usr.bin/calendar/calendar.c

   1 /*      $NetBSD: calendar.c,v 1.52 2015/07/01 06:48:25 dholland Exp $   */
   2
   3 /*
   4  * Copyright (c) 1989, 1993, 1994
   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. Neither the name of the University nor the names of its contributors
  16  *    may be used to endorse or promote products derived from this software
  17  *    without specific prior written permission.
  18  *
  19  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  29  * SUCH DAMAGE.
  30  */
  31
  32 #include <sys/cdefs.h>
  33 #ifndef lint
  34 __COPYRIGHT("@(#) Copyright (c) 1989, 1993\
  35  The Regents of the University of California.  All rights reserved.");
  36 #endif /* not lint */
  37
  38 #ifndef lint
  39 #if 0
  40 static char sccsid[] = "@(#)calendar.c  8.4 (Berkeley) 1/7/95";
  41 #endif
  42 __RCSID("$NetBSD: calendar.c,v 1.52 2015/07/01 06:48:25 dholland Exp $");
  43 #endif /* not lint */
  44
  45 #include <sys/param.h>
  46 #include <sys/ioctl.h>
  47 #include <sys/time.h>
  48 #include <sys/stat.h>
  49 #include <sys/uio.h>
  50 #include <sys/wait.h>
  51
  52 #include <assert.h>
  53 #include <ctype.h>
  54 #include <err.h>
  55 #include <errno.h>
  56 #include <fcntl.h>
  57 #include <pwd.h>
  58 #include <stdbool.h>
  59 #include <stdio.h>
  60 #include <stdlib.h>
  61 #include <string.h>
  62 #include <time.h>
  63 #include <tzfile.h>
  64 #include <unistd.h>
  65
  66 #include "pathnames.h"
  67
  68         /* flags used by calendar file parser */
  69 #define F_ISMONTH       0x01
  70 #define F_ISDAY         0x02
  71 #define F_ISDOW         0x04
  72 #define F_WILDMONTH     0x10
  73 #define F_WILDDAY       0x20
  74
  75 static unsigned short lookahead = 1;
  76 static unsigned short weekend = 2;
  77 static char *fname = NULL;
  78 static char *datestr = NULL;
  79 static const char *defaultnames[] = {"calendar", ".calendar", _PATH_SYSTEM_CALENDAR, NULL};
  80 static struct passwd *pw;
  81 static char path[MAXPATHLEN + 1];
  82 static bool doall = false;
  83 static bool cpp_restricted = false;
  84
  85 /* 1-based month, 0-based days, cumulative */
  86 static const int daytab[][14] = {
  87         { 0, -1, 30, 58, 89, 119, 150, 180, 211, 242, 272, 303, 333, 364 },
  88         { 0, -1, 30, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334, 365 },
  89 };
  90 static struct tm *tp;
  91 static const int *cumdays;
  92 static int offset, yrdays;
  93 static char dayname[10];
  94
  95 static struct iovec header[] = {
  96         { __UNCONST("From: "), 6 },
  97         { NULL, 0 },
  98         { __UNCONST(" (Reminder Service)\nTo: "), 24 },
  99         { NULL, 0 },
 100         { __UNCONST("\nSubject: "), 10 },
 101         { NULL, 0 },
 102         { __UNCONST("'s Calendar\nPrecedence: bulk\n\n"),  30 },
 103 };
 104
 105 static const char *days[] = {
 106         "sun", "mon", "tue", "wed", "thu", "fri", "sat", NULL,
 107 };
 108
 109 static const char *months[] = {
 110         "jan", "feb", "mar", "apr", "may", "jun",
 111         "jul", "aug", "sep", "oct", "nov", "dec", NULL,
 112 };
 113
 114 static void      atodays(int, char *, unsigned short *);
 115 static void      cal(void);
 116 static void      closecal(FILE *);
 117 static void      changeuser(void);
 118 static int       getday(char *);
 119 static int       getfield(char *, char **, int *);
 120 static void      getmmdd(struct tm *, char *);
 121 static int       getmonth(char *);
 122 static bool      isnow(char *);
 123 static FILE     *opencal(FILE **);
 124 static int       tryopen(const char *, int);
 125 static void      settime(void);
 126 static void      usage(void) __dead;
 127
 128 int
 129 main(int argc, char **argv)
 130 {
 131         int ch;
 132         const char *caldir;
 133
 134         (void)setprogname(argv[0]);     /* for portability */
 135
 136         while ((ch = getopt(argc, argv, "-ad:f:l:w:x")) != -1) {
 137                 switch (ch) {
 138                 case '-':               /* backward contemptible */
 139                 case 'a':
 140                         if (getuid()) {
 141                                 errno = EPERM;
 142                                 err(EXIT_FAILURE, NULL);
 143                         }
 144                         doall = true;
 145                         break;
 146                 case 'd':
 147                         datestr = optarg;
 148                         break;
 149                 case 'f':
 150                         fname = optarg;
 151                         break;
 152                 case 'l':
 153                         atodays(ch, optarg, &lookahead);
 154                         break;
 155                 case 'w':
 156                         atodays(ch, optarg, &weekend);
 157                         break;
 158                 case 'x':
 159                         cpp_restricted = true;
 160                         break;
 161                 case '?':
 162                 default:
 163                         usage();
 164                 }
 165         }
 166         argc -= optind;
 167         argv += optind;
 168
 169         if (argc)
 170                 usage();
 171
 172         settime();
 173         if (doall) {
 174                 /*
 175                  * XXX - This ignores the user's CALENDAR_DIR variable.
 176                  *       Run under user's login shell?
 177                  */
 178                 if (setgroups(0, NULL) == -1) {
 179                         err(EXIT_FAILURE, "setgroups");
 180                 }
 181                 while ((pw = getpwent()) != NULL) {
 182                         if (setegid(pw->pw_gid) == -1) {
 183                                 warn("%s: setegid", pw->pw_name);
 184                                 continue;
 185                         }
 186                         if (seteuid(pw->pw_uid) == -1) {
 187                                 warn("%s: seteuid", pw->pw_name);
 188                                 continue;
 189                         }
 190                         if (chdir(pw->pw_dir) != -1) {
 191                                 cal();
 192                         }
 193                         if (seteuid(0) == -1) {
 194                                 warn("%s: seteuid back to 0", pw->pw_name);
 195                         }
 196                 }
 197         } else if ((caldir = getenv("CALENDAR_DIR")) != NULL) {
 198                 if (chdir(caldir) != -1)
 199                         cal();
 200         } else if ((pw = getpwuid(geteuid())) != NULL) {
 201                 if (chdir(pw->pw_dir) != -1)
 202                         cal();
 203         }
 204         return 0;
 205 }
 206
 207 static void
 208 cal(void)
 209 {
 210         bool printing;
 211         FILE *fp, *in = NULL;
 212         char *line;
 213
 214         if ((fp = opencal(&in)) == NULL || in == NULL)
 215                 return;
 216         printing = false;
 217         while ((line = fparseln(in,
 218                     NULL, NULL, NULL, FPARSELN_UNESCCOMM)) != NULL) {
 219                 if (line[0] == '\0')
 220                         continue;
 221                 if (line[0] != '\t')
 222                         printing = isnow(line);
 223                 if (printing)
 224                         (void)fprintf(fp, "%s\n", line);
 225                 free(line);
 226
 227         }
 228         closecal(fp);
 229 }
 230
 231 static void
 232 settime(void)
 233 {
 234         time_t now;
 235
 236         (void)time(&now);
 237         tp = localtime(&now);
 238         if (datestr)
 239                 getmmdd(tp, datestr);
 240
 241         if (isleap(tp->tm_year + TM_YEAR_BASE)) {
 242                 yrdays = DAYSPERLYEAR;
 243                 cumdays = daytab[1];
 244         } else {
 245                 yrdays = DAYSPERNYEAR;
 246                 cumdays = daytab[0];
 247         }
 248         /* Friday displays Monday's events */
 249         offset = tp->tm_wday == 5 ? lookahead + weekend : lookahead;
 250         header[5].iov_base = dayname;
 251         header[5].iov_len = strftime(dayname, sizeof(dayname), "%A", tp);
 252 }
 253
 254 /*
 255  * Possible date formats include any combination of:
 256  *      3-charmonth                     (January, Jan, Jan)
 257  *      3-charweekday                   (Friday, Monday, mon.)
 258  *      numeric month or day            (1, 2, 04)
 259  *
 260  * Any character may separate them, or they may not be separated.  Any line,
 261  * following a line that is matched, that starts with "whitespace", is shown
 262  * along with the matched line.
 263  */
 264 static bool
 265 isnow(char *endp)
 266 {
 267         int day;
 268         int flags;
 269         int month;
 270         int v1;
 271         int v2;
 272
 273         flags = 0;
 274
 275         /* didn't recognize anything, skip it */
 276         if (!(v1 = getfield(endp, &endp, &flags)))
 277                 return false;
 278
 279         if ((flags & (F_ISDAY|F_ISDOW)) || v1 > 12) {
 280                 /* found a day */
 281                 day = v1;
 282                 /* if no recognizable month, assume wildcard ('*') month */
 283                 if ((month = getfield(endp, &endp, &flags)) == 0) {
 284                         flags |= F_ISMONTH | F_WILDMONTH;
 285                         month = tp->tm_mon + 1;
 286                 }
 287         } else if (flags & F_ISMONTH) {
 288                 month = v1;
 289                 /* if no recognizable day, assume the first */
 290                 if ((day = getfield(endp, &endp, &flags)) == 0)
 291                         day = 1;
 292         } else {
 293                 v2 = getfield(endp, &endp, &flags);
 294                 if (flags & F_ISMONTH) {
 295                         day = v1;
 296                         month = v2;
 297                 } else {
 298                         /* F_ISDAY set, v2 > 12, or no way to tell */
 299                         month = v1;
 300                         /* if no recognizable day, assume the first */
 301                         day = v2 ? v2 : 1;
 302                 }
 303         }
 304         /* if month is out of range, treat it as '*' */
 305         if (month < 1 || month > 12) {
 306                 flags |= F_ISMONTH | F_WILDMONTH;
 307                 month = tp->tm_mon + 1;
 308         }
 309
 310         if (flags & F_WILDMONTH && flags & F_WILDDAY)
 311                 return true;
 312
 313         if (flags & F_WILDMONTH && flags & F_ISDAY && day == tp->tm_mday)
 314                 return true;
 315
 316         if (flags & F_WILDMONTH && flags & F_ISDOW && day == tp->tm_wday + 1)
 317                 return true;
 318
 319         if (flags & F_ISMONTH && flags & F_WILDDAY && month == tp->tm_mon + 1)
 320                 return true;
 321
 322         if (flags & F_ISMONTH && flags & F_ISDOW && month == tp->tm_mon + 1 &&
 323             day == tp->tm_wday + 1)
 324                 return true;
 325
 326         if (flags & F_ISDOW)
 327                 day = tp->tm_mday + (((day - 1) - tp->tm_wday + 7) % 7);
 328         day = cumdays[month] + day;
 329
 330         /* if today or today + offset days */
 331         if (day >= tp->tm_yday && day <= tp->tm_yday + offset)
 332                 return true;
 333
 334         /* if number of days left in this year + days to event in next year */
 335         if (yrdays - tp->tm_yday + day <= offset)
 336                 return true;
 337
 338         return false;
 339 }
 340
 341 static int
 342 getfield(char *p, char **endp, int *flags)
 343 {
 344         int val;
 345         char *start;
 346         char savech;
 347
 348 /*
 349  * note this macro has an arg that isn't used ... it is retained
 350  * (it is believed) to make the macro call look more "natural"
 351  * and suggest at the call site what is happening.
 352  */
 353 #define FLDCHAR(a) (*p != '\0' && !isdigit((unsigned char)*p) && \
 354     !isalpha((unsigned char)*p) && *p != '*')
 355
 356         val = 0;
 357         for (/*EMPTY*/; FLDCHAR(*p); ++p)
 358                 continue;
 359         if (*p == '*') {                        /* `*' is current month */
 360                 if (!(*flags & F_ISMONTH)) {
 361                         *flags |= F_ISMONTH | F_WILDMONTH;
 362                         *endp = p + 1;
 363                         return tp->tm_mon + 1;
 364                 } else {
 365                         *flags |= F_ISDAY | F_WILDDAY;
 366                         *endp = p + 1;
 367                         return 1;
 368                 }
 369         }
 370         if (isdigit((unsigned char)*p)) {
 371                 val = (int)strtol(p, &p, 10);   /* if 0, it's failure */
 372                 for (/*EMPTY*/; FLDCHAR(*p); ++p)
 373                         continue;
 374                 *endp = p;
 375                 return val;
 376         }
 377         for (start = p; *p != '\0' && isalpha((unsigned char)*p); p++)
 378                 continue;
 379
 380         savech = *p;
 381         if (p != start) {
 382                 *p = '\0';
 383                 if ((val = getmonth(start)) != 0)
 384                         *flags |= F_ISMONTH;
 385                 else if ((val = getday(start)) != 0)
 386                         *flags |= F_ISDOW;
 387                 else {
 388                         *p = savech;
 389                         *endp = start;
 390                         return 0;
 391                 }
 392         }
 393         for (*p = savech; FLDCHAR(*p); ++p)
 394                 continue;
 395         *endp = p;
 396         return val;
 397 }
 398
 399 static FILE *
 400 opencal(FILE **in)
 401 {
 402         int fd = -1;
 403         int pdes[2];
 404
 405         /* open up calendar file as stdin */
 406         if (fname == NULL) {
 407                 for (const char **name = defaultnames; *name != NULL; name++) {
 408                         if ((fd = tryopen(*name, O_RDONLY)) == -1)
 409                                 continue;
 410                         else
 411                                 break;
 412                 }
 413                 if (fd == -1) {
 414                         if (doall)
 415                                 return NULL;
 416                         err(EXIT_FAILURE, "Cannot open calendar file");
 417                 }
 418         } else if ((fd = tryopen(fname, O_RDONLY)) == -1) {
 419                 if (doall)
 420                         return NULL;
 421                 err(EXIT_FAILURE, "Cannot open `%s'", fname);
 422         }
 423
 424         if (pipe(pdes) == -1) {
 425                 warn("Cannot open pipe");
 426                 return NULL;
 427         }
 428
 429         switch (fork()) {
 430         case -1:
 431                 /* error */
 432                 (void)close(pdes[0]);
 433                 (void)close(pdes[1]);
 434                 return NULL;
 435         case 0:
 436                 /* child */
 437                 /* set stdin to calendar file */
 438                 if (fd != STDIN_FILENO) {
 439                         (void)dup2(fd, STDIN_FILENO);
 440                         (void)close(fd);
 441                 }
 442                 /* set stdout to pipe input */
 443                 if (pdes[1] != STDOUT_FILENO) {
 444                         (void)dup2(pdes[1], STDOUT_FILENO);
 445                         (void)close(pdes[1]);
 446                 }
 447                 (void)close(pdes[0]);
 448                 if (doall) {
 449                         /* become the user properly */
 450                         changeuser();
 451                 }
 452                 /* tell CPP to only open regular files */
 453                 if(!cpp_restricted && setenv("CPP_RESTRICTED", "", 1) == -1)
 454                         err(EXIT_FAILURE, "Cannot restrict cpp");
 455                 cpp_restricted = true;
 456
 457                 (void)execl(_PATH_CPP, "cpp", "-traditional", "-P", "-I.",
 458                     "-I" _PATH_CALENDARS, NULL);
 459                 err(EXIT_FAILURE, "Cannot exec `%s'", _PATH_CPP);
 460                 /*NOTREACHED*/
 461         default:
 462                 /* parent -- fdopen *in to pipe output */
 463                 *in = fdopen(pdes[0], "r");
 464                 (void)close(pdes[1]);
 465
 466                 /* close calendar file */
 467                 close(fd);
 468
 469                 /* not reading all calendar files, just set output to stdout */
 470                 if (!doall)
 471                         return stdout;
 472
 473                 /*
 474                  * Set output to a temporary file, so if no output
 475                  * don't send mail.
 476                  */
 477                 (void)snprintf(path, sizeof(path), "%s/_calXXXXXX", _PATH_TMP);
 478                 if ((fd = mkstemp(path)) == -1) {
 479                         warn("Cannot create temporary file");
 480                         return NULL;
 481                 }
 482                 return fdopen(fd, "w+");
 483         }
 484         /*NOTREACHED*/
 485 }
 486
 487 static int
 488 tryopen(const char *pathname, int flags)
 489 {
 490         int fd, serrno, zero;
 491         struct stat st;
 492
 493         /*
 494          * XXX: cpp_restricted has inverted sense; it is false by default,
 495          * and -x sets it to true. CPP_RESTRICTED is set in the environment
 496          * if cpp_restricted is false... go figure. This should be fixed
 497          * later.
 498          */
 499         if (doall && cpp_restricted == false) {
 500                 /*
 501                  * We are running with the user's euid, so they can't
 502                  * cause any mayhem (e.g. opening rewinding tape
 503                  * devices) that they couldn't do easily enough on
 504                  * their own. All we really need to worry about is opens
 505                  * that hang, because that would DoS the calendar run.
 506                  */
 507                 fd = open(pathname, flags | O_NONBLOCK);
 508                 if (fd == -1) {
 509                         return -1;
 510                 }
 511                 if (fstat(fd, &st) == -1) {
 512                         serrno = errno;
 513                         close(fd);
 514                         errno = serrno;
 515                         return -1;
 516                 }
 517                 if (S_ISCHR(st.st_mode) ||
 518                     S_ISBLK(st.st_mode) ||
 519                     S_ISFIFO(st.st_mode)) {
 520                         close(fd);
 521
 522                         /* Call shenanigans in the daily output */
 523                         errno = EPERM;
 524                         warn("%s: %s", pw->pw_name, pathname);
 525
 526                         errno = EPERM;
 527                         return -1;
 528                 }
 529                 if (S_ISDIR(st.st_mode)) {
 530                         /* Don't warn about this */
 531                         close(fd);
 532                         errno = EISDIR;
 533                         return -1;
 534                 }
 535                 if (!S_ISREG(st.st_mode)) {
 536                         /* There shouldn't be other cases to go here */
 537                         close(fd);
 538                         errno = EINVAL;
 539                         return -1;
 540                 }
 541                 zero = 0;
 542                 if (ioctl(fd, FIONBIO, &zero) == -1) {
 543                         serrno = errno;
 544                         warn("%s: %s: FIONBIO", pw->pw_name, pathname);
 545                         close(fd);
 546                         errno = serrno;
 547                         return -1;
 548                 }
 549                 return fd;
 550         } else {
 551                 return open(pathname, flags);
 552         }
 553 }
 554
 555 static void
 556 closecal(FILE *fp)
 557 {
 558         struct stat sbuf;
 559         ssize_t nread;
 560         int pdes[2];
 561         int status;
 562         char buf[1024];
 563
 564         if (!doall)
 565                 return;
 566
 567         (void)rewind(fp);
 568         if (fstat(fileno(fp), &sbuf) == -1 || sbuf.st_size == 0)
 569                 goto done;
 570         if (pipe(pdes) == -1)
 571                 goto done;
 572
 573         switch (fork()) {
 574         case -1:
 575                 /* error */
 576                 (void)close(pdes[0]);
 577                 (void)close(pdes[1]);
 578                 break;
 579         case 0:
 580                 /* child -- set stdin to pipe output */
 581                 if (pdes[0] != STDIN_FILENO) {
 582                         (void)dup2(pdes[0], STDIN_FILENO);
 583                         (void)close(pdes[0]);
 584                 }
 585                 (void)close(pdes[1]);
 586                 if (doall) {
 587                         /* become the user properly */
 588                         changeuser();
 589                 }
 590                 (void)execl(_PATH_SENDMAIL, "sendmail", "-i", "-t", "-F",
 591                     "\"Reminder Service\"", "-f", "root", NULL);
 592                 err(EXIT_FAILURE, "Cannot exec `%s'", _PATH_SENDMAIL);
 593                 /*NOTREACHED*/
 594         default:
 595                 /* parent -- write to pipe input */
 596                 (void)close(pdes[0]);
 597
 598                 header[1].iov_base = header[3].iov_base = (void *)pw->pw_name;
 599                 header[1].iov_len = header[3].iov_len = strlen(pw->pw_name);
 600                 (void)writev(pdes[1], header, 7);
 601                 while ((nread = read(fileno(fp), buf, sizeof(buf))) > 0)
 602                         (void)write(pdes[1], buf, (size_t)nread);
 603                 (void)close(pdes[1]);
 604                 break;
 605         }
 606
 607 done:   (void)fclose(fp);
 608         (void)unlink(path);
 609         while (wait(&status) != -1)
 610                 continue;
 611 }
 612
 613 static void
 614 changeuser(void)
 615 {
 616         uid_t uid;
 617         gid_t gid;
 618
 619         uid = geteuid();
 620         gid = getegid();
 621         assert(uid == pw->pw_uid);
 622         assert(gid == pw->pw_gid);
 623
 624         if (seteuid(0) == -1) {
 625                 err(EXIT_FAILURE, "%s: changing user: cannot reassert uid 0",
 626                     pw->pw_name);
 627         }
 628         if (setgid(gid) == -1) {
 629                 err(EXIT_FAILURE, "%s: cannot assume gid %d",
 630                     pw->pw_name, (int)gid);
 631         }
 632         if (initgroups(pw->pw_name, gid) == -1) {
 633                 err(EXIT_FAILURE, "%s: cannot initgroups", pw->pw_name);
 634         }
 635         if (setuid(uid) == -1) {
 636                 err(EXIT_FAILURE, "%s: cannot assume uid %d",
 637                     pw->pw_name, (int)uid);
 638         }
 639 }
 640
 641 static int
 642 getmonth(char *s)
 643 {
 644         const char **p;
 645
 646         for (p = months; *p; ++p)
 647                 if (strncasecmp(s, *p, 3) == 0)
 648                         return (int)(p - months) + 1;
 649         return 0;
 650 }
 651
 652 static int
 653 getday(char *s)
 654 {
 655         const char **p;
 656
 657         for (p = days; *p; ++p)
 658                 if (strncasecmp(s, *p, 3) == 0)
 659                         return (int)(p - days) + 1;
 660         return 0;
 661 }
 662
 663 static void
 664 atodays(int ch, char *arg, unsigned short *rvp)
 665 {
 666         int u;
 667
 668         u = atoi(arg);
 669         if (u < 0 || u > 366)
 670                 warnx("-%c %d out of range 0-366, ignored.", ch, u);
 671         else
 672                 *rvp = u;
 673 }
 674
 675 #define todigit(x) ((x) - '0')
 676 #define ATOI2(x) (todigit((x)[0]) * 10 + todigit((x)[1]))
 677 #define ISDIG2(x) (isdigit((unsigned char)(x)[0]) && isdigit((unsigned char)(x)[1]))
 678
 679 static void
 680 getmmdd(struct tm *ptm, char *ds)
 681 {
 682         bool ok = false;
 683         struct tm ttm;
 684
 685         ttm = *ptm;
 686         ttm.tm_isdst = -1;
 687
 688         if (ISDIG2(ds)) {
 689                 ttm.tm_mon = ATOI2(ds) - 1;
 690                 ds += 2;
 691         }
 692         if (ISDIG2(ds)) {
 693                 ttm.tm_mday = ATOI2(ds);
 694                 ds += 2;
 695                 ok = true;
 696         }
 697         if (ok) {
 698                 if (ISDIG2(ds) && ISDIG2(ds + 2)) {
 699                         ttm.tm_year = ATOI2(ds) * 100 - TM_YEAR_BASE;
 700                         ds += 2;
 701                         ttm.tm_year += ATOI2(ds);
 702                 } else if (ISDIG2(ds)) {
 703                         ttm.tm_year = ATOI2(ds);
 704                         if (ttm.tm_year < 69)
 705                                 ttm.tm_year += 2000 - TM_YEAR_BASE;
 706                         else
 707                                 ttm.tm_year += 1900 - TM_YEAR_BASE;
 708                 }
 709         }
 710         if (ok && mktime(&ttm) == -1)
 711                 ok = false;
 712
 713         if (ok)
 714                 *ptm = ttm;
 715         else {
 716                 warnx("Can't convert `%s' to date, ignored.", ds);
 717                 usage();
 718         }
 719 }
 720
 721 __dead
 722 static void
 723 usage(void)
 724 {
 725         (void)fprintf(stderr, "usage: %s [-ax] [-d MMDD[[YY]YY]"
 726             " [-f fname] [-l days] [-w days]\n", getprogname());
 727         exit(1);
 728 }