xref: /netbsd-src/sbin/savecore/savecore.c (revision fdecd6a253f999ae92b139670d9e15cc9df4497c)
1 /*	$NetBSD: savecore.c,v 1.30 1997/05/19 16:28:03 pk Exp $	*/
2 
3 /*-
4  * Copyright (c) 1986, 1992, 1993
5  *	The Regents of the University of California.  All rights reserved.
6  *
7  * Redistribution and use in source and binary forms, with or without
8  * modification, are permitted provided that the following conditions
9  * are met:
10  * 1. Redistributions of source code must retain the above copyright
11  *    notice, this list of conditions and the following disclaimer.
12  * 2. Redistributions in binary form must reproduce the above copyright
13  *    notice, this list of conditions and the following disclaimer in the
14  *    documentation and/or other materials provided with the distribution.
15  * 3. All advertising materials mentioning features or use of this software
16  *    must display the following acknowledgement:
17  *	This product includes software developed by the University of
18  *	California, Berkeley and its contributors.
19  * 4. Neither the name of the University nor the names of its contributors
20  *    may be used to endorse or promote products derived from this software
21  *    without specific prior written permission.
22  *
23  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
24  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
25  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
26  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
27  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
28  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
29  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
30  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
31  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
32  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
33  * SUCH DAMAGE.
34  */
35 
36 #ifndef lint
37 static char copyright[] =
38 "@(#) Copyright (c) 1986, 1992, 1993\n\
39 	The Regents of the University of California.  All rights reserved.\n";
40 #endif /* not lint */
41 
42 #ifndef lint
43 #if 0
44 static char sccsid[] = "@(#)savecore.c	8.3 (Berkeley) 1/2/94";
45 #else
46 static char rcsid[] = "$NetBSD: savecore.c,v 1.30 1997/05/19 16:28:03 pk Exp $";
47 #endif
48 #endif /* not lint */
49 
50 #include <sys/param.h>
51 #include <sys/stat.h>
52 #include <sys/mount.h>
53 #include <sys/syslog.h>
54 #include <sys/time.h>
55 
56 #include <dirent.h>
57 #include <errno.h>
58 #include <fcntl.h>
59 #include <nlist.h>
60 #include <paths.h>
61 #include <stdio.h>
62 #include <stdlib.h>
63 #include <string.h>
64 #include <tzfile.h>
65 #include <unistd.h>
66 #include <limits.h>
67 #include <kvm.h>
68 
69 extern FILE *zopen __P((const char *fname, const char *mode, int bits));
70 
71 #define KREAD(kd, addr, p)\
72 	(kvm_read(kd, addr, (char *)(p), sizeof(*(p))) != sizeof(*(p)))
73 
74 struct nlist current_nl[] = {	/* Namelist for currently running system. */
75 #define X_DUMPDEV	0
76 	{ "_dumpdev" },
77 #define X_DUMPLO	1
78 	{ "_dumplo" },
79 #define X_TIME		2
80 	{ "_time" },
81 #define	X_DUMPSIZE	3
82 	{ "_dumpsize" },
83 #define X_VERSION	4
84 	{ "_version" },
85 #define X_PANICSTR	5
86 	{ "_panicstr" },
87 #define	X_DUMPMAG	6
88 	{ "_dumpmag" },
89 	{ NULL },
90 };
91 int cursyms[] = { X_DUMPDEV, X_DUMPLO, X_VERSION, X_DUMPMAG, -1 };
92 int dumpsyms[] = { X_TIME, X_DUMPSIZE, X_VERSION, X_PANICSTR, X_DUMPMAG, -1 };
93 
94 struct nlist dump_nl[] = {	/* Name list for dumped system. */
95 	{ "_dumpdev" },		/* Entries MUST be the same as */
96 	{ "_dumplo" },		/*	those in current_nl[].  */
97 	{ "_time" },
98 	{ "_dumpsize" },
99 	{ "_version" },
100 	{ "_panicstr" },
101 	{ "_dumpmag" },
102 	{ NULL },
103 };
104 
105 /* Types match kernel declarations. */
106 long	dumplo;				/* where dump starts on dumpdev */
107 int	dumpmag;			/* magic number in dump */
108 int	dumpsize;			/* amount of memory dumped */
109 
110 char	*kernel;
111 char	*dirname;			/* directory to save dumps in */
112 char	*ddname;			/* name of dump device */
113 dev_t	dumpdev;			/* dump device */
114 int	dumpfd;				/* read/write descriptor on block dev */
115 kvm_t	*kd_dump;			/* kvm descriptor on block dev	*/
116 time_t	now;				/* current date */
117 char	panic_mesg[1024];
118 long	panicstr;
119 char	vers[1024];
120 
121 int	clear, compress, force, verbose;	/* flags */
122 
123 void	 check_kmem __P((void));
124 int	 check_space __P((void));
125 void	 clear_dump __P((void));
126 int	 Create __P((char *, int));
127 int	 dump_exists __P((void));
128 char	*find_dev __P((dev_t, int));
129 int	 get_crashtime __P((void));
130 void	 kmem_setup __P((void));
131 void	 log __P((int, char *, ...));
132 void	 Lseek __P((int, off_t, int));
133 int	 Open __P((char *, int rw));
134 char	*rawname __P((char *s));
135 void	 save_core __P((void));
136 void	 usage __P((void));
137 void	 Write __P((int, void *, int));
138 
139 int
140 main(argc, argv)
141 	int argc;
142 	char *argv[];
143 {
144 	int ch;
145 
146 	openlog("savecore", LOG_PERROR, LOG_DAEMON);
147 
148 	while ((ch = getopt(argc, argv, "cdfN:vz")) != -1)
149 		switch(ch) {
150 		case 'c':
151 			clear = 1;
152 			break;
153 		case 'd':		/* Not documented. */
154 		case 'v':
155 			verbose = 1;
156 			break;
157 		case 'f':
158 			force = 1;
159 			break;
160 		case 'N':
161 			kernel = optarg;
162 			break;
163 		case 'z':
164 			compress = 1;
165 			break;
166 		case '?':
167 		default:
168 			usage();
169 		}
170 	argc -= optind;
171 	argv += optind;
172 
173 	if (!clear) {
174 		if (argc != 1 && argc != 2)
175 			usage();
176 		dirname = argv[0];
177 	}
178 	if (argc == 2)
179 		kernel = argv[1];
180 
181 	(void)time(&now);
182 	kmem_setup();
183 
184 	if (clear) {
185 		clear_dump();
186 		exit(0);
187 	}
188 
189 	if (!dump_exists() && !force)
190 		exit(1);
191 
192 	check_kmem();
193 
194 	if (panicstr)
195 		syslog(LOG_ALERT, "reboot after panic: %s", panic_mesg);
196 	else
197 		syslog(LOG_ALERT, "reboot");
198 
199 	if ((!get_crashtime() || !check_space()) && !force)
200 		exit(1);
201 
202 	save_core();
203 
204 	clear_dump();
205 	exit(0);
206 }
207 
208 void
209 kmem_setup()
210 {
211 	kvm_t	*kd_kern;
212 	char	errbuf[_POSIX2_LINE_MAX];
213 	int	i, hdrsz;
214 	char	*dump_sys;
215 
216 	/*
217 	 * Some names we need for the currently running system, others for
218 	 * the system that was running when the dump was made.  The values
219 	 * obtained from the current system are used to look for things in
220 	 * /dev/kmem that cannot be found in the dump_sys namelist, but are
221 	 * presumed to be the same (since the disk partitions are probably
222 	 * the same!)
223 	 */
224 	kd_kern = kvm_openfiles(NULL, NULL, NULL, O_RDONLY, errbuf);
225 	if (kd_kern == NULL) {
226 		syslog(LOG_ERR, "%s: kvm_openfiles: %s", _PATH_UNIX, errbuf);
227 		exit(1);
228 	}
229 	if (kvm_nlist(kd_kern, current_nl) == -1)
230 		syslog(LOG_ERR, "%s: kvm_nlist: %s", _PATH_UNIX,
231 			kvm_geterr(kd_kern));
232 
233 	for (i = 0; cursyms[i] != -1; i++)
234 		if (current_nl[cursyms[i]].n_value == 0) {
235 			syslog(LOG_ERR, "%s: %s not in namelist",
236 			    _PATH_UNIX, current_nl[cursyms[i]].n_name);
237 			exit(1);
238 		}
239 
240 	if (KREAD(kd_kern, current_nl[X_DUMPDEV].n_value, &dumpdev) != 0) {
241 		if (verbose)
242 		    syslog(LOG_WARNING, "kvm_read: %s", kvm_geterr(kd_kern));
243 		exit(1);
244 	}
245 	if (dumpdev == NODEV) {
246 		syslog(LOG_WARNING, "no core dump (no dumpdev)");
247 		exit(1);
248 	}
249 	if (KREAD(kd_kern, current_nl[X_DUMPLO].n_value, &dumplo) != 0) {
250 		if (verbose)
251 		    syslog(LOG_WARNING, "kvm_read: %s", kvm_geterr(kd_kern));
252 		exit(1);
253 	}
254 	dumplo *= DEV_BSIZE;
255 	if (verbose)
256 		(void)printf("dumplo = %d (%d * %d)\n",
257 		    dumplo, dumplo / DEV_BSIZE, DEV_BSIZE);
258 	if (KREAD(kd_kern, current_nl[X_DUMPMAG].n_value, &dumpmag) != 0) {
259 		if (verbose)
260 		    syslog(LOG_WARNING, "kvm_read: %s", kvm_geterr(kd_kern));
261 		exit(1);
262 	}
263 
264 	if (kernel == NULL) {
265 		(void)kvm_read(kd_kern, current_nl[X_VERSION].n_value,
266 			vers, sizeof(vers));
267 		vers[sizeof(vers) - 1] = '\0';
268 	}
269 
270 	ddname = find_dev(dumpdev, S_IFBLK);
271 	dumpfd = Open(ddname, O_RDWR);
272 
273 	dump_sys = kernel ? kernel : _PATH_UNIX;
274 
275 	kd_dump = kvm_openfiles(dump_sys, ddname, NULL, O_RDWR, errbuf);
276 	if (kd_dump == NULL) {
277 		syslog(LOG_ERR, "%s: kvm_openfiles: %s", dump_sys, errbuf);
278 		exit(1);
279 	}
280 
281 	if (kvm_nlist(kd_dump, dump_nl) == -1)
282 		syslog(LOG_ERR, "%s: kvm_nlist: %s", dump_sys,
283 			kvm_geterr(kd_dump));
284 
285 	for (i = 0; dumpsyms[i] != -1; i++)
286 		if (dump_nl[dumpsyms[i]].n_value == 0) {
287 			syslog(LOG_ERR, "%s: %s not in namelist",
288 			    dump_sys, dump_nl[dumpsyms[i]].n_name);
289 			exit(1);
290 		}
291 	hdrsz = kvm_dump_mkheader(kd_dump, (off_t)dumplo);
292 
293 	/*
294 	 * If 'hdrsz' == 0, kvm_dump_mkheader() failed on the magic-number
295 	 * checks, ergo no dump is present...
296 	 */
297 	if (hdrsz == 0) {
298 		syslog(LOG_WARNING, "no core dump");
299 		exit(1);
300 	}
301 	if (hdrsz == -1) {
302 		syslog(LOG_ERR, "%s: kvm_dump_mkheader: %s", dump_sys,
303 			kvm_geterr(kd_dump));
304 		exit(1);
305 	}
306 	dumplo += hdrsz;
307 	kvm_close(kd_kern);
308 }
309 
310 void
311 check_kmem()
312 {
313 	register char	*cp;
314 	register long	panicloc;
315 	char core_vers[1024];
316 
317 	(void)kvm_read(kd_dump, dump_nl[X_VERSION].n_value, core_vers,
318 		sizeof(core_vers));
319 	core_vers[sizeof(core_vers) - 1] = '\0';
320 
321 	if (strcmp(vers, core_vers) && kernel == 0)
322 		syslog(LOG_WARNING,
323 		    "warning: %s version mismatch:\n\t%s\nand\t%s\n",
324 		    _PATH_UNIX, vers, core_vers);
325 
326 	if (KREAD(kd_dump, dump_nl[X_PANICSTR].n_value, &panicstr) != 0) {
327 		if (verbose)
328 		    syslog(LOG_WARNING, "kvm_read: %s", kvm_geterr(kd_dump));
329 		return;
330 	}
331 	if (panicstr) {
332 		cp       = panic_mesg;
333 		panicloc = panicstr;
334 		do {
335 			if (KREAD(kd_dump, panicloc, cp) != 0) {
336 				if (verbose)
337 				    syslog(LOG_WARNING, "kvm_read: %s",
338 					   kvm_geterr(kd_dump));
339 				break;
340 			}
341 			panicloc++;
342 		} while (*cp++ && cp < &panic_mesg[sizeof(panic_mesg)-1]);
343 		panic_mesg[sizeof(panic_mesg) - 1] = '\0';
344 	}
345 }
346 
347 int
348 dump_exists()
349 {
350 	int newdumpmag;
351 
352 	if (KREAD(kd_dump, dump_nl[X_DUMPMAG].n_value, &newdumpmag) != 0) {
353 		if (verbose)
354 		    syslog(LOG_WARNING, "kvm_read: %s", kvm_geterr(kd_dump));
355 		return (0);
356 	}
357 
358 	/* Read the dump size. */
359 	if (KREAD(kd_dump, dump_nl[X_DUMPSIZE].n_value, &dumpsize) != 0) {
360 		if (verbose)
361 		    syslog(LOG_WARNING, "kvm_read: %s", kvm_geterr(kd_dump));
362 		return (0);
363 	}
364 	dumpsize *= getpagesize();
365 
366 	/*
367 	 * Return zero if core dump doesn't seem to be there, and note
368 	 * it for syslog.  This check and return happens after the dump size
369 	 * is read, so dumpsize is whether or not the core is valid (for -f).
370 	 */
371 	if (newdumpmag != dumpmag) {
372 		if (verbose)
373 			syslog(LOG_WARNING, "magic number mismatch (%x != %x)",
374 			    newdumpmag, dumpmag);
375 		syslog(LOG_WARNING, "no core dump");
376 		return (0);
377 	}
378 	return (1);
379 }
380 
381 void
382 clear_dump()
383 {
384 	if (kvm_dump_inval(kd_dump) == -1)
385 		syslog(LOG_ERR, "%s: kvm_clear_dump: %s", ddname,
386 			kvm_geterr(kd_dump));
387 
388 }
389 
390 char buf[1024 * 1024];
391 
392 void
393 save_core()
394 {
395 	register FILE *fp;
396 	register int bounds, ifd, nr, nw, ofd;
397 	char *rawp, path[MAXPATHLEN];
398 
399 	/*
400 	 * Get the current number and update the bounds file.  Do the update
401 	 * now, because may fail later and don't want to overwrite anything.
402 	 */
403 	umask(002);
404 	(void)snprintf(path, sizeof(path), "%s/bounds", dirname);
405 	if ((fp = fopen(path, "r")) == NULL)
406 		goto err1;
407 	if (fgets(buf, sizeof(buf), fp) == NULL) {
408 		if (ferror(fp))
409 err1:			syslog(LOG_WARNING, "%s: %s", path, strerror(errno));
410 		bounds = 0;
411 	} else
412 		bounds = atoi(buf);
413 	if (fp != NULL)
414 		(void)fclose(fp);
415 	if ((fp = fopen(path, "w")) == NULL)
416 		syslog(LOG_ERR, "%s: %m", path);
417 	else {
418 		(void)fprintf(fp, "%d\n", bounds + 1);
419 		(void)fclose(fp);
420 	}
421 	(void)fclose(fp);
422 
423 	/* Create the core file. */
424 	(void)snprintf(path, sizeof(path), "%s/netbsd.%d.core%s",
425 	    dirname, bounds, compress ? ".Z" : "");
426 	if (compress) {
427 		if ((fp = zopen(path, "w", 0)) == NULL) {
428 			syslog(LOG_ERR, "%s: %s", path, strerror(errno));
429 			exit(1);
430 		}
431 	} else {
432 		ofd = Create(path, S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH);
433 		fp  = fdopen(ofd, "w");
434 		if (fp == NULL) {
435 			syslog(LOG_ERR, "%s: fdopen: %s", path);
436 			exit(1);
437 		}
438 	}
439 
440 	/* Open the raw device. */
441 	rawp = rawname(ddname);
442 	if ((ifd = open(rawp, O_RDONLY)) == -1) {
443 		syslog(LOG_WARNING, "%s: %m; using block device", rawp);
444 		ifd = dumpfd;
445 	}
446 
447 	/* Seek to the start of the core. */
448 	Lseek(ifd, (off_t)dumplo, L_SET);
449 
450 	if (kvm_dump_wrtheader(kd_dump, fp, dumpsize) == -1) {
451 		syslog(LOG_ERR, "kvm_dump_wrtheader: %s : %s", path,
452 			kvm_geterr(kd_dump));
453 		exit(1);
454 	}
455 
456 	/* Copy the core file. */
457 	syslog(LOG_NOTICE, "writing %score to %s",
458 	    compress ? "compressed " : "", path);
459 	for (; dumpsize > 0; dumpsize -= nr) {
460 		(void)printf("%6dK\r", dumpsize / 1024);
461 		(void)fflush(stdout);
462 		nr = read(ifd, buf, MIN(dumpsize, sizeof(buf)));
463 		if (nr <= 0) {
464 			if (nr == 0)
465 				syslog(LOG_WARNING,
466 				    "WARNING: EOF on dump device");
467 			else
468 				syslog(LOG_ERR, "%s: %m", rawp);
469 			goto err2;
470 		}
471 		nw = fwrite(buf, 1, nr, fp);
472 		if (nw != nr) {
473 			syslog(LOG_ERR, "%s: %s",
474 			    path, strerror(nw == 0 ? EIO : errno));
475 err2:			syslog(LOG_WARNING,
476 			    "WARNING: core may be incomplete");
477 			(void)printf("\n");
478 			exit(1);
479 		}
480 	}
481 	(void)close(ifd);
482 	(void)fclose(fp);
483 
484 	/* Copy the kernel. */
485 	ifd = Open(kernel ? kernel : _PATH_UNIX, O_RDONLY);
486 	(void)snprintf(path, sizeof(path), "%s/netbsd.%d%s",
487 	    dirname, bounds, compress ? ".Z" : "");
488 	if (compress) {
489 		if ((fp = zopen(path, "w", 0)) == NULL) {
490 			syslog(LOG_ERR, "%s: %s", path, strerror(errno));
491 			exit(1);
492 		}
493 	} else
494 		ofd = Create(path, S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH);
495 	syslog(LOG_NOTICE, "writing %skernel to %s",
496 	    compress ? "compressed " : "", path);
497 	while ((nr = read(ifd, buf, sizeof(buf))) > 0) {
498 		if (compress)
499 			nw = fwrite(buf, 1, nr, fp);
500 		else
501 			nw = write(ofd, buf, nr);
502 		if (nw != nr) {
503 			syslog(LOG_ERR, "%s: %s",
504 			    path, strerror(nw == 0 ? EIO : errno));
505 			syslog(LOG_WARNING,
506 			    "WARNING: kernel may be incomplete");
507 			exit(1);
508 		}
509 	}
510 	if (nr < 0) {
511 		syslog(LOG_ERR, "%s: %s",
512 		    kernel ? kernel : _PATH_UNIX, strerror(errno));
513 		syslog(LOG_WARNING,
514 		    "WARNING: kernel may be incomplete");
515 		exit(1);
516 	}
517 	if (compress)
518 		(void)fclose(fp);
519 	else
520 		(void)close(ofd);
521 }
522 
523 char *
524 find_dev(dev, type)
525 	register dev_t dev;
526 	register int type;
527 {
528 	register DIR *dfd;
529 	struct dirent *dir;
530 	struct stat sb;
531 	char *dp, devname[MAXPATHLEN + 1];
532 
533 	if ((dfd = opendir(_PATH_DEV)) == NULL) {
534 		syslog(LOG_ERR, "%s: %s", _PATH_DEV, strerror(errno));
535 		exit(1);
536 	}
537 	(void)strcpy(devname, _PATH_DEV);
538 	while ((dir = readdir(dfd))) {
539 		(void)strcpy(devname + sizeof(_PATH_DEV) - 1, dir->d_name);
540 		if (lstat(devname, &sb)) {
541 			syslog(LOG_ERR, "%s: %s", devname, strerror(errno));
542 			continue;
543 		}
544 		if ((sb.st_mode & S_IFMT) != type)
545 			continue;
546 		if (dev == sb.st_rdev) {
547 			closedir(dfd);
548 			if ((dp = strdup(devname)) == NULL) {
549 				syslog(LOG_ERR, "%s", strerror(errno));
550 				exit(1);
551 			}
552 			return (dp);
553 		}
554 	}
555 	closedir(dfd);
556 	syslog(LOG_ERR, "can't find device %d/%d", major(dev), minor(dev));
557 	exit(1);
558 }
559 
560 char *
561 rawname(s)
562 	char *s;
563 {
564 	char *sl, name[MAXPATHLEN];
565 
566 	if ((sl = strrchr(s, '/')) == NULL || sl[1] == '0') {
567 		syslog(LOG_ERR,
568 		    "can't make raw dump device name from %s", s);
569 		return (s);
570 	}
571 	(void)snprintf(name, sizeof(name), "%.*s/r%s", sl - s, s, sl + 1);
572 	if ((sl = strdup(name)) == NULL) {
573 		syslog(LOG_ERR, "%s", strerror(errno));
574 		exit(1);
575 	}
576 	return (sl);
577 }
578 
579 int
580 get_crashtime()
581 {
582 	time_t dumptime;			/* Time the dump was taken. */
583 
584 	if (KREAD(kd_dump, dump_nl[X_TIME].n_value, &dumptime) != 0) {
585 		if (verbose)
586 		    syslog(LOG_WARNING, "kvm_read: %s", kvm_geterr(kd_dump));
587 		return (0);
588 	}
589 	if (dumptime == 0) {
590 		if (verbose)
591 			syslog(LOG_ERR, "dump time is zero");
592 		return (0);
593 	}
594 	(void)printf("savecore: system went down at %s", ctime(&dumptime));
595 #define	LEEWAY	(7 * SECSPERDAY)
596 	if (dumptime < now - LEEWAY || dumptime > now + LEEWAY) {
597 		(void)printf("dump time is unreasonable\n");
598 		return (0);
599 	}
600 	return (1);
601 }
602 
603 int
604 check_space()
605 {
606 	register FILE *fp;
607 	char *tkernel;
608 	off_t minfree, spacefree, kernelsize, needed;
609 	struct stat st;
610 	struct statfs fsbuf;
611 	char buf[100], path[MAXPATHLEN];
612 
613 	tkernel = kernel ? kernel : _PATH_UNIX;
614 	if (stat(tkernel, &st) < 0) {
615 		syslog(LOG_ERR, "%s: %m", tkernel);
616 		exit(1);
617 	}
618 	kernelsize = st.st_blocks * S_BLKSIZE;
619 	if (statfs(dirname, &fsbuf) < 0) {
620 		syslog(LOG_ERR, "%s: %m", dirname);
621 		exit(1);
622 	}
623  	spacefree = (fsbuf.f_bavail * fsbuf.f_bsize) / 1024;
624 
625 	(void)snprintf(path, sizeof(path), "%s/minfree", dirname);
626 	if ((fp = fopen(path, "r")) == NULL)
627 		minfree = 0;
628 	else {
629 		if (fgets(buf, sizeof(buf), fp) == NULL)
630 			minfree = 0;
631 		else
632 			minfree = atoi(buf);
633 		(void)fclose(fp);
634 	}
635 
636 	needed = (dumpsize + kernelsize) / 1024;
637  	if (minfree > 0 && spacefree - needed < minfree) {
638 		syslog(LOG_WARNING,
639 		    "no dump, not enough free space on device");
640 		return (0);
641 	}
642 	if (spacefree - needed < minfree)
643 		syslog(LOG_WARNING,
644 		    "dump performed, but free space threshold crossed");
645 	return (1);
646 }
647 
648 int
649 Open(name, rw)
650 	char *name;
651 	int rw;
652 {
653 	int fd;
654 
655 	if ((fd = open(name, rw, 0)) < 0) {
656 		syslog(LOG_ERR, "%s: %m", name);
657 		exit(1);
658 	}
659 	return (fd);
660 }
661 
662 void
663 Lseek(fd, off, flag)
664 	int fd, flag;
665 	off_t off;
666 {
667 	off_t ret;
668 
669 	ret = lseek(fd, off, flag);
670 	if (ret == -1) {
671 		syslog(LOG_ERR, "lseek: %m");
672 		exit(1);
673 	}
674 }
675 
676 int
677 Create(file, mode)
678 	char *file;
679 	int mode;
680 {
681 	register int fd;
682 
683 	fd = open(file, O_WRONLY | O_CREAT | O_TRUNC, mode);
684 	if (fd < 0) {
685 		syslog(LOG_ERR, "%s: %m", file);
686 		exit(1);
687 	}
688 	return (fd);
689 }
690 
691 void
692 Write(fd, bp, size)
693 	int fd, size;
694 	void *bp;
695 {
696 	int n;
697 
698 	if ((n = write(fd, bp, size)) < size) {
699 		syslog(LOG_ERR, "write: %s", strerror(n == -1 ? errno : EIO));
700 		exit(1);
701 	}
702 }
703 
704 void
705 usage()
706 {
707 	(void)syslog(LOG_ERR, "usage: savecore [-cfvz] [-N system] directory");
708 	exit(1);
709 }
710