[lldb-dev] Windows crash after D9056

[Aidan Dodds]

Hi,

We have been seeing a crash on windows when connecting to an android 
target using lldb-server.
I am not sure if this affects other platforms too.
I think this was introduced with http://reviews.llvm.org/D9056.

I tracked the crash back to the workings of ModuleCache::GetAndPut().

The crash seems to be due to a file descriptor being released twice, 
once by the original "File lock_file" and again by the "LockFile lock" 
who share the same file descriptor.

The file descriptor sharing happens because of this line:
ModuleCache.cpp @ 164
LockFile lock (lock_file.GetDescriptor ());

Both destructors attempt to release effectively the same file 
descriptor.  I was able to fix the crash by duplicating the file handle 
in the lock file constructor using _dup().  (patch attached)
I wasn't sure if this was the right fix however. Has anyone else seen this?
Should "File lock_file" perhaps transfer its file descriptor completely 
rather then share it?

Thanks,
Aidan
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