[Qemu-devel] [PATCH v10 14/25] qapi: Make all visitors supply uint64 callbacks

[Eric Blake]

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 <address@hidden>

---
v10: improve commit message, split out dealloc type_size change
v9: hoist in part of 11/35, drop Marc-Andre's R-b
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
---
 include/qapi/visitor-impl.h  |  9 ++++++---
 qapi/qapi-visit-core.c       | 36 +++++++++++-------------------------
 qapi/qapi-dealloc-visitor.c  |  6 ++++++
 qapi/qmp-input-visitor.c     | 17 +++++++++++++++++
 qapi/qmp-output-visitor.c    |  9 +++++++++
 qapi/string-input-visitor.c  | 15 +++++++++++++++
 qapi/string-output-visitor.c |  9 +++++++++
 7 files changed, 73 insertions(+), 28 deletions(-)

diff --git a/include/qapi/visitor-impl.h b/include/qapi/visitor-impl.h
index 319efe8..92c4bcb 100644
--- a/include/qapi/visitor-impl.h
+++ b/include/qapi/visitor-impl.h
@@ -40,6 +40,12 @@ struct Visitor
     void (*type_int64)(Visitor *v, int64_t *obj, const char *name,
                        Error **errp);
     /* Must be set. */
+    void (*type_uint64)(Visitor *v, uint64_t *obj, const char *name,
+                        Error **errp);
+    /* Optional; fallback is type_uint64().  */
+    void (*type_size)(Visitor *v, uint64_t *obj, const char *name,
+                      Error **errp);
+    /* Must be set. */
     void (*type_bool)(Visitor *v, bool *obj, const char *name, Error **errp);
     void (*type_str)(Visitor *v, char **obj, const char *name, Error **errp);
     void (*type_number)(Visitor *v, double *obj, const char *name,
@@ -53,12 +59,9 @@ struct Visitor
     void (*type_uint8)(Visitor *v, uint8_t *obj, const char *name, Error 
**errp);
     void (*type_uint16)(Visitor *v, uint16_t *obj, const char *name, Error 
**errp);
     void (*type_uint32)(Visitor *v, uint32_t *obj, const char *name, Error 
**errp);
-    void (*type_uint64)(Visitor *v, uint64_t *obj, const char *name, Error 
**errp);
     void (*type_int8)(Visitor *v, int8_t *obj, const char *name, Error **errp);
     void (*type_int16)(Visitor *v, int16_t *obj, const char *name, Error 
**errp);
     void (*type_int32)(Visitor *v, int32_t *obj, const char *name, Error 
**errp);
-    /* visit_type_size() falls back to (*type_uint64)() if type_size is unset 
*/
-    void (*type_size)(Visitor *v, uint64_t *obj, const char *name, Error 
**errp);
     bool (*start_union)(Visitor *v, bool data_present, Error **errp);
 };

diff --git a/qapi/qapi-visit-core.c b/qapi/qapi-visit-core.c
index 3a888ab..ac5a861 100644
--- a/qapi/qapi-visit-core.c
+++ b/qapi/qapi-visit-core.c
@@ -96,14 +96,14 @@ 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,
@@ -116,14 +116,14 @@ 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,
@@ -136,14 +136,14 @@ 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,
@@ -156,15 +156,7 @@ 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)
@@ -234,16 +226,10 @@ 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/qapi-dealloc-visitor.c b/qapi/qapi-dealloc-visitor.c
index 8ecfc10..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)
 {
@@ -215,6 +220,7 @@ 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;
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;
-- 
2.5.0