1/*
2 * utils.c - various utility functions used in pppd.
3 *
4 * Copyright (c) 1999-2002 Paul Mackerras. All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 *
10 * 1. Redistributions of source code must retain the above copyright
11 *    notice, this list of conditions and the following disclaimer.
12 *
13 * 2. The name(s) of the authors of this software must not be used to
14 *    endorse or promote products derived from this software without
15 *    prior written permission.
16 *
17 * 3. Redistributions of any form whatsoever must retain the following
18 *    acknowledgment:
19 *    "This product includes software developed by Paul Mackerras
20 *     <paulus@samba.org>".
21 *
22 * THE AUTHORS OF THIS SOFTWARE DISCLAIM ALL WARRANTIES WITH REGARD TO
23 * THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
24 * AND FITNESS, IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY
25 * SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
26 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN
27 * AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING
28 * OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
29 */
30
31#define RCSID	"$Id: utils.c,v 1.25 2008/06/03 12:06:37 paulus Exp $"
32
33#include <stdio.h>
34#include <ctype.h>
35#include <stdlib.h>
36#include <string.h>
37#include <unistd.h>
38#include <signal.h>
39#include <errno.h>
40#include <fcntl.h>
41#include <syslog.h>
42#include <netdb.h>
43#include <time.h>
44#include <utmp.h>
45#include <pwd.h>
46#include <sys/param.h>
47#include <sys/types.h>
48#include <sys/wait.h>
49#include <sys/time.h>
50#include <sys/resource.h>
51#include <sys/stat.h>
52#include <sys/socket.h>
53#include <netinet/in.h>
54#ifdef SVR4
55#include <sys/mkdev.h>
56#endif
57
58#include "pppd.h"
59#include "fsm.h"
60#include "lcp.h"
61
62static const char rcsid[] = RCSID;
63
64#if defined(SUNOS4)
65extern char *strerror();
66#endif
67
68static void logit __P((int, char *, va_list));
69static void log_write __P((int, char *));
70static void vslp_printer __P((void *, char *, ...));
71static void format_packet __P((u_char *, int, printer_func, void *));
72
73struct buffer_info {
74    char *ptr;
75    int len;
76};
77
78#if !defined(__ANDROID__)
79
80/*
81 * strlcpy - like strcpy/strncpy, doesn't overflow destination buffer,
82 * always leaves destination null-terminated (for len > 0).
83 */
84size_t
85strlcpy(dest, src, len)
86    char *dest;
87    const char *src;
88    size_t len;
89{
90    size_t ret = strlen(src);
91
92    if (len != 0) {
93	if (ret < len)
94	    strcpy(dest, src);
95	else {
96	    strncpy(dest, src, len - 1);
97	    dest[len-1] = 0;
98	}
99    }
100    return ret;
101}
102
103/*
104 * strlcat - like strcat/strncat, doesn't overflow destination buffer,
105 * always leaves destination null-terminated (for len > 0).
106 */
107size_t
108strlcat(dest, src, len)
109    char *dest;
110    const char *src;
111    size_t len;
112{
113    size_t dlen = strlen(dest);
114
115    return dlen + strlcpy(dest + dlen, src, (len > dlen? len - dlen: 0));
116}
117#endif
118
119
120/*
121 * slprintf - format a message into a buffer.  Like sprintf except we
122 * also specify the length of the output buffer, and we handle
123 * %m (error message), %v (visible string),
124 * %q (quoted string), %t (current time) and %I (IP address) formats.
125 * Doesn't do floating-point formats.
126 * Returns the number of chars put into buf.
127 */
128int
129slprintf __V((char *buf, int buflen, char *fmt, ...))
130{
131    va_list args;
132    int n;
133
134#if defined(__STDC__)
135    va_start(args, fmt);
136#else
137    char *buf;
138    int buflen;
139    char *fmt;
140    va_start(args);
141    buf = va_arg(args, char *);
142    buflen = va_arg(args, int);
143    fmt = va_arg(args, char *);
144#endif
145    n = vslprintf(buf, buflen, fmt, args);
146    va_end(args);
147    return n;
148}
149
150/*
151 * vslprintf - like slprintf, takes a va_list instead of a list of args.
152 */
153#define OUTCHAR(c)	(buflen > 0? (--buflen, *buf++ = (c)): 0)
154
155int
156vslprintf(buf, buflen, fmt, args)
157    char *buf;
158    int buflen;
159    char *fmt;
160    va_list args;
161{
162    int c, i, n;
163    int width, prec, fillch;
164    int base, len, neg, quoted;
165    unsigned long val = 0;
166    char *str, *f, *buf0;
167    unsigned char *p;
168    char num[32];
169    time_t t;
170    u_int32_t ip;
171    static char hexchars[] = "0123456789abcdef";
172    struct buffer_info bufinfo;
173
174    buf0 = buf;
175    --buflen;
176    while (buflen > 0) {
177	for (f = fmt; *f != '%' && *f != 0; ++f)
178	    ;
179	if (f > fmt) {
180	    len = f - fmt;
181	    if (len > buflen)
182		len = buflen;
183	    memcpy(buf, fmt, len);
184	    buf += len;
185	    buflen -= len;
186	    fmt = f;
187	}
188	if (*fmt == 0)
189	    break;
190	c = *++fmt;
191	width = 0;
192	prec = -1;
193	fillch = ' ';
194	if (c == '0') {
195	    fillch = '0';
196	    c = *++fmt;
197	}
198	if (c == '*') {
199	    width = va_arg(args, int);
200	    c = *++fmt;
201	} else {
202	    while (isdigit(c)) {
203		width = width * 10 + c - '0';
204		c = *++fmt;
205	    }
206	}
207	if (c == '.') {
208	    c = *++fmt;
209	    if (c == '*') {
210		prec = va_arg(args, int);
211		c = *++fmt;
212	    } else {
213		prec = 0;
214		while (isdigit(c)) {
215		    prec = prec * 10 + c - '0';
216		    c = *++fmt;
217		}
218	    }
219	}
220	str = 0;
221	base = 0;
222	neg = 0;
223	++fmt;
224	switch (c) {
225	case 'l':
226	    c = *fmt++;
227	    switch (c) {
228	    case 'd':
229		val = va_arg(args, long);
230#if defined(__ANDROID__)
231		if ((long)val < 0) {
232		    neg = 1;
233		    val = (unsigned long)(-(long)val);
234		}
235#else
236		if (val < 0) {
237		    neg = 1;
238		    val = -val;
239		}
240#endif
241		base = 10;
242		break;
243	    case 'u':
244		val = va_arg(args, unsigned long);
245		base = 10;
246		break;
247	    default:
248		OUTCHAR('%');
249		OUTCHAR('l');
250		--fmt;		/* so %lz outputs %lz etc. */
251		continue;
252	    }
253	    break;
254	case 'd':
255	    i = va_arg(args, int);
256	    if (i < 0) {
257		neg = 1;
258		val = -i;
259	    } else
260		val = i;
261	    base = 10;
262	    break;
263	case 'u':
264	    val = va_arg(args, unsigned int);
265	    base = 10;
266	    break;
267	case 'o':
268	    val = va_arg(args, unsigned int);
269	    base = 8;
270	    break;
271	case 'x':
272	case 'X':
273	    val = va_arg(args, unsigned int);
274	    base = 16;
275	    break;
276	case 'p':
277	    val = (unsigned long) va_arg(args, void *);
278	    base = 16;
279	    neg = 2;
280	    break;
281	case 's':
282	    str = va_arg(args, char *);
283	    break;
284	case 'c':
285	    num[0] = va_arg(args, int);
286	    num[1] = 0;
287	    str = num;
288	    break;
289	case 'm':
290	    str = strerror(errno);
291	    break;
292	case 'I':
293	    ip = va_arg(args, u_int32_t);
294	    ip = ntohl(ip);
295	    slprintf(num, sizeof(num), "%d.%d.%d.%d", (ip >> 24) & 0xff,
296		     (ip >> 16) & 0xff, (ip >> 8) & 0xff, ip & 0xff);
297	    str = num;
298	    break;
299	case 't':
300	    time(&t);
301	    str = ctime(&t);
302	    str += 4;		/* chop off the day name */
303	    str[15] = 0;	/* chop off year and newline */
304	    break;
305	case 'v':		/* "visible" string */
306	case 'q':		/* quoted string */
307	    quoted = c == 'q';
308	    p = va_arg(args, unsigned char *);
309	    if (p == NULL)
310		    p = (unsigned char *)"<NULL>";
311	    if (fillch == '0' && prec >= 0) {
312		n = prec;
313	    } else {
314		n = strlen((char *)p);
315		if (prec >= 0 && n > prec)
316		    n = prec;
317	    }
318	    while (n > 0 && buflen > 0) {
319		c = *p++;
320		--n;
321		if (!quoted && c >= 0x80) {
322		    OUTCHAR('M');
323		    OUTCHAR('-');
324		    c -= 0x80;
325		}
326		if (quoted && (c == '"' || c == '\\'))
327		    OUTCHAR('\\');
328		if (c < 0x20 || (0x7f <= c && c < 0xa0)) {
329		    if (quoted) {
330			OUTCHAR('\\');
331			switch (c) {
332			case '\t':	OUTCHAR('t');	break;
333			case '\n':	OUTCHAR('n');	break;
334			case '\b':	OUTCHAR('b');	break;
335			case '\f':	OUTCHAR('f');	break;
336			default:
337			    OUTCHAR('x');
338			    OUTCHAR(hexchars[c >> 4]);
339			    OUTCHAR(hexchars[c & 0xf]);
340			}
341		    } else {
342			if (c == '\t')
343			    OUTCHAR(c);
344			else {
345			    OUTCHAR('^');
346			    OUTCHAR(c ^ 0x40);
347			}
348		    }
349		} else
350		    OUTCHAR(c);
351	    }
352	    continue;
353	case 'P':		/* print PPP packet */
354	    bufinfo.ptr = buf;
355	    bufinfo.len = buflen + 1;
356	    p = va_arg(args, unsigned char *);
357	    n = va_arg(args, int);
358	    format_packet(p, n, vslp_printer, &bufinfo);
359	    buf = bufinfo.ptr;
360	    buflen = bufinfo.len - 1;
361	    continue;
362	case 'B':
363	    p = va_arg(args, unsigned char *);
364	    for (n = prec; n > 0; --n) {
365		c = *p++;
366		if (fillch == ' ')
367		    OUTCHAR(' ');
368		OUTCHAR(hexchars[(c >> 4) & 0xf]);
369		OUTCHAR(hexchars[c & 0xf]);
370	    }
371	    continue;
372	default:
373	    *buf++ = '%';
374	    if (c != '%')
375		--fmt;		/* so %z outputs %z etc. */
376	    --buflen;
377	    continue;
378	}
379	if (base != 0) {
380	    str = num + sizeof(num);
381	    *--str = 0;
382	    while (str > num + neg) {
383		*--str = hexchars[val % base];
384		val = val / base;
385		if (--prec <= 0 && val == 0)
386		    break;
387	    }
388	    switch (neg) {
389	    case 1:
390		*--str = '-';
391		break;
392	    case 2:
393		*--str = 'x';
394		*--str = '0';
395		break;
396	    }
397	    len = num + sizeof(num) - 1 - str;
398	} else {
399	    len = strlen(str);
400	    if (prec >= 0 && len > prec)
401		len = prec;
402	}
403	if (width > 0) {
404	    if (width > buflen)
405		width = buflen;
406	    if ((n = width - len) > 0) {
407		buflen -= n;
408		for (; n > 0; --n)
409		    *buf++ = fillch;
410	    }
411	}
412	if (len > buflen)
413	    len = buflen;
414	memcpy(buf, str, len);
415	buf += len;
416	buflen -= len;
417    }
418    *buf = 0;
419    return buf - buf0;
420}
421
422/*
423 * vslp_printer - used in processing a %P format
424 */
425static void
426vslp_printer __V((void *arg, char *fmt, ...))
427{
428    int n;
429    va_list pvar;
430    struct buffer_info *bi;
431
432#if defined(__STDC__)
433    va_start(pvar, fmt);
434#else
435    void *arg;
436    char *fmt;
437    va_start(pvar);
438    arg = va_arg(pvar, void *);
439    fmt = va_arg(pvar, char *);
440#endif
441
442    bi = (struct buffer_info *) arg;
443    n = vslprintf(bi->ptr, bi->len, fmt, pvar);
444    va_end(pvar);
445
446    bi->ptr += n;
447    bi->len -= n;
448}
449
450#ifdef unused
451/*
452 * log_packet - format a packet and log it.
453 */
454
455void
456log_packet(p, len, prefix, level)
457    u_char *p;
458    int len;
459    char *prefix;
460    int level;
461{
462	init_pr_log(prefix, level);
463	format_packet(p, len, pr_log, &level);
464	end_pr_log();
465}
466#endif /* unused */
467
468/*
469 * format_packet - make a readable representation of a packet,
470 * calling `printer(arg, format, ...)' to output it.
471 */
472static void
473format_packet(p, len, printer, arg)
474    u_char *p;
475    int len;
476    printer_func printer;
477    void *arg;
478{
479    int i, n;
480    u_short proto;
481    struct protent *protp;
482
483    if (len >= PPP_HDRLEN && p[0] == PPP_ALLSTATIONS && p[1] == PPP_UI) {
484	p += 2;
485	GETSHORT(proto, p);
486	len -= PPP_HDRLEN;
487	for (i = 0; (protp = protocols[i]) != NULL; ++i)
488	    if (proto == protp->protocol)
489		break;
490	if (protp != NULL) {
491	    printer(arg, "[%s", protp->name);
492	    n = (*protp->printpkt)(p, len, printer, arg);
493	    printer(arg, "]");
494	    p += n;
495	    len -= n;
496	} else {
497	    for (i = 0; (protp = protocols[i]) != NULL; ++i)
498		if (proto == (protp->protocol & ~0x8000))
499		    break;
500	    if (protp != 0 && protp->data_name != 0) {
501		printer(arg, "[%s data]", protp->data_name);
502		if (len > 8)
503		    printer(arg, "%.8B ...", p);
504		else
505		    printer(arg, "%.*B", len, p);
506		len = 0;
507	    } else
508		printer(arg, "[proto=0x%x]", proto);
509	}
510    }
511
512    if (len > 32)
513	printer(arg, "%.32B ...", p);
514    else
515	printer(arg, "%.*B", len, p);
516}
517
518/*
519 * init_pr_log, end_pr_log - initialize and finish use of pr_log.
520 */
521
522static char line[256];		/* line to be logged accumulated here */
523static char *linep;		/* current pointer within line */
524static int llevel;		/* level for logging */
525
526void
527init_pr_log(prefix, level)
528     const char *prefix;
529     int level;
530{
531	linep = line;
532	if (prefix != NULL) {
533		strlcpy(line, prefix, sizeof(line));
534		linep = line + strlen(line);
535	}
536	llevel = level;
537}
538
539void
540end_pr_log()
541{
542	if (linep != line) {
543		*linep = 0;
544		log_write(llevel, line);
545	}
546}
547
548/*
549 * pr_log - printer routine for outputting to syslog
550 */
551void
552pr_log __V((void *arg, char *fmt, ...))
553{
554	int l, n;
555	va_list pvar;
556	char *p, *eol;
557	char buf[256];
558
559#if defined(__STDC__)
560	va_start(pvar, fmt);
561#else
562	void *arg;
563	char *fmt;
564	va_start(pvar);
565	arg = va_arg(pvar, void *);
566	fmt = va_arg(pvar, char *);
567#endif
568
569	n = vslprintf(buf, sizeof(buf), fmt, pvar);
570	va_end(pvar);
571
572	p = buf;
573	eol = strchr(buf, '\n');
574	if (linep != line) {
575		l = (eol == NULL)? n: eol - buf;
576		if (linep + l < line + sizeof(line)) {
577			if (l > 0) {
578				memcpy(linep, buf, l);
579				linep += l;
580			}
581			if (eol == NULL)
582				return;
583			p = eol + 1;
584			eol = strchr(p, '\n');
585		}
586		*linep = 0;
587		log_write(llevel, line);
588		linep = line;
589	}
590
591	while (eol != NULL) {
592		*eol = 0;
593		log_write(llevel, p);
594		p = eol + 1;
595		eol = strchr(p, '\n');
596	}
597
598	/* assumes sizeof(buf) <= sizeof(line) */
599	l = buf + n - p;
600	if (l > 0) {
601		memcpy(line, p, n);
602		linep = line + l;
603	}
604}
605
606/*
607 * print_string - print a readable representation of a string using
608 * printer.
609 */
610void
611print_string(p, len, printer, arg)
612    char *p;
613    int len;
614    printer_func printer;
615    void *arg;
616{
617    int c;
618
619    printer(arg, "\"");
620    for (; len > 0; --len) {
621	c = *p++;
622	if (' ' <= c && c <= '~') {
623	    if (c == '\\' || c == '"')
624		printer(arg, "\\");
625	    printer(arg, "%c", c);
626	} else {
627	    switch (c) {
628	    case '\n':
629		printer(arg, "\\n");
630		break;
631	    case '\r':
632		printer(arg, "\\r");
633		break;
634	    case '\t':
635		printer(arg, "\\t");
636		break;
637	    default:
638		printer(arg, "\\%.3o", c);
639	    }
640	}
641    }
642    printer(arg, "\"");
643}
644
645/*
646 * logit - does the hard work for fatal et al.
647 */
648static void
649logit(level, fmt, args)
650    int level;
651    char *fmt;
652    va_list args;
653{
654    char buf[1024];
655
656    vslprintf(buf, sizeof(buf), fmt, args);
657    log_write(level, buf);
658}
659
660static void
661log_write(level, buf)
662    int level;
663    char *buf;
664{
665    syslog(level, "%s", buf);
666    if (log_to_fd >= 0 && (level != LOG_DEBUG || debug)) {
667	int n = strlen(buf);
668
669	if (n > 0 && buf[n-1] == '\n')
670	    --n;
671	if (write(log_to_fd, buf, n) != n
672	    || write(log_to_fd, "\n", 1) != 1)
673	    log_to_fd = -1;
674    }
675}
676
677/*
678 * fatal - log an error message and die horribly.
679 */
680void
681fatal __V((char *fmt, ...))
682{
683    va_list pvar;
684
685#if defined(__STDC__)
686    va_start(pvar, fmt);
687#else
688    char *fmt;
689    va_start(pvar);
690    fmt = va_arg(pvar, char *);
691#endif
692
693    logit(LOG_ERR, fmt, pvar);
694    va_end(pvar);
695
696    die(1);			/* as promised */
697}
698
699/*
700 * error - log an error message.
701 */
702void
703error __V((char *fmt, ...))
704{
705    va_list pvar;
706
707#if defined(__STDC__)
708    va_start(pvar, fmt);
709#else
710    char *fmt;
711    va_start(pvar);
712    fmt = va_arg(pvar, char *);
713#endif
714
715    logit(LOG_ERR, fmt, pvar);
716    va_end(pvar);
717    ++error_count;
718}
719
720/*
721 * warn - log a warning message.
722 */
723void
724warn __V((char *fmt, ...))
725{
726    va_list pvar;
727
728#if defined(__STDC__)
729    va_start(pvar, fmt);
730#else
731    char *fmt;
732    va_start(pvar);
733    fmt = va_arg(pvar, char *);
734#endif
735
736    logit(LOG_WARNING, fmt, pvar);
737    va_end(pvar);
738}
739
740/*
741 * notice - log a notice-level message.
742 */
743void
744notice __V((char *fmt, ...))
745{
746    va_list pvar;
747
748#if defined(__STDC__)
749    va_start(pvar, fmt);
750#else
751    char *fmt;
752    va_start(pvar);
753    fmt = va_arg(pvar, char *);
754#endif
755
756    logit(LOG_NOTICE, fmt, pvar);
757    va_end(pvar);
758}
759
760/*
761 * info - log an informational message.
762 */
763void
764info __V((char *fmt, ...))
765{
766    va_list pvar;
767
768#if defined(__STDC__)
769    va_start(pvar, fmt);
770#else
771    char *fmt;
772    va_start(pvar);
773    fmt = va_arg(pvar, char *);
774#endif
775
776    logit(LOG_INFO, fmt, pvar);
777    va_end(pvar);
778}
779
780/*
781 * dbglog - log a debug message.
782 */
783void
784dbglog __V((char *fmt, ...))
785{
786    va_list pvar;
787
788#if defined(__STDC__)
789    va_start(pvar, fmt);
790#else
791    char *fmt;
792    va_start(pvar);
793    fmt = va_arg(pvar, char *);
794#endif
795
796    logit(LOG_DEBUG, fmt, pvar);
797    va_end(pvar);
798}
799
800/*
801 * dump_packet - print out a packet in readable form if it is interesting.
802 * Assumes len >= PPP_HDRLEN.
803 */
804void
805dump_packet(const char *tag, unsigned char *p, int len)
806{
807    int proto;
808
809    if (!debug)
810	return;
811
812    /*
813     * don't print LCP echo request/reply packets if debug <= 1
814     * and the link is up.
815     */
816    proto = (p[2] << 8) + p[3];
817    if (debug <= 1 && unsuccess == 0 && proto == PPP_LCP
818	&& len >= PPP_HDRLEN + HEADERLEN) {
819	unsigned char *lcp = p + PPP_HDRLEN;
820	int l = (lcp[2] << 8) + lcp[3];
821
822	if ((lcp[0] == ECHOREQ || lcp[0] == ECHOREP)
823	    && l >= HEADERLEN && l <= len - PPP_HDRLEN)
824	    return;
825    }
826
827    dbglog("%s %P", tag, p, len);
828}
829
830/*
831 * complete_read - read a full `count' bytes from fd,
832 * unless end-of-file or an error other than EINTR is encountered.
833 */
834ssize_t
835complete_read(int fd, void *buf, size_t count)
836{
837	size_t done;
838	ssize_t nb;
839	char *ptr = buf;
840
841	for (done = 0; done < count; ) {
842		nb = read(fd, ptr, count - done);
843		if (nb < 0) {
844			if (errno == EINTR)
845				continue;
846			return -1;
847		}
848		if (nb == 0)
849			break;
850		done += nb;
851		ptr += nb;
852	}
853	return done;
854}
855
856/* Procedures for locking the serial device using a lock file. */
857#ifndef LOCK_DIR
858#ifdef __linux__
859#define LOCK_DIR	"/var/lock"
860#else
861#ifdef SVR4
862#define LOCK_DIR	"/var/spool/locks"
863#else
864#define LOCK_DIR	"/var/spool/lock"
865#endif
866#endif
867#endif /* LOCK_DIR */
868
869static char lock_file[MAXPATHLEN];
870
871/*
872 * lock - create a lock file for the named device
873 */
874int
875lock(dev)
876    char *dev;
877{
878#ifdef LOCKLIB
879    int result;
880
881    result = mklock (dev, (void *) 0);
882    if (result == 0) {
883	strlcpy(lock_file, dev, sizeof(lock_file));
884	return 0;
885    }
886
887    if (result > 0)
888        notice("Device %s is locked by pid %d", dev, result);
889    else
890	error("Can't create lock file %s", lock_file);
891    return -1;
892
893#else /* LOCKLIB */
894
895    char lock_buffer[12];
896    int fd, pid, n;
897
898#ifdef SVR4
899    struct stat sbuf;
900
901    if (stat(dev, &sbuf) < 0) {
902	error("Can't get device number for %s: %m", dev);
903	return -1;
904    }
905    if ((sbuf.st_mode & S_IFMT) != S_IFCHR) {
906	error("Can't lock %s: not a character device", dev);
907	return -1;
908    }
909    slprintf(lock_file, sizeof(lock_file), "%s/LK.%03d.%03d.%03d",
910	     LOCK_DIR, major(sbuf.st_dev),
911	     major(sbuf.st_rdev), minor(sbuf.st_rdev));
912#else
913    char *p;
914    char lockdev[MAXPATHLEN];
915
916    if ((p = strstr(dev, "dev/")) != NULL) {
917	dev = p + 4;
918	strncpy(lockdev, dev, MAXPATHLEN-1);
919	lockdev[MAXPATHLEN-1] = 0;
920	while ((p = strrchr(lockdev, '/')) != NULL) {
921	    *p = '_';
922	}
923	dev = lockdev;
924    } else
925	if ((p = strrchr(dev, '/')) != NULL)
926	    dev = p + 1;
927
928    slprintf(lock_file, sizeof(lock_file), "%s/LCK..%s", LOCK_DIR, dev);
929#endif
930
931    while ((fd = open(lock_file, O_EXCL | O_CREAT | O_RDWR, 0644)) < 0) {
932	if (errno != EEXIST) {
933	    error("Can't create lock file %s: %m", lock_file);
934	    break;
935	}
936
937	/* Read the lock file to find out who has the device locked. */
938	fd = open(lock_file, O_RDONLY, 0);
939	if (fd < 0) {
940	    if (errno == ENOENT) /* This is just a timing problem. */
941		continue;
942	    error("Can't open existing lock file %s: %m", lock_file);
943	    break;
944	}
945#ifndef LOCK_BINARY
946	n = read(fd, lock_buffer, 11);
947#else
948	n = read(fd, &pid, sizeof(pid));
949#endif /* LOCK_BINARY */
950	close(fd);
951	fd = -1;
952	if (n <= 0) {
953	    error("Can't read pid from lock file %s", lock_file);
954	    break;
955	}
956
957	/* See if the process still exists. */
958#ifndef LOCK_BINARY
959	lock_buffer[n] = 0;
960	pid = atoi(lock_buffer);
961#endif /* LOCK_BINARY */
962	if (pid == getpid())
963	    return 1;		/* somebody else locked it for us */
964	if (pid == 0
965	    || (kill(pid, 0) == -1 && errno == ESRCH)) {
966	    if (unlink (lock_file) == 0) {
967		notice("Removed stale lock on %s (pid %d)", dev, pid);
968		continue;
969	    }
970	    warn("Couldn't remove stale lock on %s", dev);
971	} else
972	    notice("Device %s is locked by pid %d", dev, pid);
973	break;
974    }
975
976    if (fd < 0) {
977	lock_file[0] = 0;
978	return -1;
979    }
980
981    pid = getpid();
982#ifndef LOCK_BINARY
983    slprintf(lock_buffer, sizeof(lock_buffer), "%10d\n", pid);
984    write (fd, lock_buffer, 11);
985#else
986    write(fd, &pid, sizeof (pid));
987#endif
988    close(fd);
989    return 0;
990
991#endif
992}
993
994/*
995 * relock - called to update our lockfile when we are about to detach,
996 * thus changing our pid (we fork, the child carries on, and the parent dies).
997 * Note that this is called by the parent, with pid equal to the pid
998 * of the child.  This avoids a potential race which would exist if
999 * we had the child rewrite the lockfile (the parent might die first,
1000 * and another process could think the lock was stale if it checked
1001 * between when the parent died and the child rewrote the lockfile).
1002 */
1003int
1004relock(pid)
1005    int pid;
1006{
1007#ifdef LOCKLIB
1008    /* XXX is there a way to do this? */
1009    return -1;
1010#else /* LOCKLIB */
1011
1012    int fd;
1013    char lock_buffer[12];
1014
1015    if (lock_file[0] == 0)
1016	return -1;
1017    fd = open(lock_file, O_WRONLY, 0);
1018    if (fd < 0) {
1019	error("Couldn't reopen lock file %s: %m", lock_file);
1020	lock_file[0] = 0;
1021	return -1;
1022    }
1023
1024#ifndef LOCK_BINARY
1025    slprintf(lock_buffer, sizeof(lock_buffer), "%10d\n", pid);
1026    write (fd, lock_buffer, 11);
1027#else
1028    write(fd, &pid, sizeof(pid));
1029#endif /* LOCK_BINARY */
1030    close(fd);
1031    return 0;
1032
1033#endif /* LOCKLIB */
1034}
1035
1036/*
1037 * unlock - remove our lockfile
1038 */
1039void
1040unlock()
1041{
1042    if (lock_file[0]) {
1043#ifdef LOCKLIB
1044	(void) rmlock(lock_file, (void *) 0);
1045#else
1046	unlink(lock_file);
1047#endif
1048	lock_file[0] = 0;
1049    }
1050}
1051
1052