• Travis Bischel's avatar
    compress/gzip: do not count header bytes written in Write · f1deee0e
    Travis Bischel authored
    Before, if an underlying writer errored within 10 bytes (plus any gzip
    header metadata), a gzip.Write would erroneously report up to 10 bytes
    written that were not actually written of the input slice. This is
    especially problematic when the input slice is less than 10 bytes.
    
    The error came from counting the 10 header byte write. If writing the
    header is completely successful, the 10 bytes written is overridden by
    the flate write with the input slice.
    
    This removes counting the 10 required header bytes, and also changes the
    return to use zero until the slice is used.
    
    The old Write could return one byte written when it actually was not.
    This is difficult to verify because the smallest input slice is one
    byte; a test checking that the input slice was the byte written would be
    quite involved. Thankfully, gzip's minimum header write is 10 bytes. If
    we test that two bytes are not falsely written, we indirectly cover the
    one byte case.
    
    Fixes #24625
    
    Change-Id: I1c1f8cd791e0c4cffc22aa8acd95186582c832ba
    Reviewed-on: https://go-review.googlesource.com/103861Reviewed-by: 's avatarJoe Tsai <joetsai@google.com>
    Run-TryBot: Joe Tsai <joetsai@google.com>
    TryBot-Result: Gobot Gobot <gobot@golang.org>
    f1deee0e
gzip_test.go 5.98 KB