XattrListFiller.java

package co.paralleluniverse.fuse;

import java.nio.ByteBuffer;
import java.util.Arrays;
import java.util.HashSet;
import java.util.Set;

public final class XattrListFiller {
    private final ByteBuffer buffer;
    private final long maxSize;
    private long currentSize = 0;
    private final Set<String> addedXattrs = new HashSet<String>();

    XattrListFiller(ByteBuffer buffer, long size) {
        this.buffer = buffer;
        maxSize = size;
    }

    public final boolean add(Iterable<String> xattrs) {
        byte[] bytes;
        int size;
        boolean hasNullByte;
        for (final String xattr : xattrs) {
            if (addedXattrs.contains(xattr))
                continue;
            
            if (currentSize >= maxSize && buffer != null)
                return false;
            
            bytes = xattr.getBytes();
            hasNullByte = bytes[bytes.length - 1] == 0;
            size = bytes.length + (hasNullByte ? 0 : 1);
            if (currentSize + size > maxSize && buffer != null)
                return false;
            
            addedXattrs.add(xattr);
            if (buffer != null) {
                buffer.put(bytes);
                if (!hasNullByte)
                    buffer.put((byte) 0);
            }
            currentSize += size;
        }
        return true;
    }

    public final boolean add(String... xattrs) {
        return add(Arrays.asList(xattrs));
    }

    public final long requiredSize() {
        return currentSize;
    }

    @Override
    public String toString() {
        final StringBuilder output = new StringBuilder();
        int count = 0;
        for (final String xattr : addedXattrs) {
            output.append(xattr);
            if (count < addedXattrs.size() - 1) {
                output.append(", ");
            }
            count++;
        }
        return output.toString();
    }
}