xref: /dflybsd-src/lib/libkvm/kvm_proc.c (revision 07caec20a93f40352fd28eec40bb9b40199edf40)
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  * $FreeBSD: src/lib/libkvm/kvm_proc.c,v 1.25.2.3 2002/08/24 07:27:46 kris Exp $
38  * $DragonFly: src/lib/libkvm/kvm_proc.c,v 1.8 2006/09/10 01:26:26 dillon Exp $
39  *
40  * @(#)kvm_proc.c	8.3 (Berkeley) 9/23/93
41  */
42 
43 /*
44  * Proc traversal interface for kvm.  ps and w are (probably) the exclusive
45  * users of this code, so we've factored it out into a separate module.
46  * Thus, we keep this grunge out of the other kvm applications (i.e.,
47  * most other applications are interested only in open/close/read/nlist).
48  */
49 
50 #include <sys/user.h>
51 #include <sys/conf.h>
52 #include <sys/param.h>
53 #include <sys/proc.h>
54 #include <sys/exec.h>
55 #include <sys/stat.h>
56 #include <sys/ioctl.h>
57 #include <sys/tty.h>
58 #include <sys/file.h>
59 #include <stdio.h>
60 #include <stdlib.h>
61 #include <unistd.h>
62 #include <nlist.h>
63 #include <kvm.h>
64 
65 #include <vm/vm.h>
66 #include <vm/vm_param.h>
67 #include <vm/swap_pager.h>
68 
69 #include <sys/sysctl.h>
70 
71 #include <limits.h>
72 #include <memory.h>
73 #include <paths.h>
74 
75 #include "kvm_private.h"
76 
77 #if used
78 static char *
79 kvm_readswap(kvm_t *kd, const struct proc *p, u_long va, u_long *cnt)
80 {
81 #if defined(__FreeBSD__) || defined(__DragonFly__)
82 	/* XXX Stubbed out, our vm system is differnet */
83 	_kvm_err(kd, kd->program, "kvm_readswap not implemented");
84 	return(0);
85 #endif
86 }
87 #endif
88 
89 #define KREAD(kd, addr, obj) \
90 	(kvm_read(kd, addr, (char *)(obj), sizeof(*obj)) != sizeof(*obj))
91 
92 /*
93  * Read proc's from memory file into buffer bp, which has space to hold
94  * at most maxcnt procs.
95  */
96 static int
97 kvm_proclist(kvm_t *kd, int what, int arg, struct proc *p,
98 	     struct kinfo_proc *bp, int maxcnt)
99 {
100 	int cnt = 0;
101 	struct eproc eproc;
102 	struct pgrp pgrp;
103 	struct session sess;
104 	struct tty tty;
105 	struct proc proc;
106 	struct thread thread;
107 	struct proc pproc;
108 	struct cdev cdev;
109 
110 	for (; cnt < maxcnt && p != NULL; p = proc.p_list.le_next) {
111 		if (KREAD(kd, (u_long)p, &proc)) {
112 			_kvm_err(kd, kd->program, "can't read proc at %x", p);
113 			return (-1);
114 		}
115 		if (KREAD(kd, (u_long)proc.p_thread, &thread)) {
116 			_kvm_err(kd, kd->program, "can't read thread at %x",
117 			    proc.p_thread);
118 			return (-1);
119 		}
120 		KREAD(kd, (u_long)proc.p_ucred, &eproc.e_ucred);
121 
122 		switch(what) {
123 
124 		case KERN_PROC_PID:
125 			if (proc.p_pid != (pid_t)arg)
126 				continue;
127 			break;
128 
129 		case KERN_PROC_UID:
130 			if (eproc.e_ucred.cr_uid != (uid_t)arg)
131 				continue;
132 			break;
133 
134 		case KERN_PROC_RUID:
135 			if (eproc.e_ucred.cr_ruid != (uid_t)arg)
136 				continue;
137 			break;
138 		}
139 		/*
140 		 * We're going to add another proc to the set.  If this
141 		 * will overflow the buffer, assume the reason is because
142 		 * nprocs (or the proc list) is corrupt and declare an error.
143 		 */
144 		if (cnt >= maxcnt) {
145 			_kvm_err(kd, kd->program, "nprocs corrupt");
146 			return (-1);
147 		}
148 		/*
149 		 * gather eproc
150 		 */
151 		eproc.e_paddr = p;
152 		if (KREAD(kd, (u_long)proc.p_pgrp, &pgrp)) {
153 			_kvm_err(kd, kd->program, "can't read pgrp at %x",
154 				 proc.p_pgrp);
155 			return (-1);
156 		}
157 		if (proc.p_oppid)
158 		  eproc.e_ppid = proc.p_oppid;
159 		else if (proc.p_pptr) {
160 		  if (KREAD(kd, (u_long)proc.p_pptr, &pproc)) {
161 			_kvm_err(kd, kd->program, "can't read pproc at %x",
162 				 proc.p_pptr);
163 			return (-1);
164 		  }
165 		  eproc.e_ppid = pproc.p_pid;
166 		} else
167 		  eproc.e_ppid = 0;
168 		eproc.e_sess = pgrp.pg_session;
169 		eproc.e_pgid = pgrp.pg_id;
170 		eproc.e_jobc = pgrp.pg_jobc;
171 		if (KREAD(kd, (u_long)pgrp.pg_session, &sess)) {
172 			_kvm_err(kd, kd->program, "can't read session at %x",
173 				pgrp.pg_session);
174 			return (-1);
175 		}
176 		(void)memcpy(eproc.e_login, sess.s_login,
177 						sizeof(eproc.e_login));
178 		if ((proc.p_flag & P_CONTROLT) && sess.s_ttyp != NULL) {
179 			if (KREAD(kd, (u_long)sess.s_ttyp, &tty)) {
180 				_kvm_err(kd, kd->program,
181 					 "can't read tty at %x", sess.s_ttyp);
182 				return (-1);
183 			}
184 			if (tty.t_dev && tty.t_dev != NOCDEV) {
185 				if (KREAD(kd, (u_long)tty.t_dev, &cdev)) {
186 					eproc.e_tdev = cdev.si_udev;
187 				} else {
188 					eproc.e_tdev = NODEV;
189 				}
190 			} else {
191 				eproc.e_tdev = NODEV;
192 			}
193 			eproc.e_tsess = tty.t_session;
194 			if (tty.t_pgrp != NULL) {
195 				if (KREAD(kd, (u_long)tty.t_pgrp, &pgrp)) {
196 					_kvm_err(kd, kd->program,
197 						 "can't read tpgrp at %x",
198 						tty.t_pgrp);
199 					return (-1);
200 				}
201 				eproc.e_tpgid = pgrp.pg_id;
202 			} else
203 				eproc.e_tpgid = -1;
204 		} else
205 			eproc.e_tdev = NODEV;
206 		eproc.e_flag = sess.s_ttyvp ? EPROC_CTTY : 0;
207 		if (sess.s_leader == p)
208 			eproc.e_flag |= EPROC_SLEADER;
209 		if (thread.td_wmesg)
210 			(void)kvm_read(kd, (u_long)thread.td_wmesg,
211 			    eproc.e_wmesg, WMESGLEN);
212 
213 #ifdef sparc
214 		(void)kvm_read(kd, (u_long)&proc.p_vmspace->vm_rssize,
215 		    (char *)&eproc.e_vm.vm_rssize,
216 		    sizeof(eproc.e_vm.vm_rssize));
217 		(void)kvm_read(kd, (u_long)&proc.p_vmspace->vm_tsize,
218 		    (char *)&eproc.e_vm.vm_tsize,
219 		    3 * sizeof(eproc.e_vm.vm_rssize));	/* XXX */
220 #else
221 		(void)kvm_read(kd, (u_long)proc.p_vmspace,
222 		    (char *)&eproc.e_vm, sizeof(eproc.e_vm));
223 #endif
224 		eproc.e_xsize = eproc.e_xrssize = 0;
225 		eproc.e_xccount = eproc.e_xswrss = 0;
226 
227 		switch (what) {
228 
229 		case KERN_PROC_PGRP:
230 			if (eproc.e_pgid != (pid_t)arg)
231 				continue;
232 			break;
233 
234 		case KERN_PROC_TTY:
235 			if ((proc.p_flag & P_CONTROLT) == 0 ||
236 			     eproc.e_tdev != (dev_t)arg)
237 				continue;
238 			break;
239 		}
240 		bcopy(&proc, &bp->kp_proc, sizeof(proc));
241 		bcopy(&eproc, &bp->kp_eproc, sizeof(eproc));
242 		++bp;
243 		++cnt;
244 	}
245 	return (cnt);
246 }
247 
248 /*
249  * Build proc info array by reading in proc list from a crash dump.
250  * Return number of procs read.  maxcnt is the max we will read.
251  */
252 static int
253 kvm_deadprocs(kvm_t *kd, int what, int arg, u_long a_allproc,
254 	      u_long a_zombproc, int maxcnt)
255 {
256 	struct kinfo_proc *bp = kd->procbase;
257 	int acnt, zcnt;
258 	struct proc *p;
259 
260 	if (KREAD(kd, a_allproc, &p)) {
261 		_kvm_err(kd, kd->program, "cannot read allproc");
262 		return (-1);
263 	}
264 	acnt = kvm_proclist(kd, what, arg, p, bp, maxcnt);
265 	if (acnt < 0)
266 		return (acnt);
267 
268 	if (KREAD(kd, a_zombproc, &p)) {
269 		_kvm_err(kd, kd->program, "cannot read zombproc");
270 		return (-1);
271 	}
272 	zcnt = kvm_proclist(kd, what, arg, p, bp + acnt, maxcnt - acnt);
273 	if (zcnt < 0)
274 		zcnt = 0;
275 
276 	return (acnt + zcnt);
277 }
278 
279 struct kinfo_proc *
280 kvm_getprocs(kvm_t *kd, int op, int arg, int *cnt)
281 {
282 	int mib[4], st, nprocs;
283 	size_t size;
284 
285 	if (kd->procbase != 0) {
286 		free((void *)kd->procbase);
287 		/*
288 		 * Clear this pointer in case this call fails.  Otherwise,
289 		 * kvm_close() will free it again.
290 		 */
291 		kd->procbase = 0;
292 	}
293 	if (ISALIVE(kd)) {
294 		size = 0;
295 		mib[0] = CTL_KERN;
296 		mib[1] = KERN_PROC;
297 		mib[2] = op;
298 		mib[3] = arg;
299 		st = sysctl(mib, op == KERN_PROC_ALL ? 3 : 4, NULL, &size, NULL, 0);
300 		if (st == -1) {
301 			_kvm_syserr(kd, kd->program, "kvm_getprocs");
302 			return (0);
303 		}
304 		do {
305 			size += size / 10;
306 			kd->procbase = (struct kinfo_proc *)
307 			    _kvm_realloc(kd, kd->procbase, size);
308 			if (kd->procbase == 0)
309 				return (0);
310 			st = sysctl(mib, op == KERN_PROC_ALL ? 3 : 4,
311 			    kd->procbase, &size, NULL, 0);
312 		} while (st == -1 && errno == ENOMEM);
313 		if (st == -1) {
314 			_kvm_syserr(kd, kd->program, "kvm_getprocs");
315 			return (0);
316 		}
317 		if (size % sizeof(struct kinfo_proc) != 0) {
318 			_kvm_err(kd, kd->program,
319 				"proc size mismatch (%d total, %d chunks)",
320 				size, sizeof(struct kinfo_proc));
321 			return (0);
322 		}
323 		nprocs = size / sizeof(struct kinfo_proc);
324 	} else {
325 		struct nlist nl[4], *p;
326 
327 		nl[0].n_name = "_nprocs";
328 		nl[1].n_name = "_allproc";
329 		nl[2].n_name = "_zombproc";
330 		nl[3].n_name = 0;
331 
332 		if (kvm_nlist(kd, nl) != 0) {
333 			for (p = nl; p->n_type != 0; ++p)
334 				;
335 			_kvm_err(kd, kd->program,
336 				 "%s: no such symbol", p->n_name);
337 			return (0);
338 		}
339 		if (KREAD(kd, nl[0].n_value, &nprocs)) {
340 			_kvm_err(kd, kd->program, "can't read nprocs");
341 			return (0);
342 		}
343 		size = nprocs * sizeof(struct kinfo_proc);
344 		kd->procbase = (struct kinfo_proc *)_kvm_malloc(kd, size);
345 		if (kd->procbase == 0)
346 			return (0);
347 
348 		nprocs = kvm_deadprocs(kd, op, arg, nl[1].n_value,
349 				      nl[2].n_value, nprocs);
350 #ifdef notdef
351 		size = nprocs * sizeof(struct kinfo_proc);
352 		(void)realloc(kd->procbase, size);
353 #endif
354 	}
355 	*cnt = nprocs;
356 	return (kd->procbase);
357 }
358 
359 void
360 _kvm_freeprocs(kvm_t *kd)
361 {
362 	if (kd->procbase) {
363 		free(kd->procbase);
364 		kd->procbase = 0;
365 	}
366 }
367 
368 void *
369 _kvm_realloc(kvm_t *kd, void *p, size_t n)
370 {
371 	void *np = (void *)realloc(p, n);
372 
373 	if (np == 0) {
374 		free(p);
375 		_kvm_err(kd, kd->program, "out of memory");
376 	}
377 	return (np);
378 }
379 
380 #ifndef MAX
381 #define MAX(a, b) ((a) > (b) ? (a) : (b))
382 #endif
383 
384 /*
385  * Read in an argument vector from the user address space of process p.
386  * addr if the user-space base address of narg null-terminated contiguous
387  * strings.  This is used to read in both the command arguments and
388  * environment strings.  Read at most maxcnt characters of strings.
389  */
390 static char **
391 kvm_argv(kvm_t *kd, const struct proc *p, u_long addr, int narg, int maxcnt)
392 {
393 	char *np, *cp, *ep, *ap;
394 	u_long oaddr = -1;
395 	int len, cc;
396 	char **argv;
397 
398 	/*
399 	 * Check that there aren't an unreasonable number of agruments,
400 	 * and that the address is in user space.
401 	 */
402 	if (narg > 512 || addr < VM_MIN_ADDRESS || addr >= VM_MAXUSER_ADDRESS)
403 		return (0);
404 
405 	/*
406 	 * kd->argv : work space for fetching the strings from the target
407 	 *            process's space, and is converted for returning to caller
408 	 */
409 	if (kd->argv == 0) {
410 		/*
411 		 * Try to avoid reallocs.
412 		 */
413 		kd->argc = MAX(narg + 1, 32);
414 		kd->argv = (char **)_kvm_malloc(kd, kd->argc *
415 						sizeof(*kd->argv));
416 		if (kd->argv == 0)
417 			return (0);
418 	} else if (narg + 1 > kd->argc) {
419 		kd->argc = MAX(2 * kd->argc, narg + 1);
420 		kd->argv = (char **)_kvm_realloc(kd, kd->argv, kd->argc *
421 						sizeof(*kd->argv));
422 		if (kd->argv == 0)
423 			return (0);
424 	}
425 	/*
426 	 * kd->argspc : returned to user, this is where the kd->argv
427 	 *              arrays are left pointing to the collected strings.
428 	 */
429 	if (kd->argspc == 0) {
430 		kd->argspc = (char *)_kvm_malloc(kd, PAGE_SIZE);
431 		if (kd->argspc == 0)
432 			return (0);
433 		kd->arglen = PAGE_SIZE;
434 	}
435 	/*
436 	 * kd->argbuf : used to pull in pages from the target process.
437 	 *              the strings are copied out of here.
438 	 */
439 	if (kd->argbuf == 0) {
440 		kd->argbuf = (char *)_kvm_malloc(kd, PAGE_SIZE);
441 		if (kd->argbuf == 0)
442 			return (0);
443 	}
444 
445 	/* Pull in the target process'es argv vector */
446 	cc = sizeof(char *) * narg;
447 	if (kvm_uread(kd, p, addr, (char *)kd->argv, cc) != cc)
448 		return (0);
449 	/*
450 	 * ap : saved start address of string we're working on in kd->argspc
451 	 * np : pointer to next place to write in kd->argspc
452 	 * len: length of data in kd->argspc
453 	 * argv: pointer to the argv vector that we are hunting around the
454 	 *       target process space for, and converting to addresses in
455 	 *       our address space (kd->argspc).
456 	 */
457 	ap = np = kd->argspc;
458 	argv = kd->argv;
459 	len = 0;
460 	/*
461 	 * Loop over pages, filling in the argument vector.
462 	 * Note that the argv strings could be pointing *anywhere* in
463 	 * the user address space and are no longer contiguous.
464 	 * Note that *argv is modified when we are going to fetch a string
465 	 * that crosses a page boundary.  We copy the next part of the string
466 	 * into to "np" and eventually convert the pointer.
467 	 */
468 	while (argv < kd->argv + narg && *argv != 0) {
469 
470 		/* get the address that the current argv string is on */
471 		addr = (u_long)*argv & ~(PAGE_SIZE - 1);
472 
473 		/* is it the same page as the last one? */
474 		if (addr != oaddr) {
475 			if (kvm_uread(kd, p, addr, kd->argbuf, PAGE_SIZE) !=
476 			    PAGE_SIZE)
477 				return (0);
478 			oaddr = addr;
479 		}
480 
481 		/* offset within the page... kd->argbuf */
482 		addr = (u_long)*argv & (PAGE_SIZE - 1);
483 
484 		/* cp = start of string, cc = count of chars in this chunk */
485 		cp = kd->argbuf + addr;
486 		cc = PAGE_SIZE - addr;
487 
488 		/* dont get more than asked for by user process */
489 		if (maxcnt > 0 && cc > maxcnt - len)
490 			cc = maxcnt - len;
491 
492 		/* pointer to end of string if we found it in this page */
493 		ep = memchr(cp, '\0', cc);
494 		if (ep != 0)
495 			cc = ep - cp + 1;
496 		/*
497 		 * at this point, cc is the count of the chars that we are
498 		 * going to retrieve this time. we may or may not have found
499 		 * the end of it.  (ep points to the null if the end is known)
500 		 */
501 
502 		/* will we exceed the malloc/realloced buffer? */
503 		if (len + cc > kd->arglen) {
504 			int off;
505 			char **pp;
506 			char *op = kd->argspc;
507 
508 			kd->arglen *= 2;
509 			kd->argspc = (char *)_kvm_realloc(kd, kd->argspc,
510 							  kd->arglen);
511 			if (kd->argspc == 0)
512 				return (0);
513 			/*
514 			 * Adjust argv pointers in case realloc moved
515 			 * the string space.
516 			 */
517 			off = kd->argspc - op;
518 			for (pp = kd->argv; pp < argv; pp++)
519 				*pp += off;
520 			ap += off;
521 			np += off;
522 		}
523 		/* np = where to put the next part of the string in kd->argspc*/
524 		/* np is kinda redundant.. could use "kd->argspc + len" */
525 		memcpy(np, cp, cc);
526 		np += cc;	/* inc counters */
527 		len += cc;
528 
529 		/*
530 		 * if end of string found, set the *argv pointer to the
531 		 * saved beginning of string, and advance. argv points to
532 		 * somewhere in kd->argv..  This is initially relative
533 		 * to the target process, but when we close it off, we set
534 		 * it to point in our address space.
535 		 */
536 		if (ep != 0) {
537 			*argv++ = ap;
538 			ap = np;
539 		} else {
540 			/* update the address relative to the target process */
541 			*argv += cc;
542 		}
543 
544 		if (maxcnt > 0 && len >= maxcnt) {
545 			/*
546 			 * We're stopping prematurely.  Terminate the
547 			 * current string.
548 			 */
549 			if (ep == 0) {
550 				*np = '\0';
551 				*argv++ = ap;
552 			}
553 			break;
554 		}
555 	}
556 	/* Make sure argv is terminated. */
557 	*argv = 0;
558 	return (kd->argv);
559 }
560 
561 static void
562 ps_str_a(struct ps_strings *p, u_long *addr, int *n)
563 {
564 	*addr = (u_long)p->ps_argvstr;
565 	*n = p->ps_nargvstr;
566 }
567 
568 static void
569 ps_str_e(struct ps_strings *p, u_long *addr, int *n)
570 {
571 	*addr = (u_long)p->ps_envstr;
572 	*n = p->ps_nenvstr;
573 }
574 
575 /*
576  * Determine if the proc indicated by p is still active.
577  * This test is not 100% foolproof in theory, but chances of
578  * being wrong are very low.
579  */
580 static int
581 proc_verify(kvm_t *kd, u_long kernp, const struct proc *p)
582 {
583 	struct kinfo_proc kp;
584 	int mib[4];
585 	size_t len;
586 
587 	mib[0] = CTL_KERN;
588 	mib[1] = KERN_PROC;
589 	mib[2] = KERN_PROC_PID;
590 	mib[3] = p->p_pid;
591 	len = sizeof(kp);
592 	if (sysctl(mib, 4, &kp, &len, NULL, 0) == -1)
593 		return (0);
594 	return (p->p_pid == kp.kp_proc.p_pid &&
595 	    (kp.kp_proc.p_stat != SZOMB || p->p_stat == SZOMB));
596 }
597 
598 static char **
599 kvm_doargv(kvm_t *kd, const struct kinfo_proc *kp, int nchr,
600 	   void (*info)(struct ps_strings *, u_long *, int *))
601 {
602 	const struct proc *p = &kp->kp_proc;
603 	char **ap;
604 	u_long addr;
605 	int cnt;
606 	static struct ps_strings arginfo;
607 	static u_long ps_strings;
608 	size_t len;
609 
610 	if (ps_strings == NULL) {
611 		len = sizeof(ps_strings);
612 		if (sysctlbyname("kern.ps_strings", &ps_strings, &len, NULL,
613 		    0) == -1)
614 			ps_strings = PS_STRINGS;
615 	}
616 
617 	/*
618 	 * Pointers are stored at the top of the user stack.
619 	 */
620 	if (p->p_stat == SZOMB ||
621 	    kvm_uread(kd, p, ps_strings, (char *)&arginfo,
622 		      sizeof(arginfo)) != sizeof(arginfo))
623 		return (0);
624 
625 	(*info)(&arginfo, &addr, &cnt);
626 	if (cnt == 0)
627 		return (0);
628 	ap = kvm_argv(kd, p, addr, cnt, nchr);
629 	/*
630 	 * For live kernels, make sure this process didn't go away.
631 	 */
632 	if (ap != 0 && ISALIVE(kd) &&
633 	    !proc_verify(kd, (u_long)kp->kp_eproc.e_paddr, p))
634 		ap = 0;
635 	return (ap);
636 }
637 
638 /*
639  * Get the command args.  This code is now machine independent.
640  */
641 char **
642 kvm_getargv(kvm_t *kd, const struct kinfo_proc *kp, int nchr)
643 {
644 	int oid[4];
645 	int i;
646 	size_t bufsz;
647 	static unsigned long buflen;
648 	static char *buf, *p;
649 	static char **bufp;
650 	static int argc;
651 
652 	if (!ISALIVE(kd)) {
653 		_kvm_err(kd, kd->program,
654 		    "cannot read user space from dead kernel");
655 		return (0);
656 	}
657 
658 	if (!buflen) {
659 		bufsz = sizeof(buflen);
660 		i = sysctlbyname("kern.ps_arg_cache_limit",
661 		    &buflen, &bufsz, NULL, 0);
662 		if (i == -1) {
663 			buflen = 0;
664 		} else {
665 			buf = malloc(buflen);
666 			if (buf == NULL)
667 				buflen = 0;
668 			argc = 32;
669 			bufp = malloc(sizeof(char *) * argc);
670 		}
671 	}
672 	if (buf != NULL) {
673 		oid[0] = CTL_KERN;
674 		oid[1] = KERN_PROC;
675 		oid[2] = KERN_PROC_ARGS;
676 		oid[3] = kp->kp_proc.p_pid;
677 		bufsz = buflen;
678 		i = sysctl(oid, 4, buf, &bufsz, 0, 0);
679 		if (i == 0 && bufsz > 0) {
680 			i = 0;
681 			p = buf;
682 			do {
683 				bufp[i++] = p;
684 				p += strlen(p) + 1;
685 				if (i >= argc) {
686 					argc += argc;
687 					bufp = realloc(bufp,
688 					    sizeof(char *) * argc);
689 				}
690 			} while (p < buf + bufsz);
691 			bufp[i++] = 0;
692 			return (bufp);
693 		}
694 	}
695 	if (kp->kp_proc.p_flag & P_SYSTEM)
696 		return (NULL);
697 	return (kvm_doargv(kd, kp, nchr, ps_str_a));
698 }
699 
700 char **
701 kvm_getenvv(kvm_t *kd, const struct kinfo_proc *kp, int nchr)
702 {
703 	return (kvm_doargv(kd, kp, nchr, ps_str_e));
704 }
705 
706 /*
707  * Read from user space.  The user context is given by p.
708  */
709 ssize_t
710 kvm_uread(kvm_t *kd, const struct proc *p, u_long uva, char *buf, size_t len)
711 {
712 	char *cp;
713 	char procfile[MAXPATHLEN];
714 	ssize_t amount;
715 	int fd;
716 
717 	if (!ISALIVE(kd)) {
718 		_kvm_err(kd, kd->program,
719 		    "cannot read user space from dead kernel");
720 		return (0);
721 	}
722 
723 	sprintf(procfile, "/proc/%d/mem", p->p_pid);
724 	fd = open(procfile, O_RDONLY, 0);
725 	if (fd < 0) {
726 		_kvm_err(kd, kd->program, "cannot open %s", procfile);
727 		close(fd);
728 		return (0);
729 	}
730 
731 	cp = buf;
732 	while (len > 0) {
733 		errno = 0;
734 		if (lseek(fd, (off_t)uva, 0) == -1 && errno != 0) {
735 			_kvm_err(kd, kd->program, "invalid address (%x) in %s",
736 			    uva, procfile);
737 			break;
738 		}
739 		amount = read(fd, cp, len);
740 		if (amount < 0) {
741 			_kvm_syserr(kd, kd->program, "error reading %s",
742 			    procfile);
743 			break;
744 		}
745 		if (amount == 0) {
746 			_kvm_err(kd, kd->program, "EOF reading %s", procfile);
747 			break;
748 		}
749 		cp += amount;
750 		uva += amount;
751 		len -= amount;
752 	}
753 
754 	close(fd);
755 	return ((ssize_t)(cp - buf));
756 }
757