drlvm/vm/vmcore/src/verifier-3363/base/vf_resolve.cpp

/*
 *  Licensed to the Apache Software Foundation (ASF) under one or more
 *  contributor license agreements.  See the NOTICE file distributed with
 *  this work for additional information regarding copyright ownership.
 *  The ASF licenses this file to You under the Apache License, Version 2.0
 *  (the "License"); you may not use this file except in compliance with
 *  the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 */
#include "open/vm_class_manipulation.h"
#include "open/vm_class_loading.h"

#include "verifier.h"
#include "context_base.h"

/**
 * Checkes constraint for given class and loads classes if it's needed.
 */
vf_Result vf_force_check_constraint(Class_Handle klass,
    vf_TypeConstraint* constraint)    // class constraint
{
    // get target class
    Class_Handle target = vf_resolve_class( klass, constraint->target, true );
    if( !target ) {
        return VF_ErrorLoadClass;
    }

    //no need to load the source
    if(class_is_interface(target)){
        return VF_OK;
    }


    // get stack reference class
    Class_Handle source = vf_resolve_class( klass, constraint->source, true );
    if( !source ) {
        return VF_ErrorLoadClass;
    }

    // check restriction
    if( !vf_is_extending( source, target ) ) {
        return VF_ErrorIncompatibleArgument;
    }
    return VF_OK;
} // vf_force_check_constraint


/**
 * Returns true if 'from' is (not necessarily directly) extending 'to'.
 */
int vf_is_extending(Class_Handle from, Class_Handle to) {
    while (from) {
        if( from == to ) return true;
        from = class_get_super_class(from);
    }
    return false;
}

/**
 * Receives class by given class name, loads it if it's needed.
 */
Class_Handle
    vf_resolve_class( Class_Handle k_class,    // current class
    const char *name,         // resolved class name
    bool need_load)      // load flag
{
    Class_Handle result;

    // get class loader
    Class_Loader_Handle class_loader = class_get_class_loader( k_class );

    result = need_load ?
        class_loader_load_class( class_loader, name )
        : class_loader_lookup_class( class_loader, name );

    //we assume that this pre-defined constant is not a valid class-handler
    assert(CLASS_NOT_LOADED != result);
    
    return result;
} // vf_resolve_class