projects / unix-history / blame
| Commit | Line | Data |
|---|---|---|
| fcd2465c DF |
1 | /* |
| 2 | * Copyright (c) 1983 Regents of the University of California. | |
| b094f5ae KB |
3 | * All rights reserved. |
| 4 | * | |
| 5 | * Redistribution and use in source and binary forms are permitted | |
| 50c7758a KB |
6 | * provided that the above copyright notice and this paragraph are |
| 7 | * duplicated in all such forms and that any documentation, | |
| 8 | * advertising materials, and other materials related to such | |
| 9 | * distribution and use acknowledge that the software was developed | |
| 10 | * by the University of California, Berkeley. The name of the | |
| 11 | * University may not be used to endorse or promote products derived | |
| 12 | * from this software without specific prior written permission. | |
| 13 | * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR | |
| 14 | * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED | |
| 15 | * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE. | |
| fcd2465c DF |
16 | */ |
| 17 | ||
| b094f5ae | 18 | #if defined(SYSLIBC_SCCS) && !defined(lint) |
| 50c7758a | 19 | .asciz "@(#)Ovfork.s 5.5 (Berkeley) %G%" |
| b094f5ae | 20 | #endif /* SYSLIBC_SCCS and not lint */ |
| fcd2465c | 21 | |
| 1dcd2d9e KM |
22 | /* |
| 23 | * @(#)vfork.s 4.1 (Berkeley) 12/21/80 | |
| 24 | * C library -- vfork | |
| 25 | */ | |
| 26 | ||
| 27 | /* | |
| 28 | * pid = vfork(); | |
| 29 | * | |
| 30 | * r1 == 0 in parent process, r1 == 1 in child process. | |
| 31 | * r0 == pid of child in parent, r0 == pid of parent in child. | |
| 32 | * | |
| 33 | * trickery here, due to keith sklower, uses ret to clear the stack, | |
| 34 | * and then returns with a jump indirect, since only one person can return | |
| 35 | * with a ret off this stack... we do the ret before we vfork! | |
| 36 | */ | |
| 37 | ||
| 38 | .set vfork,66 | |
| 39 | .globl _vfork | |
| 40 | ||
| 41 | _vfork: | |
| 42 | .word 0x0000 | |
| 43 | movl 16(fp),r2 | |
| 44 | movab here,16(fp) | |
| 45 | ret | |
| 46 | here: | |
| 47 | chmk $vfork | |
| 48 | bcc vforkok | |
| 49 | jmp verror | |
| 50 | vforkok: | |
| 51 | tstl r1 # child process ? | |
| 52 | bneq child # yes | |
| 53 | bcc parent # if c-bit not set, fork ok | |
| 54 | .globl _errno | |
| 55 | verror: | |
| 56 | movl r0,_errno | |
| 57 | mnegl $1,r0 | |
| 58 | jmp (r2) | |
| 59 | child: | |
| 60 | clrl r0 | |
| 61 | parent: | |
| 62 | jmp (r2) |