Name: auR10023 Date: 01/16/2001


Method java.io.InputStreamReader.read(char[],int,int) does not raise IOException for
unaccepted codes.

Here is the part of the UTF-8 specification:
...
   UCS-4 range (hex.) UTF-8 octet sequence (binary)
   0000 0000-0000 007F 0xxxxxxx
   0000 0080-0000 07FF 110xxxxx 10xxxxxx
   0000 0800-0000 FFFF 1110xxxx 10xxxxxx 10xxxxxx

   0001 0000-001F FFFF 11110xxx 10xxxxxx 10xxxxxx 10xxxxxx
   0020 0000-03FF FFFF 111110xx 10xxxxxx 10xxxxxx 10xxxxxx 10xxxxxx
   0400 0000-7FFF FFFF 1111110x 10xxxxxx ... 10xxxxxx
...

That means that binary octet sequence 10000000 is illegal for UTF-8 encoding.
In jdk1.3 this method throws IOException in this case.

Here is the test demonstrating the bug:
------------------- t.java -------------
import java.io.*;

public class t{
    public static void main(String [] args) {
        byte[] bytes = { -128 };
        char[] readChars = new char[10];

        ByteArrayInputStream bais = new ByteArrayInputStream(bytes);
        InputStreamReader isr = null;
        try {
            isr = new InputStreamReader(bais, "UTF8");
        } catch(UnsupportedEncodingException e){
            System.out.println("Unexpected exception");
            return;
        }
        try {
            int len = isr.read(readChars,0,readChars.length);
            System.out.println(len + " chars read: ");
            for (int i = 0; i < len; i++) {
                System.out.println("char " + i + ": " + readChars[0]);
            }
            System.out.println("Test failed: No exceptions thrown");
        } catch (IOException ioe) {
            System.out.println("Test passed. Thrown: " + ioe);
            return;
        }
    }
}

----------- output from the test: --------------------
#> java -version
java version "1.4.0-beta"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.4.0-beta-b46)
Java HotSpot(TM) Client VM (build 1.4beta-B45, mixed mode)

#> java t
10 chars read:
char 0: u
char 1: u
char 2: u
char 3: u
char 4: u
char 5: u
char 6: u
char 7: u
char 8: u
char 9: u
Test failed: No exceptions thrown

#> java -version
java version "1.3.0"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.3.0-C)
Java HotSpot(TM) Client VM (build 1.3.0-C, interpreted mode)
#> java t
Test passed. Thrown: sun.io.MalformedInputException

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