328 lines
9.1 KiB
C
328 lines
9.1 KiB
C
/*
|
|
* Copyright (c) 1982, 1986, 1989, 1991, 1993
|
|
* The Regents of the University of California. All rights reserved.
|
|
* (c) UNIX System Laboratories, Inc.
|
|
* All or some portions of this file are derived from material licensed
|
|
* to the University of California by American Telephone and Telegraph
|
|
* Co. or Unix System Laboratories, Inc. and are reproduced herein with
|
|
* the permission of UNIX System Laboratories, Inc.
|
|
*
|
|
* Redistribution and use in source and binary forms, with or without
|
|
* modification, are permitted provided that the following conditions
|
|
* are met:
|
|
* 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
|
|
* SUCH DAMAGE.
|
|
*
|
|
* @(#)kern_fork.c 8.6 (Berkeley) 4/8/94
|
|
* $Id: kern_fork.c,v 1.9 1994/10/10 01:00:43 phk Exp $
|
|
*/
|
|
|
|
#include <sys/param.h>
|
|
#include <sys/systm.h>
|
|
#include <sys/filedesc.h>
|
|
#include <sys/kernel.h>
|
|
#include <sys/malloc.h>
|
|
#include <sys/proc.h>
|
|
#include <sys/resourcevar.h>
|
|
#include <sys/vnode.h>
|
|
#include <sys/file.h>
|
|
#include <sys/acct.h>
|
|
#include <sys/ktrace.h>
|
|
|
|
#include <vm/vm.h>
|
|
|
|
static int fork1(struct proc *, int, int *);
|
|
|
|
struct fork_args {
|
|
int dummy;
|
|
};
|
|
/* ARGSUSED */
|
|
int
|
|
fork(p, uap, retval)
|
|
struct proc *p;
|
|
struct fork_args *uap;
|
|
int retval[];
|
|
{
|
|
|
|
return (fork1(p, 0, retval));
|
|
}
|
|
|
|
/* ARGSUSED */
|
|
int
|
|
vfork(p, uap, retval)
|
|
struct proc *p;
|
|
struct fork_args *uap;
|
|
int retval[];
|
|
{
|
|
|
|
return (fork1(p, 1, retval));
|
|
}
|
|
|
|
int nprocs = 1; /* process 0 */
|
|
|
|
static int
|
|
fork1(p1, isvfork, retval)
|
|
register struct proc *p1;
|
|
int isvfork, retval[];
|
|
{
|
|
register struct proc *p2;
|
|
register uid_t uid;
|
|
struct proc *newproc;
|
|
struct proc **hash;
|
|
int count;
|
|
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 use the last process; 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 - 1 && uid != 0) || nprocs >= maxproc) {
|
|
tablefull("proc");
|
|
return (EAGAIN);
|
|
}
|
|
/*
|
|
* 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);
|
|
return (EAGAIN);
|
|
}
|
|
|
|
/* Allocate new proc. */
|
|
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).
|
|
*/
|
|
nextpid++;
|
|
retry:
|
|
/*
|
|
* 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) {
|
|
nextpid = 100;
|
|
pidchecked = 0;
|
|
}
|
|
if (nextpid >= pidchecked) {
|
|
int doingzomb = 0;
|
|
|
|
pidchecked = PID_MAX;
|
|
/*
|
|
* 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;
|
|
again:
|
|
for (; p2 != NULL; p2 = p2->p_next) {
|
|
while (p2->p_pid == nextpid ||
|
|
p2->p_pgrp->pg_id == nextpid) {
|
|
nextpid++;
|
|
if (nextpid >= pidchecked)
|
|
goto retry;
|
|
}
|
|
if (p2->p_pid > nextpid && pidchecked > p2->p_pid)
|
|
pidchecked = p2->p_pid;
|
|
if (p2->p_pgrp->pg_id > nextpid &&
|
|
pidchecked > p2->p_pgrp->pg_id)
|
|
pidchecked = p2->p_pgrp->pg_id;
|
|
}
|
|
if (!doingzomb) {
|
|
doingzomb = 1;
|
|
p2 = zombproc;
|
|
goto again;
|
|
}
|
|
}
|
|
|
|
|
|
/*
|
|
* 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
|
|
* it works.
|
|
*/
|
|
nprocs++;
|
|
p2 = newproc;
|
|
#define Vp2 ((volatile struct proc *)p2)
|
|
Vp2->p_stat = SIDL; /* protect against others */
|
|
Vp2->p_pid = nextpid;
|
|
/*
|
|
* This is really:
|
|
* p2->p_next = allproc;
|
|
* allproc->p_prev = &p2->p_next;
|
|
* p2->p_prev = &allproc;
|
|
* allproc = p2;
|
|
* The assignment via allproc is legal since it is never NULL.
|
|
*/
|
|
*(volatile struct proc **)&Vp2->p_next = allproc;
|
|
*(volatile struct proc ***)&allproc->p_prev =
|
|
(volatile struct proc **)&Vp2->p_next;
|
|
*(volatile struct proc ***)&Vp2->p_prev = &allproc;
|
|
allproc = Vp2;
|
|
#undef Vp2
|
|
p2->p_forw = p2->p_back = NULL; /* shouldn't be necessary */
|
|
|
|
/* Insert on the hash chain. */
|
|
hash = &pidhash[PIDHASH(p2->p_pid)];
|
|
p2->p_hash = *hash;
|
|
*hash = p2;
|
|
|
|
/*
|
|
* 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.
|
|
*/
|
|
bzero(&p2->p_startzero,
|
|
(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.
|
|
*/
|
|
p2->p_flag = P_INMEM;
|
|
if (p1->p_flag & P_PROFIL)
|
|
startprofclock(p2);
|
|
MALLOC(p2->p_cred, struct pcred *, sizeof(struct pcred),
|
|
M_SUBPROC, M_WAITOK);
|
|
bcopy(p1->p_cred, p2->p_cred, sizeof(*p2->p_cred));
|
|
p2->p_cred->p_refcnt = 1;
|
|
crhold(p1->p_ucred);
|
|
|
|
/* bump references to the text vnode (for procfs) */
|
|
p2->p_textvp = p1->p_textvp;
|
|
if (p2->p_textvp)
|
|
VREF(p2->p_textvp);
|
|
|
|
p2->p_fd = fdcopy(p1);
|
|
/*
|
|
* 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
|
|
* copy-on-write.)
|
|
*/
|
|
if (p1->p_limit->p_lflags & PL_SHAREMOD)
|
|
p2->p_limit = limcopy(p1->p_limit);
|
|
else {
|
|
p2->p_limit = p1->p_limit;
|
|
p2->p_limit->p_refcnt++;
|
|
}
|
|
|
|
if (p1->p_session->s_ttyvp != NULL && p1->p_flag & P_CONTROLT)
|
|
p2->p_flag |= P_CONTROLT;
|
|
if (isvfork)
|
|
p2->p_flag |= P_PPWAIT;
|
|
p2->p_pgrpnxt = p1->p_pgrpnxt;
|
|
p1->p_pgrpnxt = p2;
|
|
p2->p_pptr = p1;
|
|
p2->p_osptr = p1->p_cptr;
|
|
if (p1->p_cptr)
|
|
p1->p_cptr->p_ysptr = p2;
|
|
p1->p_cptr = p2;
|
|
#ifdef KTRACE
|
|
/*
|
|
* 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)
|
|
VREF(p2->p_tracep);
|
|
}
|
|
#endif
|
|
|
|
/*
|
|
* set priority of child to be that of parent
|
|
*/
|
|
p2->p_estcpu = p1->p_estcpu;
|
|
|
|
/*
|
|
* This begins the section where we must prevent the parent
|
|
* from being swapped.
|
|
*/
|
|
p1->p_flag |= P_NOSWAP;
|
|
|
|
/*
|
|
* 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.
|
|
*/
|
|
retval[0] = p1->p_pid;
|
|
retval[1] = 1;
|
|
if (vm_fork(p1, p2, isvfork)) {
|
|
/*
|
|
* Child process. Set start time and get to work.
|
|
*/
|
|
microtime(&runtime);
|
|
p2->p_stats->p_start = runtime;
|
|
p2->p_acflag = AFORK;
|
|
return (0);
|
|
}
|
|
|
|
/*
|
|
* Make child runnable and add to run queue.
|
|
*/
|
|
(void) splhigh();
|
|
p2->p_stat = SRUN;
|
|
setrunqueue(p2);
|
|
(void) spl0();
|
|
|
|
/*
|
|
* Now can be swapped.
|
|
*/
|
|
p1->p_flag &= ~P_NOSWAP;
|
|
|
|
/*
|
|
* Preserve synchronization semantics of vfork. If waiting for
|
|
* child to exec or exit, set P_PPWAIT on child, and sleep on our
|
|
* proc (in case of exit).
|
|
*/
|
|
if (isvfork)
|
|
while (p2->p_flag & P_PPWAIT)
|
|
tsleep(p1, PWAIT, "ppwait", 0);
|
|
|
|
/*
|
|
* Return child pid to parent process,
|
|
* marking us as parent via retval[1].
|
|
*/
|
|
retval[0] = p2->p_pid;
|
|
retval[1] = 0;
|
|
return (0);
|
|
}
|