/*
* @(#)ResourceInputStream.java 1.19 02/09/04 @(#)
*
* Copyright (c) 1999-2002 Sun Microsystems, Inc. All rights reserved.
* PROPRIETARY/CONFIDENTIAL
* Use is subject to license terms.
*/
package com.sun.midp.io;
import java.io.IOException;
import java.io.InputStream;
import java.util.Vector;
import java.util.Enumeration;
/**
* Input stream class for accessing resource files in classpath.
*/
public class ResourceInputStream extends InputStream {
/**
* native handle to underlying stream
*/
private int handle = -1;
/**
* The index of the next character to read from the input stream buffer.
* This value should always be nonnegative
* and not larger than the value of <code>size</code>.
*/
protected int pos;
/**
* The index one greater than the last valid character in the input
* stream buffer.
* This value should always be nonnegative.
*/
protected int size;
/**
* Fixes the resource name to be conformant with the CLDC 1.0
* specification. We are not allowed to use "../" to get outside
* of the .jar file.
*
* @param name the name of the resource in classpath to access.
* @return the fixed string.
* @exception IOException if the resource name points to a
* classfile, as determined by the resource name's
* extension.
*/
private String fixResourceName(String name) throws IOException {
Vector dirVector = new Vector();
int startIdx = 0;
int endIdx = 0;
String curDir;
while ((endIdx = name.indexOf('/', startIdx)) != -1) {
if (endIdx == startIdx) {
// We have a leading '/' or two consecutive '/'s
startIdx++;
continue;
}
curDir = name.substring(startIdx, endIdx);
startIdx = endIdx + 1;
if (curDir.equals(".")) {
// Ignore a single '.' directory
continue;
}
if (curDir.equals("..")) {
// Go up a level
int size = dirVector.size();
if (size > 0) {
dirVector.removeElementAt(size - 1);
} else {
// Do not allow "/../resource"
throw new IOException();
}
continue;
}
dirVector.addElement(curDir);
}
// save directory structure
int nameLength = name.length();
StringBuffer dirName = new StringBuffer(nameLength);
int numElements = dirVector.size();
for (int i = 0; i < numElements; i++) {
dirName.append((String)dirVector.elementAt(i));
dirName.append("/");
}
// save filename
if (startIdx < nameLength) {
String filename = name.substring(startIdx);
// Throw IOE if the resource ends with ".class", but, not
// if the entire name is ".class"
if ((filename.endsWith(".class")) &&
(! ".class".equals(filename))) {
throw new IOException();
}
dirName.append(name.substring(startIdx));
}
return dirName.toString();
}
/**
* Construct a resource input stream for accessing objects in the jar file.
*
* @param name the name of the resource in classpath to access. The
* name must not have a leading '/'.
* @exception IOException if an I/O error occurs.
*/
public ResourceInputStream(String name) throws IOException {
if (handle != -1) {
throw new IOException();
}
String fixedName = fixResourceName(name);
handle = open(fixedName.getBytes()); // open() sets 'size' data member
pos = 0;
}
/**
* Reads the next byte of data from the input stream.
*
* @return the next byte of data, or <code>-1</code> if the end
* of the stream is reached.
* @exception IOException if an I/O error occurs.
*/
public int read() throws IOException {
if (pos < size) {
pos++;
} else {
return -1;
}
return read(handle);
}
/**
* Gets the number of bytes remaining to be read.
*
* @return the number of bytes remaining in the resource.
* @exception IOException if an I/O error occurs.
*/
public int available() throws IOException {
return size - pos;
}
/**
* Reads bytes into a byte array.
*
* @param b the buffer to read into.
* @param off offset to start at in the buffer.
* @param len number of bytes to read.
* @return the number of bytes read, or <code>-1</code> if the end
* of the stream is reached.
* @exception IOException if an I/O error occurs.
*/
public int read(byte b[], int off, int len) throws IOException {
if (b == null) {
throw new NullPointerException();
} else if ((off < 0) || (off > b.length) || (len < 0) ||
((off + len) > b.length) || ((off + len) < 0)) {
throw new IndexOutOfBoundsException();
}
if (pos >= size) {
return -1;
}
if (pos + len > size) {
len = size - pos;
}
if (len <= 0) {
return 0;
}
int result = readBytes(handle, b, off, pos, len);
if (result > -1) {
pos += result;
}
return result;
}
/**
* Resets the buffer position to zero.
* The value of <code>pos</code> is set to 0.
*/
public synchronized void reset() {
if (handle == -1) {
return;
}
pos = 0;
}
/**
* closes the open resource stream.
* @exception IOException if an I/O error occurs.
*/
public void close() throws IOException {
close(handle);
handle = -1;
}
/**
* native interface to open resource as stream.
* @param name name of the resource in CLASSPATH
* @return the Object reference to the located resource.
* @exception IOException if I/O error occurs.
*/
private native int open(byte name[]) throws IOException;
/**
* native interface to read a byte from the opened resource.
* @param handle for the opened resource
* @return a character read from the opened resource.
* @exception IOException if I/O error occurs.
*/
private native int read(int handle) throws IOException;
/**
* native interface to read bytes from the opened resource.
* @param handle for the opened resource
* @param b array for the data
* @param offset Offset in byte array to start reading into
* @param pos position in resource to start reading
* @param len number of bytes to read
* @return number of characters read into the buffer
* @exception IOException if I/O error occurs.
*/
private native int readBytes(int handle, byte[] b, int offset,
int pos, int len) throws IOException;
/**
* native interface to close the opened resource.
* @param handle for the opened resource
* @exception IOException if I/O error occurs.
*/
private native void close(int handle) throws IOException;
/**
* native finalizaion
*/
private native void finalize();
}
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