read

/*
 *  call-seq:
 *     dir.read => string or nil
 *
 *  Reads the next entry from <em>dir</em> and returns it as a string.
 *  Returns <code>nil</code> at the end of the stream.
 *
 *     d = Dir.new("testdir")
 *     d.read   #=> "."
 *     d.read   #=> ".."
 *     d.read   #=> "config.h"
 */
static VALUE
dir_read(dir)
    VALUE dir;
{
    struct dir_data *dirp;
    struct dirent *dp;

    GetDIR(dir, dirp);
    errno = 0;
    dp = readdir(dirp->dir);
    if (dp) {
        return rb_tainted_str_new(dp->d_name, NAMLEN(dp));
    }
    else if (errno == 0) {      /* end of stream */
        return Qnil;
    }
    else {
        rb_sys_fail(0);
    }
    return Qnil;                /* not reached */
}