Re: [PATCH 1/2] iotests: Make _filter_img_create more active

[Maxim Levitsky <mlevitsk@redhat.com>]

On Tue, 2020-06-16 at 15:17 +0200, Max Reitz wrote:
> Right now, _filter_img_create just filters out everything that looks
> format-dependent, and applies some filename filters.  That means that we
> have to add another filter line every time some format gets a new
> creation option.  This can be avoided by instead discarding everything
> and just keeping what we know is format-independent (format, size,
> backing file, encryption information[1], preallocation) or just
> interesting to have in the reference output (external data file path).
> 
> Furthermore, we probably want to sort these options.  Format drivers are
> not required to define them in any specific order, so the output is
> effectively random (although this has never bothered us until now).  We
> need a specific order for our reference outputs, though.  Unfortunately,
> just using a plain "sort" would change a lot of existing reference
> outputs, so we have to pre-filter the option keys to keep our existing
> order (fmt, size, backing*, data, encryption info, preallocation).
> 
> [1] Actually, the only thing that is really important is whether
>     encryption is enabled or not.  A patch by Maxim thus removes all
>     other "encrypt.*" options from the output:
>     https://lists.nongnu.org/archive/html/qemu-block/2020-06/msg00339.html
>     But that patch needs to come later so we can get away with changing
>     as few reference outputs in this patch here as possible.
> 
> Signed-off-by: Max Reitz <mreitz@redhat.com>
> ---
>  tests/qemu-iotests/112.out       |   2 +-
>  tests/qemu-iotests/153           |   9 ++-
>  tests/qemu-iotests/common.filter | 100 +++++++++++++++++++++++--------
>  3 files changed, 81 insertions(+), 30 deletions(-)
> 
> diff --git a/tests/qemu-iotests/112.out b/tests/qemu-iotests/112.out
> index ae0318cabe..182655dbf6 100644
> --- a/tests/qemu-iotests/112.out
> +++ b/tests/qemu-iotests/112.out
> @@ -5,7 +5,7 @@ QA output created by 112
>  qemu-img: TEST_DIR/t.IMGFMT: Refcount width must be a power of two and may not exceed 64 bits
>  Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=67108864
>  qemu-img: TEST_DIR/t.IMGFMT: Refcount width must be a power of two and may not exceed 64 bits
> -Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=67108864 refcount_bits=-1
> +Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=67108864
>  qemu-img: TEST_DIR/t.IMGFMT: Refcount width must be a power of two and may not exceed 64 bits
>  Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=67108864
>  qemu-img: TEST_DIR/t.IMGFMT: Refcount width must be a power of two and may not exceed 64 bits
> diff --git a/tests/qemu-iotests/153 b/tests/qemu-iotests/153
> index cf961d3609..11e3d28841 100755
> --- a/tests/qemu-iotests/153
> +++ b/tests/qemu-iotests/153
> @@ -167,11 +167,10 @@ done
>  
>  echo
>  echo "== Creating ${TEST_IMG}.[abc] ==" | _filter_testdir
> -(
> -    $QEMU_IMG create -f qcow2 "${TEST_IMG}.a" -b "${TEST_IMG}"
> -    $QEMU_IMG create -f qcow2 "${TEST_IMG}.b" -b "${TEST_IMG}"
> -    $QEMU_IMG create -f qcow2 "${TEST_IMG}.c" -b "${TEST_IMG}.b"
> -) | _filter_img_create
> +$QEMU_IMG create -f qcow2 "${TEST_IMG}.a" -b "${TEST_IMG}" | _filter_img_create
> +$QEMU_IMG create -f qcow2 "${TEST_IMG}.b" -b "${TEST_IMG}" | _filter_img_create
> +$QEMU_IMG create -f qcow2 "${TEST_IMG}.c" -b "${TEST_IMG}.b" \
> +    | _filter_img_create
>  
>  echo
>  echo "== Two devices sharing the same file in backing chain =="

I guess this is done because now the filter expectes only a single
qemu-img output. IMHO this is better anyway.

> diff --git a/tests/qemu-iotests/common.filter b/tests/qemu-iotests/common.filter
> index 03e4f71808..f104ad7a9b 100644
> --- a/tests/qemu-iotests/common.filter
> +++ b/tests/qemu-iotests/common.filter
> @@ -122,38 +122,90 @@ _filter_actual_image_size()
>  # replace driver-specific options in the "Formatting..." line
>  _filter_img_create()
>  {
> -    data_file_filter=()
> -    if data_file=$(_get_data_file "$TEST_IMG"); then
> -        data_file_filter=(-e "s# data_file=$data_file##")
> +    # Keep QMP output unchanged
> +    qmp_pre=''
> +    qmp_post=''
> +    to_filter=''
> +
> +    while read -r line; do
> +        if echo "$line" | grep -q '^{.*}$'; then
> +            if [ -z "$to_filter" ]; then
> +                # Use $'\n' so the newline is not dropped on variable
> +                # expansion
> +                qmp_pre="$qmp_pre$line"$'\n'
> +            else
> +                qmp_post="$qmp_post$line"$'\n'
> +            fi
> +        else
> +            to_filter="$to_filter$line"$'\n'
> +        fi
> +    done

The above code basically assumes that qmp output starts with '{' and ends with '}'
which I guess is fair, and then it assumes that we can have set of qmp commands prior
to qemu-img line and another set of qmp commands after it.
To me it feels like we should have another filter for that, since
qemu-img itself doesn't use qmp.
Which test needs it?

> +
> +    readarray -td '' formatting_line < \
> +        <(echo "$to_filter" | sed -e 's/, fmt=/\x0/')
OK, took me a while to understand what this does, but looks OK.

> +
> +    filename_part=${formatting_line[0]}
> +    if [ -n "${formatting_line[1]}" ]; then
> +        options="fmt=${formatting_line[1]}"
> +    else
> +        options=''
>      fi
> 
OK.

>  
> -    $SED "${data_file_filter[@]}" \
> +    # Set grep_data_file to '\|data_file' to keep it; make it empty
> +    # to drop it.
> +    # We want to drop it if it is part of the global $IMGOPTS, and we
> +    # want to keep it otherwise (if the test specifically wants to
> +    # test data files).
> +    grep_data_file='\|data_file'
> +    if _get_data_file "$TEST_IMG" > /dev/null; then
> +        grep_data_file=''
> +    fi
> +
> +    filename_filters=(
>          -e "s#$REMOTE_TEST_DIR#TEST_DIR#g" \
>          -e "s#$IMGPROTO:$TEST_DIR#TEST_DIR#g" \
>          -e "s#$TEST_DIR#TEST_DIR#g" \
>          -e "s#$SOCK_DIR#SOCK_DIR#g" \
>          -e "s#$IMGFMT#IMGFMT#g" \
>          -e 's#nbd:127.0.0.1:[0-9]\\+#TEST_DIR/t.IMGFMT#g' \
> -        -e 's#nbd+unix:///\??socket=SOCK_DIR/nbd#TEST_DIR/t.IMGFMT#g' \
> -        -e "s# encryption=off##g" \
> -        -e "s# cluster_size=[0-9]\\+##g" \
> -        -e "s# table_size=[0-9]\\+##g" \
> -        -e "s# compat=[^ ]*##g" \
> -        -e "s# compat6=\\(on\\|off\\)##g" \
> -        -e "s# static=\\(on\\|off\\)##g" \
> -        -e "s# zeroed_grain=\\(on\\|off\\)##g" \
> -        -e "s# subformat=[^ ]*##g" \
> -        -e "s# adapter_type=[^ ]*##g" \
> -        -e "s# hwversion=[^ ]*##g" \
> -        -e "s# lazy_refcounts=\\(on\\|off\\)##g" \
> -        -e "s# block_size=[0-9]\\+##g" \
> -        -e "s# block_state_zero=\\(on\\|off\\)##g" \
> -        -e "s# log_size=[0-9]\\+##g" \
> -        -e "s# refcount_bits=[0-9]\\+##g" \
> -        -e "s# key-secret=[a-zA-Z0-9]\\+##g" \
> -        -e "s# iter-time=[0-9]\\+##g" \
> -        -e "s# force_size=\\(on\\|off\\)##g" \
> -        -e "s# compression_type=[a-zA-Z0-9]\\+##g"
> +        -e 's#nbd+unix:///\??socket=SOCK_DIR/nbd#TEST_DIR/t.IMGFMT#g'
> +    )
> +
> +    filename_part=$(echo "$filename_part" | $SED "${filename_filters[@]}")
Looks good as well.

> +
> +    # Break the option line before each option (preserving pre-existing
> +    # line breaks by replacing them by \0 and restoring them at the end),
> +    # then filter out the options we want to keep and sort them according
> +    # to some order that all block drivers used at the time of writing
> +    # this function.
> +    options=$(
> +        echo "$options" \
> +        | tr '\n' '\0' \
> +        | sed -e 's/\x0$//' -e 's/ \([a-z0-9_.-]*\)=/\n\1=/g' \
You sometimes use $SED and sometimes sed. Is this intentional?

> +        | grep -ae "^\(fmt\\|size\\|backing\\|preallocation\\|encrypt$grep_data_file\\)" \
> +        | $SED "${filename_filters[@]}" \
> +            -e 's/^\(fmt\)/0-\1/' \
> +            -e 's/^\(size\)/1-\1/' \
> +            -e 's/^\(backing\)/2-\1/' \
> +            -e 's/^\(data_file\)/3-\1/' \
> +            -e 's/^\(encryption\)/4-\1/' \
> +            -e 's/^\(encrypt\.format\)/5-\1/' \
> +            -e 's/^\(encrypt\.key-secret\)/6-\1/' \
> +            -e 's/^\(encrypt\.iter-time\)/7-\1/' \
> +            -e 's/^\(preallocation\)/8-\1/' \
All right, I understand this now, but do we have to do this?
Maybe it is better to just update the outputs once to avoid keeping
the custom sort order?

> +        | sort \
> +        | $SED -e 's/^[0-9]-//' \
> +        | tr '\n\0' ' \n' \
> +        | $SED -e 's/^ *$//' -e 's/ *$//'
> +    )

For the above bash pipeline overall: It was hard to decipher :-), but I must admit
I learned something from it.

> +
> +    echo -n "$qmp_pre"
> +    if [ -n "$options" ]; then
> +        echo "$filename_part, $options"
> +    elif [ -n "$filename_part" ]; then
> +        echo "$filename_part"
> +    fi
> +    echo -n "$qmp_post"
>  }
>  
>  _filter_img_create_size()

Overall I like the idea of this patch.

Best regards,
	Maxim Levitsky