sysv_sem.c revision 92665 
1/* $FreeBSD: head/sys/kern/sysv_sem.c 92665 2002-03-19 10:57:40Z peter $ */
2
3/*
4 * Implementation of SVID semaphores
5 *
6 * Author:  Daniel Boulet
7 *
8 * This software is provided ``AS IS'' without any warranties of any kind.
9 */
10
11#include "opt_sysvipc.h"
12
13#include <sys/param.h>
14#include <sys/systm.h>
15#include <sys/sysproto.h>
16#include <sys/kernel.h>
17#include <sys/proc.h>
18#include <sys/lock.h>
19#include <sys/mutex.h>
20#include <sys/sem.h>
21#include <sys/syscall.h>
22#include <sys/sysent.h>
23#include <sys/sysctl.h>
24#include <sys/malloc.h>
25#include <sys/jail.h>
26
27static MALLOC_DEFINE(M_SEM, "sem", "SVID compatible semaphores");
28
29static void seminit __P((void));
30static int sysvsem_modload __P((struct module *, int, void *));
31static int semunload __P((void));
32static void semexit_myhook __P((struct proc *p));
33static int sysctl_sema __P((SYSCTL_HANDLER_ARGS));
34
35#ifndef _SYS_SYSPROTO_H_
36struct __semctl_args;
37int __semctl __P((struct thread *td, struct __semctl_args *uap));
38struct semget_args;
39int semget __P((struct thread *td, struct semget_args *uap));
40struct semop_args;
41int semop __P((struct thread *td, struct semop_args *uap));
42#endif
43
44static struct sem_undo *semu_alloc __P((struct thread *td));
45static int semundo_adjust __P((struct thread *td, struct sem_undo **supptr,
46		int semid, int semnum, int adjval));
47static void semundo_clear __P((int semid, int semnum));
48
49/* XXX casting to (sy_call_t *) is bogus, as usual. */
50static sy_call_t *semcalls[] = {
51	(sy_call_t *)__semctl, (sy_call_t *)semget,
52	(sy_call_t *)semop
53};
54
55static int	semtot = 0;
56static struct semid_ds *sema;	/* semaphore id pool */
57static struct sem *sem;		/* semaphore pool */
58static struct sem_undo *semu_list; /* list of active undo structures */
59static int	*semu;		/* undo structure pool */
60
61struct sem {
62	u_short	semval;		/* semaphore value */
63	pid_t	sempid;		/* pid of last operation */
64	u_short	semncnt;	/* # awaiting semval > cval */
65	u_short	semzcnt;	/* # awaiting semval = 0 */
66};
67
68/*
69 * Undo structure (one per process)
70 */
71struct sem_undo {
72	struct	sem_undo *un_next;	/* ptr to next active undo structure */
73	struct	proc *un_proc;		/* owner of this structure */
74	short	un_cnt;			/* # of active entries */
75	struct undo {
76		short	un_adjval;	/* adjust on exit values */
77		short	un_num;		/* semaphore # */
78		int	un_id;		/* semid */
79	} un_ent[1];			/* undo entries */
80};
81
82/*
83 * Configuration parameters
84 */
85#ifndef SEMMNI
86#define SEMMNI	10		/* # of semaphore identifiers */
87#endif
88#ifndef SEMMNS
89#define SEMMNS	60		/* # of semaphores in system */
90#endif
91#ifndef SEMUME
92#define SEMUME	10		/* max # of undo entries per process */
93#endif
94#ifndef SEMMNU
95#define SEMMNU	30		/* # of undo structures in system */
96#endif
97
98/* shouldn't need tuning */
99#ifndef SEMMAP
100#define SEMMAP	30		/* # of entries in semaphore map */
101#endif
102#ifndef SEMMSL
103#define SEMMSL	SEMMNS		/* max # of semaphores per id */
104#endif
105#ifndef SEMOPM
106#define SEMOPM	100		/* max # of operations per semop call */
107#endif
108
109#define SEMVMX	32767		/* semaphore maximum value */
110#define SEMAEM	16384		/* adjust on exit max value */
111
112/*
113 * Due to the way semaphore memory is allocated, we have to ensure that
114 * SEMUSZ is properly aligned.
115 */
116
117#define SEM_ALIGN(bytes) (((bytes) + (sizeof(long) - 1)) & ~(sizeof(long) - 1))
118
119/* actual size of an undo structure */
120#define SEMUSZ	SEM_ALIGN(offsetof(struct sem_undo, un_ent[SEMUME]))
121
122/*
123 * Macro to find a particular sem_undo vector
124 */
125#define SEMU(ix)	((struct sem_undo *)(((intptr_t)semu)+ix * seminfo.semusz))
126
127/*
128 * semaphore info struct
129 */
130struct seminfo seminfo = {
131                SEMMAP,         /* # of entries in semaphore map */
132                SEMMNI,         /* # of semaphore identifiers */
133                SEMMNS,         /* # of semaphores in system */
134                SEMMNU,         /* # of undo structures in system */
135                SEMMSL,         /* max # of semaphores per id */
136                SEMOPM,         /* max # of operations per semop call */
137                SEMUME,         /* max # of undo entries per process */
138                SEMUSZ,         /* size in bytes of undo structure */
139                SEMVMX,         /* semaphore maximum value */
140                SEMAEM          /* adjust on exit max value */
141};
142
143SYSCTL_DECL(_kern_ipc);
144SYSCTL_INT(_kern_ipc, OID_AUTO, semmap, CTLFLAG_RW, &seminfo.semmap, 0, "");
145SYSCTL_INT(_kern_ipc, OID_AUTO, semmni, CTLFLAG_RD, &seminfo.semmni, 0, "");
146SYSCTL_INT(_kern_ipc, OID_AUTO, semmns, CTLFLAG_RD, &seminfo.semmns, 0, "");
147SYSCTL_INT(_kern_ipc, OID_AUTO, semmnu, CTLFLAG_RD, &seminfo.semmnu, 0, "");
148SYSCTL_INT(_kern_ipc, OID_AUTO, semmsl, CTLFLAG_RW, &seminfo.semmsl, 0, "");
149SYSCTL_INT(_kern_ipc, OID_AUTO, semopm, CTLFLAG_RD, &seminfo.semopm, 0, "");
150SYSCTL_INT(_kern_ipc, OID_AUTO, semume, CTLFLAG_RD, &seminfo.semume, 0, "");
151SYSCTL_INT(_kern_ipc, OID_AUTO, semusz, CTLFLAG_RD, &seminfo.semusz, 0, "");
152SYSCTL_INT(_kern_ipc, OID_AUTO, semvmx, CTLFLAG_RW, &seminfo.semvmx, 0, "");
153SYSCTL_INT(_kern_ipc, OID_AUTO, semaem, CTLFLAG_RW, &seminfo.semaem, 0, "");
154SYSCTL_PROC(_kern_ipc, OID_AUTO, sema, CTLFLAG_RD,
155    NULL, 0, sysctl_sema, "", "");
156
157static void
158seminit(void)
159{
160	register int i;
161
162	TUNABLE_INT_FETCH("kern.ipc.semmap", &seminfo.semmap);
163	TUNABLE_INT_FETCH("kern.ipc.semmni", &seminfo.semmni);
164	TUNABLE_INT_FETCH("kern.ipc.semmns", &seminfo.semmns);
165	TUNABLE_INT_FETCH("kern.ipc.semmnu", &seminfo.semmnu);
166	TUNABLE_INT_FETCH("kern.ipc.semmsl", &seminfo.semmsl);
167	TUNABLE_INT_FETCH("kern.ipc.semopm", &seminfo.semopm);
168	TUNABLE_INT_FETCH("kern.ipc.semume", &seminfo.semume);
169	TUNABLE_INT_FETCH("kern.ipc.semusz", &seminfo.semusz);
170	TUNABLE_INT_FETCH("kern.ipc.semvmx", &seminfo.semvmx);
171	TUNABLE_INT_FETCH("kern.ipc.semaem", &seminfo.semaem);
172
173	sem = malloc(sizeof(struct sem) * seminfo.semmns, M_SEM, M_WAITOK);
174	if (sem == NULL)
175		panic("sem is NULL");
176	sema = malloc(sizeof(struct semid_ds) * seminfo.semmni, M_SEM, M_WAITOK);
177	if (sema == NULL)
178		panic("sema is NULL");
179	semu = malloc(seminfo.semmnu * seminfo.semusz, M_SEM, M_WAITOK);
180	if (semu == NULL)
181		panic("semu is NULL");
182
183	for (i = 0; i < seminfo.semmni; i++) {
184		sema[i].sem_base = 0;
185		sema[i].sem_perm.mode = 0;
186	}
187	for (i = 0; i < seminfo.semmnu; i++) {
188		register struct sem_undo *suptr = SEMU(i);
189		suptr->un_proc = NULL;
190	}
191	semu_list = NULL;
192	at_exit(semexit_myhook);
193}
194
195static int
196semunload(void)
197{
198
199	if (semtot != 0)
200		return (EBUSY);
201
202	free(sem, M_SEM);
203	free(sema, M_SEM);
204	free(semu, M_SEM);
205	rm_at_exit(semexit_myhook);
206	return (0);
207}
208
209static int
210sysvsem_modload(struct module *module, int cmd, void *arg)
211{
212	int error = 0;
213
214	switch (cmd) {
215	case MOD_LOAD:
216		seminit();
217		break;
218	case MOD_UNLOAD:
219		error = semunload();
220		break;
221	case MOD_SHUTDOWN:
222		break;
223	default:
224		error = EINVAL;
225		break;
226	}
227	return (error);
228}
229
230static moduledata_t sysvsem_mod = {
231	"sysvsem",
232	&sysvsem_modload,
233	NULL
234};
235
236SYSCALL_MODULE_HELPER(semsys);
237SYSCALL_MODULE_HELPER(__semctl);
238SYSCALL_MODULE_HELPER(semget);
239SYSCALL_MODULE_HELPER(semop);
240
241DECLARE_MODULE(sysvsem, sysvsem_mod,
242	SI_SUB_SYSV_SEM, SI_ORDER_FIRST);
243MODULE_VERSION(sysvsem, 1);
244
245/*
246 * Entry point for all SEM calls
247 *
248 * MPSAFE
249 */
250int
251semsys(td, uap)
252	struct thread *td;
253	/* XXX actually varargs. */
254	struct semsys_args /* {
255		u_int	which;
256		int	a2;
257		int	a3;
258		int	a4;
259		int	a5;
260	} */ *uap;
261{
262	int error;
263
264	if (!jail_sysvipc_allowed && jailed(td->td_ucred))
265		return (ENOSYS);
266	if (uap->which >= sizeof(semcalls)/sizeof(semcalls[0]))
267		return (EINVAL);
268	mtx_lock(&Giant);
269	error = (*semcalls[uap->which])(td, &uap->a2);
270	mtx_unlock(&Giant);
271	return (error);
272}
273
274/*
275 * Allocate a new sem_undo structure for a process
276 * (returns ptr to structure or NULL if no more room)
277 */
278
279static struct sem_undo *
280semu_alloc(td)
281	struct thread *td;
282{
283	register int i;
284	register struct sem_undo *suptr;
285	register struct sem_undo **supptr;
286	int attempt;
287
288	/*
289	 * Try twice to allocate something.
290	 * (we'll purge any empty structures after the first pass so
291	 * two passes are always enough)
292	 */
293
294	for (attempt = 0; attempt < 2; attempt++) {
295		/*
296		 * Look for a free structure.
297		 * Fill it in and return it if we find one.
298		 */
299
300		for (i = 0; i < seminfo.semmnu; i++) {
301			suptr = SEMU(i);
302			if (suptr->un_proc == NULL) {
303				suptr->un_next = semu_list;
304				semu_list = suptr;
305				suptr->un_cnt = 0;
306				suptr->un_proc = td->td_proc;
307				return(suptr);
308			}
309		}
310
311		/*
312		 * We didn't find a free one, if this is the first attempt
313		 * then try to free some structures.
314		 */
315
316		if (attempt == 0) {
317			/* All the structures are in use - try to free some */
318			int did_something = 0;
319
320			supptr = &semu_list;
321			while ((suptr = *supptr) != NULL) {
322				if (suptr->un_cnt == 0)  {
323					suptr->un_proc = NULL;
324					*supptr = suptr->un_next;
325					did_something = 1;
326				} else
327					supptr = &(suptr->un_next);
328			}
329
330			/* If we didn't free anything then just give-up */
331			if (!did_something)
332				return(NULL);
333		} else {
334			/*
335			 * The second pass failed even though we freed
336			 * something after the first pass!
337			 * This is IMPOSSIBLE!
338			 */
339			panic("semu_alloc - second attempt failed");
340		}
341	}
342	return (NULL);
343}
344
345/*
346 * Adjust a particular entry for a particular proc
347 */
348
349static int
350semundo_adjust(td, supptr, semid, semnum, adjval)
351	register struct thread *td;
352	struct sem_undo **supptr;
353	int semid, semnum;
354	int adjval;
355{
356	struct proc *p = td->td_proc;
357	register struct sem_undo *suptr;
358	register struct undo *sunptr;
359	int i;
360
361	/* Look for and remember the sem_undo if the caller doesn't provide
362	   it */
363
364	suptr = *supptr;
365	if (suptr == NULL) {
366		for (suptr = semu_list; suptr != NULL;
367		    suptr = suptr->un_next) {
368			if (suptr->un_proc == p) {
369				*supptr = suptr;
370				break;
371			}
372		}
373		if (suptr == NULL) {
374			if (adjval == 0)
375				return(0);
376			suptr = semu_alloc(td);
377			if (suptr == NULL)
378				return(ENOSPC);
379			*supptr = suptr;
380		}
381	}
382
383	/*
384	 * Look for the requested entry and adjust it (delete if adjval becomes
385	 * 0).
386	 */
387	sunptr = &suptr->un_ent[0];
388	for (i = 0; i < suptr->un_cnt; i++, sunptr++) {
389		if (sunptr->un_id != semid || sunptr->un_num != semnum)
390			continue;
391		if (adjval != 0) {
392			adjval += sunptr->un_adjval;
393			if (adjval > seminfo.semaem || adjval < -seminfo.semaem)
394				return (ERANGE);
395		}
396		sunptr->un_adjval = adjval;
397		if (sunptr->un_adjval == 0) {
398			suptr->un_cnt--;
399			if (i < suptr->un_cnt)
400				suptr->un_ent[i] =
401				    suptr->un_ent[suptr->un_cnt];
402		}
403		return(0);
404	}
405
406	/* Didn't find the right entry - create it */
407	if (adjval == 0)
408		return(0);
409	if (adjval > seminfo.semaem || adjval < -seminfo.semaem)
410		return (ERANGE);
411	if (suptr->un_cnt != seminfo.semume) {
412		sunptr = &suptr->un_ent[suptr->un_cnt];
413		suptr->un_cnt++;
414		sunptr->un_adjval = adjval;
415		sunptr->un_id = semid; sunptr->un_num = semnum;
416	} else
417		return(EINVAL);
418	return(0);
419}
420
421static void
422semundo_clear(semid, semnum)
423	int semid, semnum;
424{
425	register struct sem_undo *suptr;
426
427	for (suptr = semu_list; suptr != NULL; suptr = suptr->un_next) {
428		register struct undo *sunptr = &suptr->un_ent[0];
429		register int i = 0;
430
431		while (i < suptr->un_cnt) {
432			if (sunptr->un_id == semid) {
433				if (semnum == -1 || sunptr->un_num == semnum) {
434					suptr->un_cnt--;
435					if (i < suptr->un_cnt) {
436						suptr->un_ent[i] =
437						  suptr->un_ent[suptr->un_cnt];
438						continue;
439					}
440				}
441				if (semnum != -1)
442					break;
443			}
444			i++, sunptr++;
445		}
446	}
447}
448
449/*
450 * Note that the user-mode half of this passes a union, not a pointer
451 */
452#ifndef _SYS_SYSPROTO_H_
453struct __semctl_args {
454	int	semid;
455	int	semnum;
456	int	cmd;
457	union	semun *arg;
458};
459#endif
460
461/*
462 * MPSAFE
463 */
464int
465__semctl(td, uap)
466	struct thread *td;
467	register struct __semctl_args *uap;
468{
469	int semid = uap->semid;
470	int semnum = uap->semnum;
471	int cmd = uap->cmd;
472	union semun *arg = uap->arg;
473	union semun real_arg;
474	struct ucred *cred = td->td_ucred;
475	int i, rval, error;
476	struct semid_ds sbuf;
477	register struct semid_ds *semaptr;
478	u_short usval;
479
480#ifdef SEM_DEBUG
481	printf("call to semctl(%d, %d, %d, 0x%x)\n", semid, semnum, cmd, arg);
482#endif
483	if (!jail_sysvipc_allowed && jailed(td->td_ucred))
484		return (ENOSYS);
485
486	mtx_lock(&Giant);
487	switch(cmd) {
488	case SEM_STAT:
489		if (semid < 0 || semid >= seminfo.semmni)
490			UGAR(EINVAL);
491		semaptr = &sema[semid];
492		if ((semaptr->sem_perm.mode & SEM_ALLOC) == 0 )
493			UGAR(EINVAL);
494		if ((error = ipcperm(td, &semaptr->sem_perm, IPC_R)))
495			UGAR(error);
496		if ((error = copyin(arg, &real_arg, sizeof(real_arg))) != 0)
497			UGAR(error);
498		error = copyout((caddr_t)semaptr, real_arg.buf,
499			sizeof(struct semid_ds));
500		rval = IXSEQ_TO_IPCID(semid,semaptr->sem_perm);
501		if (error == 0)
502			td->td_retval[0] = rval;
503		goto done2;
504	}
505
506	semid = IPCID_TO_IX(semid);
507	if (semid < 0 || semid >= seminfo.semmni) {
508		error = EINVAL;
509		goto done2;
510	}
511
512	semaptr = &sema[semid];
513	if ((semaptr->sem_perm.mode & SEM_ALLOC) == 0 ||
514	    semaptr->sem_perm.seq != IPCID_TO_SEQ(uap->semid)) {
515		error = EINVAL;
516		goto done2;
517	}
518
519	error = 0;
520	rval = 0;
521
522	switch (cmd) {
523	case IPC_RMID:
524		if ((error = ipcperm(td, &semaptr->sem_perm, IPC_M)))
525			goto done2;
526		semaptr->sem_perm.cuid = cred->cr_uid;
527		semaptr->sem_perm.uid = cred->cr_uid;
528		semtot -= semaptr->sem_nsems;
529		for (i = semaptr->sem_base - sem; i < semtot; i++)
530			sem[i] = sem[i + semaptr->sem_nsems];
531		for (i = 0; i < seminfo.semmni; i++) {
532			if ((sema[i].sem_perm.mode & SEM_ALLOC) &&
533			    sema[i].sem_base > semaptr->sem_base)
534				sema[i].sem_base -= semaptr->sem_nsems;
535		}
536		semaptr->sem_perm.mode = 0;
537		semundo_clear(semid, -1);
538		wakeup((caddr_t)semaptr);
539		break;
540
541	case IPC_SET:
542		if ((error = ipcperm(td, &semaptr->sem_perm, IPC_M)))
543			goto done2;
544		if ((error = copyin(arg, &real_arg, sizeof(real_arg))) != 0)
545			goto done2;
546		if ((error = copyin(real_arg.buf, (caddr_t)&sbuf,
547		    sizeof(sbuf))) != 0) {
548			goto done2;
549		}
550		semaptr->sem_perm.uid = sbuf.sem_perm.uid;
551		semaptr->sem_perm.gid = sbuf.sem_perm.gid;
552		semaptr->sem_perm.mode = (semaptr->sem_perm.mode & ~0777) |
553		    (sbuf.sem_perm.mode & 0777);
554		semaptr->sem_ctime = time_second;
555		break;
556
557	case IPC_STAT:
558		if ((error = ipcperm(td, &semaptr->sem_perm, IPC_R)))
559			goto done2;
560		if ((error = copyin(arg, &real_arg, sizeof(real_arg))) != 0)
561			goto done2;
562		error = copyout((caddr_t)semaptr, real_arg.buf,
563				sizeof(struct semid_ds));
564		break;
565
566	case GETNCNT:
567		if ((error = ipcperm(td, &semaptr->sem_perm, IPC_R)))
568			goto done2;
569		if (semnum < 0 || semnum >= semaptr->sem_nsems) {
570			error = EINVAL;
571			goto done2;
572		}
573		rval = semaptr->sem_base[semnum].semncnt;
574		break;
575
576	case GETPID:
577		if ((error = ipcperm(td, &semaptr->sem_perm, IPC_R)))
578			goto done2;
579		if (semnum < 0 || semnum >= semaptr->sem_nsems) {
580			error = EINVAL;
581			goto done2;
582		}
583		rval = semaptr->sem_base[semnum].sempid;
584		break;
585
586	case GETVAL:
587		if ((error = ipcperm(td, &semaptr->sem_perm, IPC_R)))
588			goto done2;
589		if (semnum < 0 || semnum >= semaptr->sem_nsems) {
590			error = EINVAL;
591			goto done2;
592		}
593		rval = semaptr->sem_base[semnum].semval;
594		break;
595
596	case GETALL:
597		if ((error = ipcperm(td, &semaptr->sem_perm, IPC_R)))
598			goto done2;
599		if ((error = copyin(arg, &real_arg, sizeof(real_arg))) != 0)
600			goto done2;
601		for (i = 0; i < semaptr->sem_nsems; i++) {
602			error = copyout((caddr_t)&semaptr->sem_base[i].semval,
603			    &real_arg.array[i], sizeof(real_arg.array[0]));
604			if (error != 0)
605				break;
606		}
607		break;
608
609	case GETZCNT:
610		if ((error = ipcperm(td, &semaptr->sem_perm, IPC_R)))
611			goto done2;
612		if (semnum < 0 || semnum >= semaptr->sem_nsems) {
613			error = EINVAL;
614			goto done2;
615		}
616		rval = semaptr->sem_base[semnum].semzcnt;
617		break;
618
619	case SETVAL:
620		if ((error = ipcperm(td, &semaptr->sem_perm, IPC_W)))
621			goto done2;
622		if (semnum < 0 || semnum >= semaptr->sem_nsems) {
623			error = EINVAL;
624			goto done2;
625		}
626		if ((error = copyin(arg, &real_arg, sizeof(real_arg))) != 0)
627			goto done2;
628		if (real_arg.val < 0 || real_arg.val > seminfo.semvmx) {
629			error = ERANGE;
630			goto done2;
631		}
632		semaptr->sem_base[semnum].semval = real_arg.val;
633		semundo_clear(semid, semnum);
634		wakeup((caddr_t)semaptr);
635		break;
636
637	case SETALL:
638		if ((error = ipcperm(td, &semaptr->sem_perm, IPC_W)))
639			goto done2;
640		if ((error = copyin(arg, &real_arg, sizeof(real_arg))) != 0)
641			goto done2;
642		for (i = 0; i < semaptr->sem_nsems; i++) {
643			error = copyin(&real_arg.array[i],
644			    (caddr_t)&usval, sizeof(real_arg.array[0]));
645			if (error != 0)
646				break;
647			if (usval > seminfo.semvmx) {
648				error = ERANGE;
649				break;
650			}
651			semaptr->sem_base[i].semval = usval;
652		}
653		semundo_clear(semid, -1);
654		wakeup((caddr_t)semaptr);
655		break;
656
657	default:
658		error = EINVAL;
659		break;
660	}
661
662	if (error == 0)
663		td->td_retval[0] = rval;
664done2:
665	mtx_unlock(&Giant);
666	return(error);
667}
668
669#ifndef _SYS_SYSPROTO_H_
670struct semget_args {
671	key_t	key;
672	int	nsems;
673	int	semflg;
674};
675#endif
676
677/*
678 * MPSAFE
679 */
680int
681semget(td, uap)
682	struct thread *td;
683	register struct semget_args *uap;
684{
685	int semid, error = 0;
686	int key = uap->key;
687	int nsems = uap->nsems;
688	int semflg = uap->semflg;
689	struct ucred *cred = td->td_ucred;
690
691#ifdef SEM_DEBUG
692	printf("semget(0x%x, %d, 0%o)\n", key, nsems, semflg);
693#endif
694	if (!jail_sysvipc_allowed && jailed(td->td_ucred))
695		return (ENOSYS);
696
697	mtx_lock(&Giant);
698	if (key != IPC_PRIVATE) {
699		for (semid = 0; semid < seminfo.semmni; semid++) {
700			if ((sema[semid].sem_perm.mode & SEM_ALLOC) &&
701			    sema[semid].sem_perm.key == key)
702				break;
703		}
704		if (semid < seminfo.semmni) {
705#ifdef SEM_DEBUG
706			printf("found public key\n");
707#endif
708			if ((error = ipcperm(td, &sema[semid].sem_perm,
709			    semflg & 0700))) {
710				goto done2;
711			}
712			if (nsems > 0 && sema[semid].sem_nsems < nsems) {
713#ifdef SEM_DEBUG
714				printf("too small\n");
715#endif
716				error = EINVAL;
717				goto done2;
718			}
719			if ((semflg & IPC_CREAT) && (semflg & IPC_EXCL)) {
720#ifdef SEM_DEBUG
721				printf("not exclusive\n");
722#endif
723				error = EEXIST;
724				goto done2;
725			}
726			goto found;
727		}
728	}
729
730#ifdef SEM_DEBUG
731	printf("need to allocate the semid_ds\n");
732#endif
733	if (key == IPC_PRIVATE || (semflg & IPC_CREAT)) {
734		if (nsems <= 0 || nsems > seminfo.semmsl) {
735#ifdef SEM_DEBUG
736			printf("nsems out of range (0<%d<=%d)\n", nsems,
737			    seminfo.semmsl);
738#endif
739			error = EINVAL;
740			goto done2;
741		}
742		if (nsems > seminfo.semmns - semtot) {
743#ifdef SEM_DEBUG
744			printf("not enough semaphores left (need %d, got %d)\n",
745			    nsems, seminfo.semmns - semtot);
746#endif
747			error = ENOSPC;
748			goto done2;
749		}
750		for (semid = 0; semid < seminfo.semmni; semid++) {
751			if ((sema[semid].sem_perm.mode & SEM_ALLOC) == 0)
752				break;
753		}
754		if (semid == seminfo.semmni) {
755#ifdef SEM_DEBUG
756			printf("no more semid_ds's available\n");
757#endif
758			error = ENOSPC;
759			goto done2;
760		}
761#ifdef SEM_DEBUG
762		printf("semid %d is available\n", semid);
763#endif
764		sema[semid].sem_perm.key = key;
765		sema[semid].sem_perm.cuid = cred->cr_uid;
766		sema[semid].sem_perm.uid = cred->cr_uid;
767		sema[semid].sem_perm.cgid = cred->cr_gid;
768		sema[semid].sem_perm.gid = cred->cr_gid;
769		sema[semid].sem_perm.mode = (semflg & 0777) | SEM_ALLOC;
770		sema[semid].sem_perm.seq =
771		    (sema[semid].sem_perm.seq + 1) & 0x7fff;
772		sema[semid].sem_nsems = nsems;
773		sema[semid].sem_otime = 0;
774		sema[semid].sem_ctime = time_second;
775		sema[semid].sem_base = &sem[semtot];
776		semtot += nsems;
777		bzero(sema[semid].sem_base,
778		    sizeof(sema[semid].sem_base[0])*nsems);
779#ifdef SEM_DEBUG
780		printf("sembase = 0x%x, next = 0x%x\n", sema[semid].sem_base,
781		    &sem[semtot]);
782#endif
783	} else {
784#ifdef SEM_DEBUG
785		printf("didn't find it and wasn't asked to create it\n");
786#endif
787		error = ENOENT;
788		goto done2;
789	}
790
791found:
792	td->td_retval[0] = IXSEQ_TO_IPCID(semid, sema[semid].sem_perm);
793done2:
794	mtx_unlock(&Giant);
795	return (error);
796}
797
798#ifndef _SYS_SYSPROTO_H_
799struct semop_args {
800	int	semid;
801	struct	sembuf *sops;
802	u_int	nsops;
803};
804#endif
805
806/*
807 * MPSAFE
808 */
809int
810semop(td, uap)
811	struct thread *td;
812	register struct semop_args *uap;
813{
814	int semid = uap->semid;
815	u_int nsops = uap->nsops;
816	struct sembuf *sops = NULL;
817	register struct semid_ds *semaptr;
818	register struct sembuf *sopptr = 0;
819	register struct sem *semptr = 0;
820	struct sem_undo *suptr;
821	int i, j, error;
822	int do_wakeup, do_undos;
823
824#ifdef SEM_DEBUG
825	printf("call to semop(%d, 0x%x, %u)\n", semid, sops, nsops);
826#endif
827
828	if (!jail_sysvipc_allowed && jailed(td->td_ucred))
829		return (ENOSYS);
830
831	mtx_lock(&Giant);
832	semid = IPCID_TO_IX(semid);	/* Convert back to zero origin */
833
834	if (semid < 0 || semid >= seminfo.semmni) {
835		error = EINVAL;
836		goto done2;
837	}
838
839	semaptr = &sema[semid];
840	if ((semaptr->sem_perm.mode & SEM_ALLOC) == 0) {
841		error = EINVAL;
842		goto done2;
843	}
844	if (semaptr->sem_perm.seq != IPCID_TO_SEQ(uap->semid)) {
845		error = EINVAL;
846		goto done2;
847	}
848	if (nsops > seminfo.semopm) {
849#ifdef SEM_DEBUG
850		printf("too many sops (max=%d, nsops=%d)\n", seminfo.semopm,
851		    nsops);
852#endif
853		error = E2BIG;
854		goto done2;
855	}
856
857	/* Allocate memory for sem_ops */
858	sops = malloc(nsops * sizeof(sops[0]), M_SEM, M_WAITOK);
859	if (!sops)
860		panic("Failed to allocate %d sem_ops", nsops);
861
862	if ((error = copyin(uap->sops, sops, nsops * sizeof(sops[0]))) != 0) {
863#ifdef SEM_DEBUG
864		printf("error = %d from copyin(%08x, %08x, %d)\n", error,
865		    uap->sops, sops, nsops * sizeof(sops[0]));
866#endif
867		goto done2;
868	}
869
870	/*
871	 * Initial pass thru sops to see what permissions are needed.
872	 * Also perform any checks that don't need repeating on each
873	 * attempt to satisfy the request vector.
874	 */
875	j = 0;		/* permission needed */
876	do_undos = 0;
877	for (i = 0; i < nsops; i++) {
878		sopptr = &sops[i];
879		if (sopptr->sem_num >= semaptr->sem_nsems) {
880			error = EFBIG;
881			goto done2;
882		}
883		if (sopptr->sem_flg & SEM_UNDO && sopptr->sem_op != 0)
884			do_undos = 1;
885		j |= (sopptr->sem_op == 0) ? SEM_R : SEM_A;
886	}
887
888	if ((error = ipcperm(td, &semaptr->sem_perm, j))) {
889#ifdef SEM_DEBUG
890		printf("error = %d from ipaccess\n", error);
891#endif
892		goto done2;
893	}
894
895	/*
896	 * Loop trying to satisfy the vector of requests.
897	 * If we reach a point where we must wait, any requests already
898	 * performed are rolled back and we go to sleep until some other
899	 * process wakes us up.  At this point, we start all over again.
900	 *
901	 * This ensures that from the perspective of other tasks, a set
902	 * of requests is atomic (never partially satisfied).
903	 */
904	for (;;) {
905		do_wakeup = 0;
906		error = 0;	/* error return if necessary */
907
908		for (i = 0; i < nsops; i++) {
909			sopptr = &sops[i];
910			semptr = &semaptr->sem_base[sopptr->sem_num];
911
912#ifdef SEM_DEBUG
913			printf("semop:  semaptr=%x, sem_base=%x, semptr=%x, sem[%d]=%d : op=%d, flag=%s\n",
914			    semaptr, semaptr->sem_base, semptr,
915			    sopptr->sem_num, semptr->semval, sopptr->sem_op,
916			    (sopptr->sem_flg & IPC_NOWAIT) ? "nowait" : "wait");
917#endif
918
919			if (sopptr->sem_op < 0) {
920				if (semptr->semval + sopptr->sem_op < 0) {
921#ifdef SEM_DEBUG
922					printf("semop:  can't do it now\n");
923#endif
924					break;
925				} else {
926					semptr->semval += sopptr->sem_op;
927					if (semptr->semval == 0 &&
928					    semptr->semzcnt > 0)
929						do_wakeup = 1;
930				}
931			} else if (sopptr->sem_op == 0) {
932				if (semptr->semval != 0) {
933#ifdef SEM_DEBUG
934					printf("semop:  not zero now\n");
935#endif
936					break;
937				}
938			} else if (semptr->semval + sopptr->sem_op >
939			    seminfo.semvmx) {
940				error = ERANGE;
941				break;
942			} else {
943				if (semptr->semncnt > 0)
944					do_wakeup = 1;
945				semptr->semval += sopptr->sem_op;
946			}
947		}
948
949		/*
950		 * Did we get through the entire vector?
951		 */
952		if (i >= nsops)
953			goto done;
954
955		/*
956		 * No ... rollback anything that we've already done
957		 */
958#ifdef SEM_DEBUG
959		printf("semop:  rollback 0 through %d\n", i-1);
960#endif
961		for (j = 0; j < i; j++)
962			semaptr->sem_base[sops[j].sem_num].semval -=
963			    sops[j].sem_op;
964
965		/* If we detected an error, return it */
966		if (error != 0)
967			goto done2;
968
969		/*
970		 * If the request that we couldn't satisfy has the
971		 * NOWAIT flag set then return with EAGAIN.
972		 */
973		if (sopptr->sem_flg & IPC_NOWAIT) {
974			error = EAGAIN;
975			goto done2;
976		}
977
978		if (sopptr->sem_op == 0)
979			semptr->semzcnt++;
980		else
981			semptr->semncnt++;
982
983#ifdef SEM_DEBUG
984		printf("semop:  good night!\n");
985#endif
986		error = tsleep((caddr_t)semaptr, (PZERO - 4) | PCATCH,
987		    "semwait", 0);
988#ifdef SEM_DEBUG
989		printf("semop:  good morning (error=%d)!\n", error);
990#endif
991
992		if (error != 0) {
993			error = EINTR;
994			goto done2;
995		}
996#ifdef SEM_DEBUG
997		printf("semop:  good morning!\n");
998#endif
999
1000		/*
1001		 * Make sure that the semaphore still exists
1002		 */
1003		if ((semaptr->sem_perm.mode & SEM_ALLOC) == 0 ||
1004		    semaptr->sem_perm.seq != IPCID_TO_SEQ(uap->semid)) {
1005			error = EIDRM;
1006			goto done2;
1007		}
1008
1009		/*
1010		 * The semaphore is still alive.  Readjust the count of
1011		 * waiting processes.
1012		 */
1013		if (sopptr->sem_op == 0)
1014			semptr->semzcnt--;
1015		else
1016			semptr->semncnt--;
1017	}
1018
1019done:
1020	/*
1021	 * Process any SEM_UNDO requests.
1022	 */
1023	if (do_undos) {
1024		suptr = NULL;
1025		for (i = 0; i < nsops; i++) {
1026			/*
1027			 * We only need to deal with SEM_UNDO's for non-zero
1028			 * op's.
1029			 */
1030			int adjval;
1031
1032			if ((sops[i].sem_flg & SEM_UNDO) == 0)
1033				continue;
1034			adjval = sops[i].sem_op;
1035			if (adjval == 0)
1036				continue;
1037			error = semundo_adjust(td, &suptr, semid,
1038			    sops[i].sem_num, -adjval);
1039			if (error == 0)
1040				continue;
1041
1042			/*
1043			 * Oh-Oh!  We ran out of either sem_undo's or undo's.
1044			 * Rollback the adjustments to this point and then
1045			 * rollback the semaphore ups and down so we can return
1046			 * with an error with all structures restored.  We
1047			 * rollback the undo's in the exact reverse order that
1048			 * we applied them.  This guarantees that we won't run
1049			 * out of space as we roll things back out.
1050			 */
1051			for (j = i - 1; j >= 0; j--) {
1052				if ((sops[j].sem_flg & SEM_UNDO) == 0)
1053					continue;
1054				adjval = sops[j].sem_op;
1055				if (adjval == 0)
1056					continue;
1057				if (semundo_adjust(td, &suptr, semid,
1058				    sops[j].sem_num, adjval) != 0)
1059					panic("semop - can't undo undos");
1060			}
1061
1062			for (j = 0; j < nsops; j++)
1063				semaptr->sem_base[sops[j].sem_num].semval -=
1064				    sops[j].sem_op;
1065
1066#ifdef SEM_DEBUG
1067			printf("error = %d from semundo_adjust\n", error);
1068#endif
1069			goto done2;
1070		} /* loop through the sops */
1071	} /* if (do_undos) */
1072
1073	/* We're definitely done - set the sempid's and time */
1074	for (i = 0; i < nsops; i++) {
1075		sopptr = &sops[i];
1076		semptr = &semaptr->sem_base[sopptr->sem_num];
1077		semptr->sempid = td->td_proc->p_pid;
1078	}
1079	semaptr->sem_otime = time_second;
1080
1081	/*
1082	 * Do a wakeup if any semaphore was up'd whilst something was
1083	 * sleeping on it.
1084	 */
1085	if (do_wakeup) {
1086#ifdef SEM_DEBUG
1087		printf("semop:  doing wakeup\n");
1088#endif
1089		wakeup((caddr_t)semaptr);
1090#ifdef SEM_DEBUG
1091		printf("semop:  back from wakeup\n");
1092#endif
1093	}
1094#ifdef SEM_DEBUG
1095	printf("semop:  done\n");
1096#endif
1097	td->td_retval[0] = 0;
1098done2:
1099	if (sops)
1100	    free(sops, M_SEM);
1101	mtx_unlock(&Giant);
1102	return (error);
1103}
1104
1105/*
1106 * Go through the undo structures for this process and apply the adjustments to
1107 * semaphores.
1108 */
1109static void
1110semexit_myhook(p)
1111	struct proc *p;
1112{
1113	register struct sem_undo *suptr;
1114	register struct sem_undo **supptr;
1115
1116	/*
1117	 * Go through the chain of undo vectors looking for one
1118	 * associated with this process.
1119	 */
1120
1121	for (supptr = &semu_list; (suptr = *supptr) != NULL;
1122	    supptr = &suptr->un_next) {
1123		if (suptr->un_proc == p)
1124			break;
1125	}
1126
1127	if (suptr == NULL)
1128		return;
1129
1130#ifdef SEM_DEBUG
1131	printf("proc @%08x has undo structure with %d entries\n", p,
1132	    suptr->un_cnt);
1133#endif
1134
1135	/*
1136	 * If there are any active undo elements then process them.
1137	 */
1138	if (suptr->un_cnt > 0) {
1139		int ix;
1140
1141		for (ix = 0; ix < suptr->un_cnt; ix++) {
1142			int semid = suptr->un_ent[ix].un_id;
1143			int semnum = suptr->un_ent[ix].un_num;
1144			int adjval = suptr->un_ent[ix].un_adjval;
1145			struct semid_ds *semaptr;
1146
1147			semaptr = &sema[semid];
1148			if ((semaptr->sem_perm.mode & SEM_ALLOC) == 0)
1149				panic("semexit - semid not allocated");
1150			if (semnum >= semaptr->sem_nsems)
1151				panic("semexit - semnum out of range");
1152
1153#ifdef SEM_DEBUG
1154			printf("semexit:  %08x id=%d num=%d(adj=%d) ; sem=%d\n",
1155			    suptr->un_proc, suptr->un_ent[ix].un_id,
1156			    suptr->un_ent[ix].un_num,
1157			    suptr->un_ent[ix].un_adjval,
1158			    semaptr->sem_base[semnum].semval);
1159#endif
1160
1161			if (adjval < 0) {
1162				if (semaptr->sem_base[semnum].semval < -adjval)
1163					semaptr->sem_base[semnum].semval = 0;
1164				else
1165					semaptr->sem_base[semnum].semval +=
1166					    adjval;
1167			} else
1168				semaptr->sem_base[semnum].semval += adjval;
1169
1170			wakeup((caddr_t)semaptr);
1171#ifdef SEM_DEBUG
1172			printf("semexit:  back from wakeup\n");
1173#endif
1174		}
1175	}
1176
1177	/*
1178	 * Deallocate the undo vector.
1179	 */
1180#ifdef SEM_DEBUG
1181	printf("removing vector\n");
1182#endif
1183	suptr->un_proc = NULL;
1184	*supptr = suptr->un_next;
1185}
1186
1187static int
1188sysctl_sema(SYSCTL_HANDLER_ARGS)
1189{
1190
1191	return (SYSCTL_OUT(req, sema,
1192	    sizeof(struct semid_ds) * seminfo.semmni));
1193}
1194