From 074c89b05dae971c7118cb769fd34e22135c8f4c Mon Sep 17 00:00:00 2001

From: Hanna Reitz <hreitz@redhat.com>

Date: Mon, 20 Jun 2022 18:26:53 +0200

Subject: [PATCH 06/20] block: Improve empty format-specific info dump

RH-Author: Hanna Czenczek <hreitz@redhat.com>

RH-MergeRequest: 145: Show protocol-level information in qemu-img info

RH-Bugzilla: 1860292

RH-Acked-by: Kevin Wolf <kwolf@redhat.com>

RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>

RH-Acked-by: Stefano Garzarella <sgarzare@redhat.com>

RH-Commit: [1/12] be551e83f426e620e673302198b51368bfd324ce (hreitz/qemu-kvm-c-9-s)

When a block driver supports obtaining format-specific information, but

that object only contains optional fields, it is possible that none of

them are present, so that dump_qobject() (called by

bdrv_image_info_specific_dump()) will not print anything.

The callers of bdrv_image_info_specific_dump() put a header above this

information ("Format specific information:\n"), which will look strange

when there is nothing below.  Modify bdrv_image_info_specific_dump() to

print this header instead of its callers, and only if there is indeed

something to be printed.

Signed-off-by: Hanna Reitz <hreitz@redhat.com>

Message-Id: <20220620162704.80987-2-hreitz@redhat.com>

Reviewed-by: Kevin Wolf <kwolf@redhat.com>

Signed-off-by: Kevin Wolf <kwolf@redhat.com>

(cherry picked from commit 3716470b24f0f63090d59bcf28ad8fe6fb7835bd)

Signed-off-by: Hanna Czenczek <hreitz@redhat.com>

---

 block/qapi.c         | 41 +++++++++++++++++++++++++++++++++++++----

 include/block/qapi.h |  3 ++-

 qemu-io-cmds.c       |  4 ++--

 3 files changed, 41 insertions(+), 7 deletions(-)

diff --git a/block/qapi.c b/block/qapi.c

index cf557e3aea..51202b470a 100644

--- a/block/qapi.c

+++ b/block/qapi.c

@@ -777,7 +777,35 @@ static void dump_qdict(int indentation, QDict *dict)

     }

 }

-void bdrv_image_info_specific_dump(ImageInfoSpecific *info_spec)

+/*

+ * Return whether dumping the given QObject with dump_qobject() would

+ * yield an empty dump, i.e. not print anything.

+ */

+static bool qobject_is_empty_dump(const QObject *obj)

+{

+    switch (qobject_type(obj)) {

+    case QTYPE_QNUM:

+    case QTYPE_QSTRING:

+    case QTYPE_QBOOL:

+        return false;

+

+    case QTYPE_QDICT:

+        return qdict_size(qobject_to(QDict, obj)) == 0;

+

+    case QTYPE_QLIST:

+        return qlist_empty(qobject_to(QList, obj));

+

+    default:

+        abort();

+    }

+}

+

+/**

+ * Dumps the given ImageInfoSpecific object in a human-readable form,

+ * prepending an optional prefix if the dump is not empty.

+ */

+void bdrv_image_info_specific_dump(ImageInfoSpecific *info_spec,

+                                   const char *prefix)

 {

     QObject *obj, *data;

     Visitor *v = qobject_output_visitor_new(&obj);

@@ -785,7 +813,12 @@ void bdrv_image_info_specific_dump(ImageInfoSpecific *info_spec)

     visit_type_ImageInfoSpecific(v, NULL, &info_spec, &error_abort);

     visit_complete(v, &obj);

     data = qdict_get(qobject_to(QDict, obj), "data");

-    dump_qobject(1, data);

+    if (!qobject_is_empty_dump(data)) {

+        if (prefix) {

+            qemu_printf("%s", prefix);

+        }

+        dump_qobject(1, data);

+    }

     qobject_unref(obj);

     visit_free(v);

 }

@@ -866,7 +899,7 @@ void bdrv_image_info_dump(ImageInfo *info)

     }

     if (info->has_format_specific) {

-        qemu_printf("Format specific information:\n");

-        bdrv_image_info_specific_dump(info->format_specific);

+        bdrv_image_info_specific_dump(info->format_specific,

+                                      "Format specific information:\n");

     }

 }

diff --git a/include/block/qapi.h b/include/block/qapi.h

index 22c7807c89..c09859ea78 100644

--- a/include/block/qapi.h

+++ b/include/block/qapi.h

@@ -40,6 +40,7 @@ void bdrv_query_image_info(BlockDriverState *bs,

                            Error **errp);

 void bdrv_snapshot_dump(QEMUSnapshotInfo *sn);

-void bdrv_image_info_specific_dump(ImageInfoSpecific *info_spec);

+void bdrv_image_info_specific_dump(ImageInfoSpecific *info_spec,

+                                   const char *prefix);

 void bdrv_image_info_dump(ImageInfo *info);

 #endif

diff --git a/qemu-io-cmds.c b/qemu-io-cmds.c

index 952dc940f1..f4a374528e 100644

--- a/qemu-io-cmds.c

+++ b/qemu-io-cmds.c

@@ -1825,8 +1825,8 @@ static int info_f(BlockBackend *blk, int argc, char **argv)

         return -EIO;

     }

     if (spec_info) {

-        printf("Format specific information:\n");

-        bdrv_image_info_specific_dump(spec_info);

+        bdrv_image_info_specific_dump(spec_info,

+                                      "Format specific information:\n");

         qapi_free_ImageInfoSpecific(spec_info);

     }

-- 

2.31.1