base: Add debugging to track down CreateFileMapping() errors.

base/memory/shared_memory_win.cc

 // 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.
 
 #include "base/memory/shared_memory.h"
 
 #include <aclapi.h>
 #include <stddef.h>
 #include <stdint.h>
 
+#include "base/debug/alias.h"
+#include "base/debug/dump_without_crashing.h"
 #include "base/logging.h"
 #include "base/metrics/histogram_macros.h"
 #include "base/rand_util.h"
 #include "base/strings/stringprintf.h"
 #include "base/strings/utf_string_conversions.h"
 
 namespace {
 
 // Errors that can occur during Shared Memory construction.
 // These match tools/metrics/histograms/histograms.xml.
@@ skipping 80 matching lines @@
 //
 // By removing all access control permissions of a file mapping immediately
 // after creation, ::DuplicateHandle() effectively only copies the file
 // permissions.
 HANDLE CreateFileMappingWithReducedPermissions(SECURITY_ATTRIBUTES* sa,
                                                size_t rounded_size,
                                                LPCWSTR name) {
   HANDLE h = CreateFileMapping(INVALID_HANDLE_VALUE, sa, PAGE_READWRITE, 0,
                                static_cast<DWORD>(rounded_size), name);
   if (!h) {
+    // Debugging to help track down https://crbug.com/585013
+    DWORD last_error = ::GetLastError();
+    base::debug::Alias(&last_error);
+    base::debug::DumpWithoutCrashing();

[Nico, 2016/05/24 00:22:13]

is this code perf-sensitive? Should this just be full-on crash?

[erikchen, 2016/05/24 00:41:20]

This is perf-sensitive, but shouldn't be hit often. I don't want a full-on crash
because that would take down the browser process, whereas now the bug just takes
down the renderer process.

+
     LogError(CREATE_FILE_MAPPING_FAILURE);
     return nullptr;
   }
 
   HANDLE h2;
   BOOL success = ::DuplicateHandle(
       GetCurrentProcess(), h, GetCurrentProcess(), &h2,
       FILE_MAP_READ | FILE_MAP_WRITE | SECTION_QUERY, FALSE, 0);
   BOOL rv = ::CloseHandle(h);
   DCHECK(rv);
@@ skipping 262 matching lines @@
     ::CloseHandle(mapped_file_);
     mapped_file_ = NULL;
   }
 }
 
 SharedMemoryHandle SharedMemory::handle() const {
   return SharedMemoryHandle(mapped_file_, base::GetCurrentProcId());
 }
 
 }  // namespace base