d2d3e8751c
structs and prototypes for syscalls. Ifdefed duplicated decentralized declarations of args structs. It's convenient to have this visible but they are hard to maintain. Some are already different from the central declarations. 4.4lite2 puts them in comments in the function headers but I wanted to avoid the large changes for that.
332 lines
9.2 KiB
C
332 lines
9.2 KiB
C
/*
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* Copyright (c) 1982, 1986, 1989, 1991, 1993
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* The Regents of the University of California. All rights reserved.
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* (c) UNIX System Laboratories, Inc.
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* All or some portions of this file are derived from material licensed
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* to the University of California by American Telephone and Telegraph
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* Co. or Unix System Laboratories, Inc. and are reproduced herein with
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* the permission of UNIX System Laboratories, Inc.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the University of
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* California, Berkeley and its contributors.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* @(#)kern_fork.c 8.6 (Berkeley) 4/8/94
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* $Id: kern_fork.c,v 1.13 1995/10/08 00:06:05 swallace Exp $
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*/
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/sysproto.h>
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#include <sys/filedesc.h>
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#include <sys/kernel.h>
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#include <sys/malloc.h>
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#include <sys/proc.h>
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#include <sys/resourcevar.h>
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#include <sys/vnode.h>
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#include <sys/file.h>
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#include <sys/acct.h>
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#include <sys/ktrace.h>
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#include <vm/vm.h>
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static int fork1(struct proc *, int, int *);
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#ifndef _SYS_SYSPROTO_H_
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struct fork_args {
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int dummy;
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};
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#endif
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/* ARGSUSED */
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int
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fork(p, uap, retval)
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struct proc *p;
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struct fork_args *uap;
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int retval[];
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{
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return (fork1(p, 0, retval));
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}
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/* ARGSUSED */
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int
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vfork(p, uap, retval)
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struct proc *p;
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struct fork_args *uap;
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int retval[];
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{
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return (fork1(p, 1, retval));
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}
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int nprocs = 1; /* process 0 */
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static int
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fork1(p1, isvfork, retval)
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register struct proc *p1;
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int isvfork, retval[];
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{
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register struct proc *p2;
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register uid_t uid;
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struct proc *newproc;
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struct proc **hash;
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int count;
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static int nextpid, pidchecked = 0;
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/*
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* Although process entries are dynamically created, we still keep
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* a global limit on the maximum number we will create. Don't allow
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* a nonprivileged user to use the last process; don't let root
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* exceed the limit. The variable nprocs is the current number of
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* processes, maxproc is the limit.
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*/
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uid = p1->p_cred->p_ruid;
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if ((nprocs >= maxproc - 1 && uid != 0) || nprocs >= maxproc) {
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tablefull("proc");
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return (EAGAIN);
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}
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/*
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* Increment the count of procs running with this uid. Don't allow
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* a nonprivileged user to exceed their current limit.
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*/
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count = chgproccnt(uid, 1);
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if (uid != 0 && count > p1->p_rlimit[RLIMIT_NPROC].rlim_cur) {
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(void)chgproccnt(uid, -1);
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return (EAGAIN);
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}
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/* Allocate new proc. */
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MALLOC(newproc, struct proc *, sizeof(struct proc), M_PROC, M_WAITOK);
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/*
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* Find an unused process ID. We remember a range of unused IDs
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* ready to use (from nextpid+1 through pidchecked-1).
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*/
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nextpid++;
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retry:
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/*
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* If the process ID prototype has wrapped around,
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* restart somewhat above 0, as the low-numbered procs
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* tend to include daemons that don't exit.
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*/
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if (nextpid >= PID_MAX) {
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nextpid = 100;
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pidchecked = 0;
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}
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if (nextpid >= pidchecked) {
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int doingzomb = 0;
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pidchecked = PID_MAX;
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/*
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* Scan the active and zombie procs to check whether this pid
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* is in use. Remember the lowest pid that's greater
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* than nextpid, so we can avoid checking for a while.
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*/
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p2 = (struct proc *)allproc;
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again:
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for (; p2 != NULL; p2 = p2->p_next) {
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while (p2->p_pid == nextpid ||
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p2->p_pgrp->pg_id == nextpid) {
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nextpid++;
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if (nextpid >= pidchecked)
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goto retry;
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}
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if (p2->p_pid > nextpid && pidchecked > p2->p_pid)
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pidchecked = p2->p_pid;
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if (p2->p_pgrp->pg_id > nextpid &&
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pidchecked > p2->p_pgrp->pg_id)
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pidchecked = p2->p_pgrp->pg_id;
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}
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if (!doingzomb) {
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doingzomb = 1;
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p2 = zombproc;
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goto again;
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}
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}
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/*
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* Link onto allproc (this should probably be delayed).
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* Heavy use of volatile here to prevent the compiler from
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* rearranging code. Yes, it *is* terribly ugly, but at least
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* it works.
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*/
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nprocs++;
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p2 = newproc;
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#define Vp2 ((volatile struct proc *)p2)
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Vp2->p_stat = SIDL; /* protect against others */
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Vp2->p_pid = nextpid;
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/*
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* This is really:
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* p2->p_next = allproc;
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* allproc->p_prev = &p2->p_next;
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* p2->p_prev = &allproc;
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* allproc = p2;
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* The assignment via allproc is legal since it is never NULL.
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*/
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*(volatile struct proc **)&Vp2->p_next = allproc;
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*(volatile struct proc ***)&allproc->p_prev =
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(volatile struct proc **)&Vp2->p_next;
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*(volatile struct proc ***)&Vp2->p_prev = &allproc;
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allproc = Vp2;
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#undef Vp2
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p2->p_forw = p2->p_back = NULL; /* shouldn't be necessary */
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/* Insert on the hash chain. */
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hash = &pidhash[PIDHASH(p2->p_pid)];
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p2->p_hash = *hash;
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*hash = p2;
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/*
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* Make a proc table entry for the new process.
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* Start by zeroing the section of proc that is zero-initialized,
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* then copy the section that is copied directly from the parent.
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*/
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bzero(&p2->p_startzero,
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(unsigned) ((caddr_t)&p2->p_endzero - (caddr_t)&p2->p_startzero));
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bcopy(&p1->p_startcopy, &p2->p_startcopy,
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(unsigned) ((caddr_t)&p2->p_endcopy - (caddr_t)&p2->p_startcopy));
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/*
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* Duplicate sub-structures as needed.
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* Increase reference counts on shared objects.
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* The p_stats and p_sigacts substructs are set in vm_fork.
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*/
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p2->p_flag = P_INMEM;
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if (p1->p_flag & P_PROFIL)
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startprofclock(p2);
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MALLOC(p2->p_cred, struct pcred *, sizeof(struct pcred),
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M_SUBPROC, M_WAITOK);
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bcopy(p1->p_cred, p2->p_cred, sizeof(*p2->p_cred));
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p2->p_cred->p_refcnt = 1;
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crhold(p1->p_ucred);
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/* bump references to the text vnode (for procfs) */
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p2->p_textvp = p1->p_textvp;
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if (p2->p_textvp)
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VREF(p2->p_textvp);
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p2->p_fd = fdcopy(p1);
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/*
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* If p_limit is still copy-on-write, bump refcnt,
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* otherwise get a copy that won't be modified.
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* (If PL_SHAREMOD is clear, the structure is shared
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* copy-on-write.)
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*/
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if (p1->p_limit->p_lflags & PL_SHAREMOD)
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p2->p_limit = limcopy(p1->p_limit);
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else {
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p2->p_limit = p1->p_limit;
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p2->p_limit->p_refcnt++;
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}
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if (p1->p_session->s_ttyvp != NULL && p1->p_flag & P_CONTROLT)
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p2->p_flag |= P_CONTROLT;
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if (isvfork)
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p2->p_flag |= P_PPWAIT;
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p2->p_pgrpnxt = p1->p_pgrpnxt;
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p1->p_pgrpnxt = p2;
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p2->p_pptr = p1;
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p2->p_osptr = p1->p_cptr;
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if (p1->p_cptr)
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p1->p_cptr->p_ysptr = p2;
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p1->p_cptr = p2;
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#ifdef KTRACE
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/*
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* Copy traceflag and tracefile if enabled.
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* If not inherited, these were zeroed above.
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*/
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if (p1->p_traceflag&KTRFAC_INHERIT) {
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p2->p_traceflag = p1->p_traceflag;
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if ((p2->p_tracep = p1->p_tracep) != NULL)
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VREF(p2->p_tracep);
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}
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#endif
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/*
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* set priority of child to be that of parent
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*/
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p2->p_estcpu = p1->p_estcpu;
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/*
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* This begins the section where we must prevent the parent
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* from being swapped.
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*/
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p1->p_flag |= P_NOSWAP;
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/*
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* Set return values for child before vm_fork,
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* so they can be copied to child stack.
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* We return parent pid, and mark as child in retval[1].
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* NOTE: the kernel stack may be at a different location in the child
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* process, and thus addresses of automatic variables (including retval)
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* may be invalid after vm_fork returns in the child process.
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*/
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retval[0] = p1->p_pid;
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retval[1] = 1;
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if (vm_fork(p1, p2, isvfork)) {
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/*
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* Child process. Set start time and get to work.
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*/
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microtime(&runtime);
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p2->p_stats->p_start = runtime;
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p2->p_acflag = AFORK;
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return (0);
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}
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/*
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* Make child runnable and add to run queue.
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*/
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(void) splhigh();
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p2->p_stat = SRUN;
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setrunqueue(p2);
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(void) spl0();
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/*
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* Now can be swapped.
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*/
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p1->p_flag &= ~P_NOSWAP;
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/*
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* Preserve synchronization semantics of vfork. If waiting for
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* child to exec or exit, set P_PPWAIT on child, and sleep on our
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* proc (in case of exit).
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*/
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if (isvfork)
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while (p2->p_flag & P_PPWAIT)
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tsleep(p1, PWAIT, "ppwait", 0);
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/*
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* Return child pid to parent process,
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* marking us as parent via retval[1].
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*/
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retval[0] = p2->p_pid;
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retval[1] = 0;
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return (0);
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}
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