/*
 *  call-seq:
 *     ios.close_read    => nil
 *  
 *  Closes the read end of a duplex I/O stream (i.e., one that contains
 *  both a read and a write stream, such as a pipe). Will raise an
 *  <code>IOError</code> if the stream is not duplexed.
 *     
 *     f = IO.popen("/bin/sh","r+")
 *     f.close_read
 *     f.readlines
 *     
 *  <em>produces:</em>
 *     
 *     prog.rb:3:in `readlines': not opened for reading (IOError)
 *      from prog.rb:3
 */

static VALUE
rb_io_close_read(io)
    VALUE io;
{
    OpenFile *fptr;
    int n;

    if (rb_safe_level() >= 4 && !OBJ_TAINTED(io)) {
        rb_raise(rb_eSecurityError, "Insecure: can't close");
    }
    GetOpenFile(io, fptr);
    if (fptr->f2 == 0 && (fptr->mode & FMODE_WRITABLE)) {
        rb_raise(rb_eIOError, "closing non-duplex IO for reading");
    }
    if (fptr->f2 == 0) {
        return rb_io_close(io);
    }
    n = fclose(fptr->f);
    fptr->mode &= ~FMODE_READABLE;
    fptr->f = fptr->f2;
    fptr->f2 = 0;
    if (n != 0) rb_sys_fail(fptr->path);

    return Qnil;
}