term-utils/wall.c

   1 /*
   2  * Copyright (c) 1988, 1990, 1993
   3  *      The Regents of the University of California.  All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  * 3. All advertising materials mentioning features or use of this software
  14  *    must display the following acknowledgement:
  15  *      This product includes software developed by the University of
  16  *      California, Berkeley and its contributors.
  17  * 4. Neither the name of the University nor the names of its contributors
  18  *    may be used to endorse or promote products derived from this software
  19  *    without specific prior written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  31  * SUCH DAMAGE.
  32  *
  33  * Modified Sun Mar 12 10:34:34 1995, faith@cs.unc.edu, for Linux
  34  */
  35
  36 /*
  37  * This program is not related to David Wall, whose Stanford Ph.D. thesis
  38  * is entitled "Mechanisms for Broadcast and Selective Broadcast".
  39  *
  40  * 1999-02-22 Arkadiusz Miśkiewicz <misiek@pld.ORG.PL>
  41  * - added Native Language Support
  42  *
  43  */
  44
  45 #include <sys/param.h>
  46 #include <sys/stat.h>
  47 #include <sys/time.h>
  48 #include <sys/uio.h>
  49
  50 #include <errno.h>
  51 #include <paths.h>
  52 #include <ctype.h>
  53 #include <pwd.h>
  54 #include <stdio.h>
  55 #include <stdlib.h>
  56 #include <string.h>
  57 #include <time.h>
  58 #include <unistd.h>
  59 #include <utmpx.h>
  60 #include <getopt.h>
  61 #include <sys/types.h>
  62 #include <grp.h>
  63
  64 #if defined(USE_SYSTEMD) && HAVE_DECL_SD_SESSION_GET_USERNAME == 1
  65 # include <systemd/sd-login.h>
  66 # include <systemd/sd-daemon.h>
  67 #endif
  68
  69 #include "nls.h"
  70 #include "xalloc.h"
  71 #include "strutils.h"
  72 #include "ttymsg.h"
  73 #include "pathnames.h"
  74 #include "carefulputc.h"
  75 #include "c.h"
  76 #include "cctype.h"
  77 #include "fileutils.h"
  78 #include "closestream.h"
  79 #include "timeutils.h"
  80 #include "pwdutils.h"
  81
  82 #define TERM_WIDTH      79
  83 #define WRITE_TIME_OUT  300             /* in seconds */
  84
  85 /* Function prototypes */
  86 static char *makemsg(char *fname, char **mvec, int mvecsz,
  87                     size_t *mbufsize, int print_banner);
  88
  89 static void __attribute__((__noreturn__)) usage(void)
  90 {
  91         FILE *out = stdout;
  92         fputs(USAGE_HEADER, out);
  93         fprintf(out,
  94               _(" %s [options] [<file> | <message>]\n"), program_invocation_short_name);
  95
  96         fputs(USAGE_SEPARATOR, out);
  97         fputs(_("Write a message to all users.\n"), out);
  98
  99         fputs(USAGE_OPTIONS, out);
 100         fputs(_(" -g, --group <group>     only send message to group\n"), out);
 101         fputs(_(" -n, --nobanner          do not print banner, works only for root\n"), out);
 102         fputs(_(" -t, --timeout <timeout> write timeout in seconds\n"), out);
 103         fputs(USAGE_SEPARATOR, out);
 104         printf(USAGE_HELP_OPTIONS(25));
 105         printf(USAGE_MAN_TAIL("wall(1)"));
 106
 107         exit(EXIT_SUCCESS);
 108 }
 109
 110 struct group_workspace {
 111         gid_t   requested_group;
 112         int     ngroups;
 113
 114 /* getgrouplist() on OSX takes int* not gid_t* */
 115 #ifdef __APPLE__
 116         int     *groups;
 117 #else
 118         gid_t   *groups;
 119 #endif
 120 };
 121
 122 static gid_t get_group_gid(const char *group)
 123 {
 124         struct group *gr;
 125         gid_t gid;
 126
 127         if ((gr = getgrnam(group)))
 128                 return gr->gr_gid;
 129
 130         gid = strtou32_or_err(group, _("invalid group argument"));
 131         if (!getgrgid(gid))
 132                 errx(EXIT_FAILURE, _("%s: unknown gid"), group);
 133
 134         return gid;
 135 }
 136
 137 static struct group_workspace *init_group_workspace(const char *group)
 138 {
 139         struct group_workspace *buf = xmalloc(sizeof(struct group_workspace));
 140
 141         buf->requested_group = get_group_gid(group);
 142         buf->ngroups = sysconf(_SC_NGROUPS_MAX) + 1;  /* room for the primary gid */
 143         buf->groups = xcalloc(sizeof(*buf->groups), buf->ngroups);
 144
 145         return buf;
 146 }
 147
 148 static void free_group_workspace(struct group_workspace *buf)
 149 {
 150         if (!buf)
 151                 return;
 152
 153         free(buf->groups);
 154         free(buf);
 155 }
 156
 157 static int is_gr_member(const char *login, const struct group_workspace *buf)
 158 {
 159         struct passwd *pw;
 160         int ngroups = buf->ngroups;
 161         int rc;
 162
 163         pw = getpwnam(login);
 164         if (!pw)
 165                 return 0;
 166
 167         if (buf->requested_group == pw->pw_gid)
 168                 return 1;
 169
 170         rc = getgrouplist(login, pw->pw_gid, buf->groups, &ngroups);
 171         if (rc < 0) {
 172                 /* buffer too small, not sure how this can happen, since
 173                    we used sysconf to get the size... */
 174                 errx(EXIT_FAILURE,
 175                         _("getgrouplist found more groups than sysconf allows"));
 176         }
 177
 178         for (; ngroups >= 0; --ngroups) {
 179                 if (buf->requested_group == (gid_t) buf->groups[ngroups])
 180                         return 1;
 181         }
 182
 183         return 0;
 184 }
 185
 186 int main(int argc, char **argv)
 187 {
 188         int ch;
 189         struct iovec iov;
 190         struct utmpx *utmpptr;
 191         char *p;
 192         char line[sizeof(utmpptr->ut_line) + 1];
 193         int print_banner = TRUE;
 194         struct group_workspace *group_buf = NULL;
 195         char *mbuf, *fname = NULL;
 196         size_t mbufsize;
 197         unsigned timeout = WRITE_TIME_OUT;
 198         char **mvec = NULL;
 199         int mvecsz = 0;
 200
 201         static const struct option longopts[] = {
 202                 { "nobanner",   no_argument,            NULL, 'n' },
 203                 { "timeout",    required_argument,      NULL, 't' },
 204                 { "group",      required_argument,      NULL, 'g' },
 205                 { "version",    no_argument,            NULL, 'V' },
 206                 { "help",       no_argument,            NULL, 'h' },
 207                 { NULL, 0, NULL, 0 }
 208         };
 209
 210         setlocale(LC_ALL, "");
 211         bindtextdomain(PACKAGE, LOCALEDIR);
 212         textdomain(PACKAGE);
 213         close_stdout_atexit();
 214
 215         while ((ch = getopt_long(argc, argv, "nt:g:Vh", longopts, NULL)) != -1) {
 216                 switch (ch) {
 217                 case 'n':
 218                         if (geteuid() == 0)
 219                                 print_banner = FALSE;
 220                         else
 221                                 warnx(_("--nobanner is available only for root"));
 222                         break;
 223                 case 't':
 224                         timeout = strtou32_or_err(optarg, _("invalid timeout argument"));
 225                         if (timeout < 1)
 226                                 errx(EXIT_FAILURE, _("invalid timeout argument: %s"), optarg);
 227                         break;
 228                 case 'g':
 229                         group_buf = init_group_workspace(optarg);
 230                         break;
 231
 232                 case 'V':
 233                         print_version(EXIT_SUCCESS);
 234                 case 'h':
 235                         usage();
 236                 default:
 237                         errtryhelp(EXIT_FAILURE);
 238                 }
 239         }
 240         argc -= optind;
 241         argv += optind;
 242
 243         if (argc == 1 && access(argv[0], F_OK) == 0)
 244                 fname = argv[0];
 245         else if (argc >= 1) {
 246                 mvec = argv;
 247                 mvecsz = argc;
 248         }
 249
 250         mbuf = makemsg(fname, mvec, mvecsz, &mbufsize, print_banner);
 251
 252         iov.iov_base = mbuf;
 253         iov.iov_len = mbufsize;
 254 #if defined(USE_SYSTEMD) && HAVE_DECL_SD_SESSION_GET_USERNAME == 1
 255         if (sd_booted() > 0) {
 256                 char **sessions_list;
 257                 int sessions;
 258
 259                 sessions = sd_get_sessions(&sessions_list);
 260                 if (sessions < 0)
 261                         errx(EXIT_FAILURE, _("error getting sessions: %s"),
 262                                 strerror(-sessions));
 263
 264                 for (int i = 0; i < sessions; i++) {
 265                         char *name, *tty;
 266                         int r;
 267
 268                         if ((r = sd_session_get_username(sessions_list[i], &name)) < 0)
 269                                 errx(EXIT_FAILURE, _("get user name failed: %s"), strerror (-r));
 270
 271                         if (!(group_buf && !is_gr_member(name, group_buf))) {
 272                                 if (sd_session_get_tty(sessions_list[i], &tty) >= 0) {
 273                                         if ((p = ttymsg(&iov, 1, tty, timeout)) != NULL)
 274                                                 warnx("%s", p);
 275
 276                                         free(tty);
 277                                 }
 278                         }
 279                         free(name);
 280                         free(sessions_list[i]);
 281                 }
 282                 free(sessions_list);
 283         } else {
 284 #endif
 285         while((utmpptr = getutxent())) {
 286                 if (!utmpptr->ut_user[0])
 287                         continue;
 288 #ifdef USER_PROCESS
 289                 if (utmpptr->ut_type != USER_PROCESS)
 290                         continue;
 291 #endif
 292                 /* Joey Hess reports that use-sessreg in /etc/X11/wdm/ produces
 293                  * ut_line entries like :0, and a write to /dev/:0 fails.
 294                  *
 295                  * It also seems that some login manager may produce empty ut_line.
 296                  */
 297                 if (!*utmpptr->ut_line || *utmpptr->ut_line == ':')
 298                         continue;
 299
 300                 if (group_buf && !is_gr_member(utmpptr->ut_user, group_buf))
 301                         continue;
 302
 303                 mem2strcpy(line, utmpptr->ut_line, sizeof(utmpptr->ut_line), sizeof(line));
 304                 if ((p = ttymsg(&iov, 1, line, timeout)) != NULL)
 305                         warnx("%s", p);
 306         }
 307         endutxent();
 308 #if defined(USE_SYSTEMD) && HAVE_DECL_SD_SESSION_GET_USERNAME == 1
 309         }
 310 #endif
 311         free(mbuf);
 312         free_group_workspace(group_buf);
 313         exit(EXIT_SUCCESS);
 314 }
 315
 316 struct buffer {
 317         size_t  sz;
 318         size_t  used;
 319         char    *data;
 320 };
 321
 322 static void buf_enlarge(struct buffer *bs, size_t len)
 323 {
 324         if (bs->sz == 0 || len > bs->sz - bs->used) {
 325                 bs->sz += len < 128 ? 128 : len;
 326                 bs->data = xrealloc(bs->data, bs->sz);
 327         }
 328 }
 329
 330 static void buf_puts(struct buffer *bs, const char *s)
 331 {
 332         size_t len = strlen(s);
 333
 334         buf_enlarge(bs, len + 1);
 335         memcpy(bs->data + bs->used, s, len + 1);
 336         bs->used += len;
 337 }
 338
 339 static void __attribute__((__format__ (__printf__, 2, 3)))
 340         buf_printf(struct buffer *bs, const char *fmt, ...)
 341 {
 342         int rc;
 343         va_list ap;
 344         size_t limit;
 345
 346         buf_enlarge(bs, 0);     /* default size */
 347         limit = bs->sz - bs->used;
 348
 349         va_start(ap, fmt);
 350         rc = vsnprintf(bs->data + bs->used, limit, fmt, ap);
 351         va_end(ap);
 352
 353         if (rc >= 0 && (size_t) rc >= limit) {  /* not enough, enlarge */
 354                 buf_enlarge(bs, (size_t)rc + 1);
 355                 limit = bs->sz - bs->used;
 356                 va_start(ap, fmt);
 357                 rc = vsnprintf(bs->data  + bs->used, limit, fmt, ap);
 358                 va_end(ap);
 359         }
 360
 361         if (rc > 0)
 362                 bs->used += rc;
 363 }
 364
 365 static void buf_putc_careful(struct buffer *bs, int c)
 366 {
 367         if (isprint(c) || c == '\a' || c == '\t' || c == '\r' || c == '\n') {
 368                 buf_enlarge(bs, 1);
 369                 bs->data[bs->used++] = c;
 370         } else if (!c_isascii(c))
 371                 buf_printf(bs, "\\%3o", (unsigned char)c);
 372         else {
 373                 char tmp[] = { '^', c ^ 0x40, '\0' };
 374                 buf_puts(bs, tmp);
 375         }
 376 }
 377
 378 static char *makemsg(char *fname, char **mvec, int mvecsz,
 379                      size_t *mbufsize, int print_banner)
 380 {
 381         struct buffer _bs = {.used = 0}, *bs = &_bs;
 382         register int ch, cnt;
 383         char *p, *lbuf;
 384         long line_max;
 385
 386         line_max = sysconf(_SC_LINE_MAX);
 387         if (line_max <= 0)
 388                 line_max = 512;
 389
 390         lbuf = xmalloc(line_max);
 391
 392         if (print_banner == TRUE) {
 393                 char *hostname = xgethostname();
 394                 char *whom, *where, date[CTIME_BUFSIZ];
 395                 time_t now;
 396
 397                 whom = xgetlogin();
 398                 if (!whom) {
 399                         whom = "<someone>";
 400                         warn(_("cannot get passwd uid"));
 401                 }
 402                 where = ttyname(STDOUT_FILENO);
 403                 if (!where) {
 404                         where = "somewhere";
 405                 } else if (strncmp(where, "/dev/", 5) == 0)
 406                         where += 5;
 407
 408                 time(&now);
 409                 ctime_r(&now, date);
 410                 date[strlen(date) - 1] = '\0';
 411
 412                 /*
 413                  * all this stuff is to blank out a square for the message;
 414                  * we wrap message lines at column 79, not 80, because some
 415                  * terminals wrap after 79, some do not, and we can't tell.
 416                  * Which means that we may leave a non-blank character
 417                  * in column 80, but that can't be helped.
 418                  */
 419                 /* snprintf is not always available, but the sprintf's here
 420                    will not overflow as long as %d takes at most 100 chars */
 421                 buf_printf(bs, "\r%*s\r\n", TERM_WIDTH, " ");
 422
 423                 snprintf(lbuf, line_max,
 424                                 _("Broadcast message from %s@%s (%s) (%s):"),
 425                                 whom, hostname, where, date);
 426                 buf_printf(bs, "%-*.*s\007\007\r\n", TERM_WIDTH, TERM_WIDTH, lbuf);
 427                 free(hostname);
 428         }
 429         buf_printf(bs, "%*s\r\n", TERM_WIDTH, " ");
 430
 431          if (mvec) {
 432                 /*
 433                  * Read message from argv[]
 434                  */
 435                 int i;
 436
 437                 for (i = 0; i < mvecsz; i++) {
 438                         buf_puts(bs, mvec[i]);
 439                         if (i < mvecsz - 1)
 440                                 buf_puts(bs, " ");
 441                 }
 442                 buf_puts(bs, "\r\n");
 443         } else {
 444                 /*
 445                  * read message from <file>
 446                  */
 447                 if (fname) {
 448                         /*
 449                          * When we are not root, but suid or sgid, refuse to read files
 450                          * (e.g. device files) that the user may not have access to.
 451                          * After all, our invoker can easily do "wall < file"
 452                          * instead of "wall file".
 453                          */
 454                         uid_t uid = getuid();
 455                         if (uid && (uid != geteuid() || getgid() != getegid()))
 456                                 errx(EXIT_FAILURE, _("will not read %s - use stdin."),
 457                                      fname);
 458
 459                         if (!freopen(fname, "r", stdin))
 460                                 err(EXIT_FAILURE, _("cannot open %s"), fname);
 461
 462                 }
 463
 464                 /*
 465                  * Read message from stdin.
 466                  */
 467                 while (fgets(lbuf, line_max, stdin)) {
 468                         for (cnt = 0, p = lbuf; (ch = *p) != '\0'; ++p, ++cnt) {
 469                                 if (cnt == TERM_WIDTH || ch == '\n') {
 470                                         for (; cnt < TERM_WIDTH; ++cnt)
 471                                                 buf_puts(bs, " ");
 472                                         buf_puts(bs, "\r\n");
 473                                         cnt = 0;
 474                                 }
 475                                 if (ch == '\t')
 476                                         cnt += (7 - (cnt % 8));
 477                                 if (ch != '\n')
 478                                         buf_putc_careful(bs, ch);
 479                         }
 480                 }
 481         }
 482         buf_printf(bs, "%*s\r\n", TERM_WIDTH, " ");
 483
 484         free(lbuf);
 485
 486         bs->data[bs->used] = '\0';      /* be paranoid */
 487         *mbufsize = bs->used;
 488         return bs->data;
 489 }