Improve map insertions

snapshot/mac/mach_o_image_reader.cc

 // Copyright 2014 The Crashpad Authors. All rights reserved.
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
 // You may obtain a copy of the License at
 //
 //     http://www.apache.org/licenses/LICENSE-2.0
 //
 // Unless required by applicable law or agreed to in writing, software
 // distributed under the License is distributed on an "AS IS" BASIS,
 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
 #include "snapshot/mac/mach_o_image_reader.h"
 
 #include <mach-o/loader.h>
 #include <mach-o/nlist.h>
 #include <string.h>
 
 #include <limits>
 #include <vector>
+#include <utility>
 
 #include "base/logging.h"
 #include "base/strings/stringprintf.h"
 #include "client/crashpad_info.h"
 #include "snapshot/mac/mach_o_image_segment_reader.h"
 #include "snapshot/mac/mach_o_image_symbol_table_reader.h"
 #include "snapshot/mac/process_reader.h"
 #include "util/mac/checked_mach_address_range.h"
 
 namespace {
@@ skipping 503 matching lines @@
   // At this point, the segment itself is considered valid, but if one of the
   // next checks fails, it will render the module invalid. If any of the next
   // checks fail, this method should return false, but it doesn’t need to bother
   // removing the segment from segments_. The segment will be properly released
   // when the image is destroyed, and the image won’t be usable because
   // initialization won’t have completed. Most importantly, leaving the segment
   // in segments_ means that no other structures (such as perhaps segment_map_)
   // become inconsistent or require cleanup.
 
   const std::string segment_name = segment->Name();
-  const auto& iterator = segment_map_.find(segment_name);
-  if (iterator != segment_map_.end()) {
+  const auto insert_result =
+      segment_map_.insert(std::make_pair(segment_name, segment_index));
+  if (!insert_result.second) {
     LOG(WARNING) << base::StringPrintf("duplicate %s segment at %zu and %zu",
                                        segment_name.c_str(),
-                                       iterator->second,
+                                       insert_result.first->second,
                                        segment_index) << load_command_info;
     return false;
   }
-  segment_map_[segment_name] = segment_index;
 
   mach_vm_size_t vmsize = segment->vmsize();
 
   if (segment_name == SEG_TEXT) {
     if (vmsize == 0) {
       LOG(WARNING) << "zero-sized " SEG_TEXT " segment" << load_command_info;
       return false;
     }
 
     mach_vm_size_t fileoff = segment->fileoff();
@@ skipping 148 matching lines @@
                                  linkedit_segment,
                                  module_info_)) {
     symbol_table_.reset();
     return;
   }
 
   symbol_table_initialized_.set_valid();
 }
 
 }  // namespace crashpad