/*
* Copyright (C) 2007 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
/*
* As per the Apache license requirements, this file has been modified
* from its original state.
*
* Such modifications are Copyright (C) 2010 Ben Gruver, and are released
* under the original license
*/
package org.jf.dexlib.Util;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
/**
* File I/O utilities.
*/
public final class FileUtils {
/**
* This class is uninstantiable.
*/
private FileUtils() {
// This space intentionally left blank.
}
/**
* Reads the named file, translating {@link IOException} to a
* {@link RuntimeException} of some sort.
*
* @param fileName non-null; name of the file to read
* @return non-null; contents of the file
*/
public static byte[] readFile(String fileName)
throws IOException {
File file = new File(fileName);
return readFile(file);
}
/**
* Reads the given file, translating {@link IOException} to a
* {@link RuntimeException} of some sort.
*
* @param file non-null; the file to read
* @return non-null; contents of the file
*/
public static byte[] readFile(File file)
throws IOException {
return readFile(file, 0, -1);
}
/**
* Reads the specified block from the given file, translating
* {@link IOException} to a {@link RuntimeException} of some sort.
*
* @param file non-null; the file to read
* @param offset the offset to begin reading
* @param length the number of bytes to read, or -1 to read to the
* end of the file
* @return non-null; contents of the file
*/
public static byte[] readFile(File file, int offset, int length)
throws IOException {
if (!file.exists()) {
throw new RuntimeException(file + ": file not found");
}
if (!file.isFile()) {
throw new RuntimeException(file + ": not a file");
}
if (!file.canRead()) {
throw new RuntimeException(file + ": file not readable");
}
long longLength = file.length();
int fileLength = (int) longLength;
if (fileLength != longLength) {
throw new RuntimeException(file + ": file too long");
}
if (length == -1) {
length = fileLength - offset;
}
if (offset + length > fileLength) {
throw new RuntimeException(file + ": file too short");
}
FileInputStream in = new FileInputStream(file);
int at = offset;
while(at > 0) {
long amt = in.skip(at);
if (amt == -1) {
throw new RuntimeException(file + ": unexpected EOF");
}
at -= amt;
}
byte[] result = readStream(in, length);
in.close();
return result;
}
public static byte[] readStream(InputStream in, int length)
throws IOException {
byte[] result = new byte[length];
int at=0;
while (length > 0) {
int amt = in.read(result, at, length);
if (amt == -1) {
throw new RuntimeException("unexpected EOF");
}
at += amt;
length -= amt;
}
return result;
}
}