release/src/router/ppp/pppd/utils.c

   1 /*
   2  * utils.c - various utility functions used in pppd.
   3  *
   4  * Copyright (c) 1999 The Australian National University.
   5  * All rights reserved.
   6  *
   7  * Redistribution and use in source and binary forms are permitted
   8  * provided that the above copyright notice and this paragraph are
   9  * duplicated in all such forms and that any documentation,
  10  * advertising materials, and other materials related to such
  11  * distribution and use acknowledge that the software was developed
  12  * by the Australian National University.  The name of the University
  13  * may not be used to endorse or promote products derived from this
  14  * software without specific prior written permission.
  15  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
  16  * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
  17  * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
  18  */
  19
  20 #define RCSID   "$Id: utils.c,v 1.1.1.4 2003/10/14 08:09:53 sparq Exp $"
  21
  22 #include <stdio.h>
  23 #include <ctype.h>
  24 #include <stdlib.h>
  25 #include <string.h>
  26 #include <unistd.h>
  27 #include <signal.h>
  28 #include <errno.h>
  29 #include <fcntl.h>
  30 #include <syslog.h>
  31 #include <netdb.h>
  32 #include <utmp.h>
  33 #include <pwd.h>
  34 #include <sys/param.h>
  35 #include <sys/types.h>
  36 #include <sys/wait.h>
  37 #include <sys/time.h>
  38 #include <sys/resource.h>
  39 #include <sys/stat.h>
  40 #include <sys/socket.h>
  41 #include <netinet/in.h>
  42 #ifdef SVR4
  43 #include <sys/mkdev.h>
  44 #endif
  45
  46 #include "pppd.h"
  47
  48 static const char rcsid[] = RCSID;
  49
  50 #if defined(SUNOS4)
  51 extern char *strerror();
  52 #endif
  53
  54 static void logit __P((int, char *, va_list));
  55 static void log_write __P((int, char *));
  56 static void vslp_printer __P((void *, char *, ...));
  57 static void format_packet __P((u_char *, int, void (*) (void *, char *, ...),
  58                                void *));
  59
  60 struct buffer_info {
  61     char *ptr;
  62     int len;
  63 };
  64
  65 /*
  66  * strlcpy - like strcpy/strncpy, doesn't overflow destination buffer,
  67  * always leaves destination null-terminated (for len > 0).
  68  */
  69 size_t
  70 strlcpy(dest, src, len)
  71     char *dest;
  72     const char *src;
  73     size_t len;
  74 {
  75     size_t ret = strlen(src);
  76
  77     if (len != 0) {
  78         if (ret < len)
  79             strcpy(dest, src);
  80         else {
  81             strncpy(dest, src, len - 1);
  82             dest[len-1] = 0;
  83         }
  84     }
  85     return ret;
  86 }
  87
  88 /*
  89  * strlcat - like strcat/strncat, doesn't overflow destination buffer,
  90  * always leaves destination null-terminated (for len > 0).
  91  */
  92 size_t
  93 strlcat(dest, src, len)
  94     char *dest;
  95     const char *src;
  96     size_t len;
  97 {
  98     size_t dlen = strlen(dest);
  99
 100     return dlen + strlcpy(dest + dlen, src, (len > dlen? len - dlen: 0));
 101 }
 102
 103
 104 /*
 105  * slprintf - format a message into a buffer.  Like sprintf except we
 106  * also specify the length of the output buffer, and we handle
 107  * %r (recursive format), %m (error message), %v (visible string),
 108  * %q (quoted string), %t (current time) and %I (IP address) formats.
 109  * Doesn't do floating-point formats.
 110  * Returns the number of chars put into buf.
 111  */
 112 int
 113 slprintf __V((char *buf, int buflen, char *fmt, ...))
 114 {
 115     va_list args;
 116     int n;
 117
 118 #if defined(__STDC__)
 119     va_start(args, fmt);
 120 #else
 121     char *buf;
 122     int buflen;
 123     char *fmt;
 124     va_start(args);
 125     buf = va_arg(args, char *);
 126     buflen = va_arg(args, int);
 127     fmt = va_arg(args, char *);
 128 #endif
 129     n = vslprintf(buf, buflen, fmt, args);
 130     va_end(args);
 131     return n;
 132 }
 133
 134 /*
 135  * vslprintf - like slprintf, takes a va_list instead of a list of args.
 136  */
 137 #define OUTCHAR(c)      (buflen > 0? (--buflen, *buf++ = (c)): 0)
 138
 139 int
 140 vslprintf(buf, buflen, fmt, args)
 141     char *buf;
 142     int buflen;
 143     char *fmt;
 144     va_list args;
 145 {
 146     int c, i, n;
 147     int width, prec, fillch;
 148     int base, len, neg, quoted;
 149     unsigned long val = 0;
 150     char *str, *f, *buf0;
 151     unsigned char *p;
 152     char num[32];
 153     time_t t;
 154     u_int32_t ip;
 155     static char hexchars[] = "0123456789abcdef";
 156     struct buffer_info bufinfo;
 157
 158     buf0 = buf;
 159     --buflen;
 160     while (buflen > 0) {
 161         for (f = fmt; *f != '%' && *f != 0; ++f)
 162             ;
 163         if (f > fmt) {
 164             len = f - fmt;
 165             if (len > buflen)
 166                 len = buflen;
 167             memcpy(buf, fmt, len);
 168             buf += len;
 169             buflen -= len;
 170             fmt = f;
 171         }
 172         if (*fmt == 0)
 173             break;
 174         c = *++fmt;
 175         width = 0;
 176         prec = -1;
 177         fillch = ' ';
 178         if (c == '0') {
 179             fillch = '0';
 180             c = *++fmt;
 181         }
 182         if (c == '*') {
 183             width = va_arg(args, int);
 184             c = *++fmt;
 185         } else {
 186             while (isdigit(c)) {
 187                 width = width * 10 + c - '0';
 188                 c = *++fmt;
 189             }
 190         }
 191         if (c == '.') {
 192             c = *++fmt;
 193             if (c == '*') {
 194                 prec = va_arg(args, int);
 195                 c = *++fmt;
 196             } else {
 197                 prec = 0;
 198                 while (isdigit(c)) {
 199                     prec = prec * 10 + c - '0';
 200                     c = *++fmt;
 201                 }
 202             }
 203         }
 204         str = 0;
 205         base = 0;
 206         neg = 0;
 207         ++fmt;
 208         switch (c) {
 209         case 'd':
 210             i = va_arg(args, int);
 211             if (i < 0) {
 212                 neg = 1;
 213                 val = -i;
 214             } else
 215                 val = i;
 216             base = 10;
 217             break;
 218         case 'u':
 219             val = va_arg(args, unsigned int);
 220             base = 10;
 221             break;
 222         case 'o':
 223             val = va_arg(args, unsigned int);
 224             base = 8;
 225             break;
 226         case 'x':
 227         case 'X':
 228             val = va_arg(args, unsigned int);
 229             base = 16;
 230             break;
 231         case 'p':
 232             val = (unsigned long) va_arg(args, void *);
 233             base = 16;
 234             neg = 2;
 235             break;
 236         case 's':
 237             str = va_arg(args, char *);
 238             break;
 239         case 'c':
 240             num[0] = va_arg(args, int);
 241             num[1] = 0;
 242             str = num;
 243             break;
 244         case 'm':
 245             str = strerror(errno);
 246             break;
 247         case 'I':
 248             ip = va_arg(args, u_int32_t);
 249             ip = ntohl(ip);
 250             slprintf(num, sizeof(num), "%d.%d.%d.%d", (ip >> 24) & 0xff,
 251                      (ip >> 16) & 0xff, (ip >> 8) & 0xff, ip & 0xff);
 252             str = num;
 253             break;
 254         case 'r':
 255             f = va_arg(args, char *);
 256 #ifndef __powerpc__
 257             n = vslprintf(buf, buflen + 1, f, va_arg(args, va_list));
 258 #else
 259             /* On the powerpc, a va_list is an array of 1 structure */
 260             n = vslprintf(buf, buflen + 1, f, va_arg(args, void *));
 261 #endif
 262             buf += n;
 263             buflen -= n;
 264             continue;
 265         case 't':
 266             time(&t);
 267             str = ctime(&t);
 268             str += 4;           /* chop off the day name */
 269             str[15] = 0;        /* chop off year and newline */
 270             break;
 271         case 'v':               /* "visible" string */
 272         case 'q':               /* quoted string */
 273             quoted = c == 'q';
 274             p = va_arg(args, unsigned char *);
 275             if (fillch == '0' && prec >= 0) {
 276                 n = prec;
 277             } else {
 278                 n = strlen((char *)p);
 279                 if (prec >= 0 && n > prec)
 280                     n = prec;
 281             }
 282             while (n > 0 && buflen > 0) {
 283                 c = *p++;
 284                 --n;
 285                 if (!quoted && c >= 0x80) {
 286                     OUTCHAR('M');
 287                     OUTCHAR('-');
 288                     c -= 0x80;
 289                 }
 290                 if (quoted && (c == '"' || c == '\\'))
 291                     OUTCHAR('\\');
 292                 if (c < 0x20 || (0x7f <= c && c < 0xa0)) {
 293                     if (quoted) {
 294                         OUTCHAR('\\');
 295                         switch (c) {
 296                         case '\t':      OUTCHAR('t');   break;
 297                         case '\n':      OUTCHAR('n');   break;
 298                         case '\b':      OUTCHAR('b');   break;
 299                         case '\f':      OUTCHAR('f');   break;
 300                         default:
 301                             OUTCHAR('x');
 302                             OUTCHAR(hexchars[c >> 4]);
 303                             OUTCHAR(hexchars[c & 0xf]);
 304                         }
 305                     } else {
 306                         if (c == '\t')
 307                             OUTCHAR(c);
 308                         else {
 309                             OUTCHAR('^');
 310                             OUTCHAR(c ^ 0x40);
 311                         }
 312                     }
 313                 } else
 314                     OUTCHAR(c);
 315             }
 316             continue;
 317         case 'P':               /* print PPP packet */
 318             bufinfo.ptr = buf;
 319             bufinfo.len = buflen + 1;
 320             p = va_arg(args, unsigned char *);
 321             n = va_arg(args, int);
 322             format_packet(p, n, vslp_printer, &bufinfo);
 323             buf = bufinfo.ptr;
 324             buflen = bufinfo.len - 1;
 325             continue;
 326         case 'B':
 327             p = va_arg(args, unsigned char *);
 328             for (n = prec; n > 0; --n) {
 329                 c = *p++;
 330                 if (fillch == ' ')
 331                     OUTCHAR(' ');
 332                 OUTCHAR(hexchars[(c >> 4) & 0xf]);
 333                 OUTCHAR(hexchars[c & 0xf]);
 334             }
 335             continue;
 336         default:
 337             *buf++ = '%';
 338             if (c != '%')
 339                 --fmt;          /* so %z outputs %z etc. */
 340             --buflen;
 341             continue;
 342         }
 343         if (base != 0) {
 344             str = num + sizeof(num);
 345             *--str = 0;
 346             while (str > num + neg) {
 347                 *--str = hexchars[val % base];
 348                 val = val / base;
 349                 if (--prec <= 0 && val == 0)
 350                     break;
 351             }
 352             switch (neg) {
 353             case 1:
 354                 *--str = '-';
 355                 break;
 356             case 2:
 357                 *--str = 'x';
 358                 *--str = '0';
 359                 break;
 360             }
 361             len = num + sizeof(num) - 1 - str;
 362         } else {
 363             len = strlen(str);
 364             if (prec >= 0 && len > prec)
 365                 len = prec;
 366         }
 367         if (width > 0) {
 368             if (width > buflen)
 369                 width = buflen;
 370             if ((n = width - len) > 0) {
 371                 buflen -= n;
 372                 for (; n > 0; --n)
 373                     *buf++ = fillch;
 374             }
 375         }
 376         if (len > buflen)
 377             len = buflen;
 378         memcpy(buf, str, len);
 379         buf += len;
 380         buflen -= len;
 381     }
 382     *buf = 0;
 383     return buf - buf0;
 384 }
 385
 386 /*
 387  * vslp_printer - used in processing a %P format
 388  */
 389 static void
 390 vslp_printer __V((void *arg, char *fmt, ...))
 391 {
 392     int n;
 393     va_list pvar;
 394     struct buffer_info *bi;
 395
 396 #if defined(__STDC__)
 397     va_start(pvar, fmt);
 398 #else
 399     void *arg;
 400     char *fmt;
 401     va_start(pvar);
 402     arg = va_arg(pvar, void *);
 403     fmt = va_arg(pvar, char *);
 404 #endif
 405
 406     bi = (struct buffer_info *) arg;
 407     n = vslprintf(bi->ptr, bi->len, fmt, pvar);
 408     va_end(pvar);
 409
 410     bi->ptr += n;
 411     bi->len -= n;
 412 }
 413
 414 #ifdef unused
 415 /*
 416  * log_packet - format a packet and log it.
 417  */
 418
 419 void
 420 log_packet(p, len, prefix, level)
 421     u_char *p;
 422     int len;
 423     char *prefix;
 424     int level;
 425 {
 426         init_pr_log(prefix, level);
 427         format_packet(p, len, pr_log, &level);
 428         end_pr_log();
 429 }
 430 #endif /* unused */
 431
 432 /*
 433  * format_packet - make a readable representation of a packet,
 434  * calling `printer(arg, format, ...)' to output it.
 435  */
 436 static void
 437 format_packet(p, len, printer, arg)
 438     u_char *p;
 439     int len;
 440     void (*printer) __P((void *, char *, ...));
 441     void *arg;
 442 {
 443     int i, n;
 444     u_short proto;
 445     struct protent *protp;
 446
 447     if (len >= PPP_HDRLEN && p[0] == PPP_ALLSTATIONS && p[1] == PPP_UI) {
 448         p += 2;
 449         GETSHORT(proto, p);
 450         len -= PPP_HDRLEN;
 451         for (i = 0; (protp = protocols[i]) != NULL; ++i)
 452             if (proto == protp->protocol)
 453                 break;
 454         if (protp != NULL) {
 455             printer(arg, "[%s", protp->name);
 456             n = (*protp->printpkt)(p, len, printer, arg);
 457             printer(arg, "]");
 458             p += n;
 459             len -= n;
 460         } else {
 461             for (i = 0; (protp = protocols[i]) != NULL; ++i)
 462                 if (proto == (protp->protocol & ~0x8000))
 463                     break;
 464             if (protp != 0 && protp->data_name != 0) {
 465                 printer(arg, "[%s data]", protp->data_name);
 466                 if (len > 8)
 467                     printer(arg, "%.8B ...", p);
 468                 else
 469                     printer(arg, "%.*B", len, p);
 470                 len = 0;
 471             } else
 472                 printer(arg, "[proto=0x%x]", proto);
 473         }
 474     }
 475
 476     if (len > 32)
 477         printer(arg, "%.32B ...", p);
 478     else
 479         printer(arg, "%.*B", len, p);
 480 }
 481
 482 /*
 483  * init_pr_log, end_pr_log - initialize and finish use of pr_log.
 484  */
 485
 486 static char line[256];          /* line to be logged accumulated here */
 487 static char *linep;             /* current pointer within line */
 488 static int llevel;              /* level for logging */
 489
 490 void
 491 init_pr_log(prefix, level)
 492      char *prefix;
 493      int level;
 494 {
 495         linep = line;
 496         if (prefix != NULL) {
 497                 strlcpy(line, prefix, sizeof(line));
 498                 linep = line + strlen(line);
 499         }
 500         llevel = level;
 501 }
 502
 503 void
 504 end_pr_log()
 505 {
 506         if (linep != line) {
 507                 *linep = 0;
 508                 log_write(llevel, line);
 509         }
 510 }
 511
 512 /*
 513  * pr_log - printer routine for outputting to syslog
 514  */
 515 void
 516 pr_log __V((void *arg, char *fmt, ...))
 517 {
 518         int l, n;
 519         va_list pvar;
 520         char *p, *eol;
 521         char buf[256];
 522
 523 #if defined(__STDC__)
 524         va_start(pvar, fmt);
 525 #else
 526         void *arg;
 527         char *fmt;
 528         va_start(pvar);
 529         arg = va_arg(pvar, void *);
 530         fmt = va_arg(pvar, char *);
 531 #endif
 532
 533         n = vslprintf(buf, sizeof(buf), fmt, pvar);
 534         va_end(pvar);
 535
 536         p = buf;
 537         eol = strchr(buf, '\n');
 538         if (linep != line) {
 539                 l = (eol == NULL)? n: eol - buf;
 540                 if (linep + l < line + sizeof(line)) {
 541                         if (l > 0) {
 542                                 memcpy(linep, buf, l);
 543                                 linep += l;
 544                         }
 545                         if (eol == NULL)
 546                                 return;
 547                         p = eol + 1;
 548                         eol = strchr(p, '\n');
 549                 }
 550                 *linep = 0;
 551                 log_write(llevel, line);
 552                 linep = line;
 553         }
 554
 555         while (eol != NULL) {
 556                 *eol = 0;
 557                 log_write(llevel, p);
 558                 p = eol + 1;
 559                 eol = strchr(p, '\n');
 560         }
 561
 562         /* assumes sizeof(buf) <= sizeof(line) */
 563         l = buf + n - p;
 564         if (l > 0) {
 565                 memcpy(line, p, n);
 566                 linep = line + l;
 567         }
 568 }
 569
 570 /*
 571  * print_string - print a readable representation of a string using
 572  * printer.
 573  */
 574 void
 575 print_string(p, len, printer, arg)
 576     char *p;
 577     int len;
 578     void (*printer) __P((void *, char *, ...));
 579     void *arg;
 580 {
 581     int c;
 582
 583     printer(arg, "\"");
 584     for (; len > 0; --len) {
 585         c = *p++;
 586         if (' ' <= c && c <= '~') {
 587             if (c == '\\' || c == '"')
 588                 printer(arg, "\\");
 589             printer(arg, "%c", c);
 590         } else {
 591             switch (c) {
 592             case '\n':
 593                 printer(arg, "\\n");
 594                 break;
 595             case '\r':
 596                 printer(arg, "\\r");
 597                 break;
 598             case '\t':
 599                 printer(arg, "\\t");
 600                 break;
 601             default:
 602                 printer(arg, "\\%.3o", c);
 603             }
 604         }
 605     }
 606     printer(arg, "\"");
 607 }
 608
 609 /*
 610  * logit - does the hard work for fatal et al.
 611  */
 612 static void
 613 logit(level, fmt, args)
 614     int level;
 615     char *fmt;
 616     va_list args;
 617 {
 618     int n;
 619     char buf[1024];
 620
 621     n = vslprintf(buf, sizeof(buf), fmt, args);
 622     log_write(level, buf);
 623 }
 624
 625 static void
 626 log_write(level, buf)
 627     int level;
 628     char *buf;
 629 {
 630     syslog(level, "%s", buf);
 631     if (log_to_fd >= 0 && (level != LOG_DEBUG || debug)) {
 632         int n = strlen(buf);
 633
 634         if (n > 0 && buf[n-1] == '\n')
 635             --n;
 636         if (write(log_to_fd, buf, n) != n
 637             || write(log_to_fd, "\n", 1) != 1)
 638             log_to_fd = -1;
 639     }
 640 }
 641
 642 /*
 643  * fatal - log an error message and die horribly.
 644  */
 645 void
 646 fatal __V((char *fmt, ...))
 647 {
 648     va_list pvar;
 649
 650 #if defined(__STDC__)
 651     va_start(pvar, fmt);
 652 #else
 653     char *fmt;
 654     va_start(pvar);
 655     fmt = va_arg(pvar, char *);
 656 #endif
 657
 658     logit(LOG_ERR, fmt, pvar);
 659     va_end(pvar);
 660
 661     die(1);                     /* as promised */
 662 }
 663
 664 /*
 665  * error - log an error message.
 666  */
 667 void
 668 error __V((char *fmt, ...))
 669 {
 670     va_list pvar;
 671
 672 #if defined(__STDC__)
 673     va_start(pvar, fmt);
 674 #else
 675     char *fmt;
 676     va_start(pvar);
 677     fmt = va_arg(pvar, char *);
 678 #endif
 679
 680     logit(LOG_ERR, fmt, pvar);
 681     va_end(pvar);
 682 }
 683
 684 /*
 685  * warn - log a warning message.
 686  */
 687 void
 688 warn __V((char *fmt, ...))
 689 {
 690     va_list pvar;
 691
 692 #if defined(__STDC__)
 693     va_start(pvar, fmt);
 694 #else
 695     char *fmt;
 696     va_start(pvar);
 697     fmt = va_arg(pvar, char *);
 698 #endif
 699
 700     logit(LOG_WARNING, fmt, pvar);
 701     va_end(pvar);
 702 }
 703
 704 /*
 705  * notice - log a notice-level message.
 706  */
 707 void
 708 notice __V((char *fmt, ...))
 709 {
 710     va_list pvar;
 711
 712 #if defined(__STDC__)
 713     va_start(pvar, fmt);
 714 #else
 715     char *fmt;
 716     va_start(pvar);
 717     fmt = va_arg(pvar, char *);
 718 #endif
 719
 720     logit(LOG_NOTICE, fmt, pvar);
 721     va_end(pvar);
 722 }
 723
 724 /*
 725  * info - log an informational message.
 726  */
 727 void
 728 info __V((char *fmt, ...))
 729 {
 730     va_list pvar;
 731
 732 #if defined(__STDC__)
 733     va_start(pvar, fmt);
 734 #else
 735     char *fmt;
 736     va_start(pvar);
 737     fmt = va_arg(pvar, char *);
 738 #endif
 739
 740     logit(LOG_INFO, fmt, pvar);
 741     va_end(pvar);
 742 }
 743
 744 /*
 745  * dbglog - log a debug message.
 746  */
 747 void
 748 dbglog __V((char *fmt, ...))
 749 {
 750     va_list pvar;
 751
 752 #if defined(__STDC__)
 753     va_start(pvar, fmt);
 754 #else
 755     char *fmt;
 756     va_start(pvar);
 757     fmt = va_arg(pvar, char *);
 758 #endif
 759
 760     logit(LOG_DEBUG, fmt, pvar);
 761     va_end(pvar);
 762 }
 763
 764 /* Procedures for locking the serial device using a lock file. */
 765 #ifndef LOCK_DIR
 766 #ifdef _linux_
 767 #define LOCK_DIR        "/var/lock"
 768 #else
 769 #ifdef SVR4
 770 #define LOCK_DIR        "/var/spool/locks"
 771 #else
 772 #define LOCK_DIR        "/var/spool/lock"
 773 #endif
 774 #endif
 775 #endif /* LOCK_DIR */
 776
 777 static char lock_file[MAXPATHLEN];
 778
 779 /*
 780  * lock - create a lock file for the named device
 781  */
 782 int
 783 lock(dev)
 784     char *dev;
 785 {
 786 #ifdef LOCKLIB
 787     int result;
 788
 789     result = mklock (dev, (void *) 0);
 790     if (result == 0) {
 791         strlcpy(lock_file, sizeof(lock_file), dev);
 792         return 0;
 793     }
 794
 795     if (result > 0)
 796         notice("Device %s is locked by pid %d", dev, result);
 797     else
 798         error("Can't create lock file %s", lock_file);
 799     return -1;
 800
 801 #else /* LOCKLIB */
 802
 803     char lock_buffer[12];
 804     int fd, pid, n;
 805
 806 #ifdef SVR4
 807     struct stat sbuf;
 808
 809     if (stat(dev, &sbuf) < 0) {
 810         error("Can't get device number for %s: %m", dev);
 811         return -1;
 812     }
 813     if ((sbuf.st_mode & S_IFMT) != S_IFCHR) {
 814         error("Can't lock %s: not a character device", dev);
 815         return -1;
 816     }
 817     slprintf(lock_file, sizeof(lock_file), "%s/LK.%03d.%03d.%03d",
 818              LOCK_DIR, major(sbuf.st_dev),
 819              major(sbuf.st_rdev), minor(sbuf.st_rdev));
 820 #else
 821     char *p;
 822
 823     if ((p = strrchr(dev, '/')) != NULL)
 824         dev = p + 1;
 825     slprintf(lock_file, sizeof(lock_file), "%s/LCK..%s", LOCK_DIR, dev);
 826 #endif
 827
 828     while ((fd = open(lock_file, O_EXCL | O_CREAT | O_RDWR, 0644)) < 0) {
 829         if (errno != EEXIST) {
 830             error("Can't create lock file %s: %m", lock_file);
 831             break;
 832         }
 833
 834         /* Read the lock file to find out who has the device locked. */
 835         fd = open(lock_file, O_RDONLY, 0);
 836         if (fd < 0) {
 837             if (errno == ENOENT) /* This is just a timing problem. */
 838                 continue;
 839             error("Can't open existing lock file %s: %m", lock_file);
 840             break;
 841         }
 842 #ifndef LOCK_BINARY
 843         n = read(fd, lock_buffer, 11);
 844 #else
 845         n = read(fd, &pid, sizeof(pid));
 846 #endif /* LOCK_BINARY */
 847         close(fd);
 848         fd = -1;
 849         if (n <= 0) {
 850             error("Can't read pid from lock file %s", lock_file);
 851             break;
 852         }
 853
 854         /* See if the process still exists. */
 855 #ifndef LOCK_BINARY
 856         lock_buffer[n] = 0;
 857         pid = atoi(lock_buffer);
 858 #endif /* LOCK_BINARY */
 859         if (pid == getpid())
 860             return 1;           /* somebody else locked it for us */
 861         if (pid == 0
 862             || (kill(pid, 0) == -1 && errno == ESRCH)) {
 863             if (unlink (lock_file) == 0) {
 864                 notice("Removed stale lock on %s (pid %d)", dev, pid);
 865                 continue;
 866             }
 867             warn("Couldn't remove stale lock on %s", dev);
 868         } else
 869             notice("Device %s is locked by pid %d", dev, pid);
 870         break;
 871     }
 872
 873     if (fd < 0) {
 874         lock_file[0] = 0;
 875         return -1;
 876     }
 877
 878     pid = getpid();
 879 #ifndef LOCK_BINARY
 880     slprintf(lock_buffer, sizeof(lock_buffer), "%10d\n", pid);
 881     write (fd, lock_buffer, 11);
 882 #else
 883     write(fd, &pid, sizeof (pid));
 884 #endif
 885     close(fd);
 886     return 0;
 887
 888 #endif
 889 }
 890
 891 /*
 892  * relock - called to update our lockfile when we are about to detach,
 893  * thus changing our pid (we fork, the child carries on, and the parent dies).
 894  * Note that this is called by the parent, with pid equal to the pid
 895  * of the child.  This avoids a potential race which would exist if
 896  * we had the child rewrite the lockfile (the parent might die first,
 897  * and another process could think the lock was stale if it checked
 898  * between when the parent died and the child rewrote the lockfile).
 899  */
 900 int
 901 relock(pid)
 902     int pid;
 903 {
 904 #ifdef LOCKLIB
 905     return -1;
 906 #else /* LOCKLIB */
 907
 908     int fd;
 909     char lock_buffer[12];
 910
 911     if (lock_file[0] == 0)
 912         return -1;
 913     fd = open(lock_file, O_WRONLY, 0);
 914     if (fd < 0) {
 915         error("Couldn't reopen lock file %s: %m", lock_file);
 916         lock_file[0] = 0;
 917         return -1;
 918     }
 919
 920 #ifndef LOCK_BINARY
 921     slprintf(lock_buffer, sizeof(lock_buffer), "%10d\n", pid);
 922     write (fd, lock_buffer, 11);
 923 #else
 924     write(fd, &pid, sizeof(pid));
 925 #endif /* LOCK_BINARY */
 926     close(fd);
 927     return 0;
 928
 929 #endif /* LOCKLIB */
 930 }
 931
 932 /*
 933  * unlock - remove our lockfile
 934  */
 935 void
 936 unlock()
 937 {
 938     if (lock_file[0]) {
 939 #ifdef LOCKLIB
 940         (void) rmlock(lock_file, (void *) 0);
 941 #else
 942         unlink(lock_file);
 943 #endif
 944         lock_file[0] = 0;
 945     }
 946 }
 947