• Jeff King's avatar
    avoid infinite loop in read_istream_loose · 692f0bc7
    Jeff King authored
    The read_istream_loose function loops on inflating a chunk of data
    from an mmap'd loose object. We end the loop when we run out
    of space in our output buffer, or if we see a zlib error.
    
    We need to treat Z_BUF_ERROR specially, though, as it is not
    fatal; it is just zlib's way of telling us that we need to
    either feed it more input or give it more output space. It
    is perfectly normal for us to hit this when we are at the
    end of our buffer.
    
    However, we may also get Z_BUF_ERROR because we have run out
    of input. In a well-formed object, this should not happen,
    because we have fed the whole mmap'd contents to zlib. But
    if the object is truncated or corrupt, we will loop forever,
    never giving zlib any more data, but continuing to ask it to
    inflate.
    
    We can fix this by considering it an error when zlib returns
    Z_BUF_ERROR but we still have output space left (which means
    it must want more input, which we know is a truncation
    error). It would not be sufficient to just check whether
    zlib had consumed all the input at the start of the loop, as
    it might still want to generate output from what is in its
    internal state.
    Signed-off-by: default avatarJeff King <peff@peff.net>
    Signed-off-by: default avatarJunio C Hamano <gitster@pobox.com>
    692f0bc7
streaming.c 11.7 KB