/*
* This file is part of the Jikes RVM project (http://jikesrvm.org).
*
* This file is licensed to You under the Common Public License (CPL);
* You may not use this file except in compliance with the License. You
* may obtain a copy of the License at
*
* http://www.opensource.org/licenses/cpl1.0.php
*
* See the COPYRIGHT.txt file distributed with this work for information
* regarding copyright ownership.
*/
package org.jikesrvm.classloader;
import java.io.UTFDataFormatException;
/**
* VM_UTF8Convert
*
* Abstract class that contains conversion routines to/from utf8
* and/or pseudo-utf8. It does not support utf8 encodings of
* more than 3 bytes.
*
* The difference between utf8 and pseudo-utf8 is the special
* treatment of null. In utf8, null is encoded as a single byte
* directly, whereas in pseudo-utf8, it is encoded as a two-byte
* sequence. See the JVM spec for more information.
*/
public abstract class VM_UTF8Convert {
/**
* Strictly check the format of the utf8/pseudo-utf8 byte array in
* fromUTF8.
*/
static final boolean STRICTLY_CHECK_FORMAT = false;
/**
* Set fromUTF8 to not throw an exception when given a normal utf8
* byte array.
*/
static final boolean ALLOW_NORMAL_UTF8 = false;
/**
* Set fromUTF8 to not throw an exception when given a pseudo utf8
* byte array.
*/
static final boolean ALLOW_PSEUDO_UTF8 = true;
/**
* Set toUTF8 to write in pseudo-utf8 (rather than normal utf8).
*/
static final boolean WRITE_PSEUDO_UTF8 = true;
/**
* Convert the given sequence of (pseudo-)utf8 formatted bytes
* into a String.
*
* The acceptable input formats are controlled by the
* STRICTLY_CHECK_FORMAT, ALLOW_NORMAL_UTF8, and ALLOW_PSEUDO_UTF8
* flags.
*
* @param utf8 (pseudo-)utf8 byte array
* @throws UTFDataFormatException if the (pseudo-)utf8 byte array is not valid (pseudo-)utf8
* @return unicode string
*/
public static String fromUTF8(byte[] utf8) throws UTFDataFormatException {
char[] result = new char[utf8.length];
int result_index = 0;
for (int i = 0, n = utf8.length; i < n;) {
byte b = utf8[i++];
if (STRICTLY_CHECK_FORMAT && !ALLOW_NORMAL_UTF8) {
if (b == 0) {
throw new UTFDataFormatException("0 byte encountered at location " + (i - 1));
}
}
if (b >= 0) { // < 0x80 unsigned
// in the range '\001' to '\177'
result[result_index++] = (char) b;
continue;
}
try {
byte nb = utf8[i++];
if (b < -32) { // < 0xe0 unsigned
// '\000' or in the range '\200' to '\u07FF'
char c = result[result_index++] = (char) (((b & 0x1f) << 6) | (nb & 0x3f));
if (STRICTLY_CHECK_FORMAT) {
if (((b & 0xe0) != 0xc0) || ((nb & 0xc0) != 0x80)) {
throw new UTFDataFormatException("invalid marker bits for double byte char at location " + (i - 2));
}
if (c < '\200') {
if (!ALLOW_PSEUDO_UTF8 || (c != '\000')) {
throw new UTFDataFormatException(
"encountered double byte char that should have been single byte at location " + (i - 2));
}
} else if (c > '\u07FF') {
throw new UTFDataFormatException(
"encountered double byte char that should have been triple byte at location " + (i - 2));
}
}
} else {
byte nnb = utf8[i++];
// in the range '\u0800' to '\uFFFF'
char c = result[result_index++] = (char) (((b & 0x0f) << 12) | ((nb & 0x3f) << 6) | (nnb & 0x3f));
if (STRICTLY_CHECK_FORMAT) {
if (((b & 0xf0) != 0xe0) || ((nb & 0xc0) != 0x80) || ((nnb & 0xc0) != 0x80)) {
throw new UTFDataFormatException("invalid marker bits for triple byte char at location " + (i - 3));
}
if (c < '\u0800') {
throw new UTFDataFormatException(
"encountered triple byte char that should have been fewer bytes at location " + (i - 3));
}
}
}
} catch (ArrayIndexOutOfBoundsException e) {
throw new UTFDataFormatException("unexpected end at location " + i);
}
}
return new String(result, 0, result_index);
}
/**
* Convert the given String into a sequence of (pseudo-)utf8
* formatted bytes.
*
* The output format is controlled by the WRITE_PSEUDO_UTF8 flag.
*
* @param s String to convert
* @return array containing sequence of (pseudo-)utf8 formatted bytes
*/
public static byte[] toUTF8(String s) {
byte[] result = new byte[utfLength(s)];
int result_index = 0;
for (int i = 0, n = s.length(); i < n; ++i) {
char c = s.charAt(i);
// in all shifts below, c is an (unsigned) char,
// so either >>> or >> is ok
if (((!WRITE_PSEUDO_UTF8) || (c >= 0x0001)) && (c <= 0x007F)) {
result[result_index++] = (byte) c;
} else if (c > 0x07FF) {
result[result_index++] = (byte) (0xe0 | (byte) (c >> 12));
result[result_index++] = (byte) (0x80 | ((c & 0xfc0) >> 6));
result[result_index++] = (byte) (0x80 | (c & 0x3f));
} else {
result[result_index++] = (byte) (0xc0 | (byte) (c >> 6));
result[result_index++] = (byte) (0x80 | (c & 0x3f));
}
}
return result;
}
/**
* Returns the length of a string's UTF encoded form.
*/
public static int utfLength(String s) {
int utflen = 0;
for (int i = 0, n = s.length(); i < n; ++i) {
int c = s.charAt(i);
if (((!WRITE_PSEUDO_UTF8) || (c >= 0x0001)) && (c <= 0x007F)) {
++utflen;
} else if (c > 0x07FF) {
utflen += 3;
} else {
utflen += 2;
}
}
return utflen;
}
/**
* Check whether the given sequence of bytes is valid (pseudo-)utf8.
*
* @param bytes byte array to check
* @return true iff the given sequence is valid (pseudo-)utf8.
*/
public static boolean check(byte[] bytes) {
for (int i = 0, n = bytes.length; i < n;) {
byte b = bytes[i++];
if (!ALLOW_NORMAL_UTF8) {
if (b == 0) return false;
}
if (b >= 0) { // < 0x80 unsigned
// in the range '\001' to '\177'
continue;
}
try {
byte nb = bytes[i++];
if (b < -32) { // < 0xe0 unsigned
// '\000' or in the range '\200' to '\u07FF'
char c = (char) (((b & 0x1f) << 6) | (nb & 0x3f));
if (((b & 0xe0) != 0xc0) || ((nb & 0xc0) != 0x80)) {
return false;
}
if (c < '\200') {
if (!ALLOW_PSEUDO_UTF8 || (c != '\000')) {
return false;
}
} else if (c > '\u07FF') {
return false;
}
} else {
byte nnb = bytes[i++];
// in the range '\u0800' to '\uFFFF'
char c = (char) (((b & 0x0f) << 12) | ((nb & 0x3f) << 6) | (nnb & 0x3f));
if (((b & 0xf0) != 0xe0) || ((nb & 0xc0) != 0x80) || ((nnb & 0xc0) != 0x80)) {
return false;
}
if (c < '\u0800') {
return false;
}
}
} catch (ArrayIndexOutOfBoundsException e) {
return false;
}
}
return true;
}
}