bootdevice: add Error **errp argument for validate_bootdevices()

It will be useful for checking when we change traditional
boot order dynamically and propagate error message
to the monitor.

Signed-off-by: Gonglei <arei.gonglei@huawei.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>

bootdevice.c

@@ -55,7 +55,7 @@ int qemu_boot_set(const char *boot_order)
     return boot_set_handler(boot_set_opaque, boot_order);
 }
 
-void validate_bootdevices(const char *devices)
+void validate_bootdevices(const char *devices, Error **errp)
 {
     /* We just do some generic consistency checks */
     const char *p;
@@ -72,12 +72,12 @@ void validate_bootdevices(const char *devices)
          * features.
          */
         if (*p < 'a' || *p > 'p') {
-            fprintf(stderr, "Invalid boot device '%c'\n", *p);
-            exit(1);
+            error_setg(errp, "Invalid boot device '%c'", *p);
+            return;
         }
         if (bitmap & (1 << (*p - 'a'))) {
-            fprintf(stderr, "Boot device '%c' was given twice\n", *p);
-            exit(1);
+            error_setg(errp, "Boot device '%c' was given twice", *p);
+            return;
         }
         bitmap |= 1 << (*p - 'a');
     }

include/sysemu/sysemu.h

@@ -217,7 +217,7 @@ void device_add_bootindex_property(Object *obj, int32_t *bootindex,
                                    const char *name, const char *suffix,
                                    DeviceState *dev, Error **errp);
 void restore_boot_order(void *opaque);
-void validate_bootdevices(const char *devices);
+void validate_bootdevices(const char *devices, Error **errp);
 
 /* handler to set the boot_device order for a specific type of QEMUMachine */
 /* return 0 if success */

vl.c

@@ -4087,16 +4087,25 @@ int main(int argc, char **argv, char **envp)
     if (opts) {
         char *normal_boot_order;
         const char *order, *once;
+        Error *local_err = NULL;
 
         order = qemu_opt_get(opts, "order");
         if (order) {
-            validate_bootdevices(order);
+            validate_bootdevices(order, &local_err);
+            if (local_err) {
+                error_report("%s", error_get_pretty(local_err));
+                exit(1);
+            }
             boot_order = order;
         }
 
         once = qemu_opt_get(opts, "once");
         if (once) {
-            validate_bootdevices(once);
+            validate_bootdevices(once, &local_err);
+            if (local_err) {
+                error_report("%s", error_get_pretty(local_err));
+                exit(1);
+            }
             normal_boot_order = g_strdup(boot_order);
             boot_order = once;
             qemu_register_reset(restore_boot_order, normal_boot_order);