[ZOOKEEPER-1716] jute/Utils.fromCSVBuffer cannot parse data returnd by toCSVBuffer

• Type: Bug
• Status: Patch Available
• Priority: Major
• Resolution: Unresolved
• Affects Version/s: 3.5.0
• Component/s: jute
• Assignee: Charlie Helin
• Reporter: Robert Joseph Evans
• Created: 11/Jun/13 21:48
• Updated: 14/Oct/15 21:01

Description

I was trying to use org.apache.zookeeper.server.LogFormatter to analyze the access pattern of a particular application. As part of this I wanted to get the size of the data that was being written into ZK.

I ran into an issue where in some cases the hex data had an odd length. I looked into it and found that the buffer is being written out using Integer.toHexString(barr[idx])

Looking at the javadoce for toHexString it indicates that it does not pad the bits at all, and will output the twos compliment of the number if it is negative. I then looked at how the data was being parsed and it assumed that every byte consisted of exactly two characters, which is not true.

Utils.toCSVBuffer(new byte[] {0xff}) returns "#ffffffff"
Utils.toCSVBuffer(new byte[] {0x01}) returns "#1"

If I combine those 
Utils.fromCSVBuffer(Utils.toCSVBuffer(new byte[] {0xff, 0x01, 0xff})) will return {0xff, 0xff, 0xff, 0xff, 0x1f, 0xff, 0xff, 0xff}

I think what we want is something like

static final char[] NIBBLE_TO_HEX = {
  '0', '1', '2', '3', '4', '5', '6', '7',
  '8', '9', 'a', 'b', 'c', 'd', 'e', 'f'
};

static String toCSVBuffer(byte barr[]) {
    if (barr == null || barr.length == 0) {
        return "";
    }
    StringBuilder sb = new StringBuilder(barr.length + 1);
    sb.append('#');
    for(int idx = 0; idx < barr.length; idx++) {
        byte b = barr[idx];
        sb.append(NIBBLE_TO_HEX[b&0x0f]);
        sb.append(NIBBLE_TO_HEX[(b&0xf0)>>4]);
    }
    return sb.toString();
}