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package jnr.posix;

import jnr.ffi.*;

import java.util.ArrayList;
import java.util.List;

/**
 * The default native group layout.
 * 
 * <p>
 * This implementation should work on Solaris, Linux and MacOS.
 * </p>
 */
public final class DefaultNativeGroup extends NativeGroup implements Group {
    static final class Layout extends StructLayout {
        public Layout(jnr.ffi.Runtime runtime) {
            super(runtime);
        }

        public final UTF8StringRef gr_name = new UTF8StringRef();   // name
        public final UTF8StringRef gr_passwd = new UTF8StringRef(); // group password (encrypted)
        public final Signed32 gr_gid = new Signed32();       // group id
        public final Pointer gr_mem = new Pointer();
    }

    static final Layout layout = new Layout(jnr.ffi.Runtime.getSystemRuntime());
    private final Pointer memory;

    DefaultNativeGroup(jnr.ffi.Pointer memory) {
        super(memory.getRuntime(), layout);
        this.memory = memory;
    }

    public java.lang.String getName() {
        return layout.gr_name.get(memory);
    }

    public java.lang.String getPassword() {
        return layout.gr_passwd.get(memory);
    }

    public long getGID() {
        return layout.gr_gid.get(memory);
    }

    public java.lang.String[] getMembers() {
        List<java.lang.String> lst = new ArrayList<java.lang.String>();

        jnr.ffi.Pointer ptr = layout.gr_mem.get(memory);
        Pointer member;
        int ptrSize = runtime.addressSize();
        for (int i = 0; (member = ptr.getPointer(i)) != null; i += ptrSize) {
            lst.add(member.getString(0));
        }

        return lst.toArray(new java.lang.String[lst.size()]);
    }

}