Bug#903931: Maybe trailing garbage or data in an unsupported format is causing the problem?

[Antonio Diaz Diaz <antonio@gnu.org>]

Note in the code below that by using a multi-format zcat, other data not 
in one of the formats supported by the zcat used may be no longer 
ignored but passed to cpio (possibly compressed), which may be the cause 
of the problem.

Using the compressors directly to test the format (without *zcat 
wrappers) guarantees that the "other data" is indeed ignored.

        if zcat -t "$archive" >/dev/null 2>&1 ; then
                zcat "$archive"
        elif xzcat -t "$archive" >/dev/null 2>&1 ; then
                xzcat "$archive"
        elif lz4cat -t "$archive" >/dev/null 2>&1 ; then
                lz4cat "$archive"
        elif bzip2 -t "$archive" >/dev/null 2>&1 ; then
                bzip2 -c -d "$archive"
        elif lzop -t "$archive" >/dev/null 2>&1 ; then
                lzop -c -d "$archive"
        # Ignoring other data, which may be garbage at the end of the file
        fi | (
                if [ -n "$dir" ]; then
                        mkdir -p -- "$dir"
                        cd -- "$dir"
                fi
                cpio "$@"
        )