2015-08-21 07:04:50 +00:00
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/*
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* Core Definitions for QAPI Visitor Classes
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*
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* Copyright IBM, Corp. 2011
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*
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* Authors:
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* Anthony Liguori <aliguori@us.ibm.com>
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*
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* This work is licensed under the terms of the GNU LGPL, version 2.1 or later.
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* See the COPYING.LIB file in the top-level directory.
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*
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*/
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#ifndef QAPI_VISITOR_CORE_H
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#define QAPI_VISITOR_CORE_H
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#include "qemu/typedefs.h"
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#include "qapi/qmp/qobject.h"
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#include "qapi/error.h"
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#include <stdlib.h>
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typedef struct GenericList
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{
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union {
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void *value;
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uint64_t padding;
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};
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struct GenericList *next;
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} GenericList;
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void visit_start_struct(Visitor *v, void **obj, const char *kind,
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const char *name, size_t size, Error **errp);
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void visit_end_struct(Visitor *v, Error **errp);
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void visit_start_implicit_struct(Visitor *v, void **obj, size_t size,
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Error **errp);
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2018-02-19 17:58:24 +00:00
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void visit_end_implicit_struct(Visitor *v);
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2015-08-21 07:04:50 +00:00
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void visit_start_list(Visitor *v, const char *name, Error **errp);
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2018-02-19 17:58:24 +00:00
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GenericList *visit_next_list(Visitor *v, GenericList **list);
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void visit_end_list(Visitor *v);
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2018-02-20 03:00:34 +00:00
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/**
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* Check if an optional member @name of an object needs visiting.
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* For input visitors, set *@present according to whether the
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* corresponding visit_type_*() needs calling; for other visitors,
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2018-02-20 03:02:43 +00:00
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* leave *@present unchanged. Return *@present for convenience.
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2018-02-20 03:00:34 +00:00
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*/
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2018-02-20 03:02:43 +00:00
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bool visit_optional(Visitor *v, bool *present, const char *name);
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2018-02-20 03:00:34 +00:00
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qapi: Simplify visiting of alternate types
Previously, working with alternates required two lookup arrays
and some indirection: for type Foo, we created Foo_qtypes[]
which maps each qtype to a value of the generated FooKind enum,
then look up that value in FooKind_lookup[] like we do for other
union types.
This has a couple of subtle bugs. First, the generator was
creating a call with a parameter '(int *) &(*obj)->type' where
type is an enum type; this is unsafe if the compiler chooses
to store the enum type in a different size than int, where
assigning through the wrong size pointer can corrupt data or
cause a SIGBUS.
Related bug, not not fixed in this patch: qapi-visit.py's
gen_visit_enum() generates a cast of its enum * argument to
int *. Marked FIXME.
Second, since the values of the FooKind enum start at zero, all
entries of the Foo_qtypes[] array that were not explicitly
initialized will map to the same branch of the union as the
first member of the alternate, rather than triggering a desired
failure in visit_get_next_type(). Fortunately, the bug seldom
bites; the very next thing the input visitor does is try to
parse the incoming JSON with the wrong parser, which normally
fails; the output visitor is not used with a C struct in that
state, and the dealloc visitor has nothing to clean up (so
there is no leak).
However, the second bug IS observable in one case: parsing an
integer causes unusual behavior in an alternate that contains
at least a 'number' member but no 'int' member, because the
'number' parser accepts QTYPE_QINT in addition to the expected
QTYPE_QFLOAT (that is, since 'int' is not a member, the type
QTYPE_QINT accidentally maps to FooKind 0; if this enum value
is the 'number' branch the integer parses successfully, but if
the 'number' branch is not first, some other branch tries to
parse the integer and rejects it). A later patch will worry
about fixing alternates to always parse all inputs that a
non-alternate 'number' would accept, for now this is still
marked FIXME in the updated test-qmp-input-visitor.c, to
merely point out that new undesired behavior of 'ans' matches
the existing undesired behavior of 'asn'.
This patch fixes the default-initialization bug by deleting the
indirection, and modifying get_next_type() to directly assign a
QTypeCode parameter. This in turn fixes the type-casting bug,
as we are no longer casting a pointer to enum to a questionable
size. There is no longer a need to generate an implicit FooKind
enum associated with the alternate type (since the QMP wire
format never uses the stringized counterparts of the C union
member names). Since the updated visit_get_next_type() does not
know which qtypes are expected, the generated visitor is
modified to generate an error statement if an unexpected type is
encountered.
Callers now have to know the QTYPE_* mapping when looking at the
discriminator; but so far, only the testsuite was even using the
C struct of an alternate types. I considered the possibility of
keeping the internal enum FooKind, but initialized differently
than most generated arrays, as in:
typedef enum FooKind {
FOO_KIND_A = QTYPE_QDICT,
FOO_KIND_B = QTYPE_QINT,
} FooKind;
to create nicer aliases for knowing when to use foo->a or foo->b
when inspecting foo->type; but it turned out to add too much
complexity, especially without a client.
There is a user-visible side effect to this change, but I
consider it to be an improvement. Previously,
the invalid QMP command:
{"execute":"blockdev-add", "arguments":{"options":
{"driver":"raw", "id":"a", "file":true}}}
failed with:
{"error": {"class": "GenericError",
"desc": "Invalid parameter type for 'file', expected: QDict"}}
(visit_get_next_type() succeeded, and the error comes from the
visit_type_BlockdevOptions() expecting {}; there is no mention of
the fact that a string would also work). Now it fails with:
{"error": {"class": "GenericError",
"desc": "Invalid parameter type for 'file', expected: BlockdevRef"}}
(the error when the next type doesn't match any expected types for
the overall alternate).
Backports commit 0426d53c6530606bf7641b83f2b755fe61c280ee from qemu
2018-02-20 02:51:35 +00:00
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/**
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* Determine the qtype of the item @name in the current object visit.
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* For input visitors, set *@type to the correct qtype of a qapi
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* alternate type; for other visitors, leave *@type unchanged.
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2018-02-20 02:57:23 +00:00
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* If @promote_int, treat integers as QTYPE_FLOAT.
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qapi: Simplify visiting of alternate types
Previously, working with alternates required two lookup arrays
and some indirection: for type Foo, we created Foo_qtypes[]
which maps each qtype to a value of the generated FooKind enum,
then look up that value in FooKind_lookup[] like we do for other
union types.
This has a couple of subtle bugs. First, the generator was
creating a call with a parameter '(int *) &(*obj)->type' where
type is an enum type; this is unsafe if the compiler chooses
to store the enum type in a different size than int, where
assigning through the wrong size pointer can corrupt data or
cause a SIGBUS.
Related bug, not not fixed in this patch: qapi-visit.py's
gen_visit_enum() generates a cast of its enum * argument to
int *. Marked FIXME.
Second, since the values of the FooKind enum start at zero, all
entries of the Foo_qtypes[] array that were not explicitly
initialized will map to the same branch of the union as the
first member of the alternate, rather than triggering a desired
failure in visit_get_next_type(). Fortunately, the bug seldom
bites; the very next thing the input visitor does is try to
parse the incoming JSON with the wrong parser, which normally
fails; the output visitor is not used with a C struct in that
state, and the dealloc visitor has nothing to clean up (so
there is no leak).
However, the second bug IS observable in one case: parsing an
integer causes unusual behavior in an alternate that contains
at least a 'number' member but no 'int' member, because the
'number' parser accepts QTYPE_QINT in addition to the expected
QTYPE_QFLOAT (that is, since 'int' is not a member, the type
QTYPE_QINT accidentally maps to FooKind 0; if this enum value
is the 'number' branch the integer parses successfully, but if
the 'number' branch is not first, some other branch tries to
parse the integer and rejects it). A later patch will worry
about fixing alternates to always parse all inputs that a
non-alternate 'number' would accept, for now this is still
marked FIXME in the updated test-qmp-input-visitor.c, to
merely point out that new undesired behavior of 'ans' matches
the existing undesired behavior of 'asn'.
This patch fixes the default-initialization bug by deleting the
indirection, and modifying get_next_type() to directly assign a
QTypeCode parameter. This in turn fixes the type-casting bug,
as we are no longer casting a pointer to enum to a questionable
size. There is no longer a need to generate an implicit FooKind
enum associated with the alternate type (since the QMP wire
format never uses the stringized counterparts of the C union
member names). Since the updated visit_get_next_type() does not
know which qtypes are expected, the generated visitor is
modified to generate an error statement if an unexpected type is
encountered.
Callers now have to know the QTYPE_* mapping when looking at the
discriminator; but so far, only the testsuite was even using the
C struct of an alternate types. I considered the possibility of
keeping the internal enum FooKind, but initialized differently
than most generated arrays, as in:
typedef enum FooKind {
FOO_KIND_A = QTYPE_QDICT,
FOO_KIND_B = QTYPE_QINT,
} FooKind;
to create nicer aliases for knowing when to use foo->a or foo->b
when inspecting foo->type; but it turned out to add too much
complexity, especially without a client.
There is a user-visible side effect to this change, but I
consider it to be an improvement. Previously,
the invalid QMP command:
{"execute":"blockdev-add", "arguments":{"options":
{"driver":"raw", "id":"a", "file":true}}}
failed with:
{"error": {"class": "GenericError",
"desc": "Invalid parameter type for 'file', expected: QDict"}}
(visit_get_next_type() succeeded, and the error comes from the
visit_type_BlockdevOptions() expecting {}; there is no mention of
the fact that a string would also work). Now it fails with:
{"error": {"class": "GenericError",
"desc": "Invalid parameter type for 'file', expected: BlockdevRef"}}
(the error when the next type doesn't match any expected types for
the overall alternate).
Backports commit 0426d53c6530606bf7641b83f2b755fe61c280ee from qemu
2018-02-20 02:51:35 +00:00
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*/
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2018-02-20 02:57:23 +00:00
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void visit_get_next_type(Visitor *v, QType *type, bool promote_int,
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2015-08-21 07:04:50 +00:00
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const char *name, Error **errp);
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2018-02-19 21:02:14 +00:00
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void visit_type_enum(Visitor *v, int *obj, const char * const strings[],
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2015-08-21 07:04:50 +00:00
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const char *kind, const char *name, Error **errp);
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void visit_type_int(Visitor *v, int64_t *obj, const char *name, Error **errp);
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void visit_type_uint8(Visitor *v, uint8_t *obj, const char *name, Error **errp);
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void visit_type_uint16(Visitor *v, uint16_t *obj, const char *name, Error **errp);
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void visit_type_uint32(Visitor *v, uint32_t *obj, const char *name, Error **errp);
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void visit_type_uint64(Visitor *v, uint64_t *obj, const char *name, Error **errp);
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void visit_type_int8(Visitor *v, int8_t *obj, const char *name, Error **errp);
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void visit_type_int16(Visitor *v, int16_t *obj, const char *name, Error **errp);
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void visit_type_int32(Visitor *v, int32_t *obj, const char *name, Error **errp);
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void visit_type_int64(Visitor *v, int64_t *obj, const char *name, Error **errp);
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void visit_type_size(Visitor *v, uint64_t *obj, const char *name, Error **errp);
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void visit_type_bool(Visitor *v, bool *obj, const char *name, Error **errp);
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void visit_type_str(Visitor *v, char **obj, const char *name, Error **errp);
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void visit_type_number(Visitor *v, double *obj, const char *name, Error **errp);
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2018-02-19 22:45:25 +00:00
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void visit_type_any(Visitor *v, QObject **obj, const char *name, Error **errp);
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2015-08-21 07:04:50 +00:00
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bool visit_start_union(Visitor *v, bool data_present, Error **errp);
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#endif
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