xref: /openbsd-src/lib/libkvm/kvm_proc.c (revision db3296cf5c1dd9058ceecc3a29fe4aaa0bd26000)
1 /*	$OpenBSD: kvm_proc.c,v 1.17 2003/06/02 20:18:41 millert Exp $	*/
2 /*	$NetBSD: kvm_proc.c,v 1.30 1999/03/24 05:50:50 mrg Exp $	*/
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  * Copyright (c) 1994, 1995 Charles M. Hannum.  All rights reserved.
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. Neither the name of the University nor the names of its contributors
56  *    may be used to endorse or promote products derived from this software
57  *    without specific prior written permission.
58  *
59  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
60  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
61  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
62  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
63  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
64  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
65  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
66  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
67  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
68  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
69  * SUCH DAMAGE.
70  */
71 
72 #if defined(LIBC_SCCS) && !defined(lint)
73 #if 0
74 static char sccsid[] = "@(#)kvm_proc.c	8.3 (Berkeley) 9/23/93";
75 #else
76 static char *rcsid = "$OpenBSD: kvm_proc.c,v 1.17 2003/06/02 20:18:41 millert Exp $";
77 #endif
78 #endif /* LIBC_SCCS and not lint */
79 
80 /*
81  * Proc traversal interface for kvm.  ps and w are (probably) the exclusive
82  * users of this code, so we've factored it out into a separate module.
83  * Thus, we keep this grunge out of the other kvm applications (i.e.,
84  * most other applications are interested only in open/close/read/nlist).
85  */
86 
87 #include <sys/param.h>
88 #include <sys/user.h>
89 #include <sys/proc.h>
90 #include <sys/exec.h>
91 #include <sys/stat.h>
92 #include <sys/ioctl.h>
93 #include <sys/tty.h>
94 #include <stdlib.h>
95 #include <string.h>
96 #include <unistd.h>
97 #include <nlist.h>
98 #include <kvm.h>
99 
100 #include <uvm/uvm_extern.h>
101 #include <uvm/uvm_amap.h>
102 #include <machine/vmparam.h>
103 #include <machine/pmap.h>
104 
105 #include <sys/sysctl.h>
106 
107 #include <limits.h>
108 #include <db.h>
109 #include <paths.h>
110 
111 #include "kvm_private.h"
112 
113 #define KREAD(kd, addr, obj) \
114 	(kvm_read(kd, addr, (void *)(obj), sizeof(*obj)) != sizeof(*obj))
115 
116 ssize_t		kvm_uread(kvm_t *, const struct proc *, u_long, char *, size_t);
117 
118 static char	**kvm_argv(kvm_t *, const struct proc *, u_long, int, int);
119 static int	kvm_deadprocs(kvm_t *, int, int, u_long, u_long, int);
120 static char	**kvm_doargv(kvm_t *, const struct kinfo_proc *, int,
121 		    void (*)(struct ps_strings *, u_long *, int *));
122 static int	kvm_proclist(kvm_t *, int, int, struct proc *,
123 		    struct kinfo_proc *, int);
124 static int	proc_verify(kvm_t *, u_long, const struct proc *);
125 static void	ps_str_a(struct ps_strings *, u_long *, int *);
126 static void	ps_str_e(struct ps_strings *, u_long *, int *);
127 
128 char *
129 _kvm_uread(kd, p, va, cnt)
130 	kvm_t *kd;
131 	const struct proc *p;
132 	u_long va;
133 	u_long *cnt;
134 {
135 	u_long addr, head;
136 	u_long offset;
137 	struct vm_map_entry vme;
138 	struct vm_amap amap;
139 	struct vm_anon *anonp, anon;
140 	struct vm_page pg;
141 	u_long slot;
142 
143 	if (kd->swapspc == 0) {
144 		kd->swapspc = (char *)_kvm_malloc(kd, kd->nbpg);
145 		if (kd->swapspc == 0)
146 			return (0);
147 	}
148 
149 	/*
150 	 * Look through the address map for the memory object
151 	 * that corresponds to the given virtual address.
152 	 * The header just has the entire valid range.
153 	 */
154 	head = (u_long)&p->p_vmspace->vm_map.header;
155 	addr = head;
156 	while (1) {
157 		if (KREAD(kd, addr, &vme))
158 			return (0);
159 
160 		if (va >= vme.start && va < vme.end &&
161 		    vme.aref.ar_amap != NULL)
162 			break;
163 
164 		addr = (u_long)vme.next;
165 		if (addr == head)
166 			return (0);
167 	}
168 
169 	/*
170 	 * we found the map entry, now to find the object...
171 	 */
172 	if (vme.aref.ar_amap == NULL)
173 		return NULL;
174 
175 	addr = (u_long)vme.aref.ar_amap;
176 	if (KREAD(kd, addr, &amap))
177 		return NULL;
178 
179 	offset = va - vme.start;
180 	slot = offset / kd->nbpg + vme.aref.ar_pageoff;
181 	/* sanity-check slot number */
182 	if (slot > amap.am_nslot)
183 		return NULL;
184 
185 	addr = (u_long)amap.am_anon + (offset / kd->nbpg) * sizeof(anonp);
186 	if (KREAD(kd, addr, &anonp))
187 		return NULL;
188 
189 	addr = (u_long)anonp;
190 	if (KREAD(kd, addr, &anon))
191 		return NULL;
192 
193 	addr = (u_long)anon.u.an_page;
194 	if (addr) {
195 		if (KREAD(kd, addr, &pg))
196 			return NULL;
197 
198 		if (_kvm_pread(kd, kd->pmfd, (void *)kd->swapspc, (size_t)kd->nbpg, (off_t)pg.phys_addr) != kd->nbpg) {
199 			return NULL;
200 		}
201 	} else {
202 		if (_kvm_pread(kd, kd->swfd, (void *)kd->swapspc, (size_t)kd->nbpg, (off_t)(anon.an_swslot * kd->nbpg)) != kd->nbpg) {
203 			return NULL;
204 		}
205 	}
206 
207 	/* Found the page. */
208 	offset %= kd->nbpg;
209 	*cnt = kd->nbpg - offset;
210 	return (&kd->swapspc[offset]);
211 }
212 
213 /*
214  * Read proc's from memory file into buffer bp, which has space to hold
215  * at most maxcnt procs.
216  */
217 static int
218 kvm_proclist(kd, what, arg, p, bp, maxcnt)
219 	kvm_t *kd;
220 	int what, arg;
221 	struct proc *p;
222 	struct kinfo_proc *bp;
223 	int maxcnt;
224 {
225 	int cnt = 0;
226 	struct eproc eproc;
227 	struct pgrp pgrp;
228 	struct session sess;
229 	struct tty tty;
230 	struct proc proc;
231 
232 	for (; cnt < maxcnt && p != NULL; p = proc.p_list.le_next) {
233 		if (KREAD(kd, (u_long)p, &proc)) {
234 			_kvm_err(kd, kd->program, "can't read proc at %x", p);
235 			return (-1);
236 		}
237 		if (KREAD(kd, (u_long)proc.p_cred, &eproc.e_pcred) == 0)
238 			KREAD(kd, (u_long)eproc.e_pcred.pc_ucred,
239 			      &eproc.e_ucred);
240 
241 		switch(what) {
242 
243 		case KERN_PROC_PID:
244 			if (proc.p_pid != (pid_t)arg)
245 				continue;
246 			break;
247 
248 		case KERN_PROC_UID:
249 			if (eproc.e_ucred.cr_uid != (uid_t)arg)
250 				continue;
251 			break;
252 
253 		case KERN_PROC_RUID:
254 			if (eproc.e_pcred.p_ruid != (uid_t)arg)
255 				continue;
256 			break;
257 
258 		case KERN_PROC_ALL:
259 			if (proc.p_flag & P_SYSTEM)
260 				continue;
261 			break;
262 		}
263 		/*
264 		 * We're going to add another proc to the set.  If this
265 		 * will overflow the buffer, assume the reason is because
266 		 * nprocs (or the proc list) is corrupt and declare an error.
267 		 */
268 		if (cnt >= maxcnt) {
269 			_kvm_err(kd, kd->program, "nprocs corrupt");
270 			return (-1);
271 		}
272 		/*
273 		 * gather eproc
274 		 */
275 		eproc.e_paddr = p;
276 		if (KREAD(kd, (u_long)proc.p_pgrp, &pgrp)) {
277 			_kvm_err(kd, kd->program, "can't read pgrp at %x",
278 				 proc.p_pgrp);
279 			return (-1);
280 		}
281 		eproc.e_sess = pgrp.pg_session;
282 		eproc.e_pgid = pgrp.pg_id;
283 		eproc.e_jobc = pgrp.pg_jobc;
284 		if (KREAD(kd, (u_long)pgrp.pg_session, &sess)) {
285 			_kvm_err(kd, kd->program, "can't read session at %x",
286 				pgrp.pg_session);
287 			return (-1);
288 		}
289 		if ((proc.p_flag & P_CONTROLT) && sess.s_ttyp != NULL) {
290 			if (KREAD(kd, (u_long)sess.s_ttyp, &tty)) {
291 				_kvm_err(kd, kd->program,
292 					 "can't read tty at %x", sess.s_ttyp);
293 				return (-1);
294 			}
295 			eproc.e_tdev = tty.t_dev;
296 			eproc.e_tsess = tty.t_session;
297 			if (tty.t_pgrp != NULL) {
298 				if (KREAD(kd, (u_long)tty.t_pgrp, &pgrp)) {
299 					_kvm_err(kd, kd->program,
300 						 "can't read tpgrp at &x",
301 						tty.t_pgrp);
302 					return (-1);
303 				}
304 				eproc.e_tpgid = pgrp.pg_id;
305 			} else
306 				eproc.e_tpgid = -1;
307 		} else
308 			eproc.e_tdev = NODEV;
309 		eproc.e_flag = sess.s_ttyvp ? EPROC_CTTY : 0;
310 		if (sess.s_leader == p)
311 			eproc.e_flag |= EPROC_SLEADER;
312 		if (proc.p_wmesg)
313 			(void)kvm_read(kd, (u_long)proc.p_wmesg,
314 			    eproc.e_wmesg, WMESGLEN);
315 
316 		(void)kvm_read(kd, (u_long)proc.p_vmspace,
317 		    &eproc.e_vm, sizeof(eproc.e_vm));
318 
319 		eproc.e_xsize = eproc.e_xrssize = 0;
320 		eproc.e_xccount = eproc.e_xswrss = 0;
321 
322 		switch (what) {
323 
324 		case KERN_PROC_PGRP:
325 			if (eproc.e_pgid != (pid_t)arg)
326 				continue;
327 			break;
328 
329 		case KERN_PROC_TTY:
330 			if ((proc.p_flag & P_CONTROLT) == 0 ||
331 			     eproc.e_tdev != (dev_t)arg)
332 				continue;
333 			break;
334 		}
335 		bcopy(&proc, &bp->kp_proc, sizeof(proc));
336 		bcopy(&eproc, &bp->kp_eproc, sizeof(eproc));
337 		++bp;
338 		++cnt;
339 	}
340 	return (cnt);
341 }
342 
343 /*
344  * Build proc info array by reading in proc list from a crash dump.
345  * Return number of procs read.  maxcnt is the max we will read.
346  */
347 static int
348 kvm_deadprocs(kd, what, arg, a_allproc, a_zombproc, maxcnt)
349 	kvm_t *kd;
350 	int what, arg;
351 	u_long a_allproc;
352 	u_long a_zombproc;
353 	int maxcnt;
354 {
355 	struct kinfo_proc *bp = kd->procbase;
356 	int acnt, zcnt;
357 	struct proc *p;
358 
359 	if (KREAD(kd, a_allproc, &p)) {
360 		_kvm_err(kd, kd->program, "cannot read allproc");
361 		return (-1);
362 	}
363 	acnt = kvm_proclist(kd, what, arg, p, bp, maxcnt);
364 	if (acnt < 0)
365 		return (acnt);
366 
367 	if (KREAD(kd, a_zombproc, &p)) {
368 		_kvm_err(kd, kd->program, "cannot read zombproc");
369 		return (-1);
370 	}
371 	zcnt = kvm_proclist(kd, what, arg, p, bp + acnt, maxcnt - acnt);
372 	if (zcnt < 0)
373 		zcnt = 0;
374 
375 	return (acnt + zcnt);
376 }
377 
378 struct kinfo_proc *
379 kvm_getprocs(kd, op, arg, cnt)
380 	kvm_t *kd;
381 	int op, arg;
382 	int *cnt;
383 {
384 	size_t size;
385 	int mib[4], st, nprocs;
386 
387 	if (kd->procbase != 0) {
388 		free((void *)kd->procbase);
389 		/*
390 		 * Clear this pointer in case this call fails.  Otherwise,
391 		 * kvm_close() will free it again.
392 		 */
393 		kd->procbase = 0;
394 	}
395 	if (ISALIVE(kd)) {
396 		size = 0;
397 		mib[0] = CTL_KERN;
398 		mib[1] = KERN_PROC;
399 		mib[2] = op;
400 		mib[3] = arg;
401 		st = sysctl(mib, 4, NULL, &size, NULL, 0);
402 		if (st == -1) {
403 			_kvm_syserr(kd, kd->program, "kvm_getprocs");
404 			return (0);
405 		}
406 		kd->procbase = (struct kinfo_proc *)_kvm_malloc(kd, size);
407 		if (kd->procbase == 0)
408 			return (0);
409 		st = sysctl(mib, 4, kd->procbase, &size, NULL, 0);
410 		if (st == -1) {
411 			_kvm_syserr(kd, kd->program, "kvm_getprocs");
412 			return (0);
413 		}
414 		if (size % sizeof(struct kinfo_proc) != 0) {
415 			_kvm_err(kd, kd->program,
416 				"proc size mismatch (%d total, %d chunks)",
417 				size, sizeof(struct kinfo_proc));
418 			return (0);
419 		}
420 		nprocs = size / sizeof(struct kinfo_proc);
421 	} else {
422 		struct nlist nl[4], *p;
423 
424 		nl[0].n_name = "_nprocs";
425 		nl[1].n_name = "_allproc";
426 		nl[2].n_name = "_zombproc";
427 		nl[3].n_name = 0;
428 
429 		if (kvm_nlist(kd, nl) != 0) {
430 			for (p = nl; p->n_type != 0; ++p)
431 				;
432 			_kvm_err(kd, kd->program,
433 				 "%s: no such symbol", p->n_name);
434 			return (0);
435 		}
436 		if (KREAD(kd, nl[0].n_value, &nprocs)) {
437 			_kvm_err(kd, kd->program, "can't read nprocs");
438 			return (0);
439 		}
440 		size = nprocs * sizeof(struct kinfo_proc);
441 		kd->procbase = (struct kinfo_proc *)_kvm_malloc(kd, size);
442 		if (kd->procbase == 0)
443 			return (0);
444 
445 		nprocs = kvm_deadprocs(kd, op, arg, nl[1].n_value,
446 				      nl[2].n_value, nprocs);
447 #ifdef notdef
448 		size = nprocs * sizeof(struct kinfo_proc);
449 		(void)realloc(kd->procbase, size);
450 #endif
451 	}
452 	*cnt = nprocs;
453 	return (kd->procbase);
454 }
455 
456 void
457 _kvm_freeprocs(kd)
458 	kvm_t *kd;
459 {
460 	if (kd->procbase) {
461 		free(kd->procbase);
462 		kd->procbase = 0;
463 	}
464 }
465 
466 void *
467 _kvm_realloc(kd, p, n)
468 	kvm_t *kd;
469 	void *p;
470 	size_t n;
471 {
472 	void *np = (void *)realloc(p, n);
473 
474 	if (np == 0)
475 		_kvm_err(kd, kd->program, "out of memory");
476 	return (np);
477 }
478 
479 #ifndef MAX
480 #define MAX(a, b) ((a) > (b) ? (a) : (b))
481 #endif
482 
483 /*
484  * Read in an argument vector from the user address space of process p.
485  * addr if the user-space base address of narg null-terminated contiguous
486  * strings.  This is used to read in both the command arguments and
487  * environment strings.  Read at most maxcnt characters of strings.
488  */
489 static char **
490 kvm_argv(kd, p, addr, narg, maxcnt)
491 	kvm_t *kd;
492 	const struct proc *p;
493 	u_long addr;
494 	int narg;
495 	int maxcnt;
496 {
497 	char *np, *cp, *ep, *ap;
498 	u_long oaddr = -1;
499 	int len, cc;
500 	char **argv;
501 
502 	/*
503 	 * Check that there aren't an unreasonable number of agruments,
504 	 * and that the address is in user space.
505 	 */
506 	if (narg > ARG_MAX || addr < VM_MIN_ADDRESS || addr >= VM_MAXUSER_ADDRESS)
507 		return (0);
508 
509 	if (kd->argv == 0) {
510 		/*
511 		 * Try to avoid reallocs.
512 		 */
513 		kd->argc = MAX(narg + 1, 32);
514 		kd->argv = (char **)_kvm_malloc(kd, kd->argc *
515 						sizeof(*kd->argv));
516 		if (kd->argv == 0)
517 			return (0);
518 	} else if (narg + 1 > kd->argc) {
519 		kd->argc = MAX(2 * kd->argc, narg + 1);
520 		kd->argv = (char **)_kvm_realloc(kd, kd->argv, kd->argc *
521 						sizeof(*kd->argv));
522 		if (kd->argv == 0)
523 			return (0);
524 	}
525 	if (kd->argspc == 0) {
526 		kd->argspc = (char *)_kvm_malloc(kd, kd->nbpg);
527 		if (kd->argspc == 0)
528 			return (0);
529 		kd->arglen = kd->nbpg;
530 	}
531 	if (kd->argbuf == 0) {
532 		kd->argbuf = (char *)_kvm_malloc(kd, kd->nbpg);
533 		if (kd->argbuf == 0)
534 			return (0);
535 	}
536 	cc = sizeof(char *) * narg;
537 	if (kvm_uread(kd, p, addr, (char *)kd->argv, cc) != cc)
538 		return (0);
539 	ap = np = kd->argspc;
540 	argv = kd->argv;
541 	len = 0;
542 	/*
543 	 * Loop over pages, filling in the argument vector.
544 	 */
545 	while (argv < kd->argv + narg && *argv != 0) {
546 		addr = (u_long)*argv & ~(kd->nbpg - 1);
547 		if (addr != oaddr) {
548 			if (kvm_uread(kd, p, addr, kd->argbuf, kd->nbpg) !=
549 			    kd->nbpg)
550 				return (0);
551 			oaddr = addr;
552 		}
553 		addr = (u_long)*argv & (kd->nbpg - 1);
554 		cp = kd->argbuf + addr;
555 		cc = kd->nbpg - addr;
556 		if (maxcnt > 0 && cc > maxcnt - len)
557 			cc = maxcnt - len;;
558 		ep = memchr(cp, '\0', cc);
559 		if (ep != 0)
560 			cc = ep - cp + 1;
561 		if (len + cc > kd->arglen) {
562 			int off;
563 			char **pp;
564 			char *op = kd->argspc;
565 
566 			kd->arglen *= 2;
567 			kd->argspc = (char *)_kvm_realloc(kd, kd->argspc,
568 							  kd->arglen);
569 			if (kd->argspc == 0)
570 				return (0);
571 			/*
572 			 * Adjust argv pointers in case realloc moved
573 			 * the string space.
574 			 */
575 			off = kd->argspc - op;
576 			for (pp = kd->argv; pp < argv; pp++)
577 				*pp += off;
578 			ap += off;
579 			np += off;
580 		}
581 		memcpy(np, cp, cc);
582 		np += cc;
583 		len += cc;
584 		if (ep != 0) {
585 			*argv++ = ap;
586 			ap = np;
587 		} else
588 			*argv += cc;
589 		if (maxcnt > 0 && len >= maxcnt) {
590 			/*
591 			 * We're stopping prematurely.  Terminate the
592 			 * current string.
593 			 */
594 			if (ep == 0) {
595 				*np = '\0';
596 				*argv++ = ap;
597 			}
598 			break;
599 		}
600 	}
601 	/* Make sure argv is terminated. */
602 	*argv = 0;
603 	return (kd->argv);
604 }
605 
606 static void
607 ps_str_a(p, addr, n)
608 	struct ps_strings *p;
609 	u_long *addr;
610 	int *n;
611 {
612 	*addr = (u_long)p->ps_argvstr;
613 	*n = p->ps_nargvstr;
614 }
615 
616 static void
617 ps_str_e(p, addr, n)
618 	struct ps_strings *p;
619 	u_long *addr;
620 	int *n;
621 {
622 	*addr = (u_long)p->ps_envstr;
623 	*n = p->ps_nenvstr;
624 }
625 
626 /*
627  * Determine if the proc indicated by p is still active.
628  * This test is not 100% foolproof in theory, but chances of
629  * being wrong are very low.
630  */
631 static int
632 proc_verify(kd, kernp, p)
633 	kvm_t *kd;
634 	u_long kernp;
635 	const struct proc *p;
636 {
637 	struct proc kernproc;
638 
639 	/*
640 	 * Just read in the whole proc.  It's not that big relative
641 	 * to the cost of the read system call.
642 	 */
643 	if (kvm_read(kd, kernp, &kernproc, sizeof(kernproc)) !=
644 	    sizeof(kernproc))
645 		return (0);
646 	return (p->p_pid == kernproc.p_pid &&
647 		(kernproc.p_stat != SZOMB || p->p_stat == SZOMB));
648 }
649 
650 static char **
651 kvm_doargv(kd, kp, nchr, info)
652 	kvm_t *kd;
653 	const struct kinfo_proc *kp;
654 	int nchr;
655 	void (*info)(struct ps_strings *, u_long *, int *);
656 {
657 	const struct proc *p = &kp->kp_proc;
658 	char **ap;
659 	u_long addr;
660 	int cnt;
661 	struct ps_strings arginfo;
662 	static struct ps_strings *ps;
663 
664 	if (ps == NULL) {
665 		struct _ps_strings _ps;
666 		int mib[2];
667 		size_t len;
668 
669 		mib[0] = CTL_VM;
670 		mib[1] = VM_PSSTRINGS;
671 		len = sizeof(_ps);
672 		sysctl(mib, 2, &_ps, &len, NULL, 0);
673 		ps = (struct ps_strings *)_ps.val;
674 	}
675 
676 	/*
677 	 * Pointers are stored at the top of the user stack.
678 	 */
679 	if (p->p_stat == SZOMB ||
680 	    kvm_uread(kd, p, (u_long)ps, (char *)&arginfo,
681 		      sizeof(arginfo)) != sizeof(arginfo))
682 		return (0);
683 
684 	(*info)(&arginfo, &addr, &cnt);
685 	if (cnt == 0)
686 		return (0);
687 	ap = kvm_argv(kd, p, addr, cnt, nchr);
688 	/*
689 	 * For live kernels, make sure this process didn't go away.
690 	 */
691 	if (ap != 0 && ISALIVE(kd) &&
692 	    !proc_verify(kd, (u_long)kp->kp_eproc.e_paddr, p))
693 		ap = 0;
694 	return (ap);
695 }
696 
697 static char **
698 kvm_arg_sysctl(kvm_t *kd, const struct kinfo_proc *kp, int nchr, int env)
699 {
700 	int mib[4];
701 	size_t len, orglen;
702 	int ret;
703 	char **argv, *arg;
704 	char *buf;
705 
706 	orglen = kd->nbpg;
707 	if (kd->argbuf == NULL &&
708 	    (kd->argbuf = _kvm_malloc(kd, orglen)) == NULL)
709 		return (NULL);
710 
711 again:
712 	mib[0] = CTL_KERN;
713 	mib[1] = KERN_PROC_ARGS;
714 	mib[2] = (int)kp->kp_proc.p_pid;
715 	mib[3] = env ? KERN_PROC_ENV : KERN_PROC_ARGV;
716 
717 	len = orglen;
718 	ret = (sysctl(mib, 4, kd->argbuf, &len, NULL, 0) < 0);
719 	if (ret && errno == ENOMEM) {
720 		orglen += kd->nbpg;
721 		buf = _kvm_realloc(kd, kd->argbuf, orglen);
722 		if (buf == NULL)
723 			return (NULL);
724 		kd->argbuf = buf;
725 		goto again;
726 	}
727 
728 	if (ret) {
729 		free(kd->argbuf);
730 		kd->argbuf = NULL;
731 		_kvm_syserr(kd, kd->program, "kvm_arg_sysctl");
732 		return (NULL);
733 	}
734 #if 0
735 	for (argv = (char **)kd->argbuf; *argv != NULL; argv++)
736 		if (strlen(*argv) > nchr)
737 			*argv[nchr] = '\0';
738 #endif
739 
740 	return (char **)(kd->argbuf);
741 }
742 
743 /*
744  * Get the command args.  This code is now machine independent.
745  */
746 char **
747 kvm_getargv(kd, kp, nchr)
748 	kvm_t *kd;
749 	const struct kinfo_proc *kp;
750 	int nchr;
751 {
752 	if (ISALIVE(kd))
753 		return (kvm_arg_sysctl(kd, kp, nchr, 0));
754 	return (kvm_doargv(kd, kp, nchr, ps_str_a));
755 }
756 
757 char **
758 kvm_getenvv(kd, kp, nchr)
759 	kvm_t *kd;
760 	const struct kinfo_proc *kp;
761 	int nchr;
762 {
763 	if (ISALIVE(kd))
764 		return (kvm_arg_sysctl(kd, kp, nchr, 1));
765 	return (kvm_doargv(kd, kp, nchr, ps_str_e));
766 }
767 
768 /*
769  * Read from user space.  The user context is given by p.
770  */
771 ssize_t
772 kvm_uread(kd, p, uva, buf, len)
773 	kvm_t *kd;
774 	const struct proc *p;
775 	u_long uva;
776 	char *buf;
777 	size_t len;
778 {
779 	char *cp;
780 
781 	cp = buf;
782 	while (len > 0) {
783 		int cc;
784 		char *dp;
785 		u_long cnt;
786 
787 		dp = _kvm_uread(kd, p, uva, &cnt);
788 		if (dp == 0) {
789 			_kvm_err(kd, 0, "invalid address (%lx)", uva);
790 			return (0);
791 		}
792 		cc = MIN(cnt, len);
793 		bcopy(dp, cp, cc);
794 
795 		cp += cc;
796 		uva += cc;
797 		len -= cc;
798 	}
799 	return (ssize_t)(cp - buf);
800 }
801