Commit | Line | Data |
---|---|---|
da7c5cc6 | 1 | /* |
6795ddce | 2 | * Copyright (c) 1982, 1986, 1989, 1991 Regents of the University of California. |
c4ec2128 | 3 | * All rights reserved. |
da7c5cc6 | 4 | * |
dbf0c423 | 5 | * %sccs.include.redist.c% |
c4ec2128 | 6 | * |
f6fca708 | 7 | * @(#)kern_fork.c 7.27 (Berkeley) %G% |
da7c5cc6 | 8 | */ |
50108d5c | 9 | |
94368568 JB |
10 | #include "param.h" |
11 | #include "systm.h" | |
12 | #include "map.h" | |
5e00df3b | 13 | #include "filedesc.h" |
94368568 | 14 | #include "kernel.h" |
ae2e0122 | 15 | #include "malloc.h" |
94368568 | 16 | #include "proc.h" |
ae2e0122 | 17 | #include "resourcevar.h" |
c4ec2128 | 18 | #include "vnode.h" |
94368568 | 19 | #include "seg.h" |
94368568 JB |
20 | #include "file.h" |
21 | #include "acct.h" | |
56a12c82 | 22 | #include "ktrace.h" |
50108d5c | 23 | |
c9714ae3 KM |
24 | /* ARGSUSED */ |
25 | fork(p, uap, retval) | |
26 | struct proc *p; | |
f6fca708 | 27 | void *uap; |
c9714ae3 | 28 | int retval[]; |
50108d5c SL |
29 | { |
30 | ||
d9c2f47f | 31 | return (fork1(p, 0, retval)); |
50108d5c SL |
32 | } |
33 | ||
c9714ae3 KM |
34 | /* ARGSUSED */ |
35 | vfork(p, uap, retval) | |
36 | struct proc *p; | |
f6fca708 | 37 | void *uap; |
c9714ae3 | 38 | int retval[]; |
50108d5c SL |
39 | { |
40 | ||
d9c2f47f | 41 | return (fork1(p, 1, retval)); |
50108d5c SL |
42 | } |
43 | ||
ae2e0122 MK |
44 | int nprocs = 1; /* process 0 */ |
45 | ||
c9714ae3 KM |
46 | fork1(p1, isvfork, retval) |
47 | register struct proc *p1; | |
48 | int isvfork, retval[]; | |
50108d5c | 49 | { |
c9714ae3 | 50 | register struct proc *p2; |
ae2e0122 MK |
51 | register int count, uid; |
52 | static int nextpid, pidchecked = 0; | |
50108d5c | 53 | |
ae2e0122 MK |
54 | count = 0; |
55 | if ((uid = p1->p_ucred->cr_uid) != 0) { | |
c9714ae3 | 56 | for (p2 = allproc; p2; p2 = p2->p_nxt) |
ae2e0122 MK |
57 | if (p2->p_ucred->cr_uid == uid) |
58 | count++; | |
c9714ae3 | 59 | for (p2 = zombproc; p2; p2 = p2->p_nxt) |
ae2e0122 MK |
60 | if (p2->p_ucred->cr_uid == uid) |
61 | count++; | |
50108d5c SL |
62 | } |
63 | /* | |
ae2e0122 MK |
64 | * Although process entries are dynamically entries, |
65 | * we still keep a global limit on the maximum number | |
66 | * we will create. Don't allow a nonprivileged user | |
67 | * to exceed its current limit or to bring us within one | |
68 | * of the global limit; don't let root exceed the limit. | |
69 | * nprocs is the current number of processes, | |
70 | * maxproc is the limit. | |
50108d5c | 71 | */ |
ae2e0122 | 72 | if (nprocs >= maxproc || uid == 0 && nprocs >= maxproc + 1) { |
50108d5c | 73 | tablefull("proc"); |
c9714ae3 | 74 | return (EAGAIN); |
50108d5c | 75 | } |
ae2e0122 MK |
76 | if (count > p1->p_rlimit[RLIMIT_NPROC].rlim_cur) |
77 | return (EAGAIN); | |
50108d5c | 78 | |
50108d5c | 79 | /* |
ae2e0122 MK |
80 | * Find an unused process ID. |
81 | * We remember a range of unused IDs ready to use | |
82 | * (from nextpid+1 through pidchecked-1). | |
50108d5c | 83 | */ |
ae2e0122 | 84 | nextpid++; |
1d348849 | 85 | retry: |
ae2e0122 MK |
86 | /* |
87 | * If the process ID prototype has wrapped around, | |
88 | * restart somewhat above 0, as the low-numbered procs | |
89 | * tend to include daemons that don't exit. | |
90 | */ | |
91 | if (nextpid >= PID_MAX) { | |
92 | nextpid = 100; | |
1d348849 | 93 | pidchecked = 0; |
50108d5c | 94 | } |
ae2e0122 | 95 | if (nextpid >= pidchecked) { |
1d348849 | 96 | int doingzomb = 0; |
e9539440 | 97 | |
27ed98f2 | 98 | pidchecked = PID_MAX; |
1d348849 | 99 | /* |
ae2e0122 | 100 | * Scan the active and zombie procs to check whether this pid |
1d348849 | 101 | * is in use. Remember the lowest pid that's greater |
ae2e0122 | 102 | * than nextpid, so we can avoid checking for a while. |
1d348849 | 103 | */ |
ae2e0122 | 104 | p2 = allproc; |
1d348849 | 105 | again: |
ae2e0122 MK |
106 | for (; p2 != NULL; p2 = p2->p_nxt) { |
107 | if (p2->p_pid == nextpid || | |
108 | p2->p_pgrp->pg_id == nextpid) { | |
109 | nextpid++; | |
110 | if (nextpid >= pidchecked) | |
1d348849 MK |
111 | goto retry; |
112 | } | |
ae2e0122 MK |
113 | if (p2->p_pid > nextpid && pidchecked > p2->p_pid) |
114 | pidchecked = p2->p_pid; | |
115 | if (p2->p_pgrp->pg_id > nextpid && | |
116 | pidchecked > p2->p_pgrp->pg_id) | |
117 | pidchecked = p2->p_pgrp->pg_id; | |
1d348849 MK |
118 | } |
119 | if (!doingzomb) { | |
120 | doingzomb = 1; | |
ae2e0122 | 121 | p2 = zombproc; |
1d348849 MK |
122 | goto again; |
123 | } | |
50108d5c | 124 | } |
50108d5c | 125 | |
ae2e0122 MK |
126 | |
127 | /* | |
128 | * Allocate new proc. | |
129 | * Link onto allproc (this should probably be delayed). | |
130 | */ | |
131 | MALLOC(p2, struct proc *, sizeof(struct proc), M_PROC, M_WAITOK); | |
132 | nprocs++; | |
133 | p2->p_nxt = allproc; | |
134 | p2->p_nxt->p_prev = &p2->p_nxt; /* allproc is never NULL */ | |
135 | p2->p_prev = &allproc; | |
136 | allproc = p2; | |
137 | p2->p_link = NULL; /* shouldn't be necessary */ | |
138 | p2->p_rlink = NULL; /* shouldn't be necessary */ | |
1d348849 | 139 | |
50108d5c SL |
140 | /* |
141 | * Make a proc table entry for the new process. | |
ae2e0122 MK |
142 | * Start by zeroing the section of proc that is zero-initialized, |
143 | * then copy the section that is copied directly from the parent. | |
50108d5c | 144 | */ |
ae2e0122 MK |
145 | bzero(&p2->p_startzero, |
146 | (unsigned) ((caddr_t)&p2->p_endzero - (caddr_t)&p2->p_startzero)); | |
147 | bcopy(&p1->p_startcopy, &p2->p_startcopy, | |
148 | (unsigned) ((caddr_t)&p2->p_endcopy - (caddr_t)&p2->p_startcopy)); | |
149 | ||
150 | /* | |
151 | * Duplicate sub-structures as needed. | |
152 | * Increase reference counts on shared objects. | |
6795ddce | 153 | * The p_stats and p_sigacts substructs are set in vm_fork. |
ae2e0122 MK |
154 | */ |
155 | MALLOC(p2->p_cred, struct pcred *, sizeof(struct pcred), | |
156 | M_SUBPROC, M_WAITOK); | |
157 | bcopy(p1->p_cred, p2->p_cred, sizeof(*p2->p_cred)); | |
158 | crhold(p1->p_ucred); | |
159 | ||
160 | p2->p_fd = fdcopy(p1); | |
ae2e0122 MK |
161 | /* |
162 | * If p_limit is still copy-on-write, bump refcnt, | |
163 | * otherwise get a copy that won't be modified. | |
164 | * (If PL_SHAREMOD is clear, the structure is shared | |
165 | * copy-on-write.) | |
166 | */ | |
167 | if (p1->p_limit->p_lflags & PL_SHAREMOD) | |
168 | p2->p_limit = limcopy(p1->p_limit); | |
169 | else { | |
170 | p2->p_limit = p1->p_limit; | |
171 | p2->p_limit->p_refcnt++; | |
98111078 | 172 | } |
ae2e0122 | 173 | |
6795ddce | 174 | p2->p_flag = SLOAD | (p1->p_flag & SHPUX); |
ae2e0122 MK |
175 | if (p1->p_session->s_ttyvp != NULL && p1->p_flag & SCTTY) |
176 | p2->p_flag |= SCTTY; | |
177 | if (isvfork) | |
178 | p2->p_flag |= SPPWAIT; | |
179 | p2->p_stat = SIDL; | |
180 | p2->p_pid = nextpid; | |
56a12c82 | 181 | { |
ae2e0122 | 182 | struct proc **hash = &pidhash[PIDHASH(p2->p_pid)]; |
56a12c82 | 183 | |
ae2e0122 MK |
184 | p2->p_hash = *hash; |
185 | *hash = p2; | |
56a12c82 | 186 | } |
ae2e0122 MK |
187 | p2->p_pgrpnxt = p1->p_pgrpnxt; |
188 | p1->p_pgrpnxt = p2; | |
189 | p2->p_pptr = p1; | |
190 | p2->p_osptr = p1->p_cptr; | |
191 | if (p1->p_cptr) | |
192 | p1->p_cptr->p_ysptr = p2; | |
193 | p1->p_cptr = p2; | |
194 | #ifdef KTRACE | |
50108d5c | 195 | /* |
ae2e0122 MK |
196 | * Copy traceflag and tracefile if enabled. |
197 | * If not inherited, these were zeroed above. | |
50108d5c | 198 | */ |
ae2e0122 MK |
199 | if (p1->p_traceflag&KTRFAC_INHERIT) { |
200 | p2->p_traceflag = p1->p_traceflag; | |
201 | if ((p2->p_tracep = p1->p_tracep) != NULL) | |
202 | VREF(p2->p_tracep); | |
203 | } | |
204 | #endif | |
205 | ||
ae2e0122 MK |
206 | #if defined(tahoe) |
207 | p2->p_vmspace->p_ckey = p1->p_vmspace->p_ckey; /* XXX move this */ | |
9d4095a1 | 208 | #endif |
50108d5c SL |
209 | |
210 | /* | |
50108d5c SL |
211 | * This begins the section where we must prevent the parent |
212 | * from being swapped. | |
213 | */ | |
ae2e0122 | 214 | p1->p_flag |= SKEEP; |
6795ddce MK |
215 | /* |
216 | * Set return values for child before vm_fork, | |
217 | * so they can be copied to child stack. | |
218 | * We return parent pid, and mark as child in retval[1]. | |
f6fca708 MK |
219 | * NOTE: the kernel stack may be at a different location in the child |
220 | * process, and thus addresses of automatic variables (including retval) | |
221 | * may be invalid after vm_fork returns in the child process. | |
6795ddce MK |
222 | */ |
223 | retval[0] = p1->p_pid; | |
224 | retval[1] = 1; | |
ae2e0122 MK |
225 | if (vm_fork(p1, p2, isvfork)) { |
226 | /* | |
6795ddce | 227 | * Child process. Set start time and get to work. |
ae2e0122 | 228 | */ |
d848aba6 | 229 | (void) splclock(); |
ae2e0122 | 230 | p2->p_stats->p_start = time; |
d848aba6 | 231 | (void) spl0(); |
ae2e0122 MK |
232 | p2->p_acflag = AFORK; |
233 | return (0); | |
d848aba6 | 234 | } |
50108d5c SL |
235 | |
236 | /* | |
237 | * Make child runnable and add to run queue. | |
238 | */ | |
ae2e0122 MK |
239 | (void) splhigh(); |
240 | p2->p_stat = SRUN; | |
241 | setrq(p2); | |
50108d5c SL |
242 | (void) spl0(); |
243 | ||
50108d5c SL |
244 | /* |
245 | * Now can be swapped. | |
246 | */ | |
ae2e0122 | 247 | p1->p_flag &= ~SKEEP; |
50108d5c SL |
248 | |
249 | /* | |
f6fca708 | 250 | * Preserve synchronization semantics of vfork. |
ae2e0122 MK |
251 | * If waiting for child to exec or exit, set SPPWAIT |
252 | * on child, and sleep on our proc (in case of exit). | |
50108d5c | 253 | */ |
ae2e0122 MK |
254 | if (isvfork) |
255 | while (p2->p_flag & SPPWAIT) | |
6795ddce | 256 | tsleep((caddr_t)p1, PWAIT, "ppwait", 0); |
50108d5c SL |
257 | |
258 | /* | |
6795ddce MK |
259 | * Return child pid to parent process, |
260 | * marking us as parent via retval[1]. | |
50108d5c | 261 | */ |
ae2e0122 | 262 | retval[0] = p2->p_pid; |
6795ddce | 263 | retval[1] = 0; |
50108d5c SL |
264 | return (0); |
265 | } |