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      */
GaiException(String functionName, int error)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      */
GaiException(String functionName, int error, Throwable cause)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      */
getMessage()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      */
rethrowAsUnknownHostException(String detailMessage)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      */
rethrowAsUnknownHostException()80     public UnknownHostException rethrowAsUnknownHostException() throws UnknownHostException {
81         throw rethrowAsUnknownHostException(getMessage());
82     }
83 }
84