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

[Max Reitz]

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);
+    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
-- 
2.21.0