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path: root/contrib/libs/hyperscan/src/parser/check_refs.cpp
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/* 
 * Copyright (c) 2015-2017, Intel Corporation
 * 
 * Redistribution and use in source and binary forms, with or without 
 * modification, are permitted provided that the following conditions are met: 
 * 
 *  * Redistributions of source code must retain the above copyright notice, 
 *    this list of conditions and the following disclaimer. 
 *  * Redistributions in binary form must reproduce the above copyright 
 *    notice, this list of conditions and the following disclaimer in the 
 *    documentation and/or other materials provided with the distribution. 
 *  * Neither the name of Intel Corporation nor the names of its contributors 
 *    may be used to endorse or promote products derived from this software 
 *    without specific prior written permission. 
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" 
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE 
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 
 * POSSIBILITY OF SUCH DAMAGE. 
 */ 
 
/** \file 
 * \brief Component tree analysis that checks that references (such as 
 * back-refs, conditionals) have valid referents. 
 */ 
#include "check_refs.h" 
#include "ComponentBackReference.h" 
#include "ComponentCondReference.h" 
#include "ConstComponentVisitor.h" 
#include "parse_error.h" 
#include "util/container.h" 
#include "util/flat_containers.h"
 
#include <sstream> 
 
using namespace std; 
 
namespace ue2 { 
 
/** 
 * \brief Visitor that checks the validity of references against a known list 
 * of indices and labels. 
 */ 
class ReferenceVisitor: public DefaultConstComponentVisitor { 
private: 
    const size_t num_ids; 
    const flat_set<string> &names; 
 
public: 
    ReferenceVisitor(size_t num_groups, const flat_set<string> &targets) 
        : num_ids(num_groups), names(targets) {} 
 
    ~ReferenceVisitor() override; 
 
    void invalid_index(const char *component, unsigned id) { 
        assert(component); 
        ostringstream str; 
        str << "Invalid " << component << " to expression " << id << "."; 
        throw ParseError(str.str()); 
    } 
 
    void invalid_label(const char *component, const std::string &label) { 
        assert(component); 
        ostringstream str; 
        str << "Invalid " << component << " to label '" << label << "'."; 
        throw ParseError(str.str()); 
    } 
 
    using DefaultConstComponentVisitor::pre;

    void pre(const ComponentBackReference &c) override { 
        if (c.ref_id) { 
            if (c.ref_id >= num_ids) { 
                invalid_index("back reference", c.ref_id); 
            } 
        } else { 
            if (!contains(names, c.name)) { 
                invalid_label("back reference", c.name); 
            } 
        } 
    } 
 
    void pre(const ComponentCondReference &c) override { 
        switch (c.kind) { 
        case ComponentCondReference::CONDITION_NUMBER: 
            if (c.ref_id >= num_ids) { 
                invalid_index("conditional reference", c.ref_id); 
            } 
            break; 
        case ComponentCondReference::CONDITION_NAME: 
            if (c.ref_name == "DEFINE") { 
                // The string "DEFINE" is a special "always false" condition 
                // used to define subroutines. 
                break; 
            } 
            if (!contains(names, c.ref_name)) { 
                invalid_label("conditional reference", c.ref_name); 
            } 
            break; 
        case ComponentCondReference::CONDITION_ASSERTION: 
            break; 
        } 
    } 
}; 
 
// Out-of-line destructor to silence weak vtable warnings. 
ReferenceVisitor::~ReferenceVisitor() {} 
 
void checkReferences(const Component &root, unsigned int groupIndices, 
                     const flat_set<std::string> &groupNames) {
    ReferenceVisitor vis(groupIndices, groupNames); 
    root.accept(vis); 
} 
 
} // namespace ue2