xref: /netbsd-src/lib/libkvm/kvm_proc.c (revision e4d7c2e329d54c97e0c0bd3016bbe74f550c3d5e)
1 /*	$NetBSD: kvm_proc.c,v 1.32 2000/01/15 19:16:32 chs Exp $	*/
2 
3 /*-
4  * Copyright (c) 1998 The NetBSD Foundation, Inc.
5  * All rights reserved.
6  *
7  * This code is derived from software contributed to The NetBSD Foundation
8  * by Charles M. Hannum.
9  *
10  * Redistribution and use in source and binary forms, with or without
11  * modification, are permitted provided that the following conditions
12  * are met:
13  * 1. Redistributions of source code must retain the above copyright
14  *    notice, this list of conditions and the following disclaimer.
15  * 2. Redistributions in binary form must reproduce the above copyright
16  *    notice, this list of conditions and the following disclaimer in the
17  *    documentation and/or other materials provided with the distribution.
18  * 3. All advertising materials mentioning features or use of this software
19  *    must display the following acknowledgement:
20  *        This product includes software developed by the NetBSD
21  *        Foundation, Inc. and its contributors.
22  * 4. Neither the name of The NetBSD Foundation nor the names of its
23  *    contributors may be used to endorse or promote products derived
24  *    from this software without specific prior written permission.
25  *
26  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
27  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
28  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
29  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
30  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
31  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
32  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
33  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
34  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
35  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
36  * POSSIBILITY OF SUCH DAMAGE.
37  */
38 
39 /*-
40  * Copyright (c) 1989, 1992, 1993
41  *	The Regents of the University of California.  All rights reserved.
42  *
43  * This code is derived from software developed by the Computer Systems
44  * Engineering group at Lawrence Berkeley Laboratory under DARPA contract
45  * BG 91-66 and contributed to Berkeley.
46  *
47  * Redistribution and use in source and binary forms, with or without
48  * modification, are permitted provided that the following conditions
49  * are met:
50  * 1. Redistributions of source code must retain the above copyright
51  *    notice, this list of conditions and the following disclaimer.
52  * 2. Redistributions in binary form must reproduce the above copyright
53  *    notice, this list of conditions and the following disclaimer in the
54  *    documentation and/or other materials provided with the distribution.
55  * 3. All advertising materials mentioning features or use of this software
56  *    must display the following acknowledgement:
57  *	This product includes software developed by the University of
58  *	California, Berkeley and its contributors.
59  * 4. Neither the name of the University nor the names of its contributors
60  *    may be used to endorse or promote products derived from this software
61  *    without specific prior written permission.
62  *
63  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
64  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
65  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
66  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
67  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
68  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
69  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
70  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
71  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
72  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
73  * SUCH DAMAGE.
74  */
75 
76 #include <sys/cdefs.h>
77 #if defined(LIBC_SCCS) && !defined(lint)
78 #if 0
79 static char sccsid[] = "@(#)kvm_proc.c	8.3 (Berkeley) 9/23/93";
80 #else
81 __RCSID("$NetBSD: kvm_proc.c,v 1.32 2000/01/15 19:16:32 chs Exp $");
82 #endif
83 #endif /* LIBC_SCCS and not lint */
84 
85 /*
86  * Proc traversal interface for kvm.  ps and w are (probably) the exclusive
87  * users of this code, so we've factored it out into a separate module.
88  * Thus, we keep this grunge out of the other kvm applications (i.e.,
89  * most other applications are interested only in open/close/read/nlist).
90  */
91 
92 #include <sys/param.h>
93 #include <sys/user.h>
94 #include <sys/proc.h>
95 #include <sys/exec.h>
96 #include <sys/stat.h>
97 #include <sys/ioctl.h>
98 #include <sys/tty.h>
99 #include <stdlib.h>
100 #include <string.h>
101 #include <unistd.h>
102 #include <nlist.h>
103 #include <kvm.h>
104 
105 #include <vm/vm.h>
106 #include <vm/vm_param.h>
107 
108 #include <uvm/uvm_extern.h>
109 #include <uvm/uvm_amap.h>
110 
111 #include <sys/sysctl.h>
112 
113 #include <limits.h>
114 #include <db.h>
115 #include <paths.h>
116 
117 #include "kvm_private.h"
118 
119 #define KREAD(kd, addr, obj) \
120 	(kvm_read(kd, addr, (void *)(obj), sizeof(*obj)) != sizeof(*obj))
121 
122 char		*_kvm_uread __P((kvm_t *, const struct proc *, u_long, u_long *));
123 ssize_t		kvm_uread __P((kvm_t *, const struct proc *, u_long, char *,
124 		    size_t));
125 
126 static char	**kvm_argv __P((kvm_t *, const struct proc *, u_long, int,
127 		    int));
128 static int	kvm_deadprocs __P((kvm_t *, int, int, u_long, u_long, u_long,
129 		    int));
130 static char	**kvm_doargv __P((kvm_t *, const struct kinfo_proc *, int,
131 		    void (*)(struct ps_strings *, u_long *, int *)));
132 static int	kvm_proclist __P((kvm_t *, int, int, struct proc *,
133 		    struct kinfo_proc *, int));
134 static int	proc_verify __P((kvm_t *, u_long, const struct proc *));
135 static void	ps_str_a __P((struct ps_strings *, u_long *, int *));
136 static void	ps_str_e __P((struct ps_strings *, u_long *, int *));
137 
138 char *
139 _kvm_uread(kd, p, va, cnt)
140 	kvm_t *kd;
141 	const struct proc *p;
142 	u_long va;
143 	u_long *cnt;
144 {
145 	int true = 1;
146 	u_long addr, head;
147 	u_long offset;
148 	struct vm_map_entry vme;
149 	struct vm_amap amap;
150 	struct vm_anon *anonp, anon;
151 	struct vm_page pg;
152 	u_long slot;
153 
154 	if (kd->swapspc == 0) {
155 		kd->swapspc = (char *)_kvm_malloc(kd, (size_t)kd->nbpg);
156 		if (kd->swapspc == 0)
157 			return (0);
158 	}
159 
160 	/*
161 	 * Look through the address map for the memory object
162 	 * that corresponds to the given virtual address.
163 	 * The header just has the entire valid range.
164 	 */
165 	head = (u_long)&p->p_vmspace->vm_map.header;
166 	addr = head;
167 	while (true) {
168 		if (KREAD(kd, addr, &vme))
169 			return (0);
170 
171 		if (va >= vme.start && va < vme.end &&
172 		    vme.aref.ar_amap != NULL)
173 			break;
174 
175 		addr = (u_long)vme.next;
176 		if (addr == head)
177 			return (0);
178 
179 	}
180 
181 	/*
182 	 * we found the map entry, now to find the object...
183 	 */
184 	if (vme.aref.ar_amap == NULL)
185 		return NULL;
186 
187 	addr = (u_long)vme.aref.ar_amap;
188 	if (KREAD(kd, addr, &amap))
189 		return NULL;
190 
191 	offset = va - vme.start;
192 	slot = offset / kd->nbpg + vme.aref.ar_pageoff;
193 	/* sanity-check slot number */
194 	if (slot  > amap.am_nslot)
195 		return NULL;
196 
197 	addr = (u_long)amap.am_anon + (offset / kd->nbpg) * sizeof(anonp);
198 	if (KREAD(kd, addr, &anonp))
199 		return NULL;
200 
201 	addr = (u_long)anonp;
202 	if (KREAD(kd, addr, &anon))
203 		return NULL;
204 
205 	addr = (u_long)anon.u.an_page;
206 	if (addr) {
207 		if (KREAD(kd, addr, &pg))
208 			return NULL;
209 
210 		if (pread(kd->pmfd, (void *)kd->swapspc, (size_t)kd->nbpg,
211 		    (off_t)pg.phys_addr) != kd->nbpg)
212 			return NULL;
213 	}
214 	else {
215 		if (pread(kd->swfd, (void *)kd->swapspc, (size_t)kd->nbpg,
216 		    (off_t)(anon.an_swslot * kd->nbpg)) != kd->nbpg)
217 			return NULL;
218 	}
219 
220 	/* Found the page. */
221 	offset %= kd->nbpg;
222 	*cnt = kd->nbpg - offset;
223 	return (&kd->swapspc[(size_t)offset]);
224 }
225 
226 /*
227  * Read proc's from memory file into buffer bp, which has space to hold
228  * at most maxcnt procs.
229  */
230 static int
231 kvm_proclist(kd, what, arg, p, bp, maxcnt)
232 	kvm_t *kd;
233 	int what, arg;
234 	struct proc *p;
235 	struct kinfo_proc *bp;
236 	int maxcnt;
237 {
238 	int cnt = 0;
239 	struct eproc eproc;
240 	struct pgrp pgrp;
241 	struct session sess;
242 	struct tty tty;
243 	struct proc proc;
244 
245 	for (; cnt < maxcnt && p != NULL; p = proc.p_list.le_next) {
246 		if (KREAD(kd, (u_long)p, &proc)) {
247 			_kvm_err(kd, kd->program, "can't read proc at %x", p);
248 			return (-1);
249 		}
250 		if (KREAD(kd, (u_long)proc.p_cred, &eproc.e_pcred) == 0)
251 			if (KREAD(kd, (u_long)eproc.e_pcred.pc_ucred,
252 			    &eproc.e_ucred)) {
253 				_kvm_err(kd, kd->program,
254 				    "can't read proc credentials at %x", p);
255 				return -1;
256 			}
257 
258 		switch(what) {
259 
260 		case KERN_PROC_PID:
261 			if (proc.p_pid != (pid_t)arg)
262 				continue;
263 			break;
264 
265 		case KERN_PROC_UID:
266 			if (eproc.e_ucred.cr_uid != (uid_t)arg)
267 				continue;
268 			break;
269 
270 		case KERN_PROC_RUID:
271 			if (eproc.e_pcred.p_ruid != (uid_t)arg)
272 				continue;
273 			break;
274 		}
275 		/*
276 		 * We're going to add another proc to the set.  If this
277 		 * will overflow the buffer, assume the reason is because
278 		 * nprocs (or the proc list) is corrupt and declare an error.
279 		 */
280 		if (cnt >= maxcnt) {
281 			_kvm_err(kd, kd->program, "nprocs corrupt");
282 			return (-1);
283 		}
284 		/*
285 		 * gather eproc
286 		 */
287 		eproc.e_paddr = p;
288 		if (KREAD(kd, (u_long)proc.p_pgrp, &pgrp)) {
289 			_kvm_err(kd, kd->program, "can't read pgrp at %x",
290 				 proc.p_pgrp);
291 			return (-1);
292 		}
293 		eproc.e_sess = pgrp.pg_session;
294 		eproc.e_pgid = pgrp.pg_id;
295 		eproc.e_jobc = pgrp.pg_jobc;
296 		if (KREAD(kd, (u_long)pgrp.pg_session, &sess)) {
297 			_kvm_err(kd, kd->program, "can't read session at %x",
298 				pgrp.pg_session);
299 			return (-1);
300 		}
301 		if ((proc.p_flag & P_CONTROLT) && sess.s_ttyp != NULL) {
302 			if (KREAD(kd, (u_long)sess.s_ttyp, &tty)) {
303 				_kvm_err(kd, kd->program,
304 					 "can't read tty at %x", sess.s_ttyp);
305 				return (-1);
306 			}
307 			eproc.e_tdev = tty.t_dev;
308 			eproc.e_tsess = tty.t_session;
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 &x",
313 						tty.t_pgrp);
314 					return (-1);
315 				}
316 				eproc.e_tpgid = pgrp.pg_id;
317 			} else
318 				eproc.e_tpgid = -1;
319 		} else
320 			eproc.e_tdev = NODEV;
321 		eproc.e_flag = sess.s_ttyvp ? EPROC_CTTY : 0;
322 		if (sess.s_leader == p)
323 			eproc.e_flag |= EPROC_SLEADER;
324 		if (proc.p_wmesg)
325 			(void)kvm_read(kd, (u_long)proc.p_wmesg,
326 			    eproc.e_wmesg, WMESGLEN);
327 
328 		(void)kvm_read(kd, (u_long)proc.p_vmspace,
329 		    (void *)&eproc.e_vm, sizeof(eproc.e_vm));
330 
331 		eproc.e_xsize = eproc.e_xrssize = 0;
332 		eproc.e_xccount = eproc.e_xswrss = 0;
333 
334 		switch (what) {
335 
336 		case KERN_PROC_PGRP:
337 			if (eproc.e_pgid != (pid_t)arg)
338 				continue;
339 			break;
340 
341 		case KERN_PROC_TTY:
342 			if ((proc.p_flag & P_CONTROLT) == 0 ||
343 			     eproc.e_tdev != (dev_t)arg)
344 				continue;
345 			break;
346 		}
347 		memcpy(&bp->kp_proc, &proc, sizeof(proc));
348 		memcpy(&bp->kp_eproc, &eproc, sizeof(eproc));
349 		++bp;
350 		++cnt;
351 	}
352 	return (cnt);
353 }
354 
355 /*
356  * Build proc info array by reading in proc list from a crash dump.
357  * Return number of procs read.  maxcnt is the max we will read.
358  */
359 static int
360 kvm_deadprocs(kd, what, arg, a_allproc, a_deadproc, a_zombproc, maxcnt)
361 	kvm_t *kd;
362 	int what, arg;
363 	u_long a_allproc;
364 	u_long a_deadproc;
365 	u_long a_zombproc;
366 	int maxcnt;
367 {
368 	struct kinfo_proc *bp = kd->procbase;
369 	int acnt, dcnt, zcnt;
370 	struct proc *p;
371 
372 	if (KREAD(kd, a_allproc, &p)) {
373 		_kvm_err(kd, kd->program, "cannot read allproc");
374 		return (-1);
375 	}
376 	acnt = kvm_proclist(kd, what, arg, p, bp, maxcnt);
377 	if (acnt < 0)
378 		return (acnt);
379 
380 	if (KREAD(kd, a_deadproc, &p)) {
381 		_kvm_err(kd, kd->program, "cannot read deadproc");
382 		return (-1);
383 	}
384 
385 	dcnt = kvm_proclist(kd, what, arg, p, bp, maxcnt - acnt);
386 	if (dcnt < 0)
387 		dcnt = 0;
388 
389 	if (KREAD(kd, a_zombproc, &p)) {
390 		_kvm_err(kd, kd->program, "cannot read zombproc");
391 		return (-1);
392 	}
393 	zcnt = kvm_proclist(kd, what, arg, p, bp + acnt,
394 	    maxcnt - (acnt + dcnt));
395 	if (zcnt < 0)
396 		zcnt = 0;
397 
398 	return (acnt + zcnt);
399 }
400 
401 struct kinfo_proc *
402 kvm_getprocs(kd, op, arg, cnt)
403 	kvm_t *kd;
404 	int op, arg;
405 	int *cnt;
406 {
407 	size_t size;
408 	int mib[4], st, nprocs;
409 
410 	if (kd->procbase != 0) {
411 		free((void *)kd->procbase);
412 		/*
413 		 * Clear this pointer in case this call fails.  Otherwise,
414 		 * kvm_close() will free it again.
415 		 */
416 		kd->procbase = 0;
417 	}
418 	if (ISALIVE(kd)) {
419 		size = 0;
420 		mib[0] = CTL_KERN;
421 		mib[1] = KERN_PROC;
422 		mib[2] = op;
423 		mib[3] = arg;
424 		st = sysctl(mib, 4, NULL, &size, NULL, 0);
425 		if (st == -1) {
426 			_kvm_syserr(kd, kd->program, "kvm_getprocs");
427 			return (0);
428 		}
429 		kd->procbase = (struct kinfo_proc *)_kvm_malloc(kd, size);
430 		if (kd->procbase == 0)
431 			return (0);
432 		st = sysctl(mib, 4, kd->procbase, &size, NULL, 0);
433 		if (st == -1) {
434 			_kvm_syserr(kd, kd->program, "kvm_getprocs");
435 			return (0);
436 		}
437 		if (size % sizeof(struct kinfo_proc) != 0) {
438 			_kvm_err(kd, kd->program,
439 				"proc size mismatch (%d total, %d chunks)",
440 				size, sizeof(struct kinfo_proc));
441 			return (0);
442 		}
443 		nprocs = size / sizeof(struct kinfo_proc);
444 	} else {
445 		struct nlist nl[5], *p;
446 
447 		nl[0].n_name = "_nprocs";
448 		nl[1].n_name = "_allproc";
449 		nl[2].n_name = "_deadproc";
450 		nl[3].n_name = "_zombproc";
451 		nl[4].n_name = 0;
452 
453 		if (kvm_nlist(kd, nl) != 0) {
454 			for (p = nl; p->n_type != 0; ++p)
455 				;
456 			_kvm_err(kd, kd->program,
457 				 "%s: no such symbol", p->n_name);
458 			return (0);
459 		}
460 		if (KREAD(kd, nl[0].n_value, &nprocs)) {
461 			_kvm_err(kd, kd->program, "can't read nprocs");
462 			return (0);
463 		}
464 		size = nprocs * sizeof(struct kinfo_proc);
465 		kd->procbase = (struct kinfo_proc *)_kvm_malloc(kd, size);
466 		if (kd->procbase == 0)
467 			return (0);
468 
469 		nprocs = kvm_deadprocs(kd, op, arg, nl[1].n_value,
470 		    nl[2].n_value, nl[3].n_value, nprocs);
471 		if (nprocs < 0)
472 			return (0);
473 #ifdef notdef
474 		size = nprocs * sizeof(struct kinfo_proc);
475 		(void)realloc(kd->procbase, size);
476 #endif
477 	}
478 	*cnt = nprocs;
479 	return (kd->procbase);
480 }
481 
482 void
483 _kvm_freeprocs(kd)
484 	kvm_t *kd;
485 {
486 	if (kd->procbase) {
487 		free(kd->procbase);
488 		kd->procbase = 0;
489 	}
490 }
491 
492 void *
493 _kvm_realloc(kd, p, n)
494 	kvm_t *kd;
495 	void *p;
496 	size_t n;
497 {
498 	void *np = (void *)realloc(p, n);
499 
500 	if (np == 0)
501 		_kvm_err(kd, kd->program, "out of memory");
502 	return (np);
503 }
504 
505 #ifndef MAX
506 #define MAX(a, b) ((a) > (b) ? (a) : (b))
507 #endif
508 
509 /*
510  * Read in an argument vector from the user address space of process p.
511  * addr if the user-space base address of narg null-terminated contiguous
512  * strings.  This is used to read in both the command arguments and
513  * environment strings.  Read at most maxcnt characters of strings.
514  */
515 static char **
516 kvm_argv(kd, p, addr, narg, maxcnt)
517 	kvm_t *kd;
518 	const struct proc *p;
519 	u_long addr;
520 	int narg;
521 	int maxcnt;
522 {
523 	char *np, *cp, *ep, *ap;
524 	u_long oaddr = (u_long)~0L;
525 	u_long len;
526 	size_t cc;
527 	char **argv;
528 
529 	/*
530 	 * Check that there aren't an unreasonable number of agruments,
531 	 * and that the address is in user space.
532 	 */
533 	if (narg > ARG_MAX || addr < kd->min_uva || addr >= kd->max_uva)
534 		return (0);
535 
536 	if (kd->argv == 0) {
537 		/*
538 		 * Try to avoid reallocs.
539 		 */
540 		kd->argc = MAX(narg + 1, 32);
541 		kd->argv = (char **)_kvm_malloc(kd, kd->argc *
542 						sizeof(*kd->argv));
543 		if (kd->argv == 0)
544 			return (0);
545 	} else if (narg + 1 > kd->argc) {
546 		kd->argc = MAX(2 * kd->argc, narg + 1);
547 		kd->argv = (char **)_kvm_realloc(kd, kd->argv, kd->argc *
548 						sizeof(*kd->argv));
549 		if (kd->argv == 0)
550 			return (0);
551 	}
552 	if (kd->argspc == 0) {
553 		kd->argspc = (char *)_kvm_malloc(kd, (size_t)kd->nbpg);
554 		if (kd->argspc == 0)
555 			return (0);
556 		kd->arglen = kd->nbpg;
557 	}
558 	if (kd->argbuf == 0) {
559 		kd->argbuf = (char *)_kvm_malloc(kd, (size_t)kd->nbpg);
560 		if (kd->argbuf == 0)
561 			return (0);
562 	}
563 	cc = sizeof(char *) * narg;
564 	if (kvm_uread(kd, p, addr, (void *)kd->argv, cc) != cc)
565 		return (0);
566 	ap = np = kd->argspc;
567 	argv = kd->argv;
568 	len = 0;
569 	/*
570 	 * Loop over pages, filling in the argument vector.
571 	 */
572 	while (argv < kd->argv + narg && *argv != 0) {
573 		addr = (u_long)*argv & ~(kd->nbpg - 1);
574 		if (addr != oaddr) {
575 			if (kvm_uread(kd, p, addr, kd->argbuf,
576 			    (size_t)kd->nbpg) != kd->nbpg)
577 				return (0);
578 			oaddr = addr;
579 		}
580 		addr = (u_long)*argv & (kd->nbpg - 1);
581 		cp = kd->argbuf + (size_t)addr;
582 		cc = kd->nbpg - (size_t)addr;
583 		if (maxcnt > 0 && cc > (size_t)(maxcnt - len))
584 			cc = (size_t)(maxcnt - len);
585 		ep = memchr(cp, '\0', cc);
586 		if (ep != 0)
587 			cc = ep - cp + 1;
588 		if (len + cc > kd->arglen) {
589 			int off;
590 			char **pp;
591 			char *op = kd->argspc;
592 
593 			kd->arglen *= 2;
594 			kd->argspc = (char *)_kvm_realloc(kd, kd->argspc,
595 			    (size_t)kd->arglen);
596 			if (kd->argspc == 0)
597 				return (0);
598 			/*
599 			 * Adjust argv pointers in case realloc moved
600 			 * the string space.
601 			 */
602 			off = kd->argspc - op;
603 			for (pp = kd->argv; pp < argv; pp++)
604 				*pp += off;
605 			ap += off;
606 			np += off;
607 		}
608 		memcpy(np, cp, cc);
609 		np += cc;
610 		len += cc;
611 		if (ep != 0) {
612 			*argv++ = ap;
613 			ap = np;
614 		} else
615 			*argv += cc;
616 		if (maxcnt > 0 && len >= maxcnt) {
617 			/*
618 			 * We're stopping prematurely.  Terminate the
619 			 * current string.
620 			 */
621 			if (ep == 0) {
622 				*np = '\0';
623 				*argv++ = ap;
624 			}
625 			break;
626 		}
627 	}
628 	/* Make sure argv is terminated. */
629 	*argv = 0;
630 	return (kd->argv);
631 }
632 
633 static void
634 ps_str_a(p, addr, n)
635 	struct ps_strings *p;
636 	u_long *addr;
637 	int *n;
638 {
639 	*addr = (u_long)p->ps_argvstr;
640 	*n = p->ps_nargvstr;
641 }
642 
643 static void
644 ps_str_e(p, addr, n)
645 	struct ps_strings *p;
646 	u_long *addr;
647 	int *n;
648 {
649 	*addr = (u_long)p->ps_envstr;
650 	*n = p->ps_nenvstr;
651 }
652 
653 /*
654  * Determine if the proc indicated by p is still active.
655  * This test is not 100% foolproof in theory, but chances of
656  * being wrong are very low.
657  */
658 static int
659 proc_verify(kd, kernp, p)
660 	kvm_t *kd;
661 	u_long kernp;
662 	const struct proc *p;
663 {
664 	struct proc kernproc;
665 
666 	/*
667 	 * Just read in the whole proc.  It's not that big relative
668 	 * to the cost of the read system call.
669 	 */
670 	if (kvm_read(kd, kernp, (void *)&kernproc, sizeof(kernproc)) !=
671 	    sizeof(kernproc))
672 		return (0);
673 	return (p->p_pid == kernproc.p_pid &&
674 		(kernproc.p_stat != SZOMB || p->p_stat == SZOMB));
675 }
676 
677 static char **
678 kvm_doargv(kd, kp, nchr, info)
679 	kvm_t *kd;
680 	const struct kinfo_proc *kp;
681 	int nchr;
682 	void (*info)(struct ps_strings *, u_long *, int *);
683 {
684 	const struct proc *p = &kp->kp_proc;
685 	char **ap;
686 	u_long addr;
687 	int cnt;
688 	struct ps_strings arginfo;
689 
690 	/*
691 	 * Pointers are stored at the top of the user stack.
692 	 */
693 	if (p->p_stat == SZOMB)
694 		return (0);
695 	cnt = kvm_uread(kd, p, kd->usrstack - sizeof(arginfo),
696 	    (void *)&arginfo, sizeof(arginfo));
697 	if (cnt != sizeof(arginfo))
698 		return (0);
699 
700 	(*info)(&arginfo, &addr, &cnt);
701 	if (cnt == 0)
702 		return (0);
703 	ap = kvm_argv(kd, p, addr, cnt, nchr);
704 	/*
705 	 * For live kernels, make sure this process didn't go away.
706 	 */
707 	if (ap != 0 && ISALIVE(kd) &&
708 	    !proc_verify(kd, (u_long)kp->kp_eproc.e_paddr, p))
709 		ap = 0;
710 	return (ap);
711 }
712 
713 /*
714  * Get the command args.  This code is now machine independent.
715  */
716 char **
717 kvm_getargv(kd, kp, nchr)
718 	kvm_t *kd;
719 	const struct kinfo_proc *kp;
720 	int nchr;
721 {
722 	return (kvm_doargv(kd, kp, nchr, ps_str_a));
723 }
724 
725 char **
726 kvm_getenvv(kd, kp, nchr)
727 	kvm_t *kd;
728 	const struct kinfo_proc *kp;
729 	int nchr;
730 {
731 	return (kvm_doargv(kd, kp, nchr, ps_str_e));
732 }
733 
734 /*
735  * Read from user space.  The user context is given by p.
736  */
737 ssize_t
738 kvm_uread(kd, p, uva, buf, len)
739 	kvm_t *kd;
740 	const struct proc *p;
741 	u_long uva;
742 	char *buf;
743 	size_t len;
744 {
745 	char *cp;
746 
747 	cp = buf;
748 	while (len > 0) {
749 		size_t cc;
750 		char *dp;
751 		u_long cnt;
752 
753 		dp = _kvm_uread(kd, p, uva, &cnt);
754 		if (dp == 0) {
755 			_kvm_err(kd, 0, "invalid address (%x)", uva);
756 			return (0);
757 		}
758 		cc = (size_t)MIN(cnt, len);
759 		memcpy(cp, dp, cc);
760 		cp += cc;
761 		uva += cc;
762 		len -= cc;
763 	}
764 	return (ssize_t)(cp - buf);
765 }
766