projects / unix-history / blame
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1 | /*- |
| 2 | * Copyright (c) 1990 The Regents of the University of California. | |
| 3 | * All rights reserved. | |
| 4 | * | |
| 5 | * This code is derived from software contributed to Berkeley by | |
| 6 | * the Systems Programming Group of the University of Utah Computer | |
| 7 | * Science Department. | |
| 8 | * | |
| c0567266 KB |
9 | * Redistribution and use in source and binary forms, with or without |
| 10 | * modification, are permitted provided that the following conditions | |
| 11 | * are met: | |
| 12 | * 1. Redistributions of source code must retain the above copyright | |
| 13 | * notice, this list of conditions and the following disclaimer. | |
| 14 | * 2. Redistributions in binary form must reproduce the above copyright | |
| 15 | * notice, this list of conditions and the following disclaimer in the | |
| 16 | * documentation and/or other materials provided with the distribution. | |
| 17 | * 3. All advertising materials mentioning features or use of this software | |
| 18 | * must display the following acknowledgement: | |
| 19 | * This product includes software developed by the University of | |
| 20 | * California, Berkeley and its contributors. | |
| 21 | * 4. Neither the name of the University nor the names of its contributors | |
| 22 | * may be used to endorse or promote products derived from this software | |
| 23 | * without specific prior written permission. | |
| 24 | * | |
| 25 | * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND | |
| 26 | * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE | |
| 27 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE | |
| 28 | * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE | |
| 29 | * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL | |
| 30 | * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS | |
| 31 | * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) | |
| 32 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT | |
| 33 | * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY | |
| 34 | * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF | |
| 35 | * SUCH DAMAGE. | |
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36 | */ |
| 37 | ||
| 38 | #if defined(LIBC_SCCS) && !defined(lint) | |
| 1c15e888 | 39 | .asciz "@(#)Ovfork.s 5.1 (Berkeley) 5/12/90" |
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40 | #endif /* LIBC_SCCS and not lint */ |
| 41 | ||
| 42 | /* | |
| 43 | * @(#)vfork.s 4.1 (Berkeley) 12/21/80 | |
| 44 | * C library -- vfork | |
| 45 | */ | |
| 46 | ||
| 47 | /* | |
| 48 | * pid = vfork(); | |
| 49 | * | |
| 50 | * d1 == 0 in parent process, d1 == 1 in child process. | |
| 51 | * d0 == pid of child in parent, d0 == pid of parent in child. | |
| 52 | * | |
| 53 | * trickery here, due to keith sklower, uses ret to clear the stack, | |
| 54 | * and then returns with a jump indirect, since only one person can return | |
| 55 | * with a ret off this stack... we do the ret before we vfork! | |
| 56 | */ | |
| 57 | ||
| 58 | vfork = 66 | |
| 59 | .globl _vfork | |
| 60 | ||
| 61 | _vfork: | |
| 62 | movl sp@+,a0 | |
| 63 | movl #vfork,d0 | |
| 64 | trap #0 | |
| 65 | jcc vforkok | |
| 66 | jmp verror | |
| 67 | vforkok: | |
| 68 | tstl d1 /* child process ? */ | |
| 69 | jne child /* yes */ | |
| 70 | jcc parent /* if c-bit not set, fork ok */ | |
| 71 | .globl _errno | |
| 72 | verror: | |
| 73 | movl d0,_errno | |
| 74 | moveq #-1,d0 | |
| 75 | jmp a0@ | |
| 76 | child: | |
| 77 | clrl d0 | |
| 78 | parent: | |
| 79 | jmp a0@ |