Use best-effort allocation in ProcessInfo::BuildHandleVector.

BUG=crashpad:158

Change-Id: If8666140a7fc5315eeb791d0998226de89a22cc3
Reviewed-on: https://chromium-review.googlesource.com/438791
Reviewed-by: Mark Mentovai <mark@chromium.org>
Reviewed-by: Scott Graham <scottmg@chromium.org>

DEPS

@@ -38,7 +38,7 @@ deps = {
 
   'crashpad/third_party/mini_chromium/mini_chromium':
       Var('chromium_git') + '/chromium/mini_chromium@' +
-      '4f3cfc8e7c2b7d77f94f41a32c3ec84a6920f05d',
+      'f65519e442d23498937251e680a3b113927613b0',
 }
 
 hooks = [

util/win/process_info.cc

@@ -19,9 +19,12 @@
 #include <algorithm>
 #include <limits>
 #include <memory>
+#include <new>
 #include <type_traits>
 
 #include "base/logging.h"
+#include "base/memory/free_deleter.h"
+#include "base/process/memory.h"
 #include "base/strings/stringprintf.h"
 #include "build/build_config.h"
 #include "util/numeric/safe_assignment.h"
@@ -36,6 +39,16 @@ namespace crashpad {
 
 namespace {
 
+using UniqueMallocPtr = std::unique_ptr<uint8_t[], base::FreeDeleter>;
+
+UniqueMallocPtr UncheckedAllocate(size_t size) {
+  void* raw_ptr = nullptr;
+  if (!base::UncheckedMalloc(size, &raw_ptr))
+    return UniqueMallocPtr();
+
+  return UniqueMallocPtr(new (raw_ptr) uint8_t[size]);
+}
+
 NTSTATUS NtQueryInformationProcess(HANDLE process_handle,
                                    PROCESSINFOCLASS process_information_class,
                                    PVOID process_information,
@@ -347,14 +360,20 @@ bool ReadMemoryInfo(HANDLE process, bool is_64_bit, ProcessInfo* process_info) {
 std::vector<ProcessInfo::Handle> ProcessInfo::BuildHandleVector(
     HANDLE process) const {
   ULONG buffer_size = 2 * 1024 * 1024;
-  std::unique_ptr<uint8_t[]> buffer(new uint8_t[buffer_size]);
-
   // Typically if the buffer were too small, STATUS_INFO_LENGTH_MISMATCH would
   // return the correct size in the final argument, but it does not for
   // SystemExtendedHandleInformation, so we loop and attempt larger sizes.
   NTSTATUS status;
   ULONG returned_length;
+  UniqueMallocPtr buffer;
   for (int tries = 0; tries < 5; ++tries) {
+    buffer.reset();
+    buffer = UncheckedAllocate(buffer_size);
+    if (!buffer) {
+      LOG(ERROR) << "UncheckedAllocate";
+      return std::vector<Handle>();
+    }
+
     status = crashpad::NtQuerySystemInformation(
         static_cast<SYSTEM_INFORMATION_CLASS>(SystemExtendedHandleInformation),
         buffer.get(),
@@ -364,8 +383,6 @@ std::vector<ProcessInfo::Handle> ProcessInfo::BuildHandleVector(
       break;
 
     buffer_size *= 2;
-    buffer.reset();
-    buffer.reset(new uint8_t[buffer_size]);
   }
 
   if (!NT_SUCCESS(status)) {

util/win/process_info.h

@@ -170,6 +170,7 @@ class ProcessInfo {
                              bool is_64_bit,
                              ProcessInfo* process_info);
 
+  // This function is best-effort under low memory conditions.
   std::vector<Handle> BuildHandleVector(HANDLE process) const;
 
   pid_t process_id_;