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qapi: Make visitor functions taking Error ** return bool, not void

Browse source 
See recent commit "error: Document Error API usage rules" for
rationale.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-Id: <20200707160613.848843-18-armbru@redhat.com>
This commit is contained in:
Markus Armbruster 2020-07-07 18:05:45 +02:00
parent 3c4b89c3b2
commit 012d4c96e2
14 changed files with 456 additions and 361 deletions
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8
include/qapi/clone-visitor.h
View file

@ -20,10 +20,10 @@
*/
typedef struct QapiCloneVisitor QapiCloneVisitor;
void *qapi_clone(const void *src, void (*visit_type)(Visitor *, const char *,
void *qapi_clone(const void *src, bool (*visit_type)(Visitor *, const char *,
void **, Error **));
void qapi_clone_members(void *dst, const void *src, size_t sz,
void (*visit_type_members)(Visitor *, void *,
bool (*visit_type_members)(Visitor *, void *,
Error **));
/*
@ -34,7 +34,7 @@ void qapi_clone_members(void *dst, const void *src, size_t sz,
*/
#define QAPI_CLONE(type, src) \
((type *)qapi_clone(src, \
(void (*)(Visitor *, const char *, void**, \
(bool (*)(Visitor *, const char *, void **, \
Error **))visit_type_ ## type))
/*
@ -45,7 +45,7 @@ void qapi_clone_members(void *dst, const void *src, size_t sz,
*/
#define QAPI_CLONE_MEMBERS(type, dst, src) \
qapi_clone_members(dst, src, sizeof(type), \
(void (*)(Visitor *, void *, \
(bool (*)(Visitor *, void *, \
Error **))visit_type_ ## type ## _members)
#endif

26
include/qapi/visitor-impl.h
View file

@ -48,31 +48,31 @@ struct Visitor
*/
/* Must be set to visit structs */
void (*start_struct)(Visitor *v, const char *name, void **obj,
bool (*start_struct)(Visitor *v, const char *name, void **obj,
size_t size, Error **errp);
/* Optional; intended for input visitors */
void (*check_struct)(Visitor *v, Error **errp);
bool (*check_struct)(Visitor *v, Error **errp);
/* Must be set to visit structs */
void (*end_struct)(Visitor *v, void **obj);
/* Must be set; implementations may require @list to be non-null,
* but must document it. */
void (*start_list)(Visitor *v, const char *name, GenericList **list,
bool (*start_list)(Visitor *v, const char *name, GenericList **list,
size_t size, Error **errp);
/* Must be set */
GenericList *(*next_list)(Visitor *v, GenericList *tail, size_t size);
/* Optional; intended for input visitors */
void (*check_list)(Visitor *v, Error **errp);
bool (*check_list)(Visitor *v, Error **errp);
/* Must be set */
void (*end_list)(Visitor *v, void **list);
/* Must be set by input and clone visitors to visit alternates */
void (*start_alternate)(Visitor *v, const char *name,
bool (*start_alternate)(Visitor *v, const char *name,
GenericAlternate **obj, size_t size,
Error **errp);
@ -80,33 +80,33 @@ struct Visitor
void (*end_alternate)(Visitor *v, void **obj);
/* Must be set */
void (*type_int64)(Visitor *v, const char *name, int64_t *obj,
bool (*type_int64)(Visitor *v, const char *name, int64_t *obj,
Error **errp);
/* Must be set */
void (*type_uint64)(Visitor *v, const char *name, uint64_t *obj,
bool (*type_uint64)(Visitor *v, const char *name, uint64_t *obj,
Error **errp);
/* Optional; fallback is type_uint64() */
void (*type_size)(Visitor *v, const char *name, uint64_t *obj,
bool (*type_size)(Visitor *v, const char *name, uint64_t *obj,
Error **errp);
/* Must be set */
void (*type_bool)(Visitor *v, const char *name, bool *obj, Error **errp);
bool (*type_bool)(Visitor *v, const char *name, bool *obj, Error **errp);
/* Must be set */
void (*type_str)(Visitor *v, const char *name, char **obj, Error **errp);
bool (*type_str)(Visitor *v, const char *name, char **obj, Error **errp);
/* Must be set to visit numbers */
void (*type_number)(Visitor *v, const char *name, double *obj,
bool (*type_number)(Visitor *v, const char *name, double *obj,
Error **errp);
/* Must be set to visit arbitrary QTypes */
void (*type_any)(Visitor *v, const char *name, QObject **obj,
bool (*type_any)(Visitor *v, const char *name, QObject **obj,
Error **errp);
/* Must be set to visit explicit null values. */
void (*type_null)(Visitor *v, const char *name, QNull **obj,
bool (*type_null)(Visitor *v, const char *name, QNull **obj,
Error **errp);
/* Must be set for input visitors to visit structs, optional otherwise.

102
include/qapi/visitor.h
View file

@ -60,7 +60,7 @@
* All QAPI types have a corresponding function with a signature
* roughly compatible with this:
*
* void visit_type_FOO(Visitor *v, const char *name, T obj, Error **errp);
* bool visit_type_FOO(Visitor *v, const char *name, T obj, Error **errp);
*
* where T is FOO for scalar types, and FOO * otherwise. The scalar
* visitors are declared here; the remaining visitors are generated in
@ -95,14 +95,16 @@
* incomplete object, such an object is possible only by manual
* construction.
*
* visit_type_FOO() returns true on success, false on error.
*
* For the QAPI object types (structs, unions, and alternates), there
* is an additional generated function in qapi-visit-MODULE.h
* compatible with:
*
* void visit_type_FOO_members(Visitor *v, FOO *obj, Error **errp);
* bool visit_type_FOO_members(Visitor *v, FOO *obj, Error **errp);
*
* for visiting the members of a type without also allocating the QAPI
* struct.
* struct. It also returns true on success, false on error.
*
* Additionally, QAPI pointer types (structs, unions, alternates, and
* lists) have a generated function in qapi-types-MODULE.h compatible
@ -131,8 +133,7 @@
* Visitor *v;
*
* v = FOO_visitor_new(...);
* visit_type_Foo(v, NULL, &f, &err);
* if (err) {
* if (!visit_type_Foo(v, NULL, &f, &err)) {
* ...handle error...
* } else {
* ...use f...
@ -148,8 +149,7 @@
* Visitor *v;
*
* v = FOO_visitor_new(...);
* visit_type_FooList(v, NULL, &l, &err);
* if (err) {
* if (!visit_type_FooList(v, NULL, &l, &err)) {
* ...handle error...
* } else {
* for ( ; l; l = l->next) {
@ -186,34 +186,32 @@
* <example>
* Visitor *v;
* Error *err = NULL;
* bool ok = false;
* int value;
*
* v = FOO_visitor_new(...);
* visit_start_struct(v, NULL, NULL, 0, &err);
* if (err) {
* if (!visit_start_struct(v, NULL, NULL, 0, &err)) {
* goto out;
* }
* visit_start_list(v, "list", NULL, 0, &err);
* if (err) {
* if (!visit_start_list(v, "list", NULL, 0, &err)) {
* goto outobj;
* }
* value = 1;
* visit_type_int(v, NULL, &value, &err);
* if (err) {
* if (!visit_type_int(v, NULL, &value, &err)) {
* goto outlist;
* }
* value = 2;
* visit_type_int(v, NULL, &value, &err);
* if (err) {
* if (!visit_type_int(v, NULL, &value, &err)) {
* goto outlist;
* }
* ok = true;
* outlist:
* if (!err) {
* visit_check_list(v, &err);
* if (ok) {
* ok = visit_check_list(v, &err);
* }
* visit_end_list(v, NULL);
* if (!err) {
* visit_check_struct(v, &err);
* if (ok) {
* ok = visit_check_struct(v, &err);
* }
* outobj:
* visit_end_struct(v, NULL);
@ -286,6 +284,8 @@ void visit_free(Visitor *v);
* On failure, set *@obj to NULL and store an error through @errp.
* Can happen only when @v is an input visitor.
*
* Return true on success, false on failure.
*
* After visit_start_struct() succeeds, the caller may visit its
* members one after the other, passing the member's name and address
* within the struct. Finally, visit_end_struct() needs to be called
@ -295,7 +295,7 @@ void visit_free(Visitor *v);
* FIXME Should this be named visit_start_object, since it is also
* used for QAPI unions, and maps to JSON objects?
*/
void visit_start_struct(Visitor *v, const char *name, void **obj,
bool visit_start_struct(Visitor *v, const char *name, void **obj,
size_t size, Error **errp);
/*
@ -304,12 +304,14 @@ void visit_start_struct(Visitor *v, const char *name, void **obj,
* On failure, store an error through @errp. Can happen only when @v
* is an input visitor.
*
* Return true on success, false on failure.
*
* Should be called prior to visit_end_struct() if all other
* intermediate visit steps were successful, to allow the visitor one
* last chance to report errors. May be skipped on a cleanup path,
* where there is no need to check for further errors.
*/
void visit_check_struct(Visitor *v, Error **errp);
bool visit_check_struct(Visitor *v, Error **errp);
/*
* Complete an object visit started earlier.
@ -341,6 +343,8 @@ void visit_end_struct(Visitor *v, void **obj);
* On failure, set *@list to NULL and store an error through @errp.
* Can happen only when @v is an input visitor.
*
* Return true on success, false on failure.
*
* After visit_start_list() succeeds, the caller may visit its members
* one after the other. A real visit (where @list is non-NULL) uses
* visit_next_list() for traversing the linked list, while a virtual
@ -351,7 +355,7 @@ void visit_end_struct(Visitor *v, void **obj);
* same @list to clean up, even if intermediate visits fail. See the
* examples above.
*/
void visit_start_list(Visitor *v, const char *name, GenericList **list,
bool visit_start_list(Visitor *v, const char *name, GenericList **list,
size_t size, Error **errp);
/*
@ -376,12 +380,14 @@ GenericList *visit_next_list(Visitor *v, GenericList *tail, size_t size);
* On failure, store an error through @errp. Can happen only when @v
* is an input visitor.
*
* Return true on success, false on failure.
*
* Should be called prior to visit_end_list() if all other
* intermediate visit steps were successful, to allow the visitor one
* last chance to report errors. May be skipped on a cleanup path,
* where there is no need to check for further errors.
*/
void visit_check_list(Visitor *v, Error **errp);
bool visit_check_list(Visitor *v, Error **errp);
/*
* Complete a list visit started earlier.
@ -412,11 +418,13 @@ void visit_end_list(Visitor *v, void **list);
* On failure, set *@obj to NULL and store an error through @errp.
* Can happen only when @v is an input visitor.
*
* Return true on success, false on failure.
*
* If successful, this must be paired with visit_end_alternate() with
* the same @obj to clean up, even if visiting the contents of the
* alternate fails.
*/
void visit_start_alternate(Visitor *v, const char *name,
bool visit_start_alternate(Visitor *v, const char *name,
GenericAlternate **obj, size_t size,
Error **errp);
@ -468,12 +476,14 @@ bool visit_optional(Visitor *v, const char *name, bool *present);
* On failure, store an error through @errp. Can happen only when @v
* is an input visitor.
*
* Return true on success, false on failure.
*
* May call visit_type_str() under the hood, and the enum visit may
* fail even if the corresponding string visit succeeded; this implies
* that an input visitor's visit_type_str() must have no unwelcome
* side effects.
*/
void visit_type_enum(Visitor *v, const char *name, int *obj,
bool visit_type_enum(Visitor *v, const char *name, int *obj,
const QEnumLookup *lookup, Error **errp);
/*
@ -499,28 +509,30 @@ bool visit_is_dealloc(Visitor *v);
*
* On failure, store an error through @errp. Can happen only when @v
* is an input visitor.
*
* Return true on success, false on failure.
*/
void visit_type_int(Visitor *v, const char *name, int64_t *obj, Error **errp);
bool visit_type_int(Visitor *v, const char *name, int64_t *obj, Error **errp);
/*
* Visit a uint8_t value.
* Like visit_type_int(), except clamps the value to uint8_t range.
*/
void visit_type_uint8(Visitor *v, const char *name, uint8_t *obj,
bool visit_type_uint8(Visitor *v, const char *name, uint8_t *obj,
Error **errp);
/*
* Visit a uint16_t value.
* Like visit_type_int(), except clamps the value to uint16_t range.
*/
void visit_type_uint16(Visitor *v, const char *name, uint16_t *obj,
bool visit_type_uint16(Visitor *v, const char *name, uint16_t *obj,
Error **errp);
/*
* Visit a uint32_t value.
* Like visit_type_int(), except clamps the value to uint32_t range.
*/
void visit_type_uint32(Visitor *v, const char *name, uint32_t *obj,
bool visit_type_uint32(Visitor *v, const char *name, uint32_t *obj,
Error **errp);
/*
@ -528,34 +540,34 @@ void visit_type_uint32(Visitor *v, const char *name, uint32_t *obj,
* Like visit_type_int(), except clamps the value to uint64_t range,
* that is, ensures it is unsigned.
*/
void visit_type_uint64(Visitor *v, const char *name, uint64_t *obj,
bool visit_type_uint64(Visitor *v, const char *name, uint64_t *obj,
Error **errp);
/*
* Visit an int8_t value.
* Like visit_type_int(), except clamps the value to int8_t range.
*/
void visit_type_int8(Visitor *v, const char *name, int8_t *obj, Error **errp);
bool visit_type_int8(Visitor *v, const char *name, int8_t *obj, Error **errp);
/*
* Visit an int16_t value.
* Like visit_type_int(), except clamps the value to int16_t range.
*/
void visit_type_int16(Visitor *v, const char *name, int16_t *obj,
bool visit_type_int16(Visitor *v, const char *name, int16_t *obj,
Error **errp);
/*
* Visit an int32_t value.
* Like visit_type_int(), except clamps the value to int32_t range.
*/
void visit_type_int32(Visitor *v, const char *name, int32_t *obj,
bool visit_type_int32(Visitor *v, const char *name, int32_t *obj,
Error **errp);
/*
* Visit an int64_t value.
* Identical to visit_type_int().
*/
void visit_type_int64(Visitor *v, const char *name, int64_t *obj,
bool visit_type_int64(Visitor *v, const char *name, int64_t *obj,
Error **errp);
/*
@ -564,7 +576,7 @@ void visit_type_int64(Visitor *v, const char *name, int64_t *obj,
* recognize additional syntax, such as suffixes for easily scaling
* values.
*/
void visit_type_size(Visitor *v, const char *name, uint64_t *obj,
bool visit_type_size(Visitor *v, const char *name, uint64_t *obj,
Error **errp);
/*
@ -578,8 +590,10 @@ void visit_type_size(Visitor *v, const char *name, uint64_t *obj,
*
* On failure, store an error through @errp. Can happen only when @v
* is an input visitor.
*
* Return true on success, false on failure.
*/
void visit_type_bool(Visitor *v, const char *name, bool *obj, Error **errp);
bool visit_type_bool(Visitor *v, const char *name, bool *obj, Error **errp);
/*
* Visit a string value.
@ -598,9 +612,11 @@ void visit_type_bool(Visitor *v, const char *name, bool *obj, Error **errp);
* On failure, set *@obj to NULL and store an error through @errp.
* Can happen only when @v is an input visitor.
*
* Return true on success, false on failure.
*
* FIXME: Callers that try to output NULL *obj should not be allowed.
*/
void visit_type_str(Visitor *v, const char *name, char **obj, Error **errp);
bool visit_type_str(Visitor *v, const char *name, char **obj, Error **errp);
/*
* Visit a number (i.e. double) value.
@ -614,8 +630,10 @@ void visit_type_str(Visitor *v, const char *name, char **obj, Error **errp);
*
* On failure, store an error through @errp. Can happen only when @v
* is an input visitor.
*
* Return true on success, false on failure.
*/
void visit_type_number(Visitor *v, const char *name, double *obj,
bool visit_type_number(Visitor *v, const char *name, double *obj,
Error **errp);
/*
@ -631,11 +649,13 @@ void visit_type_number(Visitor *v, const char *name, double *obj,
* On failure, set *@obj to NULL and store an error through @errp.
* Can happen only when @v is an input visitor.
*
* Return true on success, false on failure.
*
* Note that some kinds of input can't express arbitrary QObject.
* E.g. the visitor returned by qobject_input_visitor_new_keyval()
* can't create numbers or booleans, only strings.
*/
void visit_type_any(Visitor *v, const char *name, QObject **obj, Error **errp);
bool visit_type_any(Visitor *v, const char *name, QObject **obj, Error **errp);
/*
* Visit a JSON null value.
@ -648,8 +668,10 @@ void visit_type_any(Visitor *v, const char *name, QObject **obj, Error **errp);
*
* On failure, set *@obj to NULL and store an error through @errp.
* Can happen only when @v is an input visitor.
*
* Return true on success, false on failure.
*/
void visit_type_null(Visitor *v, const char *name, QNull **obj,
bool visit_type_null(Visitor *v, const char *name, QNull **obj,
Error **errp);
#endif