qapi: Make all visitors supply uint64 callbacks

Our qapi visitor contract supports multiple integer visitors,
but left the type_uint64 visitor as optional (falling back on
type_int64); which in turn can lead to awkward behavior with
numbers larger than INT64_MAX (the user has to be aware of
twos complement, and deal with negatives).

This patch does not address the disparity in handling large
values as negatives.  It merely moves the fallback from uint64
to int64 from the visitor core to the visitors, where the issue
can actually be fixed, by implementing the missing type_uint64()
callbacks on top of the respective type_int64() callbacks, and
with a FIXME comment explaining why that's wrong.

With that done, we now have a type_uint64() callback in every
driver, so we can make it mandatory from the core.  And although
the type_int64() callback can cover the entire valid range of
type_uint{8,16,32} on valid user input, using type_uint64() to
avoid mixed signedness makes more sense.

Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <1454075341-13658-15-git-send-email-eblake@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>

1 files changed, 11 insertions, 25 deletions

diff --git a/qapi/qapi-visit-core.c b/qapi/qapi-visit-core.c
index 2446a1287b..afcd59be9a 100644
--- a/qapi/qapi-visit-core.c
+++ b/qapi/qapi-visit-core.c
@@ -97,14 +97,14 @@ void visit_type_int(Visitor *v, int64_t *obj, const char *name, Error **errp)
 
 void visit_type_uint8(Visitor *v, uint8_t *obj, const char *name, Error **errp)
 {
-    int64_t value;
+    uint64_t value;
 
     if (v->type_uint8) {
         v->type_uint8(v, obj, name, errp);
     } else {
         value = *obj;
-        v->type_int64(v, &value, name, errp);
-        if (value < 0 || value > UINT8_MAX) {
+        v->type_uint64(v, &value, name, errp);
+        if (value > UINT8_MAX) {
             /* FIXME questionable reuse of errp if callback changed
                value on error */
             error_setg(errp, QERR_INVALID_PARAMETER_VALUE,
@@ -117,14 +117,14 @@ void visit_type_uint8(Visitor *v, uint8_t *obj, const char *name, Error **errp)
 
 void visit_type_uint16(Visitor *v, uint16_t *obj, const char *name, Error **errp)
 {
-    int64_t value;
+    uint64_t value;
 
     if (v->type_uint16) {
         v->type_uint16(v, obj, name, errp);
     } else {
         value = *obj;
-        v->type_int64(v, &value, name, errp);
-        if (value < 0 || value > UINT16_MAX) {
+        v->type_uint64(v, &value, name, errp);
+        if (value > UINT16_MAX) {
             /* FIXME questionable reuse of errp if callback changed
                value on error */
             error_setg(errp, QERR_INVALID_PARAMETER_VALUE,
@@ -137,14 +137,14 @@ void visit_type_uint16(Visitor *v, uint16_t *obj, const char *name, Error **errp
 
 void visit_type_uint32(Visitor *v, uint32_t *obj, const char *name, Error **errp)
 {
-    int64_t value;
+    uint64_t value;
 
     if (v->type_uint32) {
         v->type_uint32(v, obj, name, errp);
     } else {
         value = *obj;
-        v->type_int64(v, &value, name, errp);
-        if (value < 0 || value > UINT32_MAX) {
+        v->type_uint64(v, &value, name, errp);
+        if (value > UINT32_MAX) {
             /* FIXME questionable reuse of errp if callback changed
                value on error */
             error_setg(errp, QERR_INVALID_PARAMETER_VALUE,
@@ -157,15 +157,7 @@ void visit_type_uint32(Visitor *v, uint32_t *obj, const char *name, Error **errp
 
 void visit_type_uint64(Visitor *v, uint64_t *obj, const char *name, Error **errp)
 {
-    int64_t value;
-
-    if (v->type_uint64) {
-        v->type_uint64(v, obj, name, errp);
-    } else {
-        value = *obj;
-        v->type_int64(v, &value, name, errp);
-        *obj = value;
-    }
+    v->type_uint64(v, obj, name, errp);
 }
 
 void visit_type_int8(Visitor *v, int8_t *obj, const char *name, Error **errp)
@@ -235,16 +227,10 @@ void visit_type_int64(Visitor *v, int64_t *obj, const char *name, Error **errp)
 
 void visit_type_size(Visitor *v, uint64_t *obj, const char *name, Error **errp)
 {
-    int64_t value;
-
     if (v->type_size) {
         v->type_size(v, obj, name, errp);
-    } else if (v->type_uint64) {
-        v->type_uint64(v, obj, name, errp);
     } else {
-        value = *obj;
-        v->type_int64(v, &value, name, errp);
-        *obj = value;
+        v->type_uint64(v, obj, name, errp);
     }
 }