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      1 /*
      2  * Copyright (C) 2011 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 package android.system;
     18 
     19 import java.net.UnknownHostException;
     20 import libcore.io.Libcore;
     21 
     22 /**
     23  * An unchecked exception thrown when {@code getaddrinfo} or {@code getnameinfo} fails.
     24  * This exception contains the native {@link #error} value, should sophisticated
     25  * callers need to adjust their behavior based on the exact failure.
     26  *
     27  * @hide
     28  */
     29 public final class GaiException extends RuntimeException {
     30   private final String functionName;
     31 
     32   /**
     33    * The native error value, for comparison with the {@code GAI_} constants in {@link OsConstants}.
     34    */
     35   public final int error;
     36 
     37   /**
     38    * Constructs an instance with the given function name and error value.
     39    */
     40   public GaiException(String functionName, int error) {
     41     this.functionName = functionName;
     42     this.error = error;
     43   }
     44 
     45   /**
     46    * Constructs an instance with the given function name, error value, and cause.
     47    */
     48   public GaiException(String functionName, int error, Throwable cause) {
     49     super(cause);
     50     this.functionName = functionName;
     51     this.error = error;
     52   }
     53 
     54   /**
     55    * Converts the stashed function name and error value to a human-readable string.
     56    * We do this here rather than in the constructor so that callers only pay for
     57    * this if they need it.
     58    */
     59   @Override public String getMessage() {
     60     String gaiName = OsConstants.gaiName(error);
     61     if (gaiName == null) {
     62       gaiName = "GAI_ error " + error;
     63     }
     64     String description = Libcore.os.gai_strerror(error);
     65     return functionName + " failed: " + gaiName + " (" + description + ")";
     66   }
     67 
     68   /**
     69    * @hide - internal use only.
     70    */
     71   public UnknownHostException rethrowAsUnknownHostException(String detailMessage) throws UnknownHostException {
     72     UnknownHostException newException = new UnknownHostException(detailMessage);
     73     newException.initCause(this);
     74     throw newException;
     75   }
     76 
     77   /**
     78    * @hide - internal use only.
     79    */
     80   public UnknownHostException rethrowAsUnknownHostException() throws UnknownHostException {
     81     throw rethrowAsUnknownHostException(getMessage());
     82   }
     83 }
     84