content: /*
   * Copyright 2016 HuntBugs contributors
   * 
   * Licensed 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.
   */
  package one.util.huntbugs.detect;
  
  import com.strobel.assembler.metadata.MethodReference;
  import com.strobel.assembler.metadata.TypeReference;
  import com.strobel.decompiler.ast.AstCode;
  import com.strobel.decompiler.ast.Expression;
  
  import one.util.huntbugs.flow.ValuesFlow;
  import one.util.huntbugs.registry.MethodContext;
  import one.util.huntbugs.registry.anno.AstNodes;
  import one.util.huntbugs.registry.anno.AstVisitor;
  import one.util.huntbugs.registry.anno.WarningDefinition;
  import one.util.huntbugs.util.NodeChain;
  import one.util.huntbugs.util.Types;
  
  /**
   * @author Tagir Valeev
   *
   */
  @WarningDefinition(category="BadPractice", name="ReturnValueOfRead", maxScore=60)
  @WarningDefinition(category="BadPractice", name="ReturnValueOfSkip", maxScore=50)
  public class CheckReturnValue {
      @AstVisitor(nodes=AstNodes.EXPRESSIONS)
      public void visit(Expression expr, NodeChain nc, MethodContext mc) {
          if(nc.getNode() instanceof Expression)
              return;
          if(expr.getCode() == AstCode.InvokeVirtual || expr.getCode() == AstCode.InvokeInterface) {
              MethodReference mr = (MethodReference) expr.getOperand();
              boolean skipMethod = mr.getName().equals("skip") && mr.getSignature().equals("(J)J") ||
                      mr.getName().equals("skipBytes") && mr.getSignature().equals("(I)I");
              boolean readMethod = mr.getName().equals("read") && (mr.getSignature().equals("([B)I") ||
                      mr.getSignature().equals("([BII)I") || mr.getSignature().equals("([C)I") ||
                      mr.getSignature().equals("([CII)I"));
              if(skipMethod || readMethod) {
                  TypeReference type = ValuesFlow.reduceType(expr.getArguments().get(0));
                  if(type == null)
                      type = mr.getDeclaringType();
                  if(!isInputStream(type))
                      return;
                  if(skipMethod && Types.isInstance(type, "javax/imageio/stream/ImageInputStream"))
                      return;
                  int priority = 0;
                  if(!Types.isInstance(type, "java/io/BufferedInputStream"))
                      priority += 15;
                  mc.report(skipMethod ? "ReturnValueOfSkip" : "ReturnValueOfRead", priority, expr);
              }
          }
      }
  
      private boolean isInputStream(TypeReference type) {
          return (Types.isInstance(type, "java/io/InputStream") && !Types.isInstance(type, "java/io/ByteArrayInputStream"))
              || Types.isInstance(type, "java/io/DataInput") || Types.isInstance(type, "java/io/Reader");
      }
  }
  