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/*-------------------------------------------------------------------------
*
* Copyright (c) 2003-2011, PostgreSQL Global Development Group
*
*
*-------------------------------------------------------------------------
*/
package com.foundationdb.sql.jdbc.core;
import java.io.IOException;
import com.foundationdb.sql.jdbc.util.GT;
class UTF8Encoding extends Encoding {
UTF8Encoding(String jvmEncoding) {
super(jvmEncoding);
}
private static final int MIN_2_BYTES = 0x80;
private static final int MIN_3_BYTES = 0x800;
private static final int MIN_4_BYTES = 0x10000;
private static final int MAX_CODE_POINT = 0x10ffff;
private char[] decoderArray = new char[1024];
// helper for decode
private final static void checkByte(int ch, int pos, int len) throws IOException {
if ((ch & 0xc0) != 0x80)
throw new IOException(GT.tr("Illegal UTF-8 sequence: byte {0} of {1} byte sequence is not 10xxxxxx: {2}",
new Object[] { new Integer(pos), new Integer(len), new Integer(ch) }));
}
private final static void checkMinimal(int ch, int minValue) throws IOException {
if (ch >= minValue)
return;
int actualLen;
switch (minValue) {
case MIN_2_BYTES:
actualLen = 2;
break;
case MIN_3_BYTES:
actualLen = 3;
break;
case MIN_4_BYTES:
actualLen = 4;
break;
default:
throw new IllegalArgumentException("unexpected minValue passed to checkMinimal: " + minValue);
}
int expectedLen;
if (ch < MIN_2_BYTES)
expectedLen = 1;
else if (ch < MIN_3_BYTES)
expectedLen = 2;
else if (ch < MIN_4_BYTES)
expectedLen = 3;
else
throw new IllegalArgumentException("unexpected ch passed to checkMinimal: " + ch);
throw new IOException(GT.tr("Illegal UTF-8 sequence: {0} bytes used to encode a {1} byte value: {2}",
new Object[] { new Integer(actualLen), new Integer(expectedLen), new Integer(ch) }));
}
/**
* Custom byte[] -> String conversion routine for UTF-8 only.
* This is about twice as fast as using the String(byte[],int,int,String)
* ctor, at least under JDK 1.4.2. The extra checks for illegal representations
* add about 10-15% overhead, but they seem worth it given the number of SQL_ASCII
* databases out there.
*
* @param data the array containing UTF8-encoded data
* @param offset the offset of the first byte in data to decode from
* @param length the number of bytes to decode
* @return a decoded string
* @throws IOException if something goes wrong
*/
public synchronized String decode(byte[] data, int offset, int length) throws IOException {
char[] cdata = decoderArray;
if (cdata.length < length)
cdata = decoderArray = new char[length];
int in = offset;
int out = 0;
int end = length + offset;
try
{
while (in < end)
{
int ch = data[in++] & 0xff;
// Convert UTF-8 to 21-bit codepoint.
if (ch < 0x80) {
// 0xxxxxxx -- length 1.
} else if (ch < 0xc0) {
// 10xxxxxx -- illegal!
throw new IOException(GT.tr("Illegal UTF-8 sequence: initial byte is {0}: {1}",
new Object[] { "10xxxxxx", new Integer(ch) }));
} else if (ch < 0xe0) {
// 110xxxxx 10xxxxxx
ch = ((ch & 0x1f) << 6);
checkByte(data[in], 2, 2);
ch = ch | (data[in++] & 0x3f);
checkMinimal(ch, MIN_2_BYTES);
} else if (ch < 0xf0) {
// 1110xxxx 10xxxxxx 10xxxxxx
ch = ((ch & 0x0f) << 12);
checkByte(data[in], 2, 3);
ch = ch | ((data[in++] & 0x3f) << 6);
checkByte(data[in], 3, 3);
ch = ch | (data[in++] & 0x3f);
checkMinimal(ch, MIN_3_BYTES);
} else if (ch < 0xf8) {
// 11110xxx 10xxxxxx 10xxxxxx 10xxxxxx
ch = ((ch & 0x07) << 18);
checkByte(data[in], 2, 4);
ch = ch | ((data[in++] & 0x3f) << 12);
checkByte(data[in], 3, 4);
ch = ch | ((data[in++] & 0x3f) << 6);
checkByte(data[in], 4, 4);
ch = ch | (data[in++] & 0x3f);
checkMinimal(ch, MIN_4_BYTES);
} else {
throw new IOException(GT.tr("Illegal UTF-8 sequence: initial byte is {0}: {1}",
new Object[] { "11111xxx", new Integer(ch) }));
}
if (ch > MAX_CODE_POINT)
throw new IOException(GT.tr("Illegal UTF-8 sequence: final value is out of range: {0}",
new Integer(ch)));
// Convert 21-bit codepoint to Java chars:
// 0..ffff are represented directly as a single char
// 10000..10ffff are represented as a "surrogate pair" of two chars
// See: http://java.sun.com/developer/technicalArticles/Intl/Supplementary/
if (ch > 0xffff) {
// Use a surrogate pair to represent it.
ch -= 0x10000; // ch is now 0..fffff (20 bits)
cdata[out++] = (char) (0xd800 + (ch >> 10)); // top 10 bits
cdata[out++] = (char) (0xdc00 + (ch & 0x3ff)); // bottom 10 bits
} else if (ch >= 0xd800 && ch < 0xe000) {
// Not allowed to encode the surrogate range directly.
throw new IOException(GT.tr("Illegal UTF-8 sequence: final value is a surrogate value: {0}",
new Integer(ch)));
} else {
// Normal case.
cdata[out++] = (char) ch;
}
}
}
catch (ArrayIndexOutOfBoundsException a)
{
throw new IOException("Illegal UTF-8 sequence: multibyte sequence was truncated");
}
// Check if we ran past the end without seeing an exception.
if (in > end)
throw new IOException("Illegal UTF-8 sequence: multibyte sequence was truncated");
return new String(cdata, 0, out);
}
}
