Make string_util::WriteInto() DCHECK() that the supplied |length_with_null| > 1, meaning that the...

chrome/browser/mac/install_from_dmg.mm

 // 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 "chrome/browser/mac/install_from_dmg.h"
 
 #include <ApplicationServices/ApplicationServices.h>
 #import <AppKit/AppKit.h>
 #include <CoreFoundation/CoreFoundation.h>
 #include <CoreServices/CoreServices.h>
@@ skipping 123 matching lines @@
         observed_type.assign(", observed ");
         observed_type.append(base::SysCFStringRefToUTF8(observed_type_cf));
       }
       LOG(ERROR) << "image-path: expected CFData, observed " << observed_type;
       return true;
     }
 
     CFDataRef image_path_data = static_cast<CFDataRef>(
         image_path_cftyperef.get());
     CFIndex length = CFDataGetLength(image_path_data);
+    if (length <= 0) {
+      LOG(ERROR) << "image_path_data is unexpectedly empty";
+      return true;
+    }
     char* image_path_c = WriteInto(image_path, length + 1);
     CFDataGetBytes(image_path_data,
                    CFRangeMake(0, length),
                    reinterpret_cast<UInt8*>(image_path_c));
   }
 
   return true;
 }
 
 // Returns true if |path| is located on a read-only filesystem of a disk
@@ skipping 515 matching lines @@
   const UInt8* trash_path_u8 = reinterpret_cast<const UInt8*>(
       trash_path.value().c_str());
   status = FNNotifyByPath(trash_path_u8,
                           kFNDirectoryModifiedMessage,
                           kNilOptions);
   if (status != noErr) {
     LOG(ERROR) << "FNNotifyByPath: " << status;
     return;
   }
 }