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    */
rethrowAsIOException()70   public IOException rethrowAsIOException() throws IOException {
71     IOException newException = new IOException(getMessage());
72     newException.initCause(this);
73     throw newException;
74   }
75 
76   /**
77    * @hide - internal use only.
78    */
rethrowAsSocketException()79   public SocketException rethrowAsSocketException() throws SocketException {
80     throw new SocketException(getMessage(), this);
81   }
82 }
83