xref: /openbsd-src/lib/libkvm/kvm_proc.c (revision cd1eb269cafb12c415be1749cd4a4b5422710415)
1 /*	$OpenBSD: kvm_proc.c,v 1.40 2010/01/10 03:37:50 guenther 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  *
19  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
20  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
21  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
22  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
23  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
24  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
25  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
26  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
27  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
28  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
29  * POSSIBILITY OF SUCH DAMAGE.
30  */
31 /*-
32  * Copyright (c) 1994, 1995 Charles M. Hannum.  All rights reserved.
33  * Copyright (c) 1989, 1992, 1993
34  *	The Regents of the University of California.  All rights reserved.
35  *
36  * This code is derived from software developed by the Computer Systems
37  * Engineering group at Lawrence Berkeley Laboratory under DARPA contract
38  * BG 91-66 and contributed to Berkeley.
39  *
40  * Redistribution and use in source and binary forms, with or without
41  * modification, are permitted provided that the following conditions
42  * are met:
43  * 1. Redistributions of source code must retain the above copyright
44  *    notice, this list of conditions and the following disclaimer.
45  * 2. Redistributions in binary form must reproduce the above copyright
46  *    notice, this list of conditions and the following disclaimer in the
47  *    documentation and/or other materials provided with the distribution.
48  * 3. Neither the name of the University nor the names of its contributors
49  *    may be used to endorse or promote products derived from this software
50  *    without specific prior written permission.
51  *
52  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
53  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
54  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
55  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
56  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
57  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
58  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
59  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
60  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
61  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
62  * SUCH DAMAGE.
63  */
64 
65 /*
66  * Proc traversal interface for kvm.  ps and w are (probably) the exclusive
67  * users of this code, so we've factored it out into a separate module.
68  * Thus, we keep this grunge out of the other kvm applications (i.e.,
69  * most other applications are interested only in open/close/read/nlist).
70  */
71 
72 #define __need_process
73 #include <sys/param.h>
74 #include <sys/user.h>
75 #include <sys/proc.h>
76 #include <sys/exec.h>
77 #include <sys/stat.h>
78 #include <sys/ioctl.h>
79 #include <sys/tty.h>
80 #include <stdlib.h>
81 #include <string.h>
82 #include <unistd.h>
83 #include <nlist.h>
84 #include <kvm.h>
85 
86 #include <uvm/uvm_extern.h>
87 #include <uvm/uvm_amap.h>
88 #include <machine/vmparam.h>
89 #include <machine/pmap.h>
90 
91 #include <sys/sysctl.h>
92 
93 #include <limits.h>
94 #include <db.h>
95 #include <paths.h>
96 
97 #include "kvm_private.h"
98 
99 /*
100  * Common info from kinfo_proc and kinfo_proc2 used by helper routines.
101  */
102 struct miniproc {
103 	struct	vmspace *p_vmspace;
104 	char	p_stat;
105 	struct	proc *p_paddr;
106 	pid_t	p_pid;
107 };
108 
109 /*
110  * Convert from struct proc and kinfo_proc{,2} to miniproc.
111  */
112 #define PTOMINI(kp, p) \
113 	do { \
114 		(p)->p_stat = (kp)->p_stat; \
115 		(p)->p_pid = (kp)->p_pid; \
116 		(p)->p_paddr = NULL; \
117 		(p)->p_vmspace = (kp)->p_vmspace; \
118 	} while (/*CONSTCOND*/0);
119 
120 #define KPTOMINI(kp, p) \
121 	do { \
122 		(p)->p_stat = (kp)->kp_proc.p_stat; \
123 		(p)->p_pid = (kp)->kp_proc.p_pid; \
124 		(p)->p_paddr = (kp)->kp_eproc.e_paddr; \
125 		(p)->p_vmspace = (kp)->kp_proc.p_vmspace; \
126 	} while (/*CONSTCOND*/0);
127 
128 #define KP2TOMINI(kp, p) \
129 	do { \
130 		(p)->p_stat = (kp)->p_stat; \
131 		(p)->p_pid = (kp)->p_pid; \
132 		(p)->p_paddr = (void *)(long)(kp)->p_paddr; \
133 		(p)->p_vmspace = (void *)(long)(kp)->p_vmspace; \
134 	} while (/*CONSTCOND*/0);
135 
136 
137 ssize_t		kvm_uread(kvm_t *, const struct proc *, u_long, char *, size_t);
138 
139 static char	*_kvm_ureadm(kvm_t *, const struct miniproc *, u_long, u_long *);
140 static ssize_t	kvm_ureadm(kvm_t *, const struct miniproc *, u_long, char *, size_t);
141 
142 static char	**kvm_argv(kvm_t *, const struct miniproc *, u_long, int, int);
143 
144 static int	kvm_deadprocs(kvm_t *, int, int, u_long, u_long, int);
145 static char	**kvm_doargv(kvm_t *, const struct miniproc *, int,
146 		    void (*)(struct ps_strings *, u_long *, int *));
147 static int	kvm_proclist(kvm_t *, int, int, struct proc *,
148 		    struct kinfo_proc *, int);
149 static int	proc_verify(kvm_t *, const struct miniproc *);
150 static void	ps_str_a(struct ps_strings *, u_long *, int *);
151 static void	ps_str_e(struct ps_strings *, u_long *, int *);
152 
153 static char *
154 _kvm_ureadm(kvm_t *kd, const struct miniproc *p, u_long va, u_long *cnt)
155 {
156 	u_long addr, head, offset, slot;
157 	struct vm_anon *anonp, anon;
158 	struct vm_map_entry vme;
159 	struct vm_amap amap;
160 	struct vm_page pg;
161 
162 	if (kd->swapspc == 0) {
163 		kd->swapspc = _kvm_malloc(kd, kd->nbpg);
164 		if (kd->swapspc == 0)
165 			return (0);
166 	}
167 
168 	/*
169 	 * Look through the address map for the memory object
170 	 * that corresponds to the given virtual address.
171 	 * The header just has the entire valid range.
172 	 */
173 	head = (u_long)&p->p_vmspace->vm_map.header;
174 	addr = head;
175 	while (1) {
176 		if (KREAD(kd, addr, &vme))
177 			return (0);
178 
179 		if (va >= vme.start && va < vme.end &&
180 		    vme.aref.ar_amap != NULL)
181 			break;
182 
183 		addr = (u_long)vme.next;
184 		if (addr == head)
185 			return (0);
186 	}
187 
188 	/*
189 	 * we found the map entry, now to find the object...
190 	 */
191 	if (vme.aref.ar_amap == NULL)
192 		return (NULL);
193 
194 	addr = (u_long)vme.aref.ar_amap;
195 	if (KREAD(kd, addr, &amap))
196 		return (NULL);
197 
198 	offset = va - vme.start;
199 	slot = offset / kd->nbpg + vme.aref.ar_pageoff;
200 	/* sanity-check slot number */
201 	if (slot > amap.am_nslot)
202 		return (NULL);
203 
204 	addr = (u_long)amap.am_anon + (offset / kd->nbpg) * sizeof(anonp);
205 	if (KREAD(kd, addr, &anonp))
206 		return (NULL);
207 
208 	addr = (u_long)anonp;
209 	if (KREAD(kd, addr, &anon))
210 		return (NULL);
211 
212 	addr = (u_long)anon.an_page;
213 	if (addr) {
214 		if (KREAD(kd, addr, &pg))
215 			return (NULL);
216 
217 		if (_kvm_pread(kd, kd->pmfd, (void *)kd->swapspc,
218 		    (size_t)kd->nbpg, (off_t)pg.phys_addr) != kd->nbpg)
219 			return (NULL);
220 	} else {
221 		if (kd->swfd == -1 ||
222 		    _kvm_pread(kd, kd->swfd, (void *)kd->swapspc,
223 		    (size_t)kd->nbpg,
224 		    (off_t)(anon.an_swslot * kd->nbpg)) != kd->nbpg)
225 			return (NULL);
226 	}
227 
228 	/* Found the page. */
229 	offset %= kd->nbpg;
230 	*cnt = kd->nbpg - offset;
231 	return (&kd->swapspc[offset]);
232 }
233 
234 char *
235 _kvm_uread(kvm_t *kd, const struct proc *p, u_long va, u_long *cnt)
236 {
237 	struct miniproc mp;
238 
239 	PTOMINI(p, &mp);
240 	return (_kvm_ureadm(kd, &mp, va, cnt));
241 }
242 
243 /*
244  * Read proc's from memory file into buffer bp, which has space to hold
245  * at most maxcnt procs.
246  */
247 static int
248 kvm_proclist(kvm_t *kd, int what, int arg, struct proc *p,
249     struct kinfo_proc *bp, int maxcnt)
250 {
251 	struct session sess;
252 	struct eproc eproc;
253 	struct proc proc;
254 	struct process process;
255 	struct pgrp pgrp;
256 	struct tty tty;
257 	int cnt = 0;
258 
259 	for (; cnt < maxcnt && p != NULL; p = LIST_NEXT(&proc, p_list)) {
260 		if (KREAD(kd, (u_long)p, &proc)) {
261 			_kvm_err(kd, kd->program, "can't read proc at %x", p);
262 			return (-1);
263 		}
264 		if (KREAD(kd, (u_long)proc.p_p, &process)) {
265 			_kvm_err(kd, kd->program, "can't read process at %x", proc.p_p);
266 			return (-1);
267 		}
268 		if (KREAD(kd, (u_long)process.ps_cred, &eproc.e_pcred) == 0)
269 			KREAD(kd, (u_long)eproc.e_pcred.pc_ucred,
270 			    &eproc.e_ucred);
271 
272 		switch (what) {
273 		case KERN_PROC_PID:
274 			if (proc.p_pid != (pid_t)arg)
275 				continue;
276 			break;
277 
278 		case KERN_PROC_UID:
279 			if (eproc.e_ucred.cr_uid != (uid_t)arg)
280 				continue;
281 			break;
282 
283 		case KERN_PROC_RUID:
284 			if (eproc.e_pcred.p_ruid != (uid_t)arg)
285 				continue;
286 			break;
287 
288 		case KERN_PROC_ALL:
289 			if (proc.p_flag & P_SYSTEM)
290 				continue;
291 			break;
292 		}
293 		/*
294 		 * We're going to add another proc to the set.  If this
295 		 * will overflow the buffer, assume the reason is because
296 		 * nprocs (or the proc list) is corrupt and declare an error.
297 		 */
298 		if (cnt >= maxcnt) {
299 			_kvm_err(kd, kd->program, "nprocs corrupt");
300 			return (-1);
301 		}
302 		/*
303 		 * gather eproc
304 		 */
305 		eproc.e_paddr = p;
306 		if (KREAD(kd, (u_long)proc.p_pgrp, &pgrp)) {
307 			_kvm_err(kd, kd->program, "can't read pgrp at %x",
308 			    proc.p_pgrp);
309 			return (-1);
310 		}
311 		eproc.e_sess = pgrp.pg_session;
312 		eproc.e_pgid = pgrp.pg_id;
313 		eproc.e_jobc = pgrp.pg_jobc;
314 		if (KREAD(kd, (u_long)pgrp.pg_session, &sess)) {
315 			_kvm_err(kd, kd->program, "can't read session at %x",
316 			    pgrp.pg_session);
317 			return (-1);
318 		}
319 		if ((proc.p_flag & P_CONTROLT) && sess.s_ttyp != NULL) {
320 			if (KREAD(kd, (u_long)sess.s_ttyp, &tty)) {
321 				_kvm_err(kd, kd->program,
322 				    "can't read tty at %x", sess.s_ttyp);
323 				return (-1);
324 			}
325 			eproc.e_tdev = tty.t_dev;
326 			eproc.e_tsess = tty.t_session;
327 			if (tty.t_pgrp != NULL) {
328 				if (KREAD(kd, (u_long)tty.t_pgrp, &pgrp)) {
329 					_kvm_err(kd, kd->program,
330 					    "can't read tpgrp at &x",
331 					    tty.t_pgrp);
332 					return (-1);
333 				}
334 				eproc.e_tpgid = pgrp.pg_id;
335 			} else
336 				eproc.e_tpgid = -1;
337 		} else
338 			eproc.e_tdev = NODEV;
339 		eproc.e_flag = sess.s_ttyvp ? EPROC_CTTY : 0;
340 		if (sess.s_leader == p)
341 			eproc.e_flag |= EPROC_SLEADER;
342 		if (proc.p_wmesg)
343 			(void)kvm_read(kd, (u_long)proc.p_wmesg,
344 			    eproc.e_wmesg, WMESGLEN);
345 
346 		(void)kvm_read(kd, (u_long)proc.p_vmspace,
347 		    &eproc.e_vm, sizeof(eproc.e_vm));
348 
349 		eproc.e_xsize = eproc.e_xrssize = 0;
350 		eproc.e_xccount = eproc.e_xswrss = 0;
351 
352 		switch (what) {
353 		case KERN_PROC_PGRP:
354 			if (eproc.e_pgid != (pid_t)arg)
355 				continue;
356 			break;
357 
358 		case KERN_PROC_TTY:
359 			if ((proc.p_flag & P_CONTROLT) == 0 ||
360 			    eproc.e_tdev != (dev_t)arg)
361 				continue;
362 			break;
363 		}
364 		bcopy(&proc, &bp->kp_proc, sizeof(proc));
365 		bcopy(&eproc, &bp->kp_eproc, sizeof(eproc));
366 		++bp;
367 		++cnt;
368 	}
369 	return (cnt);
370 }
371 
372 /*
373  * Build proc info array by reading in proc list from a crash dump.
374  * Return number of procs read.  maxcnt is the max we will read.
375  */
376 static int
377 kvm_deadprocs(kvm_t *kd, int what, int arg, u_long a_allproc,
378     u_long a_zombproc, int maxcnt)
379 {
380 	struct kinfo_proc *bp = kd->procbase;
381 	struct proc *p;
382 	int acnt, zcnt;
383 
384 	if (KREAD(kd, a_allproc, &p)) {
385 		_kvm_err(kd, kd->program, "cannot read allproc");
386 		return (-1);
387 	}
388 	acnt = kvm_proclist(kd, what, arg, p, bp, maxcnt);
389 	if (acnt < 0)
390 		return (acnt);
391 
392 	if (KREAD(kd, a_zombproc, &p)) {
393 		_kvm_err(kd, kd->program, "cannot read zombproc");
394 		return (-1);
395 	}
396 	zcnt = kvm_proclist(kd, what, arg, p, bp + acnt, maxcnt - acnt);
397 	if (zcnt < 0)
398 		zcnt = 0;
399 
400 	return (acnt + zcnt);
401 }
402 
403 struct kinfo_proc *
404 kvm_getprocs(kvm_t *kd, int op, int arg, int *cnt)
405 {
406 	int mib[4], st, nprocs;
407 	size_t size;
408 
409 	if (kd->procbase != 0) {
410 		free((void *)kd->procbase);
411 		/*
412 		 * Clear this pointer in case this call fails.  Otherwise,
413 		 * kvm_close() will free it again.
414 		 */
415 		kd->procbase = 0;
416 	}
417 	if (ISALIVE(kd)) {
418 		size = 0;
419 		mib[0] = CTL_KERN;
420 		mib[1] = KERN_PROC;
421 		mib[2] = op;
422 		mib[3] = arg;
423 		st = sysctl(mib, 4, NULL, &size, NULL, 0);
424 		if (st == -1) {
425 			_kvm_syserr(kd, kd->program, "kvm_getprocs");
426 			return (0);
427 		}
428 		kd->procbase = _kvm_malloc(kd, size);
429 		if (kd->procbase == 0)
430 			return (0);
431 		st = sysctl(mib, 4, kd->procbase, &size, NULL, 0);
432 		if (st == -1) {
433 			_kvm_syserr(kd, kd->program, "kvm_getprocs");
434 			return (0);
435 		}
436 		if (size % sizeof(struct kinfo_proc) != 0) {
437 			_kvm_err(kd, kd->program,
438 			    "proc size mismatch (%d total, %d chunks)",
439 			    size, sizeof(struct kinfo_proc));
440 			return (0);
441 		}
442 		nprocs = size / sizeof(struct kinfo_proc);
443 	} else {
444 		struct nlist nl[4], *p;
445 
446 		memset(nl, 0, sizeof(nl));
447 		nl[0].n_name = "_nprocs";
448 		nl[1].n_name = "_allproc";
449 		nl[2].n_name = "_zombproc";
450 		nl[3].n_name = NULL;
451 
452 		if (kvm_nlist(kd, nl) != 0) {
453 			for (p = nl; p->n_type != 0; ++p)
454 				;
455 			_kvm_err(kd, kd->program,
456 			    "%s: no such symbol", p->n_name);
457 			return (0);
458 		}
459 		if (KREAD(kd, nl[0].n_value, &nprocs)) {
460 			_kvm_err(kd, kd->program, "can't read nprocs");
461 			return (0);
462 		}
463 		size = nprocs * sizeof(struct kinfo_proc);
464 		kd->procbase = _kvm_malloc(kd, size);
465 		if (kd->procbase == 0)
466 			return (0);
467 
468 		nprocs = kvm_deadprocs(kd, op, arg, nl[1].n_value,
469 		    nl[2].n_value, nprocs);
470 #ifdef notdef
471 		size = nprocs * sizeof(struct kinfo_proc);
472 		(void)realloc(kd->procbase, size);
473 #endif
474 	}
475 	*cnt = nprocs;
476 	return (kd->procbase);
477 }
478 
479 void
480 _kvm_freeprocs(kvm_t *kd)
481 {
482 	if (kd->procbase) {
483 		free(kd->procbase);
484 		kd->procbase = 0;
485 	}
486 }
487 
488 void *
489 _kvm_realloc(kvm_t *kd, void *p, size_t n)
490 {
491 	void *np = (void *)realloc(p, n);
492 
493 	if (np == 0)
494 		_kvm_err(kd, kd->program, "out of memory");
495 	return (np);
496 }
497 
498 /*
499  * Read in an argument vector from the user address space of process p.
500  * addr if the user-space base address of narg null-terminated contiguous
501  * strings.  This is used to read in both the command arguments and
502  * environment strings.  Read at most maxcnt characters of strings.
503  */
504 static char **
505 kvm_argv(kvm_t *kd, const struct miniproc *p, u_long addr, int narg,
506     int maxcnt)
507 {
508 	char *np, *cp, *ep, *ap, **argv;
509 	u_long oaddr = -1;
510 	int len, cc;
511 
512 	/*
513 	 * Check that there aren't an unreasonable number of agruments,
514 	 * and that the address is in user space.
515 	 */
516 	if (narg > ARG_MAX || addr < VM_MIN_ADDRESS || addr >= VM_MAXUSER_ADDRESS)
517 		return (0);
518 
519 	if (kd->argv == 0) {
520 		/*
521 		 * Try to avoid reallocs.
522 		 */
523 		kd->argc = MAX(narg + 1, 32);
524 		kd->argv = _kvm_malloc(kd, kd->argc *
525 		    sizeof(*kd->argv));
526 		if (kd->argv == 0)
527 			return (0);
528 	} else if (narg + 1 > kd->argc) {
529 		kd->argc = MAX(2 * kd->argc, narg + 1);
530 		kd->argv = (char **)_kvm_realloc(kd, kd->argv, kd->argc *
531 		    sizeof(*kd->argv));
532 		if (kd->argv == 0)
533 			return (0);
534 	}
535 	if (kd->argspc == 0) {
536 		kd->argspc = _kvm_malloc(kd, kd->nbpg);
537 		if (kd->argspc == 0)
538 			return (0);
539 		kd->arglen = kd->nbpg;
540 	}
541 	if (kd->argbuf == 0) {
542 		kd->argbuf = _kvm_malloc(kd, kd->nbpg);
543 		if (kd->argbuf == 0)
544 			return (0);
545 	}
546 	cc = sizeof(char *) * narg;
547 	if (kvm_ureadm(kd, p, addr, (char *)kd->argv, cc) != cc)
548 		return (0);
549 	ap = np = kd->argspc;
550 	argv = kd->argv;
551 	len = 0;
552 
553 	/*
554 	 * Loop over pages, filling in the argument vector.
555 	 */
556 	while (argv < kd->argv + narg && *argv != 0) {
557 		addr = (u_long)*argv & ~(kd->nbpg - 1);
558 		if (addr != oaddr) {
559 			if (kvm_ureadm(kd, p, addr, kd->argbuf, kd->nbpg) !=
560 			    kd->nbpg)
561 				return (0);
562 			oaddr = addr;
563 		}
564 		addr = (u_long)*argv & (kd->nbpg - 1);
565 		cp = kd->argbuf + addr;
566 		cc = kd->nbpg - addr;
567 		if (maxcnt > 0 && cc > maxcnt - len)
568 			cc = maxcnt - len;
569 		ep = memchr(cp, '\0', cc);
570 		if (ep != 0)
571 			cc = ep - cp + 1;
572 		if (len + cc > kd->arglen) {
573 			int off;
574 			char **pp;
575 			char *op = kd->argspc;
576 
577 			kd->arglen *= 2;
578 			kd->argspc = (char *)_kvm_realloc(kd, kd->argspc,
579 			    kd->arglen);
580 			if (kd->argspc == 0)
581 				return (0);
582 			/*
583 			 * Adjust argv pointers in case realloc moved
584 			 * the string space.
585 			 */
586 			off = kd->argspc - op;
587 			for (pp = kd->argv; pp < argv; pp++)
588 				*pp += off;
589 			ap += off;
590 			np += off;
591 		}
592 		memcpy(np, cp, cc);
593 		np += cc;
594 		len += cc;
595 		if (ep != 0) {
596 			*argv++ = ap;
597 			ap = np;
598 		} else
599 			*argv += cc;
600 		if (maxcnt > 0 && len >= maxcnt) {
601 			/*
602 			 * We're stopping prematurely.  Terminate the
603 			 * current string.
604 			 */
605 			if (ep == 0) {
606 				*np = '\0';
607 				*argv++ = ap;
608 			}
609 			break;
610 		}
611 	}
612 	/* Make sure argv is terminated. */
613 	*argv = 0;
614 	return (kd->argv);
615 }
616 
617 static void
618 ps_str_a(struct ps_strings *p, u_long *addr, int *n)
619 {
620 	*addr = (u_long)p->ps_argvstr;
621 	*n = p->ps_nargvstr;
622 }
623 
624 static void
625 ps_str_e(struct ps_strings *p, u_long *addr, int *n)
626 {
627 	*addr = (u_long)p->ps_envstr;
628 	*n = p->ps_nenvstr;
629 }
630 
631 /*
632  * Determine if the proc indicated by p is still active.
633  * This test is not 100% foolproof in theory, but chances of
634  * being wrong are very low.
635  */
636 static int
637 proc_verify(kvm_t *kd, const struct miniproc *p)
638 {
639 	struct proc kernproc;
640 
641 	/*
642 	 * Just read in the whole proc.  It's not that big relative
643 	 * to the cost of the read system call.
644 	 */
645 	if (kvm_read(kd, (u_long)p->p_paddr, &kernproc, sizeof(kernproc)) !=
646 	    sizeof(kernproc))
647 		return (0);
648 	return (p->p_pid == kernproc.p_pid &&
649 	    (kernproc.p_stat != SZOMB || p->p_stat == SZOMB));
650 }
651 
652 static char **
653 kvm_doargv(kvm_t *kd, const struct miniproc *p, int nchr,
654     void (*info)(struct ps_strings *, u_long *, int *))
655 {
656 	static struct ps_strings *ps;
657 	struct ps_strings arginfo;
658 	u_long addr;
659 	char **ap;
660 	int cnt;
661 
662 	if (ps == NULL) {
663 		struct _ps_strings _ps;
664 		int mib[2];
665 		size_t len;
666 
667 		mib[0] = CTL_VM;
668 		mib[1] = VM_PSSTRINGS;
669 		len = sizeof(_ps);
670 		sysctl(mib, 2, &_ps, &len, NULL, 0);
671 		ps = (struct ps_strings *)_ps.val;
672 	}
673 
674 	/*
675 	 * Pointers are stored at the top of the user stack.
676 	 */
677 	if (p->p_stat == SZOMB ||
678 	    kvm_ureadm(kd, p, (u_long)ps, (char *)&arginfo,
679 	    sizeof(arginfo)) != sizeof(arginfo))
680 		return (0);
681 
682 	(*info)(&arginfo, &addr, &cnt);
683 	if (cnt == 0)
684 		return (0);
685 	ap = kvm_argv(kd, p, addr, cnt, nchr);
686 	/*
687 	 * For live kernels, make sure this process didn't go away.
688 	 */
689 	if (ap != 0 && ISALIVE(kd) && !proc_verify(kd, p))
690 		ap = 0;
691 	return (ap);
692 }
693 
694 static char **
695 kvm_arg_sysctl(kvm_t *kd, pid_t pid, int nchr, int env)
696 {
697 	size_t len, orglen;
698 	int mib[4], ret;
699 	char *buf;
700 
701 	orglen = env ? kd->nbpg : 8 * kd->nbpg;	/* XXX - should be ARG_MAX */
702 	if (kd->argbuf == NULL &&
703 	    (kd->argbuf = _kvm_malloc(kd, orglen)) == NULL)
704 		return (NULL);
705 
706 again:
707 	mib[0] = CTL_KERN;
708 	mib[1] = KERN_PROC_ARGS;
709 	mib[2] = (int)pid;
710 	mib[3] = env ? KERN_PROC_ENV : KERN_PROC_ARGV;
711 
712 	len = orglen;
713 	ret = (sysctl(mib, 4, kd->argbuf, &len, NULL, 0) < 0);
714 	if (ret && errno == ENOMEM) {
715 		orglen *= 2;
716 		buf = _kvm_realloc(kd, kd->argbuf, orglen);
717 		if (buf == NULL)
718 			return (NULL);
719 		kd->argbuf = buf;
720 		goto again;
721 	}
722 
723 	if (ret) {
724 		free(kd->argbuf);
725 		kd->argbuf = NULL;
726 		_kvm_syserr(kd, kd->program, "kvm_arg_sysctl");
727 		return (NULL);
728 	}
729 #if 0
730 	for (argv = (char **)kd->argbuf; *argv != NULL; argv++)
731 		if (strlen(*argv) > nchr)
732 			*argv[nchr] = '\0';
733 #endif
734 
735 	return (char **)(kd->argbuf);
736 }
737 
738 /*
739  * Get the command args.  This code is now machine independent.
740  */
741 char **
742 kvm_getargv(kvm_t *kd, const struct kinfo_proc *kp, int nchr)
743 {
744 	struct miniproc p;
745 
746 	if (ISALIVE(kd))
747 		return (kvm_arg_sysctl(kd, kp->kp_proc.p_pid, nchr, 0));
748 	KPTOMINI(kp, &p);
749 	return (kvm_doargv(kd, &p, nchr, ps_str_a));
750 }
751 
752 char **
753 kvm_getenvv(kvm_t *kd, const struct kinfo_proc *kp, int nchr)
754 {
755 	struct miniproc p;
756 
757 	if (ISALIVE(kd))
758 		return (kvm_arg_sysctl(kd, kp->kp_proc.p_pid, nchr, 1));
759 	KPTOMINI(kp, &p);
760 	return (kvm_doargv(kd, &p, nchr, ps_str_e));
761 }
762 
763 char **
764 kvm_getargv2(kvm_t *kd, const struct kinfo_proc2 *kp, int nchr)
765 {
766 	struct miniproc p;
767 
768 	if (ISALIVE(kd))
769 		return (kvm_arg_sysctl(kd, kp->p_pid, nchr, 0));
770 	KP2TOMINI(kp, &p);
771 	return (kvm_doargv(kd, &p, nchr, ps_str_a));
772 }
773 
774 char **
775 kvm_getenvv2(kvm_t *kd, const struct kinfo_proc2 *kp, int nchr)
776 {
777 	struct miniproc p;
778 
779 	if (ISALIVE(kd))
780 		return (kvm_arg_sysctl(kd, kp->p_pid, nchr, 1));
781 	KP2TOMINI(kp, &p);
782 	return (kvm_doargv(kd, &p, nchr, ps_str_e));
783 }
784 
785 /*
786  * Read from user space.  The user context is given by p.
787  */
788 static ssize_t
789 kvm_ureadm(kvm_t *kd, const struct miniproc *p, u_long uva, char *buf,
790     size_t len)
791 {
792 	char *cp = buf;
793 
794 	while (len > 0) {
795 		u_long cnt;
796 		size_t cc;
797 		char *dp;
798 
799 		dp = _kvm_ureadm(kd, p, uva, &cnt);
800 		if (dp == 0) {
801 			_kvm_err(kd, 0, "invalid address (%lx)", uva);
802 			return (0);
803 		}
804 		cc = (size_t)MIN(cnt, len);
805 		bcopy(dp, cp, cc);
806 		cp += cc;
807 		uva += cc;
808 		len -= cc;
809 	}
810 	return (ssize_t)(cp - buf);
811 }
812 
813 ssize_t
814 kvm_uread(kvm_t *kd, const struct proc *p, u_long uva, char *buf,
815     size_t len)
816 {
817 	struct miniproc mp;
818 
819 	PTOMINI(p, &mp);
820 	return (kvm_ureadm(kd, &mp, uva, buf, len));
821 }
822