rewind

/*
 *  call-seq:
 *     ios.rewind    => 0
 *  
 *  Positions <em>ios</em> to the beginning of input, resetting
 *  <code>lineno</code> to zero.
 *     
 *     f = File.new("testfile")
 *     f.readline   #=> "This is line one\n"
 *     f.rewind     #=> 0
 *     f.lineno     #=> 0
 *     f.readline   #=> "This is line one\n"
 */

static VALUE
rb_io_rewind(io)
    VALUE io;
{
    OpenFile *fptr;

    GetOpenFile(io, fptr);
    if (io_seek(fptr, 0L, 0) != 0) rb_sys_fail(fptr->path);
    clearerr(fptr->f);
    if (io == current_file) {
        gets_lineno -= fptr->lineno;
    }
    fptr->lineno = 0;

    return INT2FIX(0);
}