cosmopolitan/libc/calls/hefty/vfork.S
2020-12-27 17:18:44 -08:00

49 lines
2.4 KiB
ArmAsm

/*-*- mode:unix-assembly; indent-tabs-mode:t; tab-width:8; coding:utf-8 -*-│
vi: set et ft=asm ts=8 tw=8 fenc=utf-8 :vi
Copyright 2020 Justine Alexandra Roberts Tunney
Permission to use, copy, modify, and/or distribute this software for
any purpose with or without fee is hereby granted, provided that the
above copyright notice and this permission notice appear in all copies.
THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL
WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED
WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE
AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
PERFORMANCE OF THIS SOFTWARE.
*/
#include "libc/dce.h"
#include "libc/macros.h"
/ Forks process without copying page tables.
/
/ This is the same as fork() except it's optimized for the case
/ where the caller invokes exec() immediately afterwards.
/
/ @return pid of child process or 0 if forked process
/ @returnstwice
vfork: testb IsWindows()
jnz fork$nt
mov __NR_vfork(%rip),%eax
cmp $-1,%eax
je systemfive.enosys
pop %rsi
testb IsBsd()
jnz vfork.bsd
syscall
push %rsi
cmp $-4095,%rax
jae systemfive.error
ret
.endfn vfork,globl
vfork.bsd:
syscall
push %rsi
jc systemfive.errno
ret
.endfn vfork.bsd