/*-*- 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