Re: [Qemu-devel] [PATCH v4 11/14] block: Try to create well typed json:{} filenames

[Max Reitz]

On 24.06.19 19:39, Max Reitz wrote:
> By applying qdict_flatten(), the flat-confused input visitor, and the
> output visitor, we can at least try to bring bs->full_open_options into
> accordance with the QAPI schema.  This may not always work (there are
> some options left that have not been QAPI-fied yet), but in practice it
> usually will.
> 
> In any case, sometimes emitting wrongly typed json:{} filenames is
> better than doing it effectively half the time.
> 
> This affects some iotests because json:{} filenames are now usually
> crumpled.  In 198, "format": "auto" now appears in the qcow2 encryption
> options because going through a visitor makes optional members' default
> values explicit.
> 
> Buglink: https://bugzilla.redhat.com/show_bug.cgi?id=1534396
> Signed-off-by: Max Reitz <address@hidden>
> ---
>  block.c                    | 68 +++++++++++++++++++++++++++++++++++++-
>  tests/qemu-iotests/059.out |  2 +-
>  tests/qemu-iotests/099.out |  4 +--
>  tests/qemu-iotests/110.out |  2 +-
>  tests/qemu-iotests/198.out |  4 +--
>  5 files changed, 73 insertions(+), 7 deletions(-)
> 
> diff --git a/block.c b/block.c
> index c139540f2b..d3c1041087 100644
> --- a/block.c
> +++ b/block.c
> @@ -36,6 +36,7 @@
>  #include "qapi/qmp/qjson.h"
>  #include "qapi/qmp/qnull.h"
>  #include "qapi/qmp/qstring.h"
> +#include "qapi/qobject-input-visitor.h"
>  #include "qapi/qobject-output-visitor.h"
>  #include "qapi/qapi-visit-block-core.h"
>  #include "sysemu/block-backend.h"
> @@ -6283,6 +6284,56 @@ static bool bdrv_backing_overridden(BlockDriverState 
> *bs)
>      }
>  }
>  
> +/**
> + * Take a blockdev @options QDict and convert its values to the
> + * correct type.
> + *
> + * Fail if @options does not match the QAPI schema of BlockdevOptions.
> + *
> + * In case of failure, return NULL and set @errp.
> + *
> + * In case of success, return a correctly typed new QDict.
> + */
> +static QDict *bdrv_type_blockdev_opts(const QDict *options, Error **errp)
> +{
> +    Visitor *v;
> +    BlockdevOptions *blockdev_options;
> +    QObject *typed_opts;
> +    QDict *string_options;
> +    Error *local_err = NULL;
> +
> +    string_options = qdict_clone_shallow(options);
> +
> +    qdict_flatten(string_options);
> +    v = qobject_input_visitor_new_flat_confused(string_options, errp);

Imagine a

+    qobject_unref(string_options);

here.

Max

> +    if (!v) {
> +        error_prepend(errp, "Failed to prepare options: ");
> +        return NULL;
> +    }
> +
> +    visit_type_BlockdevOptions(v, NULL, &blockdev_options, &local_err);
> +    visit_free(v);
> +    if (local_err) {
> +        error_propagate(errp, local_err);
> +        error_prepend(errp, "Not a valid BlockdevOptions object: ");
> +        return NULL;
> +    }
> +
> +    v = qobject_output_visitor_new(&typed_opts);
> +    visit_type_BlockdevOptions(v, NULL, &blockdev_options, &local_err);
> +    if (!local_err) {
> +        visit_complete(v, &typed_opts);
> +    }
> +    visit_free(v);
> +    qapi_free_BlockdevOptions(blockdev_options);
> +    if (local_err) {
> +        error_propagate(errp, local_err);
> +        return NULL;
> +    }
> +
> +    return qobject_to(QDict, typed_opts);
> +}
> +
>  /* Updates the following BDS fields:
>   *  - exact_filename: A filename which may be used for opening a block device
>   *                    which (mostly) equals the given BDS (even without any
> @@ -6400,10 +6451,25 @@ void bdrv_refresh_filename(BlockDriverState *bs)
>      if (bs->exact_filename[0]) {
>          pstrcpy(bs->filename, sizeof(bs->filename), bs->exact_filename);
>      } else {
> -        QString *json = qobject_to_json(QOBJECT(bs->full_open_options));
> +        QString *json;
> +        QDict *typed_opts, *json_opts;
> +
> +        typed_opts = bdrv_type_blockdev_opts(bs->full_open_options, NULL);
> +
> +        /*
> +         * We cannot be certain that bs->full_open_options matches
> +         * BlockdevOptions, so bdrv_type_blockdev_opts() may fail.
> +         * That is not fatal, we can just emit bs->full_open_options
> +         * directly -- qemu will accept that, even if it does not
> +         * match the schema.
> +         */
> +        json_opts = typed_opts ?: bs->full_open_options;
> +
> +        json = qobject_to_json(QOBJECT(json_opts));
>          snprintf(bs->filename, sizeof(bs->filename), "json:%s",
>                   qstring_get_str(json));
>          qobject_unref(json);
> +        qobject_unref(typed_opts);
>      }
>  }
>  
> diff --git a/tests/qemu-iotests/059.out b/tests/qemu-iotests/059.out
> index 4fab42a28c..53109b2d49 100644
> --- a/tests/qemu-iotests/059.out
> +++ b/tests/qemu-iotests/059.out
> @@ -2050,7 +2050,7 @@ wrote 512/512 bytes at offset 10240
>  
>  === Testing monolithicFlat with internally generated JSON file name ===
>  Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=67108864 
> subformat=monolithicFlat
> -qemu-io: can't open: Cannot use relative extent paths with VMDK descriptor 
> file 'json:{"image": {"driver": "file", "filename": "TEST_DIR/t.IMGFMT"}, 
> "driver": "blkdebug", "inject-error.0.event": "read_aio"}'
> +qemu-io: can't open: Cannot use relative extent paths with VMDK descriptor 
> file 'json:{"inject-error": [{"event": "read_aio"}], "image": {"driver": 
> "file", "filename": "TEST_DIR/t.IMGFMT"}, "driver": "blkdebug"}'
>  
>  === Testing version 3 ===
>  image: TEST_DIR/iotest-version3.IMGFMT
> diff --git a/tests/qemu-iotests/099.out b/tests/qemu-iotests/099.out
> index 8cce627529..0a9c434148 100644
> --- a/tests/qemu-iotests/099.out
> +++ b/tests/qemu-iotests/099.out
> @@ -12,11 +12,11 @@ blkverify:TEST_DIR/t.IMGFMT.compare:TEST_DIR/t.IMGFMT
>  
>  === Testing JSON filename for blkdebug ===
>  
> -json:{"driver": "IMGFMT", "file": {"image": {"driver": "file", "filename": 
> "TEST_DIR/t.IMGFMT"}, "driver": "blkdebug", "inject-error.0.event": 
> "l1_update"}}
> +json:{"driver": "IMGFMT", "file": {"inject-error": [{"event": "l1_update"}], 
> "image": {"driver": "file", "filename": "TEST_DIR/t.IMGFMT"}, "driver": 
> "blkdebug"}}
>  
>  === Testing indirectly enforced JSON filename ===
>  
> -json:{"driver": "raw", "file": {"test": {"driver": "IMGFMT", "file": 
> {"image": {"driver": "file", "filename": "TEST_DIR/t.IMGFMT"}, "driver": 
> "blkdebug", "inject-error.0.event": "l1_update"}}, "driver": "blkverify", 
> "raw": {"driver": "file", "filename": "TEST_DIR/t.IMGFMT.compare"}}}
> +json:{"driver": "raw", "file": {"test": {"driver": "IMGFMT", "file": 
> {"inject-error": [{"event": "l1_update"}], "image": {"driver": "file", 
> "filename": "TEST_DIR/t.IMGFMT"}, "driver": "blkdebug"}}, "driver": 
> "blkverify", "raw": {"driver": "file", "filename": 
> "TEST_DIR/t.IMGFMT.compare"}}}
>  
>  === Testing plain filename for blkdebug ===
>  
> diff --git a/tests/qemu-iotests/110.out b/tests/qemu-iotests/110.out
> index f60b26390e..d95b92bee7 100644
> --- a/tests/qemu-iotests/110.out
> +++ b/tests/qemu-iotests/110.out
> @@ -11,7 +11,7 @@ backing file: t.IMGFMT.base (actual path: 
> TEST_DIR/t.IMGFMT.base)
>  
>  === Non-reconstructable filename ===
>  
> -image: json:{"driver": "IMGFMT", "file": {"set-state.0.event": "read_aio", 
> "image": {"driver": "file", "filename": "TEST_DIR/t.IMGFMT"}, "driver": 
> "blkdebug", "set-state.0.new_state": 42}}
> +image: json:{"driver": "IMGFMT", "file": {"set-state": [{"new_state": 42, 
> "event": "read_aio"}], "image": {"driver": "file", "filename": 
> "TEST_DIR/t.IMGFMT"}, "driver": "blkdebug"}}
>  file format: IMGFMT
>  virtual size: 64 MiB (67108864 bytes)
>  backing file: t.IMGFMT.base (actual path: TEST_DIR/t.IMGFMT.base)
> diff --git a/tests/qemu-iotests/198.out b/tests/qemu-iotests/198.out
> index e86b175e39..eef8af3cdc 100644
> --- a/tests/qemu-iotests/198.out
> +++ b/tests/qemu-iotests/198.out
> @@ -32,7 +32,7 @@ read 16777216/16777216 bytes at offset 0
>  16 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
>  
>  == checking image base ==
> -image: json:{"encrypt.key-secret": "sec0", "driver": "IMGFMT", "file": 
> {"driver": "file", "filename": "TEST_DIR/t.IMGFMT.base"}}
> +image: json:{"driver": "IMGFMT", "encrypt": {"format": "auto", "key-secret": 
> "sec0"}, "file": {"driver": "file", "filename": "TEST_DIR/t.IMGFMT.base"}}
>  file format: IMGFMT
>  virtual size: 16 MiB (16777216 bytes)
>  Format specific information:
> @@ -74,7 +74,7 @@ Format specific information:
>          master key iters: 1024
>  
>  == checking image layer ==
> -image: json:{"encrypt.key-secret": "sec1", "driver": "IMGFMT", "file": 
> {"driver": "file", "filename": "TEST_DIR/t.IMGFMT"}}
> +image: json:{"driver": "IMGFMT", "encrypt": {"format": "auto", "key-secret": 
> "sec1"}, "file": {"driver": "file", "filename": "TEST_DIR/t.IMGFMT"}}
>  file format: IMGFMT
>  virtual size: 16 MiB (16777216 bytes)
>  backing file: TEST_DIR/t.IMGFMT.base
>

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