Returning a partial object on error is an invitation for a careless
caller to leak memory.  We already fixed things in an earlier
patch to guarantee NULL if visit_start fails ("qapi: Guarantee
NULL obj on input visitor callback error"), but that does not
help the case where visit_start succeeds but some other failure
happens before visit_end, such that we leak a partially constructed
object outside visit_type_FOO(). As no one outside the testsuite
was actually relying on these semantics, it is cleaner to just
document and guarantee that ALL pointer-based visit_type_FOO()
functions always leave a safe value in *obj during an input visitor
(either the new object on success, or NULL if an error is
encountered), so callers can now unconditionally use
qapi_free_FOO() to clean up regardless of whether an error occurred.
The decision is done by adding visit_is_input(), then updating the
generated code to check if additional cleanup is needed based on
the type of visitor in use.
Note that we still leave *obj unchanged after a scalar-based
visit_type_FOO(); I did not feel like auditing all uses of
visit_type_Enum() to see if the callers would tolerate a specific
sentinel value (not to mention having to decide whether it would
be better to use 0 or ENUM__MAX as that sentinel).
Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <1461879932-9020-25-git-send-email-eblake@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>
		
	
			
		
			
				
	
	
		
			329 lines
		
	
	
		
			8.0 KiB
		
	
	
	
		
			C
		
	
	
	
	
	
			
		
		
	
	
			329 lines
		
	
	
		
			8.0 KiB
		
	
	
	
		
			C
		
	
	
	
	
	
/*
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 * Core Definitions for QAPI Visitor Classes
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 *
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 * Copyright (C) 2012-2016 Red Hat, Inc.
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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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#include "qemu/osdep.h"
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#include "qapi/error.h"
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#include "qemu-common.h"
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#include "qapi/qmp/qobject.h"
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#include "qapi/qmp/qerror.h"
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#include "qapi/visitor.h"
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#include "qapi/visitor-impl.h"
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void visit_start_struct(Visitor *v, const char *name, void **obj,
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                        size_t size, Error **errp)
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{
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    Error *err = NULL;
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    if (obj) {
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        assert(size);
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        assert(v->type != VISITOR_OUTPUT || *obj);
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    }
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    v->start_struct(v, name, obj, size, &err);
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    if (obj && v->type == VISITOR_INPUT) {
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        assert(!err != !*obj);
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    }
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    error_propagate(errp, err);
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}
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void visit_check_struct(Visitor *v, Error **errp)
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{
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    if (v->check_struct) {
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        v->check_struct(v, errp);
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    }
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}
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void visit_end_struct(Visitor *v)
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{
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    v->end_struct(v);
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}
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void visit_start_list(Visitor *v, const char *name, GenericList **list,
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                      size_t size, Error **errp)
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{
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    Error *err = NULL;
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    assert(!list || size >= sizeof(GenericList));
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    v->start_list(v, name, list, size, &err);
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    if (list && v->type == VISITOR_INPUT) {
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        assert(!(err && *list));
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    }
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    error_propagate(errp, err);
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}
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GenericList *visit_next_list(Visitor *v, GenericList *tail, size_t size)
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{
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    assert(tail && size >= sizeof(GenericList));
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    return v->next_list(v, tail, size);
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}
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void visit_end_list(Visitor *v)
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{
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    v->end_list(v);
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}
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void visit_start_alternate(Visitor *v, const char *name,
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                           GenericAlternate **obj, size_t size,
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                           bool promote_int, Error **errp)
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{
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    Error *err = NULL;
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    assert(obj && size >= sizeof(GenericAlternate));
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    assert(v->type != VISITOR_OUTPUT || *obj);
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    if (v->start_alternate) {
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        v->start_alternate(v, name, obj, size, promote_int, &err);
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    }
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    if (v->type == VISITOR_INPUT) {
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        assert(v->start_alternate && !err != !*obj);
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    }
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    error_propagate(errp, err);
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}
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void visit_end_alternate(Visitor *v)
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{
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    if (v->end_alternate) {
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        v->end_alternate(v);
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    }
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}
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bool visit_optional(Visitor *v, const char *name, bool *present)
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{
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    if (v->optional) {
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        v->optional(v, name, present);
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    }
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    return *present;
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}
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bool visit_is_input(Visitor *v)
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{
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    return v->type == VISITOR_INPUT;
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}
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void visit_type_int(Visitor *v, const char *name, int64_t *obj, Error **errp)
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{
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    assert(obj);
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    v->type_int64(v, name, obj, errp);
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}
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static void visit_type_uintN(Visitor *v, uint64_t *obj, const char *name,
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                             uint64_t max, const char *type, Error **errp)
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{
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    Error *err = NULL;
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    uint64_t value = *obj;
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    v->type_uint64(v, name, &value, &err);
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    if (err) {
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        error_propagate(errp, err);
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    } else if (value > max) {
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        error_setg(errp, QERR_INVALID_PARAMETER_VALUE,
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                   name ? name : "null", type);
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    } else {
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        *obj = value;
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    }
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}
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void visit_type_uint8(Visitor *v, const char *name, uint8_t *obj,
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                      Error **errp)
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{
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    uint64_t value = *obj;
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    visit_type_uintN(v, &value, name, UINT8_MAX, "uint8_t", errp);
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    *obj = value;
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}
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void visit_type_uint16(Visitor *v, const char *name, uint16_t *obj,
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                       Error **errp)
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{
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    uint64_t value = *obj;
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    visit_type_uintN(v, &value, name, UINT16_MAX, "uint16_t", errp);
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    *obj = value;
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}
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void visit_type_uint32(Visitor *v, const char *name, uint32_t *obj,
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                       Error **errp)
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{
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    uint64_t value = *obj;
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    visit_type_uintN(v, &value, name, UINT32_MAX, "uint32_t", errp);
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    *obj = value;
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}
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void visit_type_uint64(Visitor *v, const char *name, uint64_t *obj,
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                       Error **errp)
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{
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    assert(obj);
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    v->type_uint64(v, name, obj, errp);
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}
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static void visit_type_intN(Visitor *v, int64_t *obj, const char *name,
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                            int64_t min, int64_t max, const char *type,
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                            Error **errp)
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{
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    Error *err = NULL;
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    int64_t value = *obj;
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    v->type_int64(v, name, &value, &err);
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    if (err) {
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        error_propagate(errp, err);
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    } else if (value < min || value > max) {
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        error_setg(errp, QERR_INVALID_PARAMETER_VALUE,
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                   name ? name : "null", type);
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    } else {
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        *obj = value;
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    }
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}
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void visit_type_int8(Visitor *v, const char *name, int8_t *obj, Error **errp)
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{
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    int64_t value = *obj;
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    visit_type_intN(v, &value, name, INT8_MIN, INT8_MAX, "int8_t", errp);
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    *obj = value;
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}
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void visit_type_int16(Visitor *v, const char *name, int16_t *obj,
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                      Error **errp)
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{
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    int64_t value = *obj;
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    visit_type_intN(v, &value, name, INT16_MIN, INT16_MAX, "int16_t", errp);
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    *obj = value;
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}
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void visit_type_int32(Visitor *v, const char *name, int32_t *obj,
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                      Error **errp)
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{
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    int64_t value = *obj;
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    visit_type_intN(v, &value, name, INT32_MIN, INT32_MAX, "int32_t", errp);
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    *obj = value;
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}
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void visit_type_int64(Visitor *v, const char *name, int64_t *obj,
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                      Error **errp)
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{
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    assert(obj);
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    v->type_int64(v, name, obj, errp);
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}
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void visit_type_size(Visitor *v, const char *name, uint64_t *obj,
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                     Error **errp)
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{
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    assert(obj);
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    if (v->type_size) {
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        v->type_size(v, name, obj, errp);
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    } else {
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        v->type_uint64(v, name, obj, errp);
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    }
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}
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void visit_type_bool(Visitor *v, const char *name, bool *obj, Error **errp)
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{
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    assert(obj);
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    v->type_bool(v, name, obj, errp);
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}
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void visit_type_str(Visitor *v, const char *name, char **obj, Error **errp)
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{
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    Error *err = NULL;
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    assert(obj);
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    /* TODO: Fix callers to not pass NULL when they mean "", so that we
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     * can enable:
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    assert(v->type != VISITOR_OUTPUT || *obj);
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     */
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    v->type_str(v, name, obj, &err);
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    if (v->type == VISITOR_INPUT) {
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        assert(!err != !*obj);
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    }
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    error_propagate(errp, err);
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}
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void visit_type_number(Visitor *v, const char *name, double *obj,
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                       Error **errp)
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{
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    assert(obj);
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    v->type_number(v, name, obj, errp);
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}
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void visit_type_any(Visitor *v, const char *name, QObject **obj, Error **errp)
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{
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    Error *err = NULL;
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    assert(obj);
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    assert(v->type != VISITOR_OUTPUT || *obj);
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    v->type_any(v, name, obj, &err);
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    if (v->type == VISITOR_INPUT) {
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        assert(!err != !*obj);
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    }
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    error_propagate(errp, err);
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}
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void visit_type_null(Visitor *v, const char *name, Error **errp)
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{
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    v->type_null(v, name, errp);
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}
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static void output_type_enum(Visitor *v, const char *name, int *obj,
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                             const char *const strings[], Error **errp)
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{
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    int i = 0;
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    int value = *obj;
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    char *enum_str;
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    while (strings[i++] != NULL);
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    if (value < 0 || value >= i - 1) {
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        error_setg(errp, QERR_INVALID_PARAMETER, name ? name : "null");
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        return;
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    }
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    enum_str = (char *)strings[value];
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    visit_type_str(v, name, &enum_str, errp);
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}
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static void input_type_enum(Visitor *v, const char *name, int *obj,
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                            const char *const strings[], Error **errp)
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{
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    Error *local_err = NULL;
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    int64_t value = 0;
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    char *enum_str;
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    visit_type_str(v, name, &enum_str, &local_err);
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    if (local_err) {
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        error_propagate(errp, local_err);
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        return;
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    }
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    while (strings[value] != NULL) {
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        if (strcmp(strings[value], enum_str) == 0) {
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            break;
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        }
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        value++;
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    }
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    if (strings[value] == NULL) {
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        error_setg(errp, QERR_INVALID_PARAMETER, enum_str);
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        g_free(enum_str);
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        return;
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    }
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    g_free(enum_str);
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    *obj = value;
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}
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void visit_type_enum(Visitor *v, const char *name, int *obj,
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                     const char *const strings[], Error **errp)
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{
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    assert(obj && strings);
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    if (v->type == VISITOR_INPUT) {
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        input_type_enum(v, name, obj, strings, errp);
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    } else if (v->type == VISITOR_OUTPUT) {
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        output_type_enum(v, name, obj, strings, errp);
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    }
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}
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