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Cleaner loop structure when reading panic string from the core image.
We now check the return value of KREAD() which may solve PR 1254.

/*	$OpenBSD: savecore_old.c,v 1.16 2000/05/31 17:09:17 millert Exp $	*/
/*	$NetBSD: savecore_old.c,v 1.1.1.1 1996/03/16 10:25:11 leo Exp $	*/

/*-
 * Copyright (c) 1986, 1992, 1993
 *	The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by the University of
 *	California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#ifndef lint
static char copyright[] =
"@(#) Copyright (c) 1986, 1992, 1993\n\
	The Regents of the University of California.  All rights reserved.\n";
#endif /* not lint */

#ifndef lint
#if 0
static char sccsid[] = "@(#)savecore.c	8.3 (Berkeley) 1/2/94";
#else
static char rcsid[] = "$OpenBSD: savecore_old.c,v 1.16 2000/05/31 17:09:17 millert Exp $";
#endif
#endif /* not lint */

#include <sys/param.h>
#include <sys/stat.h>
#include <sys/mount.h>
#include <sys/syslog.h>
#include <sys/types.h>
#include <sys/time.h>
#include <sys/resource.h>

#include <dirent.h>
#include <errno.h>
#include <fcntl.h>
#include <nlist.h>
#include <paths.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <tzfile.h>
#include <unistd.h>
#include <vis.h>

extern FILE *zopen __P((const char *fname, const char *mode, int bits));

#define ok(number) ((number) - KERNBASE)

struct nlist current_nl[] = {	/* Namelist for currently running system. */
#define X_DUMPDEV	0
	{ "_dumpdev" },
#define X_DUMPLO	1
	{ "_dumplo" },
#define X_TIME		2
	{ "_time" },
#define	X_DUMPSIZE	3
	{ "_dumpsize" },
#define X_VERSION	4
	{ "_version" },
#define X_PANICSTR	5
	{ "_panicstr" },
#define	X_DUMPMAG	6
	{ "_dumpmag" },
	{ "" },
};
int cursyms[] = { X_DUMPDEV, X_DUMPLO, X_VERSION, X_DUMPMAG, -1 };
int dumpsyms[] = { X_TIME, X_DUMPSIZE, X_VERSION, X_PANICSTR, X_DUMPMAG, -1 };

struct nlist dump_nl[] = {	/* Name list for dumped system. */
	{ "_dumpdev" },		/* Entries MUST be the same as */
	{ "_dumplo" },		/*	those in current_nl[].  */
	{ "_time" },
	{ "_dumpsize" },
	{ "_version" },
	{ "_panicstr" },
	{ "_dumpmag" },
	{ "" },
};

/* Types match kernel declarations. */
long	dumplo;				/* where dump starts on dumpdev */
int	dumpmag;			/* magic number in dump */
int	dumpsize;			/* amount of memory dumped */

char	*kernel;
char	*dirname;			/* directory to save dumps in */
char	*ddname;			/* name of dump device */
dev_t	dumpdev;			/* dump device */
int	dumpfd;				/* read/write descriptor on block dev */
time_t	now;				/* current date */
char	panic_mesg[1024];
int	panicstr;
char	vers[1024];

int	clear, compress, force, verbose;	/* flags */

void	 check_kmem __P((void));
int	 check_space __P((void));
void	 clear_dump __P((void));
int	 Create __P((char *, int));
int	 dump_exists __P((void));
char	*find_dev __P((dev_t, int));
int	 get_crashtime __P((void));
void	 kmem_setup __P((void));
void	 log __P((int, char *, ...));
void	 Lseek __P((int, off_t, int));
int	 Open __P((char *, int rw));
int	 Read __P((int, void *, int));
char	*rawname __P((char *s));
void	 save_core __P((void));
void	 usage __P((void));
void	 Write __P((int, void *, int));

int
main(argc, argv)
	int argc;
	char *argv[];
{
	struct rlimit rl;
	int ch;

	openlog("savecore", LOG_PERROR, LOG_DAEMON);

	/* Increase our data size to the max if we can. */
	if (getrlimit(RLIMIT_DATA, &rl) == 0) {
		rl.rlim_cur = rl.rlim_max;
		if (setrlimit(RLIMIT_DATA, &rl) < 0)
			syslog(LOG_WARNING, "can't set rlimit data size: %m");
	}

	while ((ch = getopt(argc, argv, "cdfN:vz")) != -1)
		switch(ch) {
		case 'c':
			clear = 1;
			break;
		case 'd':		/* Not documented. */
		case 'v':
			verbose = 1;
			break;
		case 'f':
			force = 1;
			break;
		case 'N':
			kernel = optarg;
			break;
		case 'z':
			compress = 1;
			break;
		case '?':
		default:
			usage();
		}
	argc -= optind;
	argv += optind;

	if (!clear) {
		if (argc != 1 && argc != 2)
			usage();
		dirname = argv[0];
	}
	if (argc == 2)
		kernel = argv[1];

	(void)time(&now);
	kmem_setup();

	if (clear) {
		clear_dump();
		exit(0);
	}

	if (!dump_exists() && !force)
		exit(1);

	check_kmem();

	if (panicstr)
		syslog(LOG_ALERT, "reboot after panic: %s", panic_mesg);
	else
		syslog(LOG_ALERT, "reboot");

	if ((!get_crashtime() || !check_space()) && !force)
		exit(1);

	save_core();

	clear_dump();
	exit(0);
}

void
kmem_setup()
{
	FILE *fp;
	int kmem, i;
	char *dump_sys, *current_sys;
	
	/*
	 * Some names we need for the currently running system, others for
	 * the system that was running when the dump was made.  The values
	 * obtained from the current system are used to look for things in
	 * /dev/kmem that cannot be found in the dump_sys namelist, but are
	 * presumed to be the same (since the disk partitions are probably
	 * the same!)
	 */
	if ((i = open(_PATH_KSYMS, O_RDONLY)) != -1) {
		current_sys = _PATH_KSYMS;
		(void)close(i);
	} else {
		current_sys = _PATH_UNIX;
	}
	if ((nlist(current_sys, current_nl)) == -1) {
		syslog(LOG_ERR, "%s: nlist: %m", current_sys);
		if (errno == ENOENT)
			exit(1);
	}
	for (i = 0; cursyms[i] != -1; i++)
		if (current_nl[cursyms[i]].n_value == 0) {
			syslog(LOG_ERR, "%s: %s not in namelist",
			    _PATH_UNIX, current_nl[cursyms[i]].n_name);
			exit(1);
		}

	dump_sys = kernel ? kernel : _PATH_UNIX;

	if ((nlist(dump_sys, dump_nl)) == -1) {
		syslog(LOG_ERR, "%s: nlist: %m", dump_sys);
		if (errno == ENOENT)
			exit(1);
	}
	for (i = 0; dumpsyms[i] != -1; i++)
		if (dump_nl[dumpsyms[i]].n_value == 0) {
			syslog(LOG_ERR, "%s: %s not in namelist",
			    dump_sys, dump_nl[dumpsyms[i]].n_name);
			exit(1);
		}

	kmem = Open(_PATH_KMEM, O_RDONLY);
	Lseek(kmem, (off_t)current_nl[X_DUMPDEV].n_value, SEEK_SET);
	(void)Read(kmem, &dumpdev, sizeof(dumpdev));
	if (dumpdev == NODEV) {
		syslog(LOG_WARNING, "no core dump (no dumpdev)");
		exit(1);
	}
	Lseek(kmem, (off_t)current_nl[X_DUMPLO].n_value, SEEK_SET);
	(void)Read(kmem, &dumplo, sizeof(dumplo));
	dumplo *= DEV_BSIZE;
	if (verbose)
		(void)printf("dumplo = %d (%d * %d)\n",
		    dumplo, dumplo / DEV_BSIZE, DEV_BSIZE);
	Lseek(kmem, (off_t)current_nl[X_DUMPMAG].n_value, SEEK_SET);
	(void)Read(kmem, &dumpmag, sizeof(dumpmag));
	ddname = find_dev(dumpdev, S_IFBLK);
	dumpfd = Open(ddname, O_RDWR);
	fp = fdopen(kmem, "r");
	if (fp == NULL) {
		syslog(LOG_ERR, "%s: fdopen: %m", _PATH_KMEM);
		exit(1);
	}
	if (kernel)
		return;
	(void)fseek(fp, (off_t)current_nl[X_VERSION].n_value, SEEK_SET);
	(void)fgets(vers, sizeof(vers), fp);

	/* Don't fclose(fp), we use dumpfd later. */
}

void
check_kmem()
{
	register char *cp;
	FILE *fp;
	char core_vers[1024];

	fp = fdopen(dumpfd, "r");
	if (fp == NULL) {
		syslog(LOG_ERR, "%s: fdopen: %m", ddname);
		exit(1);
	}
	fseek(fp, (off_t)(dumplo + ok(dump_nl[X_VERSION].n_value)), SEEK_SET);
	fgets(core_vers, sizeof(core_vers), fp);

	if (strcmp(vers, core_vers) && kernel == 0) {
		char *p;

		p = strchr(vers, '\n');
		if (p)
			*p = '\0';
		p = strchr(core_vers, '\n');
		if (p)
			*p = '\0';
		syslog(LOG_WARNING,
		    "warning: %s version mismatch:\n\t%s\nand\t%s\n",
		    _PATH_UNIX, vers, core_vers);
	}

	(void)fseek(fp,
	    (off_t)(dumplo + ok(dump_nl[X_PANICSTR].n_value)), SEEK_SET);
	(void)fread(&panicstr, sizeof(panicstr), 1, fp);
	if (panicstr) {
		char	c, visout[5];
		size_t	vislen;

		cp = panic_mesg;
		(void)fseek(fp, dumplo + ok(panicstr), SEEK_SET);
		for (;;) {
			c = getc(fp);
			if (c == EOF || c == '\0')
				break;

			vis(visout, c, VIS_SAFE|VIS_NOSLASH, 0);
			vislen = strlen(visout);
			if (cp - panic_mesg + vislen >= sizeof(panic_mesg))
				break;
			strcat(cp, visout);
			cp += vislen;
		}
	}
	/* Don't fclose(fp), we use dumpfd later. */
}

void
clear_dump()
{
	long newdumplo;

	newdumplo = 0;
	Lseek(dumpfd, (off_t)(dumplo + ok(dump_nl[X_DUMPMAG].n_value)),
	    SEEK_SET);
	Write(dumpfd, &newdumplo, sizeof(newdumplo));
}

int
dump_exists()
{
	int newdumpmag;

	Lseek(dumpfd, (off_t)(dumplo + ok(dump_nl[X_DUMPMAG].n_value)),
	    SEEK_SET);
	(void)Read(dumpfd, &newdumpmag, sizeof(newdumpmag));

	/* Read the dump size. */
	Lseek(dumpfd, (off_t)(dumplo + ok(dump_nl[X_DUMPSIZE].n_value)),
	    SEEK_SET);
	(void)Read(dumpfd, &dumpsize, sizeof(dumpsize));
	dumpsize *= getpagesize();

	/*
	 * Return zero if core dump doesn't seem to be there, and note
	 * it for syslog.  This check and return happens after the dump size
	 * is read, so dumpsize is whether or not the core is valid (for -f).
	 */
	if (newdumpmag != dumpmag) {
		if (verbose)
			syslog(LOG_WARNING, "magic number mismatch (%x != %x)",
			    newdumpmag, dumpmag);
		syslog(LOG_WARNING, "no core dump");
		return (0);
	}
	return (1);
}

char buf[1024 * 1024];

void
save_core()
{
	register FILE *fp;
	register int bounds, ifd, nr, nw, ofd;
	char *rawp, path[MAXPATHLEN];
	mode_t um;

	um = umask(S_IRWXG|S_IRWXO);

	/*
	 * Get the current number and update the bounds file.  Do the update
	 * now, because may fail later and don't want to overwrite anything.
	 */
	(void)snprintf(path, sizeof(path), "%s/bounds", dirname);
	if ((fp = fopen(path, "r")) == NULL)
		goto err1;
	if (fgets(buf, sizeof(buf), fp) == NULL) {
		if (ferror(fp))
err1:			syslog(LOG_WARNING, "%s: %m", path);
		bounds = 0;
	} else
		bounds = atoi(buf);
	if (fp != NULL)
		(void)fclose(fp);
	if ((fp = fopen(path, "w")) == NULL)
		syslog(LOG_ERR, "%s: %m", path);
	else {
		(void)fprintf(fp, "%d\n", bounds + 1);
		(void)fclose(fp);
	}

	/* Create the core file. */
	(void)snprintf(path, sizeof(path), "%s%s.%d.core%s",
	    dirname, _PATH_UNIX, bounds, compress ? ".Z" : "");
	if (compress) {
		if ((fp = zopen(path, "w", 0)) == NULL) {
			syslog(LOG_ERR, "%s: %m", path);
			exit(1);
		}
	} else
		ofd = Create(path, S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH);

	/* Open the raw device. */
	rawp = rawname(ddname);
	if ((ifd = open(rawp, O_RDONLY)) == -1) {
		syslog(LOG_WARNING, "%s: %m; using block device", rawp);
		ifd = dumpfd;
	}

	/* Seek to the start of the core. */
	Lseek(ifd, (off_t)dumplo, SEEK_SET);

	/* Copy the core file. */
	syslog(LOG_NOTICE, "writing %score to %s",
	    compress ? "compressed " : "", path);
	for (; dumpsize > 0; dumpsize -= nr) {
		(void)printf("%6dK\r", dumpsize / 1024);
		(void)fflush(stdout);
		nr = read(ifd, buf, MIN(dumpsize, sizeof(buf)));
		if (nr <= 0) {
			if (nr == 0)
				syslog(LOG_WARNING,
				    "WARNING: EOF on dump device");
			else
				syslog(LOG_ERR, "%s: %m", rawp);
			goto err2;
		}
		if (compress)
			nw = fwrite(buf, 1, nr, fp);
		else
			nw = write(ofd, buf, nr);
		if (nw != nr) {
			syslog(LOG_ERR, "%s: %s",
			    path, strerror(nw == 0 ? EIO : errno));
err2:			syslog(LOG_WARNING,
			    "WARNING: core may be incomplete");
			(void)printf("\n");
			exit(1);
		}
	}
	(void)close(ifd);
	if (compress)
		(void)fclose(fp);
	else 
		(void)close(ofd);

	/* Copy the kernel. */
	ifd = Open(kernel ? kernel : _PATH_UNIX, O_RDONLY);
	(void)snprintf(path, sizeof(path), "%s%s.%d%s",
	    dirname, _PATH_UNIX, bounds, compress ? ".Z" : "");
	if (compress) {
		if ((fp = zopen(path, "w", 0)) == NULL) {
			syslog(LOG_ERR, "%s: %m", path);
			exit(1);
		}
	} else
		ofd = Create(path, S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH);
	syslog(LOG_NOTICE, "writing %skernel to %s",
	    compress ? "compressed " : "", path);
	while ((nr = read(ifd, buf, sizeof(buf))) > 0) {
		if (compress)
			nw = fwrite(buf, 1, nr, fp);
		else
			nw = write(ofd, buf, nr);
		if (nw != nr) {
			syslog(LOG_ERR, "%s: %s",
			    path, strerror(nw == 0 ? EIO : errno));
			syslog(LOG_WARNING,
			    "WARNING: kernel may be incomplete");
			exit(1);
		}
	}
	if (nr < 0) {
		syslog(LOG_ERR, "%s: %m", kernel ? kernel : _PATH_UNIX);
		syslog(LOG_WARNING, "WARNING: kernel may be incomplete");
		exit(1);
	}
	if (compress)
		(void)fclose(fp);
	else
		(void)close(ofd);
	(void)umask(um);
}

char *
find_dev(dev, type)
	register dev_t dev;
	register int type;
{
	register DIR *dfd;
	struct dirent *dir;
	struct stat sb;
	char *dp, devname[MAXPATHLEN + 1];

	if ((dfd = opendir(_PATH_DEV)) == NULL) {
		syslog(LOG_ERR, "%s: %m", _PATH_DEV);
		exit(1);
	}
	(void)strcpy(devname, _PATH_DEV);
	while ((dir = readdir(dfd))) {
		(void)strcpy(devname + sizeof(_PATH_DEV) - 1, dir->d_name);
		if (lstat(devname, &sb)) {
			syslog(LOG_ERR, "%s: %m", devname);
			continue;
		}
		if ((sb.st_mode & S_IFMT) != type)
			continue;
		if (dev == sb.st_rdev) {
			closedir(dfd);
			if ((dp = strdup(devname)) == NULL) {
				syslog(LOG_ERR, "%s", strerror(ENOMEM));
				exit(1);
			}
			return (dp);
		}
	}
	closedir(dfd);
	syslog(LOG_ERR, "can't find device %d/%d", major(dev), minor(dev));
	exit(1);
}

char *
rawname(s)
	char *s;
{
	char *sl, name[MAXPATHLEN];

	if ((sl = strrchr(s, '/')) == NULL || sl[1] == '0') {
		syslog(LOG_ERR,
		    "can't make raw dump device name from %s", s);
		return (s);
	}
	(void)snprintf(name, sizeof(name), "%.*s/r%s", sl - s, s, sl + 1);
	if ((sl = strdup(name)) == NULL) {
		syslog(LOG_ERR, "%s", strerror(ENOMEM));
		exit(1);
	}
	return (sl);
}

int
get_crashtime()
{
	time_t dumptime;			/* Time the dump was taken. */

	Lseek(dumpfd, (off_t)(dumplo + ok(dump_nl[X_TIME].n_value)), SEEK_SET);
	(void)Read(dumpfd, &dumptime, sizeof(dumptime));
	if (dumptime == 0) {
		if (verbose)
			syslog(LOG_ERR, "dump time is zero");
		return (0);
	}
	(void)printf("savecore: system went down at %s", ctime(&dumptime));
#define	LEEWAY	(7 * SECSPERDAY)
	if (dumptime < now - LEEWAY || dumptime > now + LEEWAY) {
		(void)printf("dump time is unreasonable\n");
		return (0);
	}
	return (1);
}

int
check_space()
{
	register FILE *fp;
	char *tkernel;
	off_t minfree, spacefree, kernelsize, needed;
	struct stat st;
	struct statfs fsbuf;
	char buf[100], path[MAXPATHLEN];

	tkernel = kernel ? kernel : _PATH_UNIX;
	if (stat(tkernel, &st) < 0) {
		syslog(LOG_ERR, "%s: %m", tkernel);
		exit(1);
	}
	kernelsize = st.st_blocks * S_BLKSIZE;
	if (statfs(dirname, &fsbuf) < 0) {
		syslog(LOG_ERR, "%s: %m", dirname);
		exit(1);
	}
 	spacefree = (fsbuf.f_bavail * fsbuf.f_bsize) / 1024;

	(void)snprintf(path, sizeof(path), "%s/minfree", dirname);
	if ((fp = fopen(path, "r")) == NULL)
		minfree = 0;
	else {
		if (fgets(buf, sizeof(buf), fp) == NULL)
			minfree = 0;
		else
			minfree = atoi(buf);
		(void)fclose(fp);
	}

	needed = (dumpsize + kernelsize) / 1024;
 	if (minfree > 0 && spacefree - needed < minfree) {
		syslog(LOG_WARNING,
		    "no dump, not enough free space on device");
		return (0);
	}
	if (spacefree - needed < minfree)
		syslog(LOG_WARNING,
		    "dump performed, but free space threshold crossed");
	return (1);
}

int
Open(name, rw)
	char *name;
	int rw;
{
	int fd;

	if ((fd = open(name, rw, 0)) < 0) {
		syslog(LOG_ERR, "%s: %m", name);
		exit(1);
	}
	return (fd);
}

int
Read(fd, bp, size)
	int fd, size;
	void *bp;
{
	int nr;

	nr = read(fd, bp, size);
	if (nr != size) {
		syslog(LOG_ERR, "read: %m");
		exit(1);
	}
	return (nr);
}

void
Lseek(fd, off, flag)
	int fd, flag;
	off_t off;
{
	off_t ret;

	ret = lseek(fd, off, flag);
	if (ret == -1) {
		syslog(LOG_ERR, "lseek: %m");
		exit(1);
	}
}

int
Create(file, mode)
	char *file;
	int mode;
{
	register int fd;

	fd = open(file, O_WRONLY | O_CREAT | O_TRUNC, mode);
	if (fd < 0) {
		syslog(LOG_ERR, "%s: %m", file);
		exit(1);
	}
	return (fd);
}

void
Write(fd, bp, size)
	int fd, size;
	void *bp;
{
	int n;

	if ((n = write(fd, bp, size)) < size) {
		syslog(LOG_ERR, "write: %s", strerror(n == -1 ? errno : EIO));
		exit(1);
	}
}

void
usage()
{
	extern char *__progname;

	fprintf(stderr, "usage: %s [-cfvz] [-N system] directory\n",
	    __progname);
	exit(1);
}