usr.bin/w/w.c

   1 /*      $NetBSD: w.c,v 1.77 2013/09/09 19:20:38 christos Exp $  */
   2
   3 /*-
   4  * Copyright (c) 1980, 1991, 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) 1980, 1991, 1993, 1994\
  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[] = "@(#)w.c 8.6 (Berkeley) 6/30/94";
  41 #else
  42 __RCSID("$NetBSD: w.c,v 1.77 2013/09/09 19:20:38 christos Exp $");
  43 #endif
  44 #endif /* not lint */
  45
  46 /*
  47  * w - print system status (who and what)
  48  *
  49  * This program is similar to the systat command on Tenex/Tops 10/20
  50  *
  51  */
  52 #include <sys/param.h>
  53 #include <sys/types.h>
  54 #include <sys/time.h>
  55 #include <sys/stat.h>
  56 #include <sys/sysctl.h>
  57 #include <sys/proc.h>
  58 #include <sys/user.h>
  59 #include <sys/ioctl.h>
  60 #include <sys/socket.h>
  61
  62 #include <netinet/in.h>
  63 #include <arpa/inet.h>
  64
  65 #include <ctype.h>
  66 #include <err.h>
  67 #include <errno.h>
  68 #include <fcntl.h>
  69 #include <kvm.h>
  70 #include <limits.h>
  71 #include <netdb.h>
  72 #include <nlist.h>
  73 #include <paths.h>
  74 #include <stdio.h>
  75 #include <stdlib.h>
  76 #include <string.h>
  77 #include <time.h>
  78 #include <tzfile.h>
  79 #include <unistd.h>
  80 #ifdef SUPPORT_UTMP
  81 #include <utmp.h>
  82 #endif
  83 #ifdef SUPPORT_UTMPX
  84 #include <utmpx.h>
  85 #endif
  86 #include <vis.h>
  87
  88 #include "extern.h"
  89
  90 #ifdef __minix
  91 /* MINIX3 note: please see this header for information about the port. */
  92 #include "minix_proc.h"
  93 #endif /* __minix */
  94
  95 struct timeval  boottime;
  96 struct winsize  ws;
  97 kvm_t          *kd;
  98 time_t          now;            /* the current time of day */
  99 int             ttywidth;       /* width of tty */
 100 int             argwidth;       /* width of tty left to print process args */
 101 int             header = 1;     /* true if -h flag: don't print heading */
 102 int             nflag;          /* true if -n flag: don't convert addrs */
 103 int             wflag;          /* true if -w flag: wide printout */
 104 int             sortidle;       /* sort bu idle time */
 105 char           *sel_user;       /* login of particular user selected */
 106 char            domain[MAXHOSTNAMELEN + 1];
 107 int maxname = 8, maxline = 3, maxhost = 16;
 108
 109 /*
 110  * One of these per active utmp entry.
 111  */
 112 struct  entry {
 113         struct  entry *next;
 114         char name[UTX_USERSIZE + 1];
 115         char line[UTX_LINESIZE + 1];
 116         char host[UTX_HOSTSIZE + 1];
 117         char type[2];
 118         struct timeval tv;
 119         dev_t   tdev;                   /* dev_t of terminal */
 120         time_t  idle;                   /* idle time of terminal in seconds */
 121         struct  kinfo_proc2 *tp;        /* `most interesting' tty proc */
 122         struct  kinfo_proc2 *pp;        /* pid proc */
 123         pid_t   pid;                    /* pid or ~0 if not known */
 124 } *ehead = NULL, **nextp = &ehead;
 125
 126 static void     pr_args(struct kinfo_proc2 *);
 127 static void     pr_header(time_t *, int);
 128 #ifndef __minix
 129 static int      proc_compare_wrapper(const struct kinfo_proc2 *,
 130     const struct kinfo_proc2 *);
 131 #endif /* !__minix */
 132 #if defined(SUPPORT_UTMP) || defined(SUPPORT_UTMPX)
 133 static int      ttystat(const char *, struct stat *);
 134 static void     process(struct entry *);
 135 #endif
 136 static void     fixhost(struct entry *ep);
 137 __dead static void      usage(int);
 138
 139 int
 140 main(int argc, char **argv)
 141 {
 142         struct kinfo_proc2 *kp;
 143         struct entry *ep;
 144         int ch, i, nentries, nusers, wcmd, curtain, use_sysctl;
 145         char *memf, *nlistf, *usrnp;
 146         const char *options;
 147         time_t then;
 148 #ifndef __minix
 149         size_t len;
 150 #endif /* !__minix */
 151 #ifdef SUPPORT_UTMP
 152         struct utmp *ut;
 153 #endif
 154 #ifdef SUPPORT_UTMPX
 155         struct utmpx *utx;
 156 #endif
 157         const char *progname;
 158 #ifndef __minix
 159         char errbuf[_POSIX2_LINE_MAX];
 160 #endif /* !__minix */
 161
 162         setprogname(argv[0]);
 163
 164         /* Are we w(1) or uptime(1)? */
 165         progname = getprogname();
 166         if (*progname == '-')
 167                 progname++;
 168         if (*progname == 'u') {
 169                 wcmd = 0;
 170                 options = "";
 171         } else {
 172                 wcmd = 1;
 173                 options = "hiM:N:nw";
 174         }
 175
 176         memf = nlistf = NULL;
 177         while ((ch = getopt(argc, argv, options)) != -1)
 178                 switch (ch) {
 179                 case 'h':
 180                         header = 0;
 181                         break;
 182                 case 'i':
 183                         sortidle = 1;
 184                         break;
 185                 case 'M':
 186                         header = 0;
 187                         memf = optarg;
 188                         break;
 189                 case 'N':
 190                         nlistf = optarg;
 191                         break;
 192                 case 'n':
 193                         nflag = 1;
 194                         break;
 195                 case 'w':
 196                         wflag = 1;
 197                         break;
 198                 case '?':
 199                 default:
 200                         usage(wcmd);
 201                 }
 202         argc -= optind;
 203         argv += optind;
 204
 205         use_sysctl = (memf == NULL && nlistf == NULL);
 206
 207 #ifndef __minix
 208         if ((kd = kvm_openfiles(nlistf, memf, NULL,
 209             memf == NULL ? KVM_NO_FILES : O_RDONLY, errbuf)) == NULL)
 210                 errx(1, "%s", errbuf);
 211 #else
 212         if (!use_sysctl)
 213                 errx(1, "The -M and -N flags are not supported on MINIX3.");
 214         kd = NULL;
 215 #endif /* __minix */
 216
 217         (void)time(&now);
 218
 219         if (use_sysctl) {
 220 #ifndef __minix
 221                 len = sizeof(curtain);
 222                 if (sysctlbyname("security.curtain", &curtain, &len,
 223                     NULL, 0) == -1)
 224 #endif /* !__minix */
 225                         curtain = 0;
 226         }
 227
 228 #ifdef SUPPORT_UTMPX
 229         setutxent();
 230 #endif
 231 #ifdef SUPPORT_UTMP
 232         setutent();
 233 #endif
 234
 235         if (*argv)
 236                 sel_user = *argv;
 237
 238         nusers = 0;
 239 #ifdef SUPPORT_UTMPX
 240         while ((utx = getutxent()) != NULL) {
 241                 if (utx->ut_type != USER_PROCESS)
 242                         continue;
 243                 ++nusers;
 244                 if (sel_user &&
 245                     strncmp(utx->ut_name, sel_user, sizeof(utx->ut_name)) != 0)
 246                         continue;
 247                 if ((ep = calloc(1, sizeof(struct entry))) == NULL)
 248                         err(1, NULL);
 249                 (void)memcpy(ep->name, utx->ut_name, sizeof(utx->ut_name));
 250                 (void)memcpy(ep->line, utx->ut_line, sizeof(utx->ut_line));
 251                 ep->name[sizeof(utx->ut_name)] = '\0';
 252                 ep->line[sizeof(utx->ut_line)] = '\0';
 253                 if (!nflag || getnameinfo((struct sockaddr *)&utx->ut_ss,
 254                     utx->ut_ss.ss_len, ep->host, sizeof(ep->host), NULL, 0,
 255                     NI_NUMERICHOST) != 0) {
 256                         (void)memcpy(ep->host, utx->ut_host,
 257                             sizeof(utx->ut_host));
 258                         ep->host[sizeof(utx->ut_host)] = '\0';
 259                 }
 260                 fixhost(ep);
 261                 ep->type[0] = 'x';
 262                 ep->tv = utx->ut_tv;
 263                 ep->pid = utx->ut_pid;
 264                 *nextp = ep;
 265                 nextp = &(ep->next);
 266                 if (wcmd != 0)
 267                         process(ep);
 268         }
 269 #endif
 270
 271 #ifdef SUPPORT_UTMP
 272         while ((ut = getutent()) != NULL) {
 273                 if (ut->ut_name[0] == '\0')
 274                         continue;
 275
 276                 if (sel_user &&
 277                     strncmp(ut->ut_name, sel_user, sizeof(ut->ut_name)) != 0)
 278                         continue;
 279
 280                 /* Don't process entries that we have utmpx for */
 281                 for (ep = ehead; ep != NULL; ep = ep->next) {
 282                         if (strncmp(ep->line, ut->ut_line,
 283                             sizeof(ut->ut_line)) == 0)
 284                                 break;
 285                 }
 286                 if (ep != NULL)
 287                         continue;
 288
 289                 ++nusers;
 290                 if ((ep = calloc(1, sizeof(struct entry))) == NULL)
 291                         err(1, NULL);
 292                 (void)memcpy(ep->name, ut->ut_name, sizeof(ut->ut_name));
 293                 (void)memcpy(ep->line, ut->ut_line, sizeof(ut->ut_line));
 294                 (void)memcpy(ep->host, ut->ut_host, sizeof(ut->ut_host));
 295                 ep->name[sizeof(ut->ut_name)] = '\0';
 296                 ep->line[sizeof(ut->ut_line)] = '\0';
 297                 ep->host[sizeof(ut->ut_host)] = '\0';
 298                 fixhost(ep);
 299                 ep->tv.tv_sec = ut->ut_time;
 300                 *nextp = ep;
 301                 nextp = &(ep->next);
 302                 if (wcmd != 0)
 303                         process(ep);
 304         }
 305 #endif
 306
 307 #ifdef SUPPORT_UTMPX
 308         endutxent();
 309 #endif
 310 #ifdef SUPPORT_UTMP
 311         endutent();
 312 #endif
 313
 314         if (header || wcmd == 0) {
 315                 pr_header(&now, nusers);
 316                 if (wcmd == 0)
 317                         exit (0);
 318         }
 319
 320         if ((kp = kvm_getproc2(kd, KERN_PROC_ALL, 0,
 321             sizeof(struct kinfo_proc2), &nentries)) == NULL)
 322                 errx(1, "%s", kvm_geterr(kd));
 323
 324         /* Include trailing space because TTY header starts one column early. */
 325         for (i = 0; i < nentries; i++, kp++) {
 326
 327                 for (ep = ehead; ep != NULL; ep = ep->next) {
 328                         if (ep->tdev != 0 && ep->tdev == kp->p_tdev &&
 329                             kp->p__pgid == kp->p_tpgid) {
 330                                 /*
 331                                  * Proc is in foreground of this
 332                                  * terminal
 333                                  */
 334                                 if (proc_compare_wrapper(ep->tp, kp))
 335                                         ep->tp = kp;
 336                                 break;
 337                         }
 338                         if (ep->pid != 0 && ep->pid == kp->p_pid) {
 339                                 ep->pp = kp;
 340                                 break;
 341                         }
 342                 }
 343         }
 344
 345         if ((ioctl(STDOUT_FILENO, TIOCGWINSZ, &ws) == -1 &&
 346             ioctl(STDERR_FILENO, TIOCGWINSZ, &ws) == -1 &&
 347             ioctl(STDIN_FILENO, TIOCGWINSZ, &ws) == -1) || ws.ws_col == 0)
 348                 ttywidth = 79;
 349         else
 350                 ttywidth = ws.ws_col - 1;
 351
 352         if (!wflag && maxhost > (ttywidth / 3))
 353                 maxhost = ttywidth / 3;
 354
 355         argwidth = printf("%-*s TTY     %-*s %*s  IDLE WHAT\n",
 356             maxname, "USER", maxhost, "FROM",
 357             7 /* "dddhhXm" */, "LOGIN@");
 358         argwidth -= sizeof("WHAT\n") - 1 /* NUL */;
 359         argwidth = ttywidth - argwidth;
 360         if (argwidth < 4)
 361                 argwidth = 8;
 362         if (wflag)
 363                 argwidth = -1;
 364
 365         /* sort by idle time */
 366         if (sortidle && ehead != NULL) {
 367                 struct entry *from = ehead, *save;
 368
 369                 ehead = NULL;
 370                 while (from != NULL) {
 371                         for (nextp = &ehead;
 372                             (*nextp) && from->idle >= (*nextp)->idle;
 373                             nextp = &(*nextp)->next)
 374                                 continue;
 375                         save = from;
 376                         from = from->next;
 377                         save->next = *nextp;
 378                         *nextp = save;
 379                 }
 380         }
 381 #if defined(SUPPORT_UTMP) && defined(SUPPORT_UTMPX)
 382         else if (ehead != NULL) {
 383                 struct entry *from = ehead, *save;
 384
 385                 ehead = NULL;
 386                 while (from != NULL) {
 387                         for (nextp = &ehead;
 388                             (*nextp) && strcmp(from->line, (*nextp)->line) > 0;
 389                             nextp = &(*nextp)->next)
 390                                 continue;
 391                         save = from;
 392                         from = from->next;
 393                         save->next = *nextp;
 394                         *nextp = save;
 395                 }
 396         }
 397 #endif
 398
 399         if (!nflag) {
 400                 int     rv;
 401                 char    *p;
 402
 403                 rv = gethostname(domain, sizeof(domain));
 404                 domain[sizeof(domain) - 1] = '\0';
 405                 if (rv < 0 || (p = strchr(domain, '.')) == 0)
 406                         domain[0] = '\0';
 407                 else
 408                         memmove(domain, p, strlen(p) + 1);
 409         }
 410
 411         for (ep = ehead; ep != NULL; ep = ep->next) {
 412                 if (ep->tp != NULL)
 413                         kp = ep->tp;
 414                 else if (ep->pp != NULL)
 415                         kp = ep->pp;
 416                 else if (ep->pid != 0) {
 417                         if (curtain)
 418                                 kp = NULL;
 419                         else {
 420                                 warnx("Stale utmp%s entry: %s %s %s",
 421                                     ep->type, ep->name, ep->line, ep->host);
 422                                 continue;
 423                         }
 424                 }
 425 #ifndef __minix
 426                 usrnp = (kp == NULL) ? ep->name : kp->p_login;
 427 #else
 428                 usrnp = ep->name; /* TODO: implement getlogin/setlogin */
 429 #endif /* __minix */
 430                 (void)printf("%-*s %-7.7s %-*.*s ",
 431                     maxname, usrnp, ep->line,
 432                     maxhost, maxhost, ep->host);
 433                 then = (time_t)ep->tv.tv_sec;
 434                 pr_attime(&then, &now);
 435                 pr_idle(ep->idle);
 436                 pr_args(kp);
 437                 (void)printf("\n");
 438         }
 439         exit(0);
 440 }
 441
 442 static void
 443 pr_args(struct kinfo_proc2 *kp)
 444 {
 445         char **argv;
 446         int left;
 447
 448         if (kp == 0)
 449                 goto nothing;
 450         left = argwidth;
 451         argv = kvm_getargv2(kd, kp, (argwidth < 0) ? 0 : argwidth);
 452         if (argv == 0) {
 453                 if (kp->p_comm == 0) {
 454                         goto nothing;
 455                 } else {
 456                         fmt_putc('(', &left);
 457                         fmt_puts((char *)kp->p_comm, &left);
 458                         fmt_putc(')', &left);
 459                         return;
 460                 }
 461         }
 462         while (*argv) {
 463                 fmt_puts(*argv, &left);
 464                 argv++;
 465                 fmt_putc(' ', &left);
 466         }
 467         return;
 468 nothing:
 469         putchar('-');
 470 }
 471
 472 static void
 473 pr_header(time_t *nowp, int nusers)
 474 {
 475         double avenrun[3];
 476         time_t uptime;
 477         int days, hrs, mins;
 478 #ifndef __minix
 479         int mib[2];
 480         size_t size, i;
 481 #else
 482         size_t i;
 483 #endif /* __minix */
 484         char buf[256];
 485
 486         /*
 487          * Print time of day.
 488          *
 489          * SCCS forces the string manipulation below, as it replaces
 490          * %, M, and % in a character string with the file name.
 491          */
 492         (void)strftime(buf, sizeof(buf), "%l:%" "M%p", localtime(nowp));
 493         buf[sizeof(buf) - 1] = '\0';
 494         (void)printf("%s ", buf);
 495
 496         /*
 497          * Print how long system has been up.
 498          * (Found by looking getting "boottime" from the kernel)
 499          */
 500 #ifndef __minix
 501         mib[0] = CTL_KERN;
 502         mib[1] = KERN_BOOTTIME;
 503         size = sizeof(boottime);
 504         if (sysctl(mib, 2, &boottime, &size, NULL, 0) != -1 &&
 505             boottime.tv_sec != 0) {
 506                 uptime = now - boottime.tv_sec;
 507 #else
 508         if (minix_getuptime(&uptime) != -1) {
 509 #endif /* __minix */
 510                 uptime += 30;
 511                 if (uptime > SECSPERMIN) {
 512                         days = uptime / SECSPERDAY;
 513                         uptime %= SECSPERDAY;
 514                         hrs = uptime / SECSPERHOUR;
 515                         uptime %= SECSPERHOUR;
 516                         mins = uptime / SECSPERMIN;
 517                         (void)printf(" up");
 518                         if (days > 0)
 519                                 (void)printf(" %d day%s,", days,
 520                                     days > 1 ? "s" : "");
 521                         if (hrs > 0 && mins > 0)
 522                                 (void)printf(" %2d:%02d,", hrs, mins);
 523                         else {
 524                                 if (hrs > 0)
 525                                         (void)printf(" %d hr%s,",
 526                                             hrs, hrs > 1 ? "s" : "");
 527                                 if (mins > 0)
 528                                         (void)printf(" %d min%s,",
 529                                             mins, mins > 1 ? "s" : "");
 530                         }
 531                 }
 532         }
 533
 534         /* Print number of users logged in to system */
 535         (void)printf(" %d user%s", nusers, nusers != 1 ? "s" : "");
 536
 537         /*
 538          * Print 1, 5, and 15 minute load averages.
 539          */
 540         if (getloadavg(avenrun, sizeof(avenrun) / sizeof(avenrun[0])) == -1)
 541                 (void)printf(", no load average information available\n");
 542         else {
 543                 (void)printf(", load averages:");
 544                 for (i = 0; i < (sizeof(avenrun) / sizeof(avenrun[0])); i++) {
 545                         if (i > 0)
 546                                 (void)printf(",");
 547                         (void)printf(" %.2f", avenrun[i]);
 548                 }
 549                 (void)printf("\n");
 550         }
 551 }
 552
 553 #if defined(SUPPORT_UTMP) || defined(SUPPORT_UTMPX)
 554 static int
 555 ttystat(const char *line, struct stat *st)
 556 {
 557         char ttybuf[MAXPATHLEN];
 558
 559         (void)snprintf(ttybuf, sizeof(ttybuf), "%s%s", _PATH_DEV, line);
 560         return stat(ttybuf, st);
 561 }
 562
 563 static void
 564 process(struct entry *ep)
 565 {
 566         struct stat st;
 567         time_t touched;
 568         int max;
 569
 570         if ((max = strlen(ep->name)) > maxname)
 571                 maxname = max;
 572         if ((max = strlen(ep->line)) > maxline)
 573                 maxline = max;
 574         if ((max = strlen(ep->host)) > maxhost)
 575                 maxhost = max;
 576
 577         ep->tdev = 0;
 578         ep->idle = (time_t)-1;
 579
 580 #ifdef SUPPORT_UTMP
 581         /*
 582          * Hack to recognize and correctly parse
 583          * ut entry made by ftpd. The "tty" used
 584          * by ftpd is not a real tty, just identifier in
 585          * form ftpPID. Pid parsed from the "tty name"
 586          * is used later to match corresponding process.
 587          * NB: This is only used for utmp entries. For utmpx,
 588          * we already have the pid.
 589          */
 590         if (ep->pid == 0 && strncmp(ep->line, "ftp", 3) == 0) {
 591                 ep->pid = strtol(ep->line + 3, NULL, 10);
 592                 return;
 593         }
 594 #endif
 595         if (ttystat(ep->line, &st) == -1)
 596                 return;
 597
 598         ep->tdev = st.st_rdev;
 599         /*
 600          * If this is the console device, attempt to ascertain
 601          * the true console device dev_t.
 602          */
 603         if (ep->tdev == 0) {
 604                 int mib[2];
 605                 size_t size;
 606
 607                 mib[0] = CTL_KERN;
 608                 mib[1] = KERN_CONSDEV;
 609                 size = sizeof(dev_t);
 610                 (void) sysctl(mib, 2, &ep->tdev, &size, NULL, 0);
 611         }
 612
 613         touched = st.st_atime;
 614         if (touched < ep->tv.tv_sec) {
 615                 /* tty untouched since before login */
 616                 touched = ep->tv.tv_sec;
 617         }
 618         if ((ep->idle = now - touched) < 0)
 619                 ep->idle = 0;
 620 }
 621 #endif
 622
 623 #ifndef __minix
 624 static int
 625 proc_compare_wrapper(const struct kinfo_proc2 *p1,
 626     const struct kinfo_proc2 *p2)
 627 {
 628         struct kinfo_lwp *l1, *l2;
 629         int cnt;
 630
 631         if (p1 == NULL)
 632                 return 1;
 633
 634         l1 = kvm_getlwps(kd, p1->p_pid, 0, sizeof(*l1), &cnt);
 635         if (l1 == NULL || cnt == 0)
 636                 return 1;
 637
 638         l2 = kvm_getlwps(kd, p2->p_pid, 0, sizeof(*l1), &cnt);
 639         if (l2 == NULL || cnt == 0)
 640                 return 0;
 641
 642         return proc_compare(p1, l1, p2, l2);
 643 }
 644 #endif /* !__minix */
 645
 646 static void
 647 fixhost(struct entry *ep)
 648 {
 649         char host_buf[sizeof(ep->host)];
 650         char *p, *x;
 651         struct hostent *hp;
 652         struct in_addr l;
 653
 654         strlcpy(host_buf, *ep->host ? ep->host : "-", sizeof(host_buf));
 655         p = host_buf;
 656
 657         /*
 658          * XXX: Historical behavior, ':' in hostname means X display number,
 659          * IPv6 not handled.
 660          */
 661         for (x = p; x < &host_buf[sizeof(host_buf)]; x++)
 662                 if (*x == '\0' || *x == ':')
 663                         break;
 664         if (x == p + sizeof(host_buf) || *x != ':')
 665                 x = NULL;
 666         else
 667                 *x++ = '\0';
 668
 669         if (!nflag && inet_aton(p, &l) &&
 670             (hp = gethostbyaddr((char *)&l, sizeof(l), AF_INET))) {
 671                 if (domain[0] != '\0') {
 672                         p = hp->h_name;
 673                         p += strlen(hp->h_name);
 674                         p -= strlen(domain);
 675                         if (p > hp->h_name &&
 676                             strcasecmp(p, domain) == 0)
 677                                 *p = '\0';
 678                 }
 679                 p = hp->h_name;
 680         }
 681
 682         if (x)
 683                 (void)snprintf(ep->host, sizeof(ep->host), "%s:%s", p, x);
 684         else
 685
 686                 strlcpy(ep->host, p, sizeof(ep->host));
 687 }
 688
 689 static void
 690 usage(int wcmd)
 691 {
 692
 693         if (wcmd)
 694                 (void)fprintf(stderr,
 695                     "Usage: %s [-hinw] [-M core] [-N system] [user]\n",
 696                     getprogname());
 697         else
 698                 (void)fprintf(stderr, "Usage: %s\n", getprogname());
 699         exit(1);
 700 }