block: Use qemu_enum_parse() in blkdebug_debug_breakpoint()

The error message on invalid blkdebug events changes from

    qemu-system-x86_64: LOCATION: Invalid event name "VALUE"

to

    qemu-system-x86_64: LOCATION: invalid parameter value: VALUE

Slight degradation, but the message is sub-par even before the patch.
When complaining about a parameter value, both parameter name and
value should be mentioned, as the value may well not be unique.  Left
for another day.

Also left is the error message's unhelpful location: it points to the
config=FILENAME rather than into that file.

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <20170822132255.23945-11-marcandre.lureau@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
[Rebased, commit message rewritten]
Cc: Kevin Wolf <kwolf@redhat.com>
Cc: Max Reitz <mreitz@redhat.com>
Cc: qemu-block@nongnu.org
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <1503564371-26090-8-git-send-email-armbru@redhat.com>

block/blkdebug.c

@@ -32,6 +32,7 @@
 #include "qapi/qmp/qbool.h"
 #include "qapi/qmp/qdict.h"
 #include "qapi/qmp/qstring.h"
+#include "qapi/util.h"
 #include "sysemu/qtest.h"
 
 typedef struct BDRVBlkdebugState {
@@ -149,20 +150,6 @@ static QemuOptsList *config_groups[] = {
     NULL
 };
 
-static int get_event_by_name(const char *name, BlkdebugEvent *event)
-{
-    int i;
-
-    for (i = 0; i < BLKDBG__MAX; i++) {
-        if (!strcmp(BlkdebugEvent_lookup[i], name)) {
-            *event = i;
-            return 0;
-        }
-    }
-
-    return -1;
-}
-
 struct add_rule_data {
     BDRVBlkdebugState *s;
     int action;
@@ -173,7 +160,7 @@ static int add_rule(void *opaque, QemuOpts *opts, Error **errp)
     struct add_rule_data *d = opaque;
     BDRVBlkdebugState *s = d->s;
     const char* event_name;
-    BlkdebugEvent event;
+    int event;
     struct BlkdebugRule *rule;
     int64_t sector;
 
@@ -182,8 +169,9 @@ static int add_rule(void *opaque, QemuOpts *opts, Error **errp)
     if (!event_name) {
         error_setg(errp, "Missing event name for rule");
         return -1;
-    } else if (get_event_by_name(event_name, &event) < 0) {
-        error_setg(errp, "Invalid event name \"%s\"", event_name);
+    }
+    event = qapi_enum_parse(BlkdebugEvent_lookup, event_name, -1, errp);
+    if (event < 0) {
         return -1;
     }
 
@@ -743,13 +731,13 @@ static int blkdebug_debug_breakpoint(BlockDriverState *bs, const char *event,
 {
     BDRVBlkdebugState *s = bs->opaque;
     struct BlkdebugRule *rule;
-    BlkdebugEvent blkdebug_event;
+    int blkdebug_event;
 
-    if (get_event_by_name(event, &blkdebug_event) < 0) {
+    blkdebug_event = qapi_enum_parse(BlkdebugEvent_lookup, event, -1, NULL);
+    if (blkdebug_event < 0) {
         return -ENOENT;
     }
 
-
     rule = g_malloc(sizeof(*rule));
     *rule = (struct BlkdebugRule) {
         .event  = blkdebug_event,