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 import libcore.util.NonNull; 23 24 /** 25 * A checked exception thrown when {@link Os} methods fail. This exception contains the native 26 * errno value, for comparison against the constants in {@link OsConstants}, should sophisticated 27 * callers need to adjust their behavior based on the exact failure. 28 */ 29 public final class ErrnoException extends Exception { 30 private final String functionName; 31 32 /** 33 * The errno value, for comparison with the {@code E} constants in {@link OsConstants}. 34 */ 35 public final int errno; 36 37 /** 38 * Constructs an instance with the given function name and errno value. 39 */ ErrnoException(String functionName, int errno)40 public ErrnoException(String functionName, int errno) { 41 this.functionName = functionName; 42 this.errno = errno; 43 } 44 45 /** 46 * Constructs an instance with the given function name, errno value, and cause. 47 */ ErrnoException(String functionName, int errno, Throwable cause)48 public ErrnoException(String functionName, int errno, Throwable cause) { 49 super(cause); 50 this.functionName = functionName; 51 this.errno = errno; 52 } 53 54 /** 55 * Converts the stashed function name and errno 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 errnoName = OsConstants.errnoName(errno); 61 if (errnoName == null) { 62 errnoName = "errno " + errno; 63 } 64 String description = Libcore.os.strerror(errno); 65 return functionName + " failed: " + errnoName + " (" + description + ")"; 66 } 67 68 /** 69 * Throws an {@link IOException} with a message based on {@link #getMessage()} and with this 70 * instance as the cause. 71 * 72 * <p>This method always terminates by throwing the exception. Callers can write 73 * {@code throw e.rethrowAsIOException()} to make that clear to the compiler. 74 */ rethrowAsIOException()75 public @NonNull IOException rethrowAsIOException() throws IOException { 76 IOException newException = new IOException(getMessage()); 77 newException.initCause(this); 78 throw newException; 79 } 80 81 /** 82 * Throws a {@link SocketException} with a message based on {@link #getMessage()} and with this 83 * instance as the cause. 84 * 85 * <p>This method always terminates by throwing the exception. Callers can write 86 * {@code throw e.rethrowAsIOException()} to make that clear to the compiler. 87 */ rethrowAsSocketException()88 public @NonNull SocketException rethrowAsSocketException() throws SocketException { 89 throw new SocketException(getMessage(), this); 90 } 91 } 92