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  • Hash : cf07db2f
    Author : Patrick Steinhardt
    Date : 2017-04-07T16:05:10

    filter: only close filter if it's been initialized correctly
    
    In the function `git_filter_list_stream_data`, we initialize, write and
    subesquently close the stream which should receive content processed by
    the filter. While we skip writing to the stream if its initialization
    failed, we still try to close it unconditionally -- even if the
    initialization failed, where the stream might not be set at all, leading
    us to segfault.
    
    Semantics in this code is not really clear. The function handling the
    same logic for files instead of data seems to do the right thing here in
    only closing the stream when initialization succeeded. When stepping
    back a bit, this is only reasonable: if a stream cannot be initialized,
    the caller would not expect it to be closed again. So actually, both
    callers of `stream_list_init` fail to do so. The data streaming function
    will always close the stream and the file streaming function will not
    close the stream if writing to it has failed.
    
    The fix is thus two-fold:
    
    - callers of `stream_list_init` now close the stream iff it has been
      initialized
    - `stream_list_init` now closes the lastly initialized stream if
      the current stream in the chain failed to initialize
    
    Add a test which segfaulted previous to these changes.