xref: /freebsd/lib/libkvm/kvm_proc.c (revision 6780ab54325a71e7e70112b11657973edde8655e)
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  * 3. All advertising materials mentioning features or use of this software
18  *    must display the following acknowledgement:
19  *	This product includes software developed by the University of
20  *	California, Berkeley and its contributors.
21  * 4. Neither the name of the University nor the names of its contributors
22  *    may be used to endorse or promote products derived from this software
23  *    without specific prior written permission.
24  *
25  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
26  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
27  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
28  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
29  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
30  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
31  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
32  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
33  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
34  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
35  * SUCH DAMAGE.
36  */
37 
38 #if 0
39 #if defined(LIBC_SCCS) && !defined(lint)
40 static char sccsid[] = "@(#)kvm_proc.c	8.3 (Berkeley) 9/23/93";
41 #endif /* LIBC_SCCS and not lint */
42 #endif
43 
44 #include <sys/cdefs.h>
45 __FBSDID("$FreeBSD$");
46 
47 /*
48  * Proc traversal interface for kvm.  ps and w are (probably) the exclusive
49  * users of this code, so we've factored it out into a separate module.
50  * Thus, we keep this grunge out of the other kvm applications (i.e.,
51  * most other applications are interested only in open/close/read/nlist).
52  */
53 
54 #include <sys/param.h>
55 #define _WANT_UCRED	/* make ucred.h give us 'struct ucred' */
56 #include <sys/ucred.h>
57 #include <sys/user.h>
58 #include <sys/proc.h>
59 #include <sys/exec.h>
60 #include <sys/stat.h>
61 #include <sys/ioctl.h>
62 #include <sys/tty.h>
63 #include <sys/file.h>
64 #include <stdio.h>
65 #include <stdlib.h>
66 #include <unistd.h>
67 #include <nlist.h>
68 #include <kvm.h>
69 
70 #include <vm/vm.h>
71 #include <vm/vm_param.h>
72 #include <vm/swap_pager.h>
73 
74 #include <sys/sysctl.h>
75 
76 #include <limits.h>
77 #include <memory.h>
78 #include <paths.h>
79 
80 #include "kvm_private.h"
81 
82 #define KREAD(kd, addr, obj) \
83 	(kvm_read(kd, addr, (char *)(obj), sizeof(*obj)) != sizeof(*obj))
84 
85 /*
86  * Read proc's from memory file into buffer bp, which has space to hold
87  * at most maxcnt procs.
88  */
89 static int
90 kvm_proclist(kd, what, arg, p, bp, maxcnt)
91 	kvm_t *kd;
92 	int what, arg;
93 	struct proc *p;
94 	struct kinfo_proc *bp;
95 	int maxcnt;
96 {
97 	int cnt = 0;
98 	struct kinfo_proc kinfo_proc, *kp;
99 	struct pgrp pgrp;
100 	struct session sess;
101 	struct tty tty;
102 	struct vmspace vmspace;
103 	struct procsig procsig;
104 	struct pstats pstats;
105 	struct ucred ucred;
106 	struct thread mtd;
107 	struct kse mke;
108 	struct ksegrp mkg;
109 	struct proc proc;
110 	struct proc pproc;
111 	struct timeval tv;
112 
113 	kp = &kinfo_proc;
114 	kp->ki_structsize = sizeof(kinfo_proc);
115 	for (; cnt < maxcnt && p != NULL; p = LIST_NEXT(&proc, p_list)) {
116 		memset(kp, 0, sizeof *kp);
117 		if (KREAD(kd, (u_long)p, &proc)) {
118 			_kvm_err(kd, kd->program, "can't read proc at %x", p);
119 			return (-1);
120 		}
121 		if (proc.p_state != PRS_ZOMBIE) {
122 			if (KREAD(kd, (u_long)TAILQ_FIRST(&proc.p_threads),
123 			    &mtd)) {
124 				_kvm_err(kd, kd->program,
125 				    "can't read thread at %x",
126 				    TAILQ_FIRST(&proc.p_threads));
127 				return (-1);
128 			}
129 			if (proc.p_flag & P_KSES == 0) {
130 				if (KREAD(kd,
131 				    (u_long)TAILQ_FIRST(&proc.p_ksegrps),
132 				    &mkg)) {
133 					_kvm_err(kd, kd->program,
134 					    "can't read ksegrp at %x",
135 					    TAILQ_FIRST(&proc.p_ksegrps));
136 					return (-1);
137 				}
138 				if (KREAD(kd,
139 				    (u_long)TAILQ_FIRST(&mkg.kg_kseq), &mke)) {
140 					_kvm_err(kd, kd->program,
141 					    "can't read kse at %x",
142 					    TAILQ_FIRST(&mkg.kg_kseq));
143 					return (-1);
144 				}
145 			}
146 		}
147 		if (KREAD(kd, (u_long)proc.p_ucred, &ucred) == 0) {
148 			kp->ki_ruid = ucred.cr_ruid;
149 			kp->ki_svuid = ucred.cr_svuid;
150 			kp->ki_rgid = ucred.cr_rgid;
151 			kp->ki_svgid = ucred.cr_svgid;
152 			kp->ki_ngroups = ucred.cr_ngroups;
153 			bcopy(ucred.cr_groups, kp->ki_groups,
154 			    NGROUPS * sizeof(gid_t));
155 			kp->ki_uid = ucred.cr_uid;
156 		}
157 
158 		switch(what) {
159 
160 		case KERN_PROC_PID:
161 			if (proc.p_pid != (pid_t)arg)
162 				continue;
163 			break;
164 
165 		case KERN_PROC_UID:
166 			if (kp->ki_uid != (uid_t)arg)
167 				continue;
168 			break;
169 
170 		case KERN_PROC_RUID:
171 			if (kp->ki_ruid != (uid_t)arg)
172 				continue;
173 			break;
174 		}
175 		/*
176 		 * We're going to add another proc to the set.  If this
177 		 * will overflow the buffer, assume the reason is because
178 		 * nprocs (or the proc list) is corrupt and declare an error.
179 		 */
180 		if (cnt >= maxcnt) {
181 			_kvm_err(kd, kd->program, "nprocs corrupt");
182 			return (-1);
183 		}
184 		/*
185 		 * gather kinfo_proc
186 		 */
187 		kp->ki_paddr = p;
188 		kp->ki_addr = proc.p_uarea;
189 		/* kp->ki_kstack = proc.p_thread.td_kstack; XXXKSE */
190 		kp->ki_args = proc.p_args;
191 		kp->ki_tracep = proc.p_tracep;
192 		kp->ki_textvp = proc.p_textvp;
193 		kp->ki_fd = proc.p_fd;
194 		kp->ki_vmspace = proc.p_vmspace;
195 		if (proc.p_procsig != NULL) {
196 			if (KREAD(kd, (u_long)proc.p_procsig, &procsig)) {
197 				_kvm_err(kd, kd->program,
198 				    "can't read procsig at %x", proc.p_procsig);
199 				return (-1);
200 			}
201 			kp->ki_sigignore = procsig.ps_sigignore;
202 			kp->ki_sigcatch = procsig.ps_sigcatch;
203 		}
204 		if ((proc.p_sflag & PS_INMEM) && proc.p_stats != NULL) {
205 			if (KREAD(kd, (u_long)proc.p_stats, &pstats)) {
206 				_kvm_err(kd, kd->program,
207 				    "can't read stats at %x", proc.p_stats);
208 				return (-1);
209 			}
210 			kp->ki_start = pstats.p_start;
211 			kp->ki_rusage = pstats.p_ru;
212 			kp->ki_childtime.tv_sec = pstats.p_cru.ru_utime.tv_sec +
213 			    pstats.p_cru.ru_stime.tv_sec;
214 			kp->ki_childtime.tv_usec =
215 			    pstats.p_cru.ru_utime.tv_usec +
216 			    pstats.p_cru.ru_stime.tv_usec;
217 		}
218 		if (proc.p_oppid)
219 			kp->ki_ppid = proc.p_oppid;
220 		else if (proc.p_pptr) {
221 			if (KREAD(kd, (u_long)proc.p_pptr, &pproc)) {
222 				_kvm_err(kd, kd->program,
223 				    "can't read pproc at %x", proc.p_pptr);
224 				return (-1);
225 			}
226 			kp->ki_ppid = pproc.p_pid;
227 		} else
228 			kp->ki_ppid = 0;
229 		if (proc.p_pgrp == NULL)
230 			goto nopgrp;
231 		if (KREAD(kd, (u_long)proc.p_pgrp, &pgrp)) {
232 			_kvm_err(kd, kd->program, "can't read pgrp at %x",
233 				 proc.p_pgrp);
234 			return (-1);
235 		}
236 		kp->ki_pgid = pgrp.pg_id;
237 		kp->ki_jobc = pgrp.pg_jobc;
238 		if (KREAD(kd, (u_long)pgrp.pg_session, &sess)) {
239 			_kvm_err(kd, kd->program, "can't read session at %x",
240 				pgrp.pg_session);
241 			return (-1);
242 		}
243 		kp->ki_sid = sess.s_sid;
244 		(void)memcpy(kp->ki_login, sess.s_login,
245 						sizeof(kp->ki_login));
246 		kp->ki_kiflag = sess.s_ttyvp ? KI_CTTY : 0;
247 		if (sess.s_leader == p)
248 			kp->ki_kiflag |= KI_SLEADER;
249 		if ((proc.p_flag & P_CONTROLT) && sess.s_ttyp != NULL) {
250 			if (KREAD(kd, (u_long)sess.s_ttyp, &tty)) {
251 				_kvm_err(kd, kd->program,
252 					 "can't read tty at %x", sess.s_ttyp);
253 				return (-1);
254 			}
255 			kp->ki_tdev = tty.t_dev;
256 			if (tty.t_pgrp != NULL) {
257 				if (KREAD(kd, (u_long)tty.t_pgrp, &pgrp)) {
258 					_kvm_err(kd, kd->program,
259 						 "can't read tpgrp at %x",
260 						tty.t_pgrp);
261 					return (-1);
262 				}
263 				kp->ki_tpgid = pgrp.pg_id;
264 			} else
265 				kp->ki_tpgid = -1;
266 			if (tty.t_session != NULL) {
267 				if (KREAD(kd, (u_long)tty.t_session, &sess)) {
268 					_kvm_err(kd, kd->program,
269 					    "can't read session at %x",
270 					    tty.t_session);
271 					return (-1);
272 				}
273 				kp->ki_tsid = sess.s_sid;
274 			}
275 		} else {
276 nopgrp:
277 			kp->ki_tdev = NODEV;
278 		}
279 		if ((proc.p_state != PRS_ZOMBIE) && mtd.td_wmesg)
280 			(void)kvm_read(kd, (u_long)mtd.td_wmesg,
281 			    kp->ki_wmesg, WMESGLEN);
282 
283 #ifdef sparc
284 		(void)kvm_read(kd, (u_long)&proc.p_vmspace->vm_rssize,
285 		    (char *)&kp->ki_rssize,
286 		    sizeof(kp->ki_rssize));
287 		(void)kvm_read(kd, (u_long)&proc.p_vmspace->vm_tsize,
288 		    (char *)&kp->ki_tsize,
289 		    3 * sizeof(kp->ki_rssize));	/* XXX */
290 #else
291 		(void)kvm_read(kd, (u_long)proc.p_vmspace,
292 		    (char *)&vmspace, sizeof(vmspace));
293 		kp->ki_size = vmspace.vm_map.size;
294 		kp->ki_rssize = vmspace.vm_swrss; /* XXX */
295 		kp->ki_swrss = vmspace.vm_swrss;
296 		kp->ki_tsize = vmspace.vm_tsize;
297 		kp->ki_dsize = vmspace.vm_dsize;
298 		kp->ki_ssize = vmspace.vm_ssize;
299 #endif
300 
301 		switch (what) {
302 
303 		case KERN_PROC_PGRP:
304 			if (kp->ki_pgid != (pid_t)arg)
305 				continue;
306 			break;
307 
308 		case KERN_PROC_TTY:
309 			if ((proc.p_flag & P_CONTROLT) == 0 ||
310 			     kp->ki_tdev != (dev_t)arg)
311 				continue;
312 			break;
313 		}
314 		if (proc.p_comm[0] != 0) {
315 			strncpy(kp->ki_comm, proc.p_comm, MAXCOMLEN);
316 			kp->ki_comm[MAXCOMLEN] = 0;
317 		}
318 		if ((proc.p_state != PRS_ZOMBIE) &&
319 		    (mtd.td_blocked != 0)) {
320 			kp->ki_kiflag |= KI_LOCKBLOCK;
321 			if (mtd.td_lockname)
322 				(void)kvm_read(kd,
323 				    (u_long)mtd.td_lockname,
324 				    kp->ki_lockname, LOCKNAMELEN);
325 			kp->ki_lockname[LOCKNAMELEN] = 0;
326 		}
327 		bintime2timeval(&proc.p_runtime, &tv);
328 		kp->ki_runtime = (u_int64_t)tv.tv_sec * 1000000 + tv.tv_usec;
329 		kp->ki_pid = proc.p_pid;
330 		kp->ki_siglist = proc.p_siglist;
331 		kp->ki_sigmask = proc.p_sigmask;
332 		kp->ki_xstat = proc.p_xstat;
333 		kp->ki_acflag = proc.p_acflag;
334 		kp->ki_lock = proc.p_lock;
335 		if (proc.p_state != PRS_ZOMBIE) {
336 			kp->ki_swtime = proc.p_swtime;
337 			kp->ki_flag = proc.p_flag;
338 			kp->ki_sflag = proc.p_sflag;
339 			kp->ki_traceflag = proc.p_traceflag;
340 			if (proc.p_state == PRS_NORMAL) {
341 				if (TD_ON_RUNQ(&mtd) ||
342 				    TD_CAN_RUN(&mtd) ||
343 				    TD_IS_RUNNING(&mtd)) {
344 					kp->ki_stat = SRUN;
345 				} else if (mtd.td_state ==
346 				    TDS_INHIBITED) {
347 					if (P_SHOULDSTOP(&proc)) {
348 						kp->ki_stat = SSTOP;
349 					} else if (
350 					    TD_IS_SLEEPING(&mtd)) {
351 						kp->ki_stat = SSLEEP;
352 					} else if (TD_ON_LOCK(&mtd)) {
353 						kp->ki_stat = SLOCK;
354 					} else {
355 						kp->ki_stat = SWAIT;
356 					}
357 				}
358 			} else {
359 				kp->ki_stat = SIDL;
360 			}
361 			/* Stuff from the thread */
362 			kp->ki_pri.pri_level = mtd.td_priority;
363 			kp->ki_pri.pri_native = mtd.td_base_pri;
364 			kp->ki_lastcpu = mtd.td_lastcpu;
365 			kp->ki_wchan = mtd.td_wchan;
366 
367 			if (!(proc.p_flag & P_KSES)) {
368 				/* stuff from the ksegrp */
369 				kp->ki_slptime = mkg.kg_slptime;
370 				kp->ki_pri.pri_class = mkg.kg_pri_class;
371 				kp->ki_pri.pri_user = mkg.kg_user_pri;
372 				kp->ki_nice = mkg.kg_nice;
373 				kp->ki_estcpu = mkg.kg_estcpu;
374 
375 				/* Stuff from the kse */
376 				kp->ki_pctcpu = mke.ke_pctcpu;
377 				kp->ki_rqindex = mke.ke_rqindex;
378 				kp->ki_oncpu = mke.ke_oncpu;
379 			} else {
380 				kp->ki_oncpu = -1;
381 				kp->ki_lastcpu = -1;
382 				kp->ki_tdflags = -1;
383 				/* All the rest are 0 for now */
384 			}
385 		} else {
386 			kp->ki_stat = SZOMB;
387 		}
388 		bcopy(&kinfo_proc, bp, sizeof(kinfo_proc));
389 		++bp;
390 		++cnt;
391 	}
392 	return (cnt);
393 }
394 
395 /*
396  * Build proc info array by reading in proc list from a crash dump.
397  * Return number of procs read.  maxcnt is the max we will read.
398  */
399 static int
400 kvm_deadprocs(kd, what, arg, a_allproc, a_zombproc, maxcnt)
401 	kvm_t *kd;
402 	int what, arg;
403 	u_long a_allproc;
404 	u_long a_zombproc;
405 	int maxcnt;
406 {
407 	struct kinfo_proc *bp = kd->procbase;
408 	int acnt, zcnt;
409 	struct proc *p;
410 
411 	if (KREAD(kd, a_allproc, &p)) {
412 		_kvm_err(kd, kd->program, "cannot read allproc");
413 		return (-1);
414 	}
415 	acnt = kvm_proclist(kd, what, arg, p, bp, maxcnt);
416 	if (acnt < 0)
417 		return (acnt);
418 
419 	if (KREAD(kd, a_zombproc, &p)) {
420 		_kvm_err(kd, kd->program, "cannot read zombproc");
421 		return (-1);
422 	}
423 	zcnt = kvm_proclist(kd, what, arg, p, bp + acnt, maxcnt - acnt);
424 	if (zcnt < 0)
425 		zcnt = 0;
426 
427 	return (acnt + zcnt);
428 }
429 
430 struct kinfo_proc *
431 kvm_getprocs(kd, op, arg, cnt)
432 	kvm_t *kd;
433 	int op, arg;
434 	int *cnt;
435 {
436 	int mib[4], st, nprocs;
437 	size_t size;
438 
439 	if (kd->procbase != 0) {
440 		free((void *)kd->procbase);
441 		/*
442 		 * Clear this pointer in case this call fails.  Otherwise,
443 		 * kvm_close() will free it again.
444 		 */
445 		kd->procbase = 0;
446 	}
447 	if (ISALIVE(kd)) {
448 		size = 0;
449 		mib[0] = CTL_KERN;
450 		mib[1] = KERN_PROC;
451 		mib[2] = op;
452 		mib[3] = arg;
453 		st = sysctl(mib, op == KERN_PROC_ALL ? 3 : 4, NULL, &size, NULL, 0);
454 		if (st == -1) {
455 			_kvm_syserr(kd, kd->program, "kvm_getprocs");
456 			return (0);
457 		}
458 		/*
459 		 * We can't continue with a size of 0 because we pass
460 		 * it to realloc() (via _kvm_realloc()), and passing 0
461 		 * to realloc() results in undefined behavior.
462 		 */
463 		if (size == 0) {
464 			/*
465 			 * XXX: We should probably return an invalid,
466 			 * but non-NULL, pointer here so any client
467 			 * program trying to dereference it will
468 			 * crash.  However, _kvm_freeprocs() calls
469 			 * free() on kd->procbase if it isn't NULL,
470 			 * and free()'ing a junk pointer isn't good.
471 			 * Then again, _kvm_freeprocs() isn't used
472 			 * anywhere . . .
473 			 */
474 			kd->procbase = _kvm_malloc(kd, 1);
475 			goto liveout;
476 		}
477 		do {
478 			size += size / 10;
479 			kd->procbase = (struct kinfo_proc *)
480 			    _kvm_realloc(kd, kd->procbase, size);
481 			if (kd->procbase == 0)
482 				return (0);
483 			st = sysctl(mib, op == KERN_PROC_ALL ? 3 : 4,
484 			    kd->procbase, &size, NULL, 0);
485 		} while (st == -1 && errno == ENOMEM);
486 		if (st == -1) {
487 			_kvm_syserr(kd, kd->program, "kvm_getprocs");
488 			return (0);
489 		}
490 		/*
491 		 * We have to check the size again because sysctl()
492 		 * may "round up" oldlenp if oldp is NULL; hence it
493 		 * might've told us that there was data to get when
494 		 * there really isn't any.
495 		 */
496 		if (size > 0 &&
497 		    kd->procbase->ki_structsize != sizeof(struct kinfo_proc)) {
498 			_kvm_err(kd, kd->program,
499 			    "kinfo_proc size mismatch (expected %d, got %d)",
500 			    sizeof(struct kinfo_proc),
501 			    kd->procbase->ki_structsize);
502 			return (0);
503 		}
504 liveout:
505 		nprocs = size == 0 ? 0 : size / kd->procbase->ki_structsize;
506 	} else {
507 		struct nlist nl[4], *p;
508 
509 		nl[0].n_name = "_nprocs";
510 		nl[1].n_name = "_allproc";
511 		nl[2].n_name = "_zombproc";
512 		nl[3].n_name = 0;
513 
514 		if (kvm_nlist(kd, nl) != 0) {
515 			for (p = nl; p->n_type != 0; ++p)
516 				;
517 			_kvm_err(kd, kd->program,
518 				 "%s: no such symbol", p->n_name);
519 			return (0);
520 		}
521 		if (KREAD(kd, nl[0].n_value, &nprocs)) {
522 			_kvm_err(kd, kd->program, "can't read nprocs");
523 			return (0);
524 		}
525 		size = nprocs * sizeof(struct kinfo_proc);
526 		kd->procbase = (struct kinfo_proc *)_kvm_malloc(kd, size);
527 		if (kd->procbase == 0)
528 			return (0);
529 
530 		nprocs = kvm_deadprocs(kd, op, arg, nl[1].n_value,
531 				      nl[2].n_value, nprocs);
532 #ifdef notdef
533 		size = nprocs * sizeof(struct kinfo_proc);
534 		(void)realloc(kd->procbase, size);
535 #endif
536 	}
537 	*cnt = nprocs;
538 	return (kd->procbase);
539 }
540 
541 void
542 _kvm_freeprocs(kd)
543 	kvm_t *kd;
544 {
545 	if (kd->procbase) {
546 		free(kd->procbase);
547 		kd->procbase = 0;
548 	}
549 }
550 
551 void *
552 _kvm_realloc(kd, p, n)
553 	kvm_t *kd;
554 	void *p;
555 	size_t n;
556 {
557 	void *np = (void *)realloc(p, n);
558 
559 	if (np == 0) {
560 		free(p);
561 		_kvm_err(kd, kd->program, "out of memory");
562 	}
563 	return (np);
564 }
565 
566 #ifndef MAX
567 #define MAX(a, b) ((a) > (b) ? (a) : (b))
568 #endif
569 
570 /*
571  * Read in an argument vector from the user address space of process kp.
572  * addr if the user-space base address of narg null-terminated contiguous
573  * strings.  This is used to read in both the command arguments and
574  * environment strings.  Read at most maxcnt characters of strings.
575  */
576 static char **
577 kvm_argv(kd, kp, addr, narg, maxcnt)
578 	kvm_t *kd;
579 	struct kinfo_proc *kp;
580 	u_long addr;
581 	int narg;
582 	int maxcnt;
583 {
584 	char *np, *cp, *ep, *ap;
585 	u_long oaddr = -1;
586 	int len, cc;
587 	char **argv;
588 
589 	/*
590 	 * Check that there aren't an unreasonable number of agruments,
591 	 * and that the address is in user space.
592 	 */
593 	if (narg > 512 || addr < VM_MIN_ADDRESS || addr >= VM_MAXUSER_ADDRESS)
594 		return (0);
595 
596 	/*
597 	 * kd->argv : work space for fetching the strings from the target
598 	 *            process's space, and is converted for returning to caller
599 	 */
600 	if (kd->argv == 0) {
601 		/*
602 		 * Try to avoid reallocs.
603 		 */
604 		kd->argc = MAX(narg + 1, 32);
605 		kd->argv = (char **)_kvm_malloc(kd, kd->argc *
606 						sizeof(*kd->argv));
607 		if (kd->argv == 0)
608 			return (0);
609 	} else if (narg + 1 > kd->argc) {
610 		kd->argc = MAX(2 * kd->argc, narg + 1);
611 		kd->argv = (char **)_kvm_realloc(kd, kd->argv, kd->argc *
612 						sizeof(*kd->argv));
613 		if (kd->argv == 0)
614 			return (0);
615 	}
616 	/*
617 	 * kd->argspc : returned to user, this is where the kd->argv
618 	 *              arrays are left pointing to the collected strings.
619 	 */
620 	if (kd->argspc == 0) {
621 		kd->argspc = (char *)_kvm_malloc(kd, PAGE_SIZE);
622 		if (kd->argspc == 0)
623 			return (0);
624 		kd->arglen = PAGE_SIZE;
625 	}
626 	/*
627 	 * kd->argbuf : used to pull in pages from the target process.
628 	 *              the strings are copied out of here.
629 	 */
630 	if (kd->argbuf == 0) {
631 		kd->argbuf = (char *)_kvm_malloc(kd, PAGE_SIZE);
632 		if (kd->argbuf == 0)
633 			return (0);
634 	}
635 
636 	/* Pull in the target process'es argv vector */
637 	cc = sizeof(char *) * narg;
638 	if (kvm_uread(kd, kp, addr, (char *)kd->argv, cc) != cc)
639 		return (0);
640 	/*
641 	 * ap : saved start address of string we're working on in kd->argspc
642 	 * np : pointer to next place to write in kd->argspc
643 	 * len: length of data in kd->argspc
644 	 * argv: pointer to the argv vector that we are hunting around the
645 	 *       target process space for, and converting to addresses in
646 	 *       our address space (kd->argspc).
647 	 */
648 	ap = np = kd->argspc;
649 	argv = kd->argv;
650 	len = 0;
651 	/*
652 	 * Loop over pages, filling in the argument vector.
653 	 * Note that the argv strings could be pointing *anywhere* in
654 	 * the user address space and are no longer contiguous.
655 	 * Note that *argv is modified when we are going to fetch a string
656 	 * that crosses a page boundary.  We copy the next part of the string
657 	 * into to "np" and eventually convert the pointer.
658 	 */
659 	while (argv < kd->argv + narg && *argv != 0) {
660 
661 		/* get the address that the current argv string is on */
662 		addr = (u_long)*argv & ~(PAGE_SIZE - 1);
663 
664 		/* is it the same page as the last one? */
665 		if (addr != oaddr) {
666 			if (kvm_uread(kd, kp, addr, kd->argbuf, PAGE_SIZE) !=
667 			    PAGE_SIZE)
668 				return (0);
669 			oaddr = addr;
670 		}
671 
672 		/* offset within the page... kd->argbuf */
673 		addr = (u_long)*argv & (PAGE_SIZE - 1);
674 
675 		/* cp = start of string, cc = count of chars in this chunk */
676 		cp = kd->argbuf + addr;
677 		cc = PAGE_SIZE - addr;
678 
679 		/* dont get more than asked for by user process */
680 		if (maxcnt > 0 && cc > maxcnt - len)
681 			cc = maxcnt - len;
682 
683 		/* pointer to end of string if we found it in this page */
684 		ep = memchr(cp, '\0', cc);
685 		if (ep != 0)
686 			cc = ep - cp + 1;
687 		/*
688 		 * at this point, cc is the count of the chars that we are
689 		 * going to retrieve this time. we may or may not have found
690 		 * the end of it.  (ep points to the null if the end is known)
691 		 */
692 
693 		/* will we exceed the malloc/realloced buffer? */
694 		if (len + cc > kd->arglen) {
695 			int off;
696 			char **pp;
697 			char *op = kd->argspc;
698 
699 			kd->arglen *= 2;
700 			kd->argspc = (char *)_kvm_realloc(kd, kd->argspc,
701 							  kd->arglen);
702 			if (kd->argspc == 0)
703 				return (0);
704 			/*
705 			 * Adjust argv pointers in case realloc moved
706 			 * the string space.
707 			 */
708 			off = kd->argspc - op;
709 			for (pp = kd->argv; pp < argv; pp++)
710 				*pp += off;
711 			ap += off;
712 			np += off;
713 		}
714 		/* np = where to put the next part of the string in kd->argspc*/
715 		/* np is kinda redundant.. could use "kd->argspc + len" */
716 		memcpy(np, cp, cc);
717 		np += cc;	/* inc counters */
718 		len += cc;
719 
720 		/*
721 		 * if end of string found, set the *argv pointer to the
722 		 * saved beginning of string, and advance. argv points to
723 		 * somewhere in kd->argv..  This is initially relative
724 		 * to the target process, but when we close it off, we set
725 		 * it to point in our address space.
726 		 */
727 		if (ep != 0) {
728 			*argv++ = ap;
729 			ap = np;
730 		} else {
731 			/* update the address relative to the target process */
732 			*argv += cc;
733 		}
734 
735 		if (maxcnt > 0 && len >= maxcnt) {
736 			/*
737 			 * We're stopping prematurely.  Terminate the
738 			 * current string.
739 			 */
740 			if (ep == 0) {
741 				*np = '\0';
742 				*argv++ = ap;
743 			}
744 			break;
745 		}
746 	}
747 	/* Make sure argv is terminated. */
748 	*argv = 0;
749 	return (kd->argv);
750 }
751 
752 static void
753 ps_str_a(p, addr, n)
754 	struct ps_strings *p;
755 	u_long *addr;
756 	int *n;
757 {
758 	*addr = (u_long)p->ps_argvstr;
759 	*n = p->ps_nargvstr;
760 }
761 
762 static void
763 ps_str_e(p, addr, n)
764 	struct ps_strings *p;
765 	u_long *addr;
766 	int *n;
767 {
768 	*addr = (u_long)p->ps_envstr;
769 	*n = p->ps_nenvstr;
770 }
771 
772 /*
773  * Determine if the proc indicated by p is still active.
774  * This test is not 100% foolproof in theory, but chances of
775  * being wrong are very low.
776  */
777 static int
778 proc_verify(curkp)
779 	struct kinfo_proc *curkp;
780 {
781 	struct kinfo_proc newkp;
782 	int mib[4];
783 	size_t len;
784 
785 	mib[0] = CTL_KERN;
786 	mib[1] = KERN_PROC;
787 	mib[2] = KERN_PROC_PID;
788 	mib[3] = curkp->ki_pid;
789 	len = sizeof(newkp);
790 	if (sysctl(mib, 4, &newkp, &len, NULL, 0) == -1)
791 		return (0);
792 	return (curkp->ki_pid == newkp.ki_pid &&
793 	    (newkp.ki_stat != SZOMB || curkp->ki_stat == SZOMB));
794 }
795 
796 static char **
797 kvm_doargv(kd, kp, nchr, info)
798 	kvm_t *kd;
799 	struct kinfo_proc *kp;
800 	int nchr;
801 	void (*info)(struct ps_strings *, u_long *, int *);
802 {
803 	char **ap;
804 	u_long addr;
805 	int cnt;
806 	static struct ps_strings arginfo;
807 	static u_long ps_strings;
808 	size_t len;
809 
810 	if (ps_strings == NULL) {
811 		len = sizeof(ps_strings);
812 		if (sysctlbyname("kern.ps_strings", &ps_strings, &len, NULL,
813 		    0) == -1)
814 			ps_strings = PS_STRINGS;
815 	}
816 
817 	/*
818 	 * Pointers are stored at the top of the user stack.
819 	 */
820 	if (kp->ki_stat == SZOMB ||
821 	    kvm_uread(kd, kp, ps_strings, (char *)&arginfo,
822 		      sizeof(arginfo)) != sizeof(arginfo))
823 		return (0);
824 
825 	(*info)(&arginfo, &addr, &cnt);
826 	if (cnt == 0)
827 		return (0);
828 	ap = kvm_argv(kd, kp, addr, cnt, nchr);
829 	/*
830 	 * For live kernels, make sure this process didn't go away.
831 	 */
832 	if (ap != 0 && ISALIVE(kd) && !proc_verify(kp))
833 		ap = 0;
834 	return (ap);
835 }
836 
837 /*
838  * Get the command args.  This code is now machine independent.
839  */
840 char **
841 kvm_getargv(kd, kp, nchr)
842 	kvm_t *kd;
843 	const struct kinfo_proc *kp;
844 	int nchr;
845 {
846 	int oid[4];
847 	int i;
848 	size_t bufsz;
849 	static unsigned long buflen;
850 	static char *buf, *p;
851 	static char **bufp;
852 	static int argc;
853 
854 	if (!ISALIVE(kd)) {
855 		_kvm_err(kd, kd->program,
856 		    "cannot read user space from dead kernel");
857 		return (0);
858 	}
859 
860 	if (!buflen) {
861 		bufsz = sizeof(buflen);
862 		i = sysctlbyname("kern.ps_arg_cache_limit",
863 		    &buflen, &bufsz, NULL, 0);
864 		if (i == -1) {
865 			buflen = 0;
866 		} else {
867 			buf = malloc(buflen);
868 			if (buf == NULL)
869 				buflen = 0;
870 			argc = 32;
871 			bufp = malloc(sizeof(char *) * argc);
872 		}
873 	}
874 	if (buf != NULL) {
875 		oid[0] = CTL_KERN;
876 		oid[1] = KERN_PROC;
877 		oid[2] = KERN_PROC_ARGS;
878 		oid[3] = kp->ki_pid;
879 		bufsz = buflen;
880 		i = sysctl(oid, 4, buf, &bufsz, 0, 0);
881 		if (i == 0 && bufsz > 0) {
882 			i = 0;
883 			p = buf;
884 			do {
885 				bufp[i++] = p;
886 				p += strlen(p) + 1;
887 				if (i >= argc) {
888 					argc += argc;
889 					bufp = realloc(bufp,
890 					    sizeof(char *) * argc);
891 				}
892 			} while (p < buf + bufsz);
893 			bufp[i++] = 0;
894 			return (bufp);
895 		}
896 	}
897 	if (kp->ki_flag & P_SYSTEM)
898 		return (NULL);
899 	return (kvm_doargv(kd, kp, nchr, ps_str_a));
900 }
901 
902 char **
903 kvm_getenvv(kd, kp, nchr)
904 	kvm_t *kd;
905 	const struct kinfo_proc *kp;
906 	int nchr;
907 {
908 	return (kvm_doargv(kd, kp, nchr, ps_str_e));
909 }
910 
911 /*
912  * Read from user space.  The user context is given by p.
913  */
914 ssize_t
915 kvm_uread(kd, kp, uva, buf, len)
916 	kvm_t *kd;
917 	struct kinfo_proc *kp;
918 	u_long uva;
919 	char *buf;
920 	size_t len;
921 {
922 	char *cp;
923 	char procfile[MAXPATHLEN];
924 	ssize_t amount;
925 	int fd;
926 
927 	if (!ISALIVE(kd)) {
928 		_kvm_err(kd, kd->program,
929 		    "cannot read user space from dead kernel");
930 		return (0);
931 	}
932 
933 	sprintf(procfile, "/proc/%d/mem", kp->ki_pid);
934 	fd = open(procfile, O_RDONLY, 0);
935 	if (fd < 0) {
936 		_kvm_err(kd, kd->program, "cannot open %s", procfile);
937 		close(fd);
938 		return (0);
939 	}
940 
941 	cp = buf;
942 	while (len > 0) {
943 		errno = 0;
944 		if (lseek(fd, (off_t)uva, 0) == -1 && errno != 0) {
945 			_kvm_err(kd, kd->program, "invalid address (%x) in %s",
946 			    uva, procfile);
947 			break;
948 		}
949 		amount = read(fd, cp, len);
950 		if (amount < 0) {
951 			_kvm_syserr(kd, kd->program, "error reading %s",
952 			    procfile);
953 			break;
954 		}
955 		if (amount == 0) {
956 			_kvm_err(kd, kd->program, "EOF reading %s", procfile);
957 			break;
958 		}
959 		cp += amount;
960 		uva += amount;
961 		len -= amount;
962 	}
963 
964 	close(fd);
965 	return ((ssize_t)(cp - buf));
966 }
967