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glibc/sysdeps/unix/sysv/linux/i386/vfork.S
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/* Copyright (C) 1999-2012 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 Lesser General Public | |
License as published by the Free Software Foundation; either | |
version 2.1 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 | |
Lesser General Public License for more details. | |
You should have received a copy of the GNU Lesser General Public | |
License along with the GNU C Library; if not, see | |
<http://www.gnu.org/licenses/>. */ | |
#include <sysdep.h> | |
#define _ERRNO_H 1 | |
#include <bits/errno.h> | |
#include <kernel-features.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 | |
cfi_adjust_cfa_offset (-4) | |
cfi_register (%eip, %ecx) | |
#ifdef SAVE_PID | |
SAVE_PID | |
#endif | |
/* Stuff the syscall number in EAX and enter into the kernel. */ | |
movl $SYS_ify (vfork), %eax | |
int $0x80 | |
/* Jump to the return PC. Don't jump directly since this | |
disturbs the branch target cache. Instead push the return | |
address back on the stack. */ | |
pushl %ecx | |
cfi_adjust_cfa_offset (4) | |
#ifdef RESTORE_PID | |
RESTORE_PID | |
#endif | |
cmpl $-4095, %eax | |
/* Branch forward if it failed. */ | |
# ifdef __ASSUME_VFORK_SYSCALL | |
jae SYSCALL_ERROR_LABEL | |
# else | |
jae .Lerror | |
# endif | |
ret | |
# ifndef __ASSUME_VFORK_SYSCALL | |
.Lerror: | |
/* Check if vfork syscall is known at all. */ | |
cmpl $-ENOSYS, %eax | |
jne SYSCALL_ERROR_LABEL | |
# endif | |
#endif | |
#ifndef __ASSUME_VFORK_SYSCALL | |
/* If we don't have vfork, fork is close enough. */ | |
movl $SYS_ify (fork), %eax | |
int $0x80 | |
cmpl $-4095, %eax | |
jae SYSCALL_ERROR_LABEL | |
ret | |
#endif | |
PSEUDO_END (__vfork) | |
libc_hidden_def (__vfork) | |
weak_alias (__vfork, vfork) |