hmp: hmp_cont(): don't rely on QERR_DEVICE_ENCRYPTED

This commit changes hmp_cont() to loop through all block devices
and proactively set an encryption key for any encrypted device
missing a key.

This change is needed because QERR_DEVICE_ENCRYPTED is going to be
dropped by a future commit.

Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
diff --git a/hmp.c b/hmp.c
index 25688ab..4efaf51 100644
--- a/hmp.c
+++ b/hmp.c
@@ -612,34 +612,35 @@
 
 static void hmp_cont_cb(void *opaque, int err)
 {
-    Monitor *mon = opaque;
-
     if (!err) {
-        hmp_cont(mon, NULL);
+        qmp_cont(NULL);
     }
 }
 
+static bool key_is_missing(const BlockInfo *bdev)
+{
+    return (bdev->inserted && bdev->inserted->encryption_key_missing);
+}
+
 void hmp_cont(Monitor *mon, const QDict *qdict)
 {
+    BlockInfoList *bdev_list, *bdev;
     Error *errp = NULL;
 
-    qmp_cont(&errp);
-    if (error_is_set(&errp)) {
-        if (error_is_type(errp, QERR_DEVICE_ENCRYPTED)) {
-            const char *device;
-
-            /* The device is encrypted. Ask the user for the password
-               and retry */
-
-            device = error_get_field(errp, "device");
-            assert(device != NULL);
-
-            monitor_read_block_device_key(mon, device, hmp_cont_cb, mon);
-            error_free(errp);
-            return;
+    bdev_list = qmp_query_block(NULL);
+    for (bdev = bdev_list; bdev; bdev = bdev->next) {
+        if (key_is_missing(bdev->value)) {
+            monitor_read_block_device_key(mon, bdev->value->device,
+                                          hmp_cont_cb, NULL);
+            goto out;
         }
-        hmp_handle_error(mon, &errp);
     }
+
+    qmp_cont(&errp);
+    hmp_handle_error(mon, &errp);
+
+out:
+    qapi_free_BlockInfoList(bdev_list);
 }
 
 void hmp_system_wakeup(Monitor *mon, const QDict *qdict)