[Qemu-devel] [PATCH v8 10/35] qapi: Make all visitors supply uint64 callbacks

[Eric Blake <eblake@redhat.com>]

Our qapi visitor contract supports multiple integer visitors,
but left the type_uint64 visitor as optional (falling back on
type_int64); it also marks the type_size visitor as optional
(falling back on type_uint64 or even type_int64).

Note that the default of falling back on type_int for unsigned
visitors can cause confusing results for values larger than
INT64_MAX (such as having to pass in a negative 2s complement
value on input, and getting a negative result on output).

This patch does not fully address the disparity in handling
large values as negatives, but does move towards a cleaner
situation where EVERY visitor provides both type_int64 and
type_uint64 variants as entry points; then each client can
either implement sane differences between the two, or document
in place with a FIXME that there is munging going on.

The dealloc visitor no longer needs a type_size callback,
since that now safely falls back to the type_uint64 callback.

Then, in qapi-visit-core.c, we can now use the guaranteed
type_uint64 callback as the fallback for all smaller unsigned
int visits.

Signed-off-by: Eric Blake <eblake@redhat.com>

---
v8: no change
v7: split off int64 callbacks and retitle, add more FIXMEs in the
code, hoist use of type_uint64 here from 3/23, improved commit
message
v6: new patch, but stems from v5 23/46
---
 qapi/qapi-dealloc-visitor.c  | 12 ++++++------
 qapi/qapi-visit-core.c       | 42 ++++++++++++++----------------------------
 qapi/qmp-input-visitor.c     | 17 +++++++++++++++++
 qapi/qmp-output-visitor.c    |  9 +++++++++
 qapi/string-input-visitor.c  | 15 +++++++++++++++
 qapi/string-output-visitor.c |  9 +++++++++
 6 files changed, 70 insertions(+), 34 deletions(-)

diff --git a/qapi/qapi-dealloc-visitor.c b/qapi/qapi-dealloc-visitor.c
index e9b9f3f..11eb828 100644
--- a/qapi/qapi-dealloc-visitor.c
+++ b/qapi/qapi-dealloc-visitor.c
@@ -140,6 +140,11 @@ static void qapi_dealloc_type_int64(Visitor *v, int64_t *obj, const char *name,
 {
 }

+static void qapi_dealloc_type_uint64(Visitor *v, uint64_t *obj,
+                                     const char *name, Error **errp)
+{
+}
+
 static void qapi_dealloc_type_bool(Visitor *v, bool *obj, const char *name,
                                    Error **errp)
 {
@@ -158,11 +163,6 @@ static void qapi_dealloc_type_anything(Visitor *v, QObject **obj,
     }
 }

-static void qapi_dealloc_type_size(Visitor *v, uint64_t *obj, const char *name,
-                                   Error **errp)
-{
-}
-
 static void qapi_dealloc_type_enum(Visitor *v, int *obj,
                                    const char * const strings[],
                                    const char *kind, const char *name,
@@ -220,11 +220,11 @@ QapiDeallocVisitor *qapi_dealloc_visitor_new(void)
     v->visitor.end_list = qapi_dealloc_end_list;
     v->visitor.type_enum = qapi_dealloc_type_enum;
     v->visitor.type_int64 = qapi_dealloc_type_int64;
+    v->visitor.type_uint64 = qapi_dealloc_type_uint64;
     v->visitor.type_bool = qapi_dealloc_type_bool;
     v->visitor.type_str = qapi_dealloc_type_str;
     v->visitor.type_number = qapi_dealloc_type_number;
     v->visitor.type_any = qapi_dealloc_type_anything;
-    v->visitor.type_size = qapi_dealloc_type_size;
     v->visitor.start_union = qapi_dealloc_start_union;

     QTAILQ_INIT(&v->stack);
diff --git a/qapi/qapi-visit-core.c b/qapi/qapi-visit-core.c
index 6295fa8..4a8ad43 100644
--- a/qapi/qapi-visit-core.c
+++ b/qapi/qapi-visit-core.c
@@ -102,15 +102,15 @@ 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) {
-            /* FIXME questionable reuse of errp if type_int64() changes
+        v->type_uint64(v, &value, name, errp);
+        if (value > UINT8_MAX) {
+            /* FIXME questionable reuse of errp if type_uint64() changes
                value on error */
             error_setg(errp, QERR_INVALID_PARAMETER_VALUE,
                        name ? name : "null", "uint8_t");
@@ -122,15 +122,15 @@ 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) {
-            /* FIXME questionable reuse of errp if type_int64() changes
+        v->type_uint64(v, &value, name, errp);
+        if (value > UINT16_MAX) {
+            /* FIXME questionable reuse of errp if type_uint64() changes
                value on error */
             error_setg(errp, QERR_INVALID_PARAMETER_VALUE,
                        name ? name : "null", "uint16_t");
@@ -142,15 +142,15 @@ 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) {
-            /* FIXME questionable reuse of errp if type_int64() changes
+        v->type_uint64(v, &value, name, errp);
+        if (value > UINT32_MAX) {
+            /* FIXME questionable reuse of errp if type_uint64() changes
                value on error */
             error_setg(errp, QERR_INVALID_PARAMETER_VALUE,
                        name ? name : "null", "uint32_t");
@@ -162,15 +162,7 @@ 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)
@@ -240,16 +232,10 @@ 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);
     }
 }

diff --git a/qapi/qmp-input-visitor.c b/qapi/qmp-input-visitor.c
index 0d8a3c3..32b60bb 100644
--- a/qapi/qmp-input-visitor.c
+++ b/qapi/qmp-input-visitor.c
@@ -239,6 +239,22 @@ static void qmp_input_type_int64(Visitor *v, int64_t *obj, const char *name,
     *obj = qint_get_int(qint);
 }

+static void qmp_input_type_uint64(Visitor *v, uint64_t *obj, const char *name,
+                                  Error **errp)
+{
+    /* FIXME: qobject_to_qint mishandles values over INT64_MAX */
+    QmpInputVisitor *qiv = to_qiv(v);
+    QInt *qint = qobject_to_qint(qmp_input_get_object(qiv, name, true));
+
+    if (!qint) {
+        error_setg(errp, QERR_INVALID_PARAMETER_TYPE, name ? name : "null",
+                   "integer");
+        return;
+    }
+
+    *obj = qint_get_int(qint);
+}
+
 static void qmp_input_type_bool(Visitor *v, bool *obj, const char *name,
                                 Error **errp)
 {
@@ -342,6 +358,7 @@ QmpInputVisitor *qmp_input_visitor_new(QObject *obj)
     v->visitor.end_list = qmp_input_end_list;
     v->visitor.type_enum = input_type_enum;
     v->visitor.type_int64 = qmp_input_type_int64;
+    v->visitor.type_uint64 = qmp_input_type_uint64;
     v->visitor.type_bool = qmp_input_type_bool;
     v->visitor.type_str = qmp_input_type_str;
     v->visitor.type_number = qmp_input_type_number;
diff --git a/qapi/qmp-output-visitor.c b/qapi/qmp-output-visitor.c
index 3984011..f8eebaa 100644
--- a/qapi/qmp-output-visitor.c
+++ b/qapi/qmp-output-visitor.c
@@ -165,6 +165,14 @@ static void qmp_output_type_int64(Visitor *v, int64_t *obj, const char *name,
     qmp_output_add(qov, name, qint_from_int(*obj));
 }

+static void qmp_output_type_uint64(Visitor *v, uint64_t *obj, const char *name,
+                                   Error **errp)
+{
+    /* FIXME: QMP outputs values larger than INT64_MAX as negative */
+    QmpOutputVisitor *qov = to_qov(v);
+    qmp_output_add(qov, name, qint_from_int(*obj));
+}
+
 static void qmp_output_type_bool(Visitor *v, bool *obj, const char *name,
                                  Error **errp)
 {
@@ -242,6 +250,7 @@ QmpOutputVisitor *qmp_output_visitor_new(void)
     v->visitor.end_list = qmp_output_end_list;
     v->visitor.type_enum = output_type_enum;
     v->visitor.type_int64 = qmp_output_type_int64;
+    v->visitor.type_uint64 = qmp_output_type_uint64;
     v->visitor.type_bool = qmp_output_type_bool;
     v->visitor.type_str = qmp_output_type_str;
     v->visitor.type_number = qmp_output_type_number;
diff --git a/qapi/string-input-visitor.c b/qapi/string-input-visitor.c
index 2f422f0..d7546b5 100644
--- a/qapi/string-input-visitor.c
+++ b/qapi/string-input-visitor.c
@@ -226,6 +226,20 @@ error:
                "an int64 value or range");
 }

+static void parse_type_uint64(Visitor *v, uint64_t *obj, const char *name,
+                              Error **errp)
+{
+    /* FIXME: parse_type_int64 mishandles values over INT64_MAX */
+    int64_t i;
+    Error *err = NULL;
+    parse_type_int64(v, &i, name, &err);
+    if (err) {
+        error_propagate(errp, err);
+    } else {
+        *obj = i;
+    }
+}
+
 static void parse_type_size(Visitor *v, uint64_t *obj, const char *name,
                             Error **errp)
 {
@@ -336,6 +350,7 @@ StringInputVisitor *string_input_visitor_new(const char *str)

     v->visitor.type_enum = input_type_enum;
     v->visitor.type_int64 = parse_type_int64;
+    v->visitor.type_uint64 = parse_type_uint64;
     v->visitor.type_size = parse_type_size;
     v->visitor.type_bool = parse_type_bool;
     v->visitor.type_str = parse_type_str;
diff --git a/qapi/string-output-visitor.c b/qapi/string-output-visitor.c
index c0a9331..3ed2b2c 100644
--- a/qapi/string-output-visitor.c
+++ b/qapi/string-output-visitor.c
@@ -197,6 +197,14 @@ static void print_type_int64(Visitor *v, int64_t *obj, const char *name,
     }
 }

+static void print_type_uint64(Visitor *v, uint64_t *obj, const char *name,
+                             Error **errp)
+{
+    /* FIXME: print_type_int64 mishandles values over INT64_MAX */
+    int64_t i = *obj;
+    print_type_int64(v, &i, name, errp);
+}
+
 static void print_type_size(Visitor *v, uint64_t *obj, const char *name,
                            Error **errp)
 {
@@ -346,6 +354,7 @@ StringOutputVisitor *string_output_visitor_new(bool human)
     v->human = human;
     v->visitor.type_enum = output_type_enum;
     v->visitor.type_int64 = print_type_int64;
+    v->visitor.type_uint64 = print_type_uint64;
     v->visitor.type_size = print_type_size;
     v->visitor.type_bool = print_type_bool;
     v->visitor.type_str = print_type_str;
-- 
2.4.3