QemuOpts: Convert qemu_opts_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>
Acked-by: Kevin Wolf <kwolf@redhat.com>

2 files changed, 7 insertions, 5 deletions

diff --git a/util/qemu-config.c b/util/qemu-config.c
index b38927a..a88461f 100644
--- a/util/qemu-config.c
+++ b/util/qemu-config.c
@@ -343,7 +343,7 @@ static int config_write_opt(const char *name, const char *value, void *opaque)
     return 0;
 }
 
-static int config_write_opts(QemuOpts *opts, void *opaque)
+static int config_write_opts(void *opaque, QemuOpts *opts, Error **errp)
 {
     struct ConfigWriteData *data = opaque;
     const char *id = qemu_opts_id(opts);
@@ -367,7 +367,7 @@ void qemu_config_write(FILE *fp)
     fprintf(fp, "# qemu config file\n\n");
     for (i = 0; lists[i] != NULL; i++) {
         data.list = lists[i];
-        qemu_opts_foreach(data.list, config_write_opts, &data);
+        qemu_opts_foreach(data.list, config_write_opts, &data, NULL);
     }
 }
 
diff --git a/util/qemu-option.c b/util/qemu-option.c
index 7672aae..07b03e3 100644
--- a/util/qemu-option.c
+++ b/util/qemu-option.c
@@ -1047,13 +1047,14 @@ void qemu_opts_validate(QemuOpts *opts, const QemuOptDesc *desc, Error **errp)
 }
 
 /**
- * For each member of @list, call @func(member, @opaque).
+ * For each member of @list, call @func(@opaque, member, @errp).
  * Call it with the current location temporarily set to the member's.
+ * @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_opts_foreach(QemuOptsList *list, qemu_opts_loopfunc func,
-                      void *opaque)
+                      void *opaque, Error **errp)
 {
     Location loc;
     QemuOpts *opts;
@@ -1062,10 +1063,11 @@ int qemu_opts_foreach(QemuOptsList *list, qemu_opts_loopfunc func,
     loc_push_none(&loc);
     QTAILQ_FOREACH(opts, &list->head, next) {
         loc_restore(&opts->loc);
-        rc = func(opts, opaque);
+        rc = func(opaque, opts, errp);
         if (rc) {
             return rc;
         }
+        assert(!errp || !*errp);
     }
     loc_pop(&loc);
     return 0;