varlink,json: introduce new varlink_dispatch() helper

varlink_dispatch() is a simple wrapper around json_dispatch() that
returns clean, standards-compliant InvalidParameter error back to
clients, if the specified JSON cannot be parsed properly.

For this json_dispatch() is extended to return the offending field's
name. Because it already has quite a few parameters, I then renamed
json_dispatch() to json_dispatch_full() and made json_dispatch() a
wrapper around it that passes the new argument as NULL. While doing so I
figured we should also get rid of the bad= argument in the short
wrapper, since it's only used in the OCI code.

To simplify the OCI code this adds a second wrapper oci_dispatch()
around json_dispatch_full(), that fills in bad= the way we want.

Net result: instead of one json_dispatch() call there are now:

1. json_dispatch_full() for the fully feature mother of all dispathers.
2. json_dispatch() for the simpler version that you want to use most of
   the time.
3. varlink_dispatch() that generates nice Varlink errors
4. oci_dispatch() that does the OCI specific error handling

And that's all there is.

1 files changed, 7 insertions, 12 deletions

diff --git a/src/sysext/sysext.c b/src/sysext/sysext.c
index 4d72019966..858868c0c5 100644
--- a/src/sysext/sysext.c
+++ b/src/sysext/sysext.c
@@ -377,8 +377,8 @@ static int vl_method_unmerge(Varlink *link, JsonVariant *parameters, VarlinkMeth
 
         assert(link);
 
-        r = json_dispatch(parameters, dispatch_table, NULL, 0, &p);
-        if (r < 0)
+        r = varlink_dispatch(link, parameters, dispatch_table, &p);
+        if (r != 0)
                 return r;
 
         r = parse_image_class_parameter(link, p.class, &image_class, &hierarchies);
@@ -1115,17 +1115,12 @@ static int parse_merge_parameters(Varlink *link, JsonVariant *parameters, Method
                 { "noexec",   JSON_VARIANT_BOOLEAN, json_dispatch_boolean,      offsetof(MethodMergeParameters, noexec),    0 },
                 {}
         };
-        int r;
 
         assert(link);
         assert(parameters);
         assert(p);
 
-        r = json_dispatch(parameters, dispatch_table, NULL, 0, p);
-        if (r < 0)
-                return r;
-
-        return 0;
+        return varlink_dispatch(link, parameters, dispatch_table, p);
 }
 
 static int vl_method_merge(Varlink *link, JsonVariant *parameters, VarlinkMethodFlags flags, void *userdata) {
@@ -1142,7 +1137,7 @@ static int vl_method_merge(Varlink *link, JsonVariant *parameters, VarlinkMethod
         assert(link);
 
         r = parse_merge_parameters(link, parameters, &p);
-        if (r < 0)
+        if (r != 0)
                 return r;
 
         r = parse_image_class_parameter(link, p.class, &image_class, &hierarchies);
@@ -1245,7 +1240,7 @@ static int vl_method_refresh(Varlink *link, JsonVariant *parameters, VarlinkMeth
         assert(link);
 
         r = parse_merge_parameters(link, parameters, &p);
-        if (r < 0)
+        if (r != 0)
                 return r;
 
         r = parse_image_class_parameter(link, p.class, &image_class, &hierarchies);
@@ -1322,8 +1317,8 @@ static int vl_method_list(Varlink *link, JsonVariant *parameters, VarlinkMethodF
 
         assert(link);
 
-        r = json_dispatch(parameters, dispatch_table, NULL, 0, &p);
-        if (r < 0)
+        r = varlink_dispatch(link, parameters, dispatch_table, &p);
+        if (r != 0)
                 return r;
 
         r = parse_image_class_parameter(link, p.class, &image_class, NULL);