QemuOpts: Convert qemu_opt_foreach() to Error

Retain the function value for now, to permit selective conversion of
its callers.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>

2 files changed, 9 insertions, 5 deletions

diff --git a/util/qemu-config.c b/util/qemu-config.c
index aff4cb37c0..35adfda496 100644
--- a/util/qemu-config.c
+++ b/util/qemu-config.c
@@ -335,7 +335,8 @@ struct ConfigWriteData {
     FILE *fp;
 };
 
-static int config_write_opt(const char *name, const char *value, void *opaque)
+static int config_write_opt(void *opaque, const char *name, const char *value,
+                            Error **errp)
 {
     struct ConfigWriteData *data = opaque;
 
@@ -353,7 +354,7 @@ static int config_write_opts(void *opaque, QemuOpts *opts, Error **errp)
     } else {
         fprintf(data->fp, "[%s]\n", data->list->name);
     }
-    qemu_opt_foreach(opts, config_write_opt, data);
+    qemu_opt_foreach(opts, config_write_opt, data, NULL);
     fprintf(data->fp, "\n");
     return 0;
 }
diff --git a/util/qemu-option.c b/util/qemu-option.c
index 296e2b3fae..840f5f7a5b 100644
--- a/util/qemu-option.c
+++ b/util/qemu-option.c
@@ -597,20 +597,23 @@ void qemu_opt_set_number(QemuOpts *opts, const char *name, int64_t val,
 }
 
 /**
- * For each member of @opts, call @func(name, value, @opaque).
+ * For each member of @opts, call @func(@opaque, name, value, @errp).
+ * @func() may store an Error through @errp, but must return non-zero then.
  * When @func() returns non-zero, break the loop and return that value.
  * Return zero when the loop completes.
  */
-int qemu_opt_foreach(QemuOpts *opts, qemu_opt_loopfunc func, void *opaque)
+int qemu_opt_foreach(QemuOpts *opts, qemu_opt_loopfunc func, void *opaque,
+                     Error **errp)
 {
     QemuOpt *opt;
     int rc;
 
     QTAILQ_FOREACH(opt, &opts->head, next) {
-        rc = func(opt->name, opt->str, opaque);
+        rc = func(opaque, opt->name, opt->str, errp);
         if (rc) {
             return rc;
         }
+        assert(!errp || !*errp);
     }
     return 0;
 }