Extract Printable Strings From Binary File

package com.darwinsys;
 
/*
 * Copyright (c) Ian F. Darwin, http://www.darwinsys.com/, 1996-2002.
 * All rights reserved. Software written by Ian F. Darwin and others.
 * $Id: LICENSE,v 1.8 2004/02/09 03:33:38 ian Exp $
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS''
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS
 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 * 
 * Java, the Duke mascot, and all variants of Sun's Java "steaming coffee
 * cup" logo are trademarks of Sun Microsystems. Sun's, and James Gosling's,
 * pioneering role in inventing and promulgating (and standardizing) the Java 
 * language and environment is gratefully acknowledged.
 * 
 * The pioneering role of Dennis Ritchie and Bjarne Stroustrup, of AT&T, for
 * inventing predecessor languages C and C++ is also gratefully acknowledged.
 */
 
import java.io.BufferedInputStream;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
 
/**
 * Strings -- extract printable strings from binary file
 * 
 * @author Ian F. Darwin, http://www.darwinsys.com/
 * @version $Id: Strings.java,v 1.3 2004/02/08 23:57:29 ian Exp $
 */
 
public class Strings {
 
    protected int minLength = 4;
 
    /**
     * Return true if the character is printable IN ASCII. Not using
     * Character.isLetterOrDigit(); applies to all unicode ranges
     */
    protected boolean isStringChar(char ch) {
	if (ch >= 'a' && ch <= 'z')
	    return true;
	if (ch >= 'A' && ch <= 'Z')
	    return true;
	if (ch >= '0' && ch <= '9')
	    return true;
	switch (ch) {
	case '/':
	case '-':
	case ':':
	case '.':
	case ',':
	case '_':
	case '$':
	case '%':
	case '\'':
	case '(':
	case ')':
	case '[':
	case ']':
	case '<':
	case '>':
	    return true;
	}
	return false;
    }
 
    /** Process one file */
    protected void process(String fileName, InputStream inStream) {
	try {
	    int i;
	    char ch;
 
	    // This line alone cuts the runtime by about 66% on large files.
	    BufferedInputStream is = new BufferedInputStream(inStream);
 
	    StringBuffer sb = new StringBuffer();
 
	    // Read a byte, cast it to char, check if part of printable string.
	    while ((i = is.read()) != -1) {
		ch = (char) i;
		if (isStringChar(ch) || (sb.length() > 0 && ch == ' '))
		    // If so, build up string.
		    sb.append(ch);
		else {
		    // if not, see if anything to output.
		    if (sb.length() == 0)
			continue;
		    if (sb.length() >= minLength) {
			report(fileName, sb);
		    }
		    sb.setLength(0);
		}
	    }
	    is.close();
	} catch (IOException e) {
	    System.out.println("IOException: " + e);
	}
    }
 
    /**
     * This simple main program looks after filenames and opening files and such
     * like for you.
     */
    public static void main(String[] av) {
	Strings o = new Strings();
	if (av.length == 0) {
	    o.process("standard input", System.in);
	} else {
	    for (int i = 0; i < av.length; i++)
		try {
		    o.process(av[i], new FileInputStream(av[i]));
		} catch (FileNotFoundException e) {
		    System.err.println(e);
		}
	}
    }
 
    /** Output a match. Made a separate method for use by subclassers. */
    protected void report(String fName, StringBuffer theString) {
	System.out.println(fName + ": " + theString);
    }
}