glibc/sysdeps/unix/sysv/linux/i386/vfork.S

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/* Copyright (C) 1999 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Contributed by Andreas Schwab <schwab@gnu.org>.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Library General Public License as
published by the Free Software Foundation; either version 2 of the
License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Library General Public License for more details.
You should have received a copy of the GNU Library General Public
License along with the GNU C Library; see the file COPYING.LIB. If not,
write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA. */
#include <sysdep.h>
#define _ERRNO_H 1
#include <bits/errno.h>
/* Clone the calling process, but without copying the whole address space.
The calling process is suspended until the new process exits or is
replaced by a call to `execve'. Return -1 for errors, 0 to the new process,
and the process ID of the new process to the old process. */
ENTRY (__vfork)
#ifdef __NR_vfork
/* Pop the return PC value into ECX. */
popl %ecx
/* Stuff the syscall number in EAX and enter into the kernel. */
movl $SYS_ify (vfork), %eax
int $0x80
cmpl $-4095, %eax
jae .Lerror /* Branch forward if it failed. */
/* Jump to the return PC. */
jmp *%ecx
.Lerror:
/* Push back the return PC. */
pushl %ecx
/* Check if vfork syscall is known at all. */
cmpl $-ENOSYS, %eax
jne SYSCALL_ERROR_LABEL
#endif
/* If we don't have vfork, fork is close enough. */
movl $SYS_ify (fork), %eax
int $0x80
cmpl $-4095, %eax
jae SYSCALL_ERROR_LABEL
.Lpseudo_end:
ret
PSEUDO_END (__vfork)
weak_alias (__vfork, vfork)