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.io.IOException;
20 import java.net.SocketException;
21 import libcore.io.Libcore;
22 
23 /**
24  * A checked exception thrown when {@link Os} methods fail. This exception contains the native
25  * errno value, for comparison against the constants in {@link OsConstants}, should sophisticated
26  * callers need to adjust their behavior based on the exact failure.
27  */
28 public final class ErrnoException extends Exception {
29     private final String functionName;
30 
31     /**
32      * The errno value, for comparison with the {@code E} constants in {@link OsConstants}.
33      */
34     public final int errno;
35 
36     /**
37      * Constructs an instance with the given function name and errno value.
38      */
ErrnoException(String functionName, int errno)39     public ErrnoException(String functionName, int errno) {
40         this.functionName = functionName;
41         this.errno = errno;
42     }
43 
44     /**
45      * Constructs an instance with the given function name, errno value, and cause.
46      */
ErrnoException(String functionName, int errno, Throwable cause)47     public ErrnoException(String functionName, int errno, Throwable cause) {
48         super(cause);
49         this.functionName = functionName;
50         this.errno = errno;
51     }
52 
53     /**
54      * Converts the stashed function name and errno value to a human-readable string.
55      * We do this here rather than in the constructor so that callers only pay for
56      * this if they need it.
57      */
getMessage()58     @Override public String getMessage() {
59         String errnoName = OsConstants.errnoName(errno);
60         if (errnoName == null) {
61             errnoName = "errno " + errno;
62         }
63         String description = Libcore.os.strerror(errno);
64         return functionName + " failed: " + errnoName + " (" + description + ")";
65     }
66 
67     /**
68      * @hide - internal use only.
69      */
70     @libcore.api.CorePlatformApi
rethrowAsIOException()71     public IOException rethrowAsIOException() throws IOException {
72         IOException newException = new IOException(getMessage());
73         newException.initCause(this);
74         throw newException;
75     }
76 
77     /**
78      * @hide - internal use only.
79      */
80     @libcore.api.CorePlatformApi
81     @libcore.api.IntraCoreApi
rethrowAsSocketException()82     public SocketException rethrowAsSocketException() throws SocketException {
83         throw new SocketException(getMessage(), this);
84     }
85 }
86