Fix stack collection with size limit

src/client/linux/minidump_writer/minidump_writer.cc

 // Copyright (c) 2010, Google Inc.
 // All rights reserved.
 //
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 // notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
@@ skipping 257 matching lines @@
   bool FillThreadStack(MDRawThread* thread, uintptr_t stack_pointer,
                        int max_stack_len, uint8_t** stack_copy) {
     *stack_copy = NULL;
     const void* stack;
     size_t stack_len;
     if (dumper_->GetStackInfo(&stack, &stack_len, stack_pointer)) {
       UntypedMDRVA memory(&minidump_writer_);
       if (max_stack_len >= 0 &&
           stack_len > static_cast<unsigned int>(max_stack_len)) {
         stack_len = max_stack_len;
+        // Skip empty chunks of length max_stack_len.
+        uintptr_t int_stack = reinterpret_cast<uintptr_t>(stack);
+        while (int_stack +  max_stack_len < stack_pointer) {

[ivanpe, 2016/05/17 01:03:10]

Please, remove the extra blank after '+'

[lv, 2016/05/23 15:54:57]

Done.

+          int_stack += max_stack_len;

[ivanpe, 2016/05/17 01:03:10]

This will be an infinite loop when max_stack_len = 0.

[lv, 2016/05/23 15:54:57]

I added an additional check. I don't think anyone uses a value of 0 here, so I
could also re-purpose 0 instead of -1 to indicate no cap, which would simplify
the code a bit. Let me know which way you prefer.

+        }
+        stack = reinterpret_cast<const void*>(int_stack);
       }
       if (!memory.Allocate(stack_len))
         return false;
       *stack_copy = reinterpret_cast<uint8_t*>(Alloc(stack_len));
       dumper_->CopyFromProcess(*stack_copy, thread->thread_id, stack,
                                stack_len);
       memory.Copy(*stack_copy, stack_len);
       thread->stack.start_of_memory_range =
           reinterpret_cast<uintptr_t>(stack);
       thread->stack.memory = memory.location();
@@ skipping 1072 matching lines @@
                    const MappingList& mappings,
                    const AppMemoryList& appmem,
                    LinuxDumper* dumper) {
   MinidumpWriter writer(filename, -1, NULL, mappings, appmem, dumper);
   if (!writer.Init())
     return false;
   return writer.Dump();
 }
 
 }  // namespace google_breakpad