usr/src/lib/libc/vax/sys/cache.lib/Ovfork.c

/*-
 * Copyright (c) 1983, 1993
 *      The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *      This product includes software developed by the University of
 *      California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#if defined(LIBC_SCCS) && !defined(lint)
        .asciz "@(#)Ovfork.c    8.1 (Berkeley) 6/4/93"
#endif /* LIBC_SCCS and not lint */

/*
 * @(#)vfork.s  4.1 (Berkeley) 12/21/80
 * C library -- vfork
 */

/*
 * pid = vfork();
 *
 * r1 == 0 in parent process, r1 == 1 in child process.
 * r0 == pid of child in parent, r0 == pid of parent in child.
 *
 * trickery here, due to keith sklower, uses ret to clear the stack,
 * and then returns with a jump indirect, since only one person can return
 * with a ret off this stack... we do the ret before we vfork!
 */

        .set    vfork,66
        .globl  _vfork
        .globl  mypid, myppid

_vfork:
        .word   0x0000
        movl    16(fp),r2
        movab   here,16(fp)
        ret
here:
        chmk    $vfork
        bcc     vforkok
        jmp     verror
vforkok:
        tstl    r1              # child process ?
        bneq    child   # yes
        bcc     parent          # if c-bit not set, fork ok
.globl  _errno
verror:
        movl    r0,_errno
        mnegl   $1,r0
        jmp     (r2)
child:
        movl    r0,myppid
        clrl    r0
        clrl    mypid
parent:
        jmp     (r2)