamed_thread| to make that thread in
+  // the child process the one from which a crash signature is
+  // extracted.
+  static bool WriteMinidumpForChild(HANDLE child,
+                                    DWORD child_blamed_thread,
+                                    const wstring& dump_path,
+                                    MinidumpCallback callback,
+                                    void* callback_context);
+
   // Get the thread ID of the thread requesting the dump (either the exception
   // thread or any other thread that called WriteMinidump directly).  This
   // may be useful if you want to include additional thread state in your
@@ -305,8 +316,9 @@ class ExceptionHandler {
   bool WriteMinidumpOnHandlerThread(EXCEPTION_POINTERS* exinfo,
                                     MDRawAssertionInfo* assertion);
 
-  // This function does the actual writing of a minidump.  It is called
-  // on the handler thread.  requesting_thread_id is the ID of the thread
+  // This function is called on the handler thread.  It calls into
+  // WriteMinidumpWithExceptionForProcess() with a handle to the
+  // current process.  requesting_thread_id is the ID of the thread
   // that requested the dump.  If the dump is requested as a result of
   // an exception, exinfo contains exception information, otherwise,
   // it is NULL.
@@ -321,6 +333,20 @@ class ExceptionHandler {
       const PMINIDUMP_CALLBACK_INPUT callback_input,
       PMINIDUMP_CALLBACK_OUTPUT callback_output);
 
+  // This function does the actual writing of a minidump.  It is
+  // called on the handler thread.  requesting_thread_id is the ID of
+  // the thread that requested the dump, if that information is
+  // meaningful.  If the dump is requested as a result of an
+  // exception, exinfo contains exception information, otherwise, it
+  // is NULL.  process is the one that will be dumped.  If
+  // requesting_thread_id is meaningful and should be added to the
+  // minidump, write_requester_stream is |true|.
+  bool WriteMinidumpWithExceptionForProcess(DWORD requesting_thread_id,
+                                            EXCEPTION_POINTERS* exinfo,
+                                            MDRawAssertionInfo* assertion,
+                                            HANDLE process,
+                                            bool write_requester_stream);
+
   // Generates a new ID and stores it in next_minidump_id_, and stores the
   // path of the next minidump to be written in next_minidump_path_.
   void UpdateNextID();