blockdev: Separate ID generation from DriveInfo creation

blockdev-add shouldn't automatically generate IDs, but will keep most of
the DriveInfo creation code.
Signed-off-by: NKevin Wolf <kwolf@redhat.com>
Reviewed-by: NMax Reitz <mreitz@redhat.com>
Reviewed-by: NWenchao Xia <xiawenc@linux.vnet.ibm.com>
Reviewed-by: NEric Blake <eblake@redhat.com>

blockdev.c

@@ -600,23 +600,25 @@ static DriveInfo *blockdev_init(QemuOpts *all_opts,
         return NULL;
     }
 
-    /* init */
-
-    dinfo = g_malloc0(sizeof(*dinfo));
-    if ((buf = qemu_opts_id(opts)) != NULL) {
-        dinfo->id = g_strdup(buf);
-    } else {
-        /* no id supplied -> create one */
-        dinfo->id = g_malloc0(32);
-        if (type == IF_IDE || type == IF_SCSI)
+    /* no id supplied -> create one */
+    if (qemu_opts_id(opts) == NULL) {
+        char *new_id;
+        if (type == IF_IDE || type == IF_SCSI) {
             mediastr = (media == MEDIA_CDROM) ? "-cd" : "-hd";
-        if (max_devs)
-            snprintf(dinfo->id, 32, "%s%i%s%i",
-                     if_name[type], bus_id, mediastr, unit_id);
-        else
-            snprintf(dinfo->id, 32, "%s%s%i",
-                     if_name[type], mediastr, unit_id);
+        }
+        if (max_devs) {
+            new_id = g_strdup_printf("%s%i%s%i", if_name[type], bus_id,
+                                     mediastr, unit_id);
+        } else {
+            new_id = g_strdup_printf("%s%s%i", if_name[type],
+                                     mediastr, unit_id);
+        }
+        qemu_opts_set_id(opts, new_id);
     }
+
+    /* init */
+    dinfo = g_malloc0(sizeof(*dinfo));
+    dinfo->id = g_strdup(qemu_opts_id(opts));
     dinfo->bdrv = bdrv_new(dinfo->id);
     dinfo->bdrv->open_flags = snapshot ? BDRV_O_SNAPSHOT : 0;
     dinfo->bdrv->read_only = ro;

include/qemu/option.h

@@ -142,6 +142,7 @@ void qemu_opts_loc_restore(QemuOpts *opts);
 int qemu_opts_set(QemuOptsList *list, const char *id,
                   const char *name, const char *value);
 const char *qemu_opts_id(QemuOpts *opts);
+void qemu_opts_set_id(QemuOpts *opts, char *id);
 void qemu_opts_del(QemuOpts *opts);
 void qemu_opts_validate(QemuOpts *opts, const QemuOptDesc *desc, Error **errp);
 int qemu_opts_do_parse(QemuOpts *opts, const char *params, const char *firstname);

util/qemu-option.c

@@ -834,6 +834,12 @@ const char *qemu_opts_id(QemuOpts *opts)
     return opts->id;
 }
 
+/* The id string will be g_free()d by qemu_opts_del */
+void qemu_opts_set_id(QemuOpts *opts, char *id)
+{
+    opts->id = id;
+}
+
 void qemu_opts_del(QemuOpts *opts)
 {
     QemuOpt *opt;