error: Fix use of error_prepend() with &error_fatal, &error_abort
From include/qapi/error.h:
* Pass an existing error to the caller with the message modified:
* error_propagate(errp, err);
* error_prepend(errp, "Could not frobnicate '%s': ", name);
Fei Li pointed out that doing error_propagate() first doesn't work
well when @errp is &error_fatal or &error_abort: the error_prepend()
is never reached.
Since I doubt fixing the documentation will stop people from getting
it wrong, introduce error_propagate_prepend(), in the hope that it
lures people away from using its constituents in the wrong order.
Update the instructions in error.h accordingly.
Convert existing error_prepend() next to error_propagate to
error_propagate_prepend(). If any of these get reached with
&error_fatal or &error_abort, the error messages improve. I didn't
check whether that's the case anywhere.
Cc: Fei Li <fli@suse.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-Id: <20181017082702.5581-2-armbru@redhat.com>
diff --git a/migration/migration.c b/migration/migration.c
index d6ae879..f0f299a 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -1546,9 +1546,9 @@
int migrate_add_blocker(Error *reason, Error **errp)
{
if (migrate_get_current()->only_migratable) {
- error_propagate(errp, error_copy(reason));
- error_prepend(errp, "disallowing migration blocker "
- "(--only_migratable) for: ");
+ error_propagate_prepend(errp, error_copy(reason),
+ "disallowing migration blocker "
+ "(--only_migratable) for: ");
return -EACCES;
}
@@ -1557,9 +1557,9 @@
return 0;
}
- error_propagate(errp, error_copy(reason));
- error_prepend(errp, "disallowing migration blocker (migration in "
- "progress) for: ");
+ error_propagate_prepend(errp, error_copy(reason),
+ "disallowing migration blocker "
+ "(migration in progress) for: ");
return -EBUSY;
}
