xref: /freebsd/lib/libkvm/kvm_proc.c (revision b1d046441de9053152c7cf03d6b60d9882687e1b)
1 /*-
2  * Copyright (c) 1989, 1992, 1993
3  *	The Regents of the University of California.  All rights reserved.
4  *
5  * This code is derived from software developed by the Computer Systems
6  * Engineering group at Lawrence Berkeley Laboratory under DARPA contract
7  * BG 91-66 and contributed to Berkeley.
8  *
9  * Redistribution and use in source and binary forms, with or without
10  * modification, are permitted provided that the following conditions
11  * are met:
12  * 1. Redistributions of source code must retain the above copyright
13  *    notice, this list of conditions and the following disclaimer.
14  * 2. Redistributions in binary form must reproduce the above copyright
15  *    notice, this list of conditions and the following disclaimer in the
16  *    documentation and/or other materials provided with the distribution.
17  * 4. Neither the name of the University nor the names of its contributors
18  *    may be used to endorse or promote products derived from this software
19  *    without specific prior written permission.
20  *
21  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31  * SUCH DAMAGE.
32  */
33 
34 #if 0
35 #if defined(LIBC_SCCS) && !defined(lint)
36 static char sccsid[] = "@(#)kvm_proc.c	8.3 (Berkeley) 9/23/93";
37 #endif /* LIBC_SCCS and not lint */
38 #endif
39 
40 #include <sys/cdefs.h>
41 __FBSDID("$FreeBSD$");
42 
43 /*
44  * Proc traversal interface for kvm.  ps and w are (probably) the exclusive
45  * users of this code, so we've factored it out into a separate module.
46  * Thus, we keep this grunge out of the other kvm applications (i.e.,
47  * most other applications are interested only in open/close/read/nlist).
48  */
49 
50 #include <sys/param.h>
51 #define	_WANT_UCRED	/* make ucred.h give us 'struct ucred' */
52 #include <sys/ucred.h>
53 #include <sys/queue.h>
54 #include <sys/_lock.h>
55 #include <sys/_mutex.h>
56 #include <sys/_task.h>
57 #include <sys/cpuset.h>
58 #include <sys/user.h>
59 #include <sys/proc.h>
60 #define	_WANT_PRISON	/* make jail.h give us 'struct prison' */
61 #include <sys/jail.h>
62 #include <sys/exec.h>
63 #include <sys/stat.h>
64 #include <sys/sysent.h>
65 #include <sys/ioctl.h>
66 #include <sys/tty.h>
67 #include <sys/file.h>
68 #include <sys/conf.h>
69 #include <stdio.h>
70 #include <stdlib.h>
71 #include <unistd.h>
72 #include <nlist.h>
73 #include <kvm.h>
74 
75 #include <sys/sysctl.h>
76 
77 #include <limits.h>
78 #include <memory.h>
79 #include <paths.h>
80 
81 #include "kvm_private.h"
82 
83 #define KREAD(kd, addr, obj) \
84 	(kvm_read(kd, addr, (char *)(obj), sizeof(*obj)) != sizeof(*obj))
85 
86 static int ticks;
87 static int hz;
88 static uint64_t cpu_tick_frequency;
89 
90 /*
91  * From sys/kern/kern_tc.c. Depends on cpu_tick_frequency, which is
92  * read/initialized before this function is ever called.
93  */
94 static uint64_t
95 cputick2usec(uint64_t tick)
96 {
97 
98 	if (cpu_tick_frequency == 0)
99 		return (0);
100 	if (tick > 18446744073709551)		/* floor(2^64 / 1000) */
101 		return (tick / (cpu_tick_frequency / 1000000));
102 	else if (tick > 18446744073709)	/* floor(2^64 / 1000000) */
103 		return ((tick * 1000) / (cpu_tick_frequency / 1000));
104 	else
105 		return ((tick * 1000000) / cpu_tick_frequency);
106 }
107 
108 /*
109  * Read proc's from memory file into buffer bp, which has space to hold
110  * at most maxcnt procs.
111  */
112 static int
113 kvm_proclist(kvm_t *kd, int what, int arg, struct proc *p,
114     struct kinfo_proc *bp, int maxcnt)
115 {
116 	int cnt = 0;
117 	struct kinfo_proc kinfo_proc, *kp;
118 	struct pgrp pgrp;
119 	struct session sess;
120 	struct cdev t_cdev;
121 	struct tty tty;
122 	struct vmspace vmspace;
123 	struct sigacts sigacts;
124 #if 0
125 	struct pstats pstats;
126 #endif
127 	struct ucred ucred;
128 	struct prison pr;
129 	struct thread mtd;
130 	struct proc proc;
131 	struct proc pproc;
132 	struct sysentvec sysent;
133 	char svname[KI_EMULNAMELEN];
134 
135 	kp = &kinfo_proc;
136 	kp->ki_structsize = sizeof(kinfo_proc);
137 	/*
138 	 * Loop on the processes. this is completely broken because we need to be
139 	 * able to loop on the threads and merge the ones that are the same process some how.
140 	 */
141 	for (; cnt < maxcnt && p != NULL; p = LIST_NEXT(&proc, p_list)) {
142 		memset(kp, 0, sizeof *kp);
143 		if (KREAD(kd, (u_long)p, &proc)) {
144 			_kvm_err(kd, kd->program, "can't read proc at %p", p);
145 			return (-1);
146 		}
147 		if (proc.p_state != PRS_ZOMBIE) {
148 			if (KREAD(kd, (u_long)TAILQ_FIRST(&proc.p_threads),
149 			    &mtd)) {
150 				_kvm_err(kd, kd->program,
151 				    "can't read thread at %p",
152 				    TAILQ_FIRST(&proc.p_threads));
153 				return (-1);
154 			}
155 		}
156 		if (KREAD(kd, (u_long)proc.p_ucred, &ucred) == 0) {
157 			kp->ki_ruid = ucred.cr_ruid;
158 			kp->ki_svuid = ucred.cr_svuid;
159 			kp->ki_rgid = ucred.cr_rgid;
160 			kp->ki_svgid = ucred.cr_svgid;
161 			kp->ki_cr_flags = ucred.cr_flags;
162 			if (ucred.cr_ngroups > KI_NGROUPS) {
163 				kp->ki_ngroups = KI_NGROUPS;
164 				kp->ki_cr_flags |= KI_CRF_GRP_OVERFLOW;
165 			} else
166 				kp->ki_ngroups = ucred.cr_ngroups;
167 			kvm_read(kd, (u_long)ucred.cr_groups, kp->ki_groups,
168 			    kp->ki_ngroups * sizeof(gid_t));
169 			kp->ki_uid = ucred.cr_uid;
170 			if (ucred.cr_prison != NULL) {
171 				if (KREAD(kd, (u_long)ucred.cr_prison, &pr)) {
172 					_kvm_err(kd, kd->program,
173 					    "can't read prison at %p",
174 					    ucred.cr_prison);
175 					return (-1);
176 				}
177 				kp->ki_jid = pr.pr_id;
178 			}
179 		}
180 
181 		switch(what & ~KERN_PROC_INC_THREAD) {
182 
183 		case KERN_PROC_GID:
184 			if (kp->ki_groups[0] != (gid_t)arg)
185 				continue;
186 			break;
187 
188 		case KERN_PROC_PID:
189 			if (proc.p_pid != (pid_t)arg)
190 				continue;
191 			break;
192 
193 		case KERN_PROC_RGID:
194 			if (kp->ki_rgid != (gid_t)arg)
195 				continue;
196 			break;
197 
198 		case KERN_PROC_UID:
199 			if (kp->ki_uid != (uid_t)arg)
200 				continue;
201 			break;
202 
203 		case KERN_PROC_RUID:
204 			if (kp->ki_ruid != (uid_t)arg)
205 				continue;
206 			break;
207 		}
208 		/*
209 		 * We're going to add another proc to the set.  If this
210 		 * will overflow the buffer, assume the reason is because
211 		 * nprocs (or the proc list) is corrupt and declare an error.
212 		 */
213 		if (cnt >= maxcnt) {
214 			_kvm_err(kd, kd->program, "nprocs corrupt");
215 			return (-1);
216 		}
217 		/*
218 		 * gather kinfo_proc
219 		 */
220 		kp->ki_paddr = p;
221 		kp->ki_addr = 0;	/* XXX uarea */
222 		/* kp->ki_kstack = proc.p_thread.td_kstack; XXXKSE */
223 		kp->ki_args = proc.p_args;
224 		kp->ki_tracep = proc.p_tracevp;
225 		kp->ki_textvp = proc.p_textvp;
226 		kp->ki_fd = proc.p_fd;
227 		kp->ki_vmspace = proc.p_vmspace;
228 		if (proc.p_sigacts != NULL) {
229 			if (KREAD(kd, (u_long)proc.p_sigacts, &sigacts)) {
230 				_kvm_err(kd, kd->program,
231 				    "can't read sigacts at %p", proc.p_sigacts);
232 				return (-1);
233 			}
234 			kp->ki_sigignore = sigacts.ps_sigignore;
235 			kp->ki_sigcatch = sigacts.ps_sigcatch;
236 		}
237 #if 0
238 		if ((proc.p_flag & P_INMEM) && proc.p_stats != NULL) {
239 			if (KREAD(kd, (u_long)proc.p_stats, &pstats)) {
240 				_kvm_err(kd, kd->program,
241 				    "can't read stats at %x", proc.p_stats);
242 				return (-1);
243 			}
244 			kp->ki_start = pstats.p_start;
245 
246 			/*
247 			 * XXX: The times here are probably zero and need
248 			 * to be calculated from the raw data in p_rux and
249 			 * p_crux.
250 			 */
251 			kp->ki_rusage = pstats.p_ru;
252 			kp->ki_childstime = pstats.p_cru.ru_stime;
253 			kp->ki_childutime = pstats.p_cru.ru_utime;
254 			/* Some callers want child-times in a single value */
255 			timeradd(&kp->ki_childstime, &kp->ki_childutime,
256 			    &kp->ki_childtime);
257 		}
258 #endif
259 		if (proc.p_oppid)
260 			kp->ki_ppid = proc.p_oppid;
261 		else if (proc.p_pptr) {
262 			if (KREAD(kd, (u_long)proc.p_pptr, &pproc)) {
263 				_kvm_err(kd, kd->program,
264 				    "can't read pproc at %p", proc.p_pptr);
265 				return (-1);
266 			}
267 			kp->ki_ppid = pproc.p_pid;
268 		} else
269 			kp->ki_ppid = 0;
270 		if (proc.p_pgrp == NULL)
271 			goto nopgrp;
272 		if (KREAD(kd, (u_long)proc.p_pgrp, &pgrp)) {
273 			_kvm_err(kd, kd->program, "can't read pgrp at %p",
274 				 proc.p_pgrp);
275 			return (-1);
276 		}
277 		kp->ki_pgid = pgrp.pg_id;
278 		kp->ki_jobc = pgrp.pg_jobc;
279 		if (KREAD(kd, (u_long)pgrp.pg_session, &sess)) {
280 			_kvm_err(kd, kd->program, "can't read session at %p",
281 				pgrp.pg_session);
282 			return (-1);
283 		}
284 		kp->ki_sid = sess.s_sid;
285 		(void)memcpy(kp->ki_login, sess.s_login,
286 						sizeof(kp->ki_login));
287 		kp->ki_kiflag = sess.s_ttyvp ? KI_CTTY : 0;
288 		if (sess.s_leader == p)
289 			kp->ki_kiflag |= KI_SLEADER;
290 		if ((proc.p_flag & P_CONTROLT) && sess.s_ttyp != NULL) {
291 			if (KREAD(kd, (u_long)sess.s_ttyp, &tty)) {
292 				_kvm_err(kd, kd->program,
293 					 "can't read tty at %p", sess.s_ttyp);
294 				return (-1);
295 			}
296 			if (tty.t_dev != NULL) {
297 				if (KREAD(kd, (u_long)tty.t_dev, &t_cdev)) {
298 					_kvm_err(kd, kd->program,
299 						 "can't read cdev at %p",
300 						tty.t_dev);
301 					return (-1);
302 				}
303 #if 0
304 				kp->ki_tdev = t_cdev.si_udev;
305 #else
306 				kp->ki_tdev = NODEV;
307 #endif
308 			}
309 			if (tty.t_pgrp != NULL) {
310 				if (KREAD(kd, (u_long)tty.t_pgrp, &pgrp)) {
311 					_kvm_err(kd, kd->program,
312 						 "can't read tpgrp at %p",
313 						tty.t_pgrp);
314 					return (-1);
315 				}
316 				kp->ki_tpgid = pgrp.pg_id;
317 			} else
318 				kp->ki_tpgid = -1;
319 			if (tty.t_session != NULL) {
320 				if (KREAD(kd, (u_long)tty.t_session, &sess)) {
321 					_kvm_err(kd, kd->program,
322 					    "can't read session at %p",
323 					    tty.t_session);
324 					return (-1);
325 				}
326 				kp->ki_tsid = sess.s_sid;
327 			}
328 		} else {
329 nopgrp:
330 			kp->ki_tdev = NODEV;
331 		}
332 		if ((proc.p_state != PRS_ZOMBIE) && mtd.td_wmesg)
333 			(void)kvm_read(kd, (u_long)mtd.td_wmesg,
334 			    kp->ki_wmesg, WMESGLEN);
335 
336 		(void)kvm_read(kd, (u_long)proc.p_vmspace,
337 		    (char *)&vmspace, sizeof(vmspace));
338 		kp->ki_size = vmspace.vm_map.size;
339 		/*
340 		 * Approximate the kernel's method of calculating
341 		 * this field.
342 		 */
343 #define		pmap_resident_count(pm) ((pm)->pm_stats.resident_count)
344 		kp->ki_rssize = pmap_resident_count(&vmspace.vm_pmap);
345 		kp->ki_swrss = vmspace.vm_swrss;
346 		kp->ki_tsize = vmspace.vm_tsize;
347 		kp->ki_dsize = vmspace.vm_dsize;
348 		kp->ki_ssize = vmspace.vm_ssize;
349 
350 		switch (what & ~KERN_PROC_INC_THREAD) {
351 
352 		case KERN_PROC_PGRP:
353 			if (kp->ki_pgid != (pid_t)arg)
354 				continue;
355 			break;
356 
357 		case KERN_PROC_SESSION:
358 			if (kp->ki_sid != (pid_t)arg)
359 				continue;
360 			break;
361 
362 		case KERN_PROC_TTY:
363 			if ((proc.p_flag & P_CONTROLT) == 0 ||
364 			     kp->ki_tdev != (dev_t)arg)
365 				continue;
366 			break;
367 		}
368 		if (proc.p_comm[0] != 0)
369 			strlcpy(kp->ki_comm, proc.p_comm, MAXCOMLEN);
370 		(void)kvm_read(kd, (u_long)proc.p_sysent, (char *)&sysent,
371 		    sizeof(sysent));
372 		(void)kvm_read(kd, (u_long)sysent.sv_name, (char *)&svname,
373 		    sizeof(svname));
374 		if (svname[0] != 0)
375 			strlcpy(kp->ki_emul, svname, KI_EMULNAMELEN);
376 		if ((proc.p_state != PRS_ZOMBIE) &&
377 		    (mtd.td_blocked != 0)) {
378 			kp->ki_kiflag |= KI_LOCKBLOCK;
379 			if (mtd.td_lockname)
380 				(void)kvm_read(kd,
381 				    (u_long)mtd.td_lockname,
382 				    kp->ki_lockname, LOCKNAMELEN);
383 			kp->ki_lockname[LOCKNAMELEN] = 0;
384 		}
385 		kp->ki_runtime = cputick2usec(proc.p_rux.rux_runtime);
386 		kp->ki_pid = proc.p_pid;
387 		kp->ki_siglist = proc.p_siglist;
388 		SIGSETOR(kp->ki_siglist, mtd.td_siglist);
389 		kp->ki_sigmask = mtd.td_sigmask;
390 		kp->ki_xstat = proc.p_xstat;
391 		kp->ki_acflag = proc.p_acflag;
392 		kp->ki_lock = proc.p_lock;
393 		if (proc.p_state != PRS_ZOMBIE) {
394 			kp->ki_swtime = (ticks - proc.p_swtick) / hz;
395 			kp->ki_flag = proc.p_flag;
396 			kp->ki_sflag = 0;
397 			kp->ki_nice = proc.p_nice;
398 			kp->ki_traceflag = proc.p_traceflag;
399 			if (proc.p_state == PRS_NORMAL) {
400 				if (TD_ON_RUNQ(&mtd) ||
401 				    TD_CAN_RUN(&mtd) ||
402 				    TD_IS_RUNNING(&mtd)) {
403 					kp->ki_stat = SRUN;
404 				} else if (mtd.td_state ==
405 				    TDS_INHIBITED) {
406 					if (P_SHOULDSTOP(&proc)) {
407 						kp->ki_stat = SSTOP;
408 					} else if (
409 					    TD_IS_SLEEPING(&mtd)) {
410 						kp->ki_stat = SSLEEP;
411 					} else if (TD_ON_LOCK(&mtd)) {
412 						kp->ki_stat = SLOCK;
413 					} else {
414 						kp->ki_stat = SWAIT;
415 					}
416 				}
417 			} else {
418 				kp->ki_stat = SIDL;
419 			}
420 			/* Stuff from the thread */
421 			kp->ki_pri.pri_level = mtd.td_priority;
422 			kp->ki_pri.pri_native = mtd.td_base_pri;
423 			kp->ki_lastcpu = mtd.td_lastcpu;
424 			kp->ki_wchan = mtd.td_wchan;
425 			if (mtd.td_name[0] != 0)
426 				strlcpy(kp->ki_tdname, mtd.td_name, MAXCOMLEN);
427 			kp->ki_oncpu = mtd.td_oncpu;
428 			if (mtd.td_name[0] != '\0')
429 				strlcpy(kp->ki_tdname, mtd.td_name, sizeof(kp->ki_tdname));
430 			kp->ki_pctcpu = 0;
431 			kp->ki_rqindex = 0;
432 		} else {
433 			kp->ki_stat = SZOMB;
434 		}
435 		bcopy(&kinfo_proc, bp, sizeof(kinfo_proc));
436 		++bp;
437 		++cnt;
438 	}
439 	return (cnt);
440 }
441 
442 /*
443  * Build proc info array by reading in proc list from a crash dump.
444  * Return number of procs read.  maxcnt is the max we will read.
445  */
446 static int
447 kvm_deadprocs(kvm_t *kd, int what, int arg, u_long a_allproc,
448     u_long a_zombproc, int maxcnt)
449 {
450 	struct kinfo_proc *bp = kd->procbase;
451 	int acnt, zcnt;
452 	struct proc *p;
453 
454 	if (KREAD(kd, a_allproc, &p)) {
455 		_kvm_err(kd, kd->program, "cannot read allproc");
456 		return (-1);
457 	}
458 	acnt = kvm_proclist(kd, what, arg, p, bp, maxcnt);
459 	if (acnt < 0)
460 		return (acnt);
461 
462 	if (KREAD(kd, a_zombproc, &p)) {
463 		_kvm_err(kd, kd->program, "cannot read zombproc");
464 		return (-1);
465 	}
466 	zcnt = kvm_proclist(kd, what, arg, p, bp + acnt, maxcnt - acnt);
467 	if (zcnt < 0)
468 		zcnt = 0;
469 
470 	return (acnt + zcnt);
471 }
472 
473 struct kinfo_proc *
474 kvm_getprocs(kvm_t *kd, int op, int arg, int *cnt)
475 {
476 	int mib[4], st, nprocs;
477 	size_t size;
478 	int temp_op;
479 
480 	if (kd->procbase != 0) {
481 		free((void *)kd->procbase);
482 		/*
483 		 * Clear this pointer in case this call fails.  Otherwise,
484 		 * kvm_close() will free it again.
485 		 */
486 		kd->procbase = 0;
487 	}
488 	if (ISALIVE(kd)) {
489 		size = 0;
490 		mib[0] = CTL_KERN;
491 		mib[1] = KERN_PROC;
492 		mib[2] = op;
493 		mib[3] = arg;
494 		temp_op = op & ~KERN_PROC_INC_THREAD;
495 		st = sysctl(mib,
496 		    temp_op == KERN_PROC_ALL || temp_op == KERN_PROC_PROC ?
497 		    3 : 4, NULL, &size, NULL, 0);
498 		if (st == -1) {
499 			_kvm_syserr(kd, kd->program, "kvm_getprocs");
500 			return (0);
501 		}
502 		/*
503 		 * We can't continue with a size of 0 because we pass
504 		 * it to realloc() (via _kvm_realloc()), and passing 0
505 		 * to realloc() results in undefined behavior.
506 		 */
507 		if (size == 0) {
508 			/*
509 			 * XXX: We should probably return an invalid,
510 			 * but non-NULL, pointer here so any client
511 			 * program trying to dereference it will
512 			 * crash.  However, _kvm_freeprocs() calls
513 			 * free() on kd->procbase if it isn't NULL,
514 			 * and free()'ing a junk pointer isn't good.
515 			 * Then again, _kvm_freeprocs() isn't used
516 			 * anywhere . . .
517 			 */
518 			kd->procbase = _kvm_malloc(kd, 1);
519 			goto liveout;
520 		}
521 		do {
522 			size += size / 10;
523 			kd->procbase = (struct kinfo_proc *)
524 			    _kvm_realloc(kd, kd->procbase, size);
525 			if (kd->procbase == 0)
526 				return (0);
527 			st = sysctl(mib, temp_op == KERN_PROC_ALL ||
528 			    temp_op == KERN_PROC_PROC ? 3 : 4,
529 			    kd->procbase, &size, NULL, 0);
530 		} while (st == -1 && errno == ENOMEM);
531 		if (st == -1) {
532 			_kvm_syserr(kd, kd->program, "kvm_getprocs");
533 			return (0);
534 		}
535 		/*
536 		 * We have to check the size again because sysctl()
537 		 * may "round up" oldlenp if oldp is NULL; hence it
538 		 * might've told us that there was data to get when
539 		 * there really isn't any.
540 		 */
541 		if (size > 0 &&
542 		    kd->procbase->ki_structsize != sizeof(struct kinfo_proc)) {
543 			_kvm_err(kd, kd->program,
544 			    "kinfo_proc size mismatch (expected %zu, got %d)",
545 			    sizeof(struct kinfo_proc),
546 			    kd->procbase->ki_structsize);
547 			return (0);
548 		}
549 liveout:
550 		nprocs = size == 0 ? 0 : size / kd->procbase->ki_structsize;
551 	} else {
552 		struct nlist nl[7], *p;
553 
554 		nl[0].n_name = "_nprocs";
555 		nl[1].n_name = "_allproc";
556 		nl[2].n_name = "_zombproc";
557 		nl[3].n_name = "_ticks";
558 		nl[4].n_name = "_hz";
559 		nl[5].n_name = "_cpu_tick_frequency";
560 		nl[6].n_name = 0;
561 
562 		if (kvm_nlist(kd, nl) != 0) {
563 			for (p = nl; p->n_type != 0; ++p)
564 				;
565 			_kvm_err(kd, kd->program,
566 				 "%s: no such symbol", p->n_name);
567 			return (0);
568 		}
569 		if (KREAD(kd, nl[0].n_value, &nprocs)) {
570 			_kvm_err(kd, kd->program, "can't read nprocs");
571 			return (0);
572 		}
573 		if (KREAD(kd, nl[3].n_value, &ticks)) {
574 			_kvm_err(kd, kd->program, "can't read ticks");
575 			return (0);
576 		}
577 		if (KREAD(kd, nl[4].n_value, &hz)) {
578 			_kvm_err(kd, kd->program, "can't read hz");
579 			return (0);
580 		}
581 		if (KREAD(kd, nl[5].n_value, &cpu_tick_frequency)) {
582 			_kvm_err(kd, kd->program,
583 			    "can't read cpu_tick_frequency");
584 			return (0);
585 		}
586 		size = nprocs * sizeof(struct kinfo_proc);
587 		kd->procbase = (struct kinfo_proc *)_kvm_malloc(kd, size);
588 		if (kd->procbase == 0)
589 			return (0);
590 
591 		nprocs = kvm_deadprocs(kd, op, arg, nl[1].n_value,
592 				      nl[2].n_value, nprocs);
593 #ifdef notdef
594 		size = nprocs * sizeof(struct kinfo_proc);
595 		(void)realloc(kd->procbase, size);
596 #endif
597 	}
598 	*cnt = nprocs;
599 	return (kd->procbase);
600 }
601 
602 void
603 _kvm_freeprocs(kvm_t *kd)
604 {
605 	if (kd->procbase) {
606 		free(kd->procbase);
607 		kd->procbase = 0;
608 	}
609 }
610 
611 void *
612 _kvm_realloc(kvm_t *kd, void *p, size_t n)
613 {
614 	void *np = (void *)realloc(p, n);
615 
616 	if (np == 0) {
617 		free(p);
618 		_kvm_err(kd, kd->program, "out of memory");
619 	}
620 	return (np);
621 }
622 
623 /*
624  * Get the command args or environment.
625  */
626 static char **
627 kvm_argv(kvm_t *kd, const struct kinfo_proc *kp, int env, int nchr)
628 {
629 	int oid[4];
630 	int i;
631 	size_t bufsz;
632 	static int buflen;
633 	static char *buf, *p;
634 	static char **bufp;
635 	static int argc;
636 
637 	if (!ISALIVE(kd)) {
638 		_kvm_err(kd, kd->program,
639 		    "cannot read user space from dead kernel");
640 		return (0);
641 	}
642 
643 	if (nchr == 0 || nchr > ARG_MAX)
644 		nchr = ARG_MAX;
645 	if (buflen == 0) {
646 		buf = malloc(nchr);
647 		if (buf == NULL) {
648 			_kvm_err(kd, kd->program, "cannot allocate memory");
649 			return (0);
650 		}
651 		buflen = nchr;
652 		argc = 32;
653 		bufp = malloc(sizeof(char *) * argc);
654 	} else if (nchr > buflen) {
655 		p = realloc(buf, nchr);
656 		if (p != NULL) {
657 			buf = p;
658 			buflen = nchr;
659 		}
660 	}
661 	oid[0] = CTL_KERN;
662 	oid[1] = KERN_PROC;
663 	oid[2] = env ? KERN_PROC_ENV : KERN_PROC_ARGS;
664 	oid[3] = kp->ki_pid;
665 	bufsz = buflen;
666 	if (sysctl(oid, 4, buf, &bufsz, 0, 0) == -1) {
667 		/*
668 		 * If the supplied buf is too short to hold the requested
669 		 * value the sysctl returns with ENOMEM. The buf is filled
670 		 * with the truncated value and the returned bufsz is equal
671 		 * to the requested len.
672 		 */
673 		if (errno != ENOMEM || bufsz != (size_t)buflen)
674 			return (0);
675 		buf[bufsz - 1] = '\0';
676 		errno = 0;
677 	} else if (bufsz == 0) {
678 		return (0);
679 	}
680 	i = 0;
681 	p = buf;
682 	do {
683 		bufp[i++] = p;
684 		p += strlen(p) + 1;
685 		if (i >= argc) {
686 			argc += argc;
687 			bufp = realloc(bufp,
688 			    sizeof(char *) * argc);
689 		}
690 	} while (p < buf + bufsz);
691 	bufp[i++] = 0;
692 	return (bufp);
693 }
694 
695 char **
696 kvm_getargv(kvm_t *kd, const struct kinfo_proc *kp, int nchr)
697 {
698 	return (kvm_argv(kd, kp, 0, nchr));
699 }
700 
701 char **
702 kvm_getenvv(kvm_t *kd, const struct kinfo_proc *kp, int nchr)
703 {
704 	return (kvm_argv(kd, kp, 1, nchr));
705 }
706