* Copyright (c) 1982, 1986, 1989, 1991, 1993
* The Regents of the University of California. All rights reserved.
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the University of
* California, Berkeley and its contributors.
* 4. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* @(#)kern_fork.c 8.1 (Berkeley) 6/10/93
#include <sys/filedesc.h>
#include <sys/resourcevar.h>
return (fork1(p
, 0, retval
));
return (fork1(p
, 1, retval
));
int nprocs
= 1; /* process 0 */
fork1(p1
, isvfork
, retval
)
register struct proc
*p1
;
register struct proc
*p2
;
static int nextpid
, pidchecked
= 0;
* Although process entries are dynamically created, we still keep
* a global limit on the maximum number we will create. Don't allow
* a nonprivileged user to bring the system within one of the global
* limit; don't let root exceed the limit. The variable nprocs is
* the current number of processes, maxproc is the limit.
uid
= p1
->p_cred
->p_ruid
;
if (nprocs
>= maxproc
|| uid
== 0 && nprocs
>= maxproc
+ 1) {
* Increment the count of procs running with this uid. Don't allow
* a nonprivileged user to exceed their current limit.
count
= chgproccnt(uid
, 1);
if (uid
!= 0 && count
> p1
->p_rlimit
[RLIMIT_NPROC
].rlim_cur
) {
(void)chgproccnt(uid
, -1);
MALLOC(newproc
, struct proc
*, sizeof(struct proc
), M_PROC
, M_WAITOK
);
* Find an unused process ID. We remember a range of unused IDs
* ready to use (from nextpid+1 through pidchecked-1).
* If the process ID prototype has wrapped around,
* restart somewhat above 0, as the low-numbered procs
* tend to include daemons that don't exit.
if (nextpid
>= PID_MAX
) {
if (nextpid
>= pidchecked
) {
* Scan the active and zombie procs to check whether this pid
* is in use. Remember the lowest pid that's greater
* than nextpid, so we can avoid checking for a while.
p2
= (struct proc
*)allproc
;
for (; p2
!= NULL
; p2
= p2
->p_nxt
) {
while (p2
->p_pid
== nextpid
||
p2
->p_pgrp
->pg_id
== nextpid
) {
if (nextpid
>= pidchecked
)
if (p2
->p_pid
> nextpid
&& pidchecked
> p2
->p_pid
)
if (p2
->p_pgrp
->pg_id
> nextpid
&&
pidchecked
> p2
->p_pgrp
->pg_id
)
pidchecked
= p2
->p_pgrp
->pg_id
;
* Link onto allproc (this should probably be delayed).
* Heavy use of volatile here to prevent the compiler from
* rearranging code. Yes, it *is* terribly ugly, but at least
#define Vp2 ((volatile struct proc *)p2)
Vp2
->p_stat
= SIDL
; /* protect against others */
* allproc->p_prev = &p2->p_nxt;
* The assignment via allproc is legal since it is never NULL.
*(volatile struct proc
**)&Vp2
->p_nxt
= allproc
;
*(volatile struct proc
***)&allproc
->p_prev
=
(volatile struct proc
**)&Vp2
->p_nxt
;
*(volatile struct proc
***)&Vp2
->p_prev
= &allproc
;
p2
->p_link
= NULL
; /* shouldn't be necessary */
p2
->p_rlink
= NULL
; /* shouldn't be necessary */
/* Insert on the hash chain. */
hash
= &pidhash
[PIDHASH(p2
->p_pid
)];
* Make a proc table entry for the new process.
* Start by zeroing the section of proc that is zero-initialized,
* then copy the section that is copied directly from the parent.
(unsigned) ((caddr_t
)&p2
->p_endzero
- (caddr_t
)&p2
->p_startzero
));
bcopy(&p1
->p_startcopy
, &p2
->p_startcopy
,
(unsigned) ((caddr_t
)&p2
->p_endcopy
- (caddr_t
)&p2
->p_startcopy
));
* Duplicate sub-structures as needed.
* Increase reference counts on shared objects.
* The p_stats and p_sigacts substructs are set in vm_fork.
if (p1
->p_flag
& SPROFIL
)
MALLOC(p2
->p_cred
, struct pcred
*, sizeof(struct pcred
),
bcopy(p1
->p_cred
, p2
->p_cred
, sizeof(*p2
->p_cred
));
p2
->p_cred
->p_refcnt
= 1;
* If p_limit is still copy-on-write, bump refcnt,
* otherwise get a copy that won't be modified.
* (If PL_SHAREMOD is clear, the structure is shared
if (p1
->p_limit
->p_lflags
& PL_SHAREMOD
)
p2
->p_limit
= limcopy(p1
->p_limit
);
p2
->p_limit
= p1
->p_limit
;
if (p1
->p_session
->s_ttyvp
!= NULL
&& p1
->p_flag
& SCTTY
)
p2
->p_pgrpnxt
= p1
->p_pgrpnxt
;
p2
->p_osptr
= p1
->p_cptr
;
p1
->p_cptr
->p_ysptr
= p2
;
* Copy traceflag and tracefile if enabled.
* If not inherited, these were zeroed above.
if (p1
->p_traceflag
&KTRFAC_INHERIT
) {
p2
->p_traceflag
= p1
->p_traceflag
;
if ((p2
->p_tracep
= p1
->p_tracep
) != NULL
)
* This begins the section where we must prevent the parent
* Set return values for child before vm_fork,
* so they can be copied to child stack.
* We return parent pid, and mark as child in retval[1].
* NOTE: the kernel stack may be at a different location in the child
* process, and thus addresses of automatic variables (including retval)
* may be invalid after vm_fork returns in the child process.
if (vm_fork(p1
, p2
, isvfork
)) {
* Child process. Set start time and get to work.
p2
->p_stats
->p_start
= time
;
* Make child runnable and add to run queue.
* Preserve synchronization semantics of vfork.
* If waiting for child to exec or exit, set SPPWAIT
* on child, and sleep on our proc (in case of exit).
while (p2
->p_flag
& SPPWAIT
)
tsleep((caddr_t
)p1
, PWAIT
, "ppwait", 0);
* Return child pid to parent process,
* marking us as parent via retval[1].