unicorn/qemu/qapi/qapi-visit-core.c

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/*
* Core Definitions for QAPI Visitor Classes
*
* Copyright IBM, Corp. 2011
*
* Authors:
* Anthony Liguori <aliguori@us.ibm.com>
*
* This work is licensed under the terms of the GNU LGPL, version 2.1 or later.
* See the COPYING.LIB file in the top-level directory.
*
*/
#include "qemu/osdep.h"
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#include "qemu-common.h"
#include "qapi/qmp/qobject.h"
#include "qapi/qmp/qerror.h"
#include "qapi/visitor.h"
#include "qapi/visitor-impl.h"
void visit_start_struct(Visitor *v, void **obj, const char *kind,
const char *name, size_t size, Error **errp)
{
v->start_struct(v, obj, kind, name, size, errp);
}
void visit_end_struct(Visitor *v, Error **errp)
{
v->end_struct(v, errp);
}
void visit_start_implicit_struct(Visitor *v, void **obj, size_t size,
Error **errp)
{
if (v->start_implicit_struct) {
v->start_implicit_struct(v, obj, size, errp);
}
}
void visit_end_implicit_struct(Visitor *v)
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{
if (v->end_implicit_struct) {
v->end_implicit_struct(v);
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}
}
void visit_start_list(Visitor *v, const char *name, Error **errp)
{
v->start_list(v, name, errp);
}
GenericList *visit_next_list(Visitor *v, GenericList **list)
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{
return v->next_list(v, list);
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}
void visit_end_list(Visitor *v)
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{
v->end_list(v);
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}
bool visit_start_union(Visitor *v, bool data_present, Error **errp)
{
if (v->start_union) {
return v->start_union(v, data_present, errp);
}
return true;
}
void visit_end_union(Visitor *v, bool data_present, Error **errp)
{
if (v->end_union) {
v->end_union(v, data_present, errp);
}
}
void visit_optional(Visitor *v, bool *present, const char *name,
Error **errp)
{
if (v->optional) {
v->optional(v, present, name, errp);
}
}
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 03:51:35 +01:00
void visit_get_next_type(Visitor *v, QType *type,
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const char *name, Error **errp)
{
if (v->get_next_type) {
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 03:51:35 +01:00
v->get_next_type(v, type, name, errp);
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}
}
void visit_type_enum(Visitor *v, int *obj, const char * const strings[],
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const char *kind, const char *name, Error **errp)
{
v->type_enum(v, obj, strings, kind, name, errp);
}
void visit_type_int(Visitor *v, int64_t *obj, const char *name, Error **errp)
{
v->type_int64(v, obj, name, errp);
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}
void visit_type_uint8(Visitor *v, uint8_t *obj, const char *name, Error **errp)
{
uint64_t value;
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if (v->type_uint8) {
v->type_uint8(v, obj, name, errp);
} else {
value = *obj;
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,
name ? name : "null", "uint8_t");
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return;
}
*obj = (uint8_t)value;
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}
}
void visit_type_uint16(Visitor *v, uint16_t *obj, const char *name, Error **errp)
{
uint64_t value;
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if (v->type_uint16) {
v->type_uint16(v, obj, name, errp);
} else {
value = *obj;
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,
name ? name : "null", "uint16_t");
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return;
}
*obj = (uint16_t)value;
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}
}
void visit_type_uint32(Visitor *v, uint32_t *obj, const char *name, Error **errp)
{
uint64_t value;
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if (v->type_uint32) {
v->type_uint32(v, obj, name, errp);
} else {
value = *obj;
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,
name ? name : "null", "uint32_t");
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return;
}
*obj = (uint32_t)value;
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}
}
void visit_type_uint64(Visitor *v, uint64_t *obj, const char *name, Error **errp)
{
v->type_uint64(v, obj, name, errp);
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}
void visit_type_int8(Visitor *v, int8_t *obj, const char *name, Error **errp)
{
int64_t value;
if (v->type_int8) {
v->type_int8(v, obj, name, errp);
} else {
value = *obj;
v->type_int64(v, &value, name, errp);
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if (value < INT8_MIN || value > INT8_MAX) {
/* FIXME questionable reuse of errp if callback changed
value on error */
error_setg(errp, QERR_INVALID_PARAMETER_VALUE,
name ? name : "null", "int8_t");
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return;
}
*obj = (int8_t)value;
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}
}
void visit_type_int16(Visitor *v, int16_t *obj, const char *name, Error **errp)
{
int64_t value;
if (v->type_int16) {
v->type_int16(v, obj, name, errp);
} else {
value = *obj;
v->type_int64(v, &value, name, errp);
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if (value < INT16_MIN || value > INT16_MAX) {
/* FIXME questionable reuse of errp if callback changed
value on error */
error_setg(errp, QERR_INVALID_PARAMETER_VALUE,
name ? name : "null", "int16_t");
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return;
}
*obj = (int16_t)value;
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}
}
void visit_type_int32(Visitor *v, int32_t *obj, const char *name, Error **errp)
{
int64_t value;
if (v->type_int32) {
v->type_int32(v, obj, name, errp);
} else {
value = *obj;
v->type_int64(v, &value, name, errp);
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if (value < INT32_MIN || value > INT32_MAX) {
/* FIXME questionable reuse of errp if callback changed
value on error */
error_setg(errp, QERR_INVALID_PARAMETER_VALUE,
name ? name : "null", "int32_t");
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return;
}
*obj = (int32_t)value;
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}
}
void visit_type_int64(Visitor *v, int64_t *obj, const char *name, Error **errp)
{
v->type_int64(v, obj, name, errp);
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}
void visit_type_size(Visitor *v, uint64_t *obj, const char *name, Error **errp)
{
if (v->type_size) {
v->type_size(v, obj, name, errp);
} else {
v->type_uint64(v, obj, name, errp);
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}
}
void visit_type_bool(Visitor *v, bool *obj, const char *name, Error **errp)
{
v->type_bool(v, obj, name, errp);
}
void visit_type_str(Visitor *v, char **obj, const char *name, Error **errp)
{
v->type_str(v, obj, name, errp);
}
void visit_type_number(Visitor *v, double *obj, const char *name, Error **errp)
{
v->type_number(v, obj, name, errp);
}
void visit_type_any(Visitor *v, QObject **obj, const char *name,
Error **errp)
{
v->type_any(v, obj, name, errp);
}
void output_type_enum(Visitor *v, int *obj, const char * const strings[],
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const char *kind, const char *name,
Error **errp)
{
int i = 0;
int value = *obj;
char *enum_str;
assert(strings);
while (strings[i++] != NULL);
if (value < 0 || value >= i - 1) {
error_setg(errp, QERR_INVALID_PARAMETER, name ? name : "null");
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return;
}
enum_str = (char *)strings[value];
visit_type_str(v, &enum_str, name, errp);
}
void input_type_enum(Visitor *v, int *obj, const char * const strings[],
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const char *kind, const char *name,
Error **errp)
{
Error *local_err = NULL;
int64_t value = 0;
char *enum_str;
assert(strings);
visit_type_str(v, &enum_str, name, &local_err);
if (local_err) {
error_propagate(errp, local_err);
return;
}
while (strings[value] != NULL) {
if (strcmp(strings[value], enum_str) == 0) {
break;
}
value++;
}
if (strings[value] == NULL) {
error_setg(errp, QERR_INVALID_PARAMETER, enum_str);
g_free(enum_str);
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return;
}
g_free(enum_str);
*obj = (int)value;
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}