Breakpad Linux: Fix crash handler writing to disk on the wrong thread....

chrome/browser/crash_handler_host_linux.cc

Index: chrome/browser/crash_handler_host_linux.cc
===================================================================
--- chrome/browser/crash_handler_host_linux.cc	(revision 75308)
+++ chrome/browser/crash_handler_host_linux.cc	(working copy)
@@ -1,4 +1,4 @@
-// Copyright (c) 2010 The Chromium Authors. All rights reserved.
+// Copyright (c) 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
@@ -8,7 +8,6 @@
 #include <stdlib.h>
 #include <sys/socket.h>
 #include <sys/syscall.h>
-#include <sys/types.h>
 #include <unistd.h>
 
 #include "base/eintr_wrapper.h"
@@ -35,6 +34,12 @@
 
 namespace {
 
+// The length of the control message:
+const unsigned kControlMsgSize =
+    CMSG_SPACE(2*sizeof(int)) + CMSG_SPACE(sizeof(struct ucred));
+// The length of the regular payload:
+const unsigned kCrashContextSize = sizeof(ExceptionHandler::CrashContext);
+
 // Handles the crash dump and frees the allocated BreakpadInfo struct.
 void CrashDumpTask(CrashHandlerHostLinux* handler, BreakpadInfo* info) {
   if (handler->IsShuttingDown())
@@ -112,13 +117,6 @@
   // for writing the minidump as well as a file descriptor and a credentials
   // block so that they can't lie about their pid.
 
-  // The length of the control message:
-  static const unsigned kControlMsgSize =
-      CMSG_SPACE(2*sizeof(int)) + CMSG_SPACE(sizeof(struct ucred));
-  // The length of the regular payload:
-  static const unsigned kCrashContextSize =
-      sizeof(ExceptionHandler::CrashContext);
-
   const size_t kIovSize = 7;
   struct msghdr msg = {0};
   struct iovec iov[kIovSize];
@@ -279,13 +277,49 @@
     bad_context->tid = crashing_tid;
   }
 
-  bool upload = true;
+  // Sanitize the string data a bit more
+  guid[kGuidSize] = crash_url[kMaxActiveURLSize] = distro[kDistroSize] = 0;
+
+  BreakpadInfo* info = new BreakpadInfo;
+
+  info->process_type_length = process_type_.length();
+  char* process_type_str = new char[info->process_type_length + 1];
+  process_type_.copy(process_type_str, info->process_type_length);
+  process_type_str[info->process_type_length] = '\0';
+  info->process_type = process_type_str;
+
+  info->crash_url_length = strlen(crash_url);
+  info->crash_url = crash_url;
+
+  info->guid_length = strlen(guid);
+  info->guid = guid;
+
+  info->distro_length = strlen(distro);
+  info->distro = distro;
+
+  info->upload = (getenv(env_vars::kHeadless) == NULL);
+  info->process_start_time = uptime;
+
+  BrowserThread::PostTask(
+      BrowserThread::FILE, FROM_HERE,
+      NewRunnableMethod(this,
+                        &CrashHandlerHostLinux::WriteDumpFile,
+                        info,
+                        crashing_pid,
+                        reinterpret_cast<char*>(&crash_context),

[piman, 2011/04/15 05:17:17]

Woah, are we passing a reference to a buffer on the stack here ? It's invalid
when WriteDumpFile executes

Also, is it really necessary to hop threads ? We are already on a worker thread.

[Lei Zhang, 2011/04/15 05:25:07]

Doh. I'll fix it in a bit.

+                        signal_fd));
+}
+
+void CrashHandlerHostLinux::WriteDumpFile(BreakpadInfo* info,
+                                          pid_t crashing_pid,
+                                          char* crash_context,
+                                          int signal_fd) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::FILE));
+
   FilePath dumps_path("/tmp");
   PathService::Get(base::DIR_TEMP, &dumps_path);
-  if (getenv(env_vars::kHeadless)) {
-    upload = false;
+  if (!info->upload)
     PathService::Get(chrome::DIR_CRASH_DUMPS, &dumps_path);
-  }
   const uint64 rand = base::RandUint64();
   const std::string minidump_filename =
       StringPrintf("%s/chromium-%s-minidump-%016" PRIx64 ".dmp",
@@ -294,11 +328,27 @@
                                       crashing_pid, crash_context,
                                       kCrashContextSize)) {
     LOG(ERROR) << "Failed to write crash dump for pid " << crashing_pid;
-    HANDLE_EINTR(close(signal_fd));

[Lei Zhang, 2011/02/17 22:49:08]

On failure, we closed |signal_fd| twice.

   }
 
+  char* minidump_filename_str = new char[minidump_filename.length() + 1];
+  minidump_filename.copy(minidump_filename_str, minidump_filename.length());
+  minidump_filename_str[minidump_filename.length()] = '\0';
+  info->filename = minidump_filename_str;
+
+  BrowserThread::PostTask(
+      BrowserThread::IO, FROM_HERE,
+      NewRunnableMethod(this,
+                        &CrashHandlerHostLinux::QueueCrashDumpTask,
+                        info,
+                        signal_fd));
+}
+
+void CrashHandlerHostLinux::QueueCrashDumpTask(BreakpadInfo* info,
+                                               int signal_fd) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
+
   // Send the done signal to the process: it can exit now.
-  memset(&msg, 0, sizeof(msg));
+  struct msghdr msg = {0};
   struct iovec done_iov;
   done_iov.iov_base = const_cast<char*>("\x42");
   done_iov.iov_len = 1;
@@ -308,34 +358,6 @@
   HANDLE_EINTR(sendmsg(signal_fd, &msg, MSG_DONTWAIT | MSG_NOSIGNAL));
   HANDLE_EINTR(close(signal_fd));
 
-  // Sanitize the string data a bit more
-  guid[kGuidSize] = crash_url[kMaxActiveURLSize] = distro[kDistroSize] = 0;
-
-  BreakpadInfo* info = new BreakpadInfo;
-
-  char* minidump_filename_str = new char[minidump_filename.length() + 1];
-  minidump_filename.copy(minidump_filename_str, minidump_filename.length());
-  minidump_filename_str[minidump_filename.length()] = '\0';
-  info->filename = minidump_filename_str;
-
-  info->process_type_length = process_type_.length();
-  char* process_type_str = new char[info->process_type_length + 1];
-  process_type_.copy(process_type_str, info->process_type_length);
-  process_type_str[info->process_type_length] = '\0';
-  info->process_type = process_type_str;
-
-  info->crash_url_length = strlen(crash_url);
-  info->crash_url = crash_url;
-
-  info->guid_length = strlen(guid);
-  info->guid = guid;
-
-  info->distro_length = strlen(distro);
-  info->distro = distro;
-
-  info->upload = upload;
-  info->process_start_time = uptime;
-
   uploader_thread_->message_loop()->PostTask(
       FROM_HERE,
       NewRunnableFunction(&CrashDumpTask, this, info));