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 #include "nls.h"
  65 #include "xalloc.h"
  66 #include "strutils.h"
  67 #include "ttymsg.h"
  68 #include "pathnames.h"
  69 #include "carefulputc.h"
  70 #include "c.h"
  71 #include "cctype.h"
  72 #include "fileutils.h"
  73 #include "closestream.h"
  74
  75 #define TERM_WIDTH      79
  76 #define WRITE_TIME_OUT  300             /* in seconds */
  77
  78 /* Function prototypes */
  79 static char *makemsg(char *fname, char **mvec, int mvecsz,
  80                     size_t *mbufsize, int print_banner);
  81
  82 static void __attribute__((__noreturn__)) usage(void)
  83 {
  84         FILE *out = stdout;
  85         fputs(USAGE_HEADER, out);
  86         fprintf(out,
  87               _(" %s [options] [<file> | <message>]\n"), program_invocation_short_name);
  88
  89         fputs(USAGE_SEPARATOR, out);
  90         fputs(_("Write a message to all users.\n"), out);
  91
  92         fputs(USAGE_OPTIONS, out);
  93         fputs(_(" -g, --group <group>     only send message to group\n"), out);
  94         fputs(_(" -n, --nobanner          do not print banner, works only for root\n"), out);
  95         fputs(_(" -t, --timeout <timeout> write timeout in seconds\n"), out);
  96         fputs(USAGE_SEPARATOR, out);
  97         printf(USAGE_HELP_OPTIONS(25));
  98         printf(USAGE_MAN_TAIL("wall(1)"));
  99
 100         exit(EXIT_SUCCESS);
 101 }
 102
 103 struct group_workspace {
 104         gid_t   requested_group;
 105         int     ngroups;
 106
 107 /* getgrouplist() on OSX takes int* not gid_t* */
 108 #ifdef __APPLE__
 109         int     *groups;
 110 #else
 111         gid_t   *groups;
 112 #endif
 113 };
 114
 115 static gid_t get_group_gid(const char *group)
 116 {
 117         struct group *gr;
 118         gid_t gid;
 119
 120         if ((gr = getgrnam(group)))
 121                 return gr->gr_gid;
 122
 123         gid = strtou32_or_err(group, _("invalid group argument"));
 124         if (!getgrgid(gid))
 125                 errx(EXIT_FAILURE, _("%s: unknown gid"), group);
 126
 127         return gid;
 128 }
 129
 130 static struct group_workspace *init_group_workspace(const char *group)
 131 {
 132         struct group_workspace *buf = xmalloc(sizeof(struct group_workspace));
 133
 134         buf->requested_group = get_group_gid(group);
 135         buf->ngroups = sysconf(_SC_NGROUPS_MAX) + 1;  /* room for the primary gid */
 136         buf->groups = xcalloc(sizeof(*buf->groups), buf->ngroups);
 137
 138         return buf;
 139 }
 140
 141 static void free_group_workspace(struct group_workspace *buf)
 142 {
 143         if (!buf)
 144                 return;
 145
 146         free(buf->groups);
 147         free(buf);
 148 }
 149
 150 static int is_gr_member(const char *login, const struct group_workspace *buf)
 151 {
 152         struct passwd *pw;
 153         int ngroups = buf->ngroups;
 154         int rc;
 155
 156         pw = getpwnam(login);
 157         if (!pw)
 158                 return 0;
 159
 160         if (buf->requested_group == pw->pw_gid)
 161                 return 1;
 162
 163         rc = getgrouplist(login, pw->pw_gid, buf->groups, &ngroups);
 164         if (rc < 0) {
 165                 /* buffer too small, not sure how this can happen, since
 166                    we used sysconf to get the size... */
 167                 errx(EXIT_FAILURE,
 168                         _("getgrouplist found more groups than sysconf allows"));
 169         }
 170
 171         for (; ngroups >= 0; --ngroups) {
 172                 if (buf->requested_group == (gid_t) buf->groups[ngroups])
 173                         return 1;
 174         }
 175
 176         return 0;
 177 }
 178
 179 int main(int argc, char **argv)
 180 {
 181         int ch;
 182         struct iovec iov;
 183         struct utmpx *utmpptr;
 184         char *p;
 185         char line[sizeof(utmpptr->ut_line) + 1];
 186         int print_banner = TRUE;
 187         struct group_workspace *group_buf = NULL;
 188         char *mbuf, *fname = NULL;
 189         size_t mbufsize;
 190         unsigned timeout = WRITE_TIME_OUT;
 191         char **mvec = NULL;
 192         int mvecsz = 0;
 193
 194         static const struct option longopts[] = {
 195                 { "nobanner",   no_argument,            NULL, 'n' },
 196                 { "timeout",    required_argument,      NULL, 't' },
 197                 { "group",      required_argument,      NULL, 'g' },
 198                 { "version",    no_argument,            NULL, 'V' },
 199                 { "help",       no_argument,            NULL, 'h' },
 200                 { NULL, 0, NULL, 0 }
 201         };
 202
 203         setlocale(LC_ALL, "");
 204         bindtextdomain(PACKAGE, LOCALEDIR);
 205         textdomain(PACKAGE);
 206         close_stdout_atexit();
 207
 208         while ((ch = getopt_long(argc, argv, "nt:g:Vh", longopts, NULL)) != -1) {
 209                 switch (ch) {
 210                 case 'n':
 211                         if (geteuid() == 0)
 212                                 print_banner = FALSE;
 213                         else
 214                                 warnx(_("--nobanner is available only for root"));
 215                         break;
 216                 case 't':
 217                         timeout = strtou32_or_err(optarg, _("invalid timeout argument"));
 218                         if (timeout < 1)
 219                                 errx(EXIT_FAILURE, _("invalid timeout argument: %s"), optarg);
 220                         break;
 221                 case 'g':
 222                         group_buf = init_group_workspace(optarg);
 223                         break;
 224
 225                 case 'V':
 226                         print_version(EXIT_SUCCESS);
 227                 case 'h':
 228                         usage();
 229                 default:
 230                         errtryhelp(EXIT_FAILURE);
 231                 }
 232         }
 233         argc -= optind;
 234         argv += optind;
 235
 236         if (argc == 1 && access(argv[0], F_OK) == 0)
 237                 fname = argv[0];
 238         else if (argc >= 1) {
 239                 mvec = argv;
 240                 mvecsz = argc;
 241         }
 242
 243         mbuf = makemsg(fname, mvec, mvecsz, &mbufsize, print_banner);
 244
 245         iov.iov_base = mbuf;
 246         iov.iov_len = mbufsize;
 247         while((utmpptr = getutxent())) {
 248                 if (!utmpptr->ut_user[0])
 249                         continue;
 250 #ifdef USER_PROCESS
 251                 if (utmpptr->ut_type != USER_PROCESS)
 252                         continue;
 253 #endif
 254                 /* Joey Hess reports that use-sessreg in /etc/X11/wdm/ produces
 255                  * ut_line entries like :0, and a write to /dev/:0 fails.
 256                  *
 257                  * It also seems that some login manager may produce empty ut_line.
 258                  */
 259                 if (!*utmpptr->ut_line || *utmpptr->ut_line == ':')
 260                         continue;
 261
 262                 if (group_buf && !is_gr_member(utmpptr->ut_user, group_buf))
 263                         continue;
 264
 265                 mem2strcpy(line, utmpptr->ut_line, sizeof(utmpptr->ut_line), sizeof(line));
 266                 if ((p = ttymsg(&iov, 1, line, timeout)) != NULL)
 267                         warnx("%s", p);
 268         }
 269         endutxent();
 270         free(mbuf);
 271         free_group_workspace(group_buf);
 272         exit(EXIT_SUCCESS);
 273 }
 274
 275 struct buffer {
 276         size_t  sz;
 277         size_t  used;
 278         char    *data;
 279 };
 280
 281 static void buf_enlarge(struct buffer *bs, size_t len)
 282 {
 283         if (bs->sz == 0 || len > bs->sz - bs->used) {
 284                 bs->sz += len < 128 ? 128 : len;
 285                 bs->data = xrealloc(bs->data, bs->sz);
 286         }
 287 }
 288
 289 static void buf_puts(struct buffer *bs, const char *s)
 290 {
 291         size_t len = strlen(s);
 292
 293         buf_enlarge(bs, len + 1);
 294         memcpy(bs->data + bs->used, s, len + 1);
 295         bs->used += len;
 296 }
 297
 298 static void buf_printf(struct buffer *bs, const char *fmt, ...)
 299 {
 300         int rc;
 301         va_list ap;
 302         size_t limit;
 303
 304         buf_enlarge(bs, 0);     /* default size */
 305         limit = bs->sz - bs->used;
 306
 307         va_start(ap, fmt);
 308         rc = vsnprintf(bs->data + bs->used, limit, fmt, ap);
 309         va_end(ap);
 310
 311         if (rc >= 0 && (size_t) rc >= limit) {  /* not enough, enlarge */
 312                 buf_enlarge(bs, (size_t)rc + 1);
 313                 limit = bs->sz - bs->used;
 314                 va_start(ap, fmt);
 315                 rc = vsnprintf(bs->data  + bs->used, limit, fmt, ap);
 316                 va_end(ap);
 317         }
 318
 319         if (rc > 0)
 320                 bs->used += rc;
 321 }
 322
 323 static void buf_putc_careful(struct buffer *bs, int c)
 324 {
 325         if (isprint(c) || c == '\a' || c == '\t' || c == '\r' || c == '\n') {
 326                 buf_enlarge(bs, 1);
 327                 bs->data[bs->used++] = c;
 328         } else if (!c_isascii(c))
 329                 buf_printf(bs, "\\%3o", (unsigned char)c);
 330         else {
 331                 char tmp[] = { '^', c ^ 0x40, '\0' };
 332                 buf_puts(bs, tmp);
 333         }
 334 }
 335
 336 static char *makemsg(char *fname, char **mvec, int mvecsz,
 337                      size_t *mbufsize, int print_banner)
 338 {
 339         struct buffer _bs = {.used = 0}, *bs = &_bs;
 340         register int ch, cnt;
 341         char *p, *lbuf;
 342         long line_max;
 343
 344         line_max = sysconf(_SC_LINE_MAX);
 345         if (line_max <= 0)
 346                 line_max = 512;
 347
 348         lbuf = xmalloc(line_max);
 349
 350         if (print_banner == TRUE) {
 351                 char *hostname = xgethostname();
 352                 char *whom, *where, *date;
 353                 struct passwd *pw;
 354                 time_t now;
 355
 356                 if (!(whom = getlogin()) || !*whom)
 357                         whom = (pw = getpwuid(getuid())) ? pw->pw_name : "???";
 358                 if (!whom) {
 359                         whom = "someone";
 360                         warn(_("cannot get passwd uid"));
 361                 }
 362                 where = ttyname(STDOUT_FILENO);
 363                 if (!where) {
 364                         where = "somewhere";
 365                 } else if (strncmp(where, "/dev/", 5) == 0)
 366                         where += 5;
 367
 368                 time(&now);
 369                 date = xstrdup(ctime(&now));
 370                 date[strlen(date) - 1] = '\0';
 371
 372                 /*
 373                  * all this stuff is to blank out a square for the message;
 374                  * we wrap message lines at column 79, not 80, because some
 375                  * terminals wrap after 79, some do not, and we can't tell.
 376                  * Which means that we may leave a non-blank character
 377                  * in column 80, but that can't be helped.
 378                  */
 379                 /* snprintf is not always available, but the sprintf's here
 380                    will not overflow as long as %d takes at most 100 chars */
 381                 buf_printf(bs, "\r%*s\r\n", TERM_WIDTH, " ");
 382
 383                 snprintf(lbuf, line_max,
 384                                 _("Broadcast message from %s@%s (%s) (%s):"),
 385                                 whom, hostname, where, date);
 386                 buf_printf(bs, "%-*.*s\007\007\r\n", TERM_WIDTH, TERM_WIDTH, lbuf);
 387                 free(hostname);
 388                 free(date);
 389         }
 390         buf_printf(bs, "%*s\r\n", TERM_WIDTH, " ");
 391
 392          if (mvec) {
 393                 /*
 394                  * Read message from argv[]
 395                  */
 396                 int i;
 397
 398                 for (i = 0; i < mvecsz; i++) {
 399                         buf_puts(bs, mvec[i]);
 400                         if (i < mvecsz - 1)
 401                                 buf_puts(bs, " ");
 402                 }
 403                 buf_puts(bs, "\r\n");
 404         } else {
 405                 /*
 406                  * read message from <file>
 407                  */
 408                 if (fname) {
 409                         /*
 410                          * When we are not root, but suid or sgid, refuse to read files
 411                          * (e.g. device files) that the user may not have access to.
 412                          * After all, our invoker can easily do "wall < file"
 413                          * instead of "wall file".
 414                          */
 415                         uid_t uid = getuid();
 416                         if (uid && (uid != geteuid() || getgid() != getegid()))
 417                                 errx(EXIT_FAILURE, _("will not read %s - use stdin."),
 418                                      fname);
 419
 420                         if (!freopen(fname, "r", stdin))
 421                                 err(EXIT_FAILURE, _("cannot open %s"), fname);
 422
 423                 }
 424
 425                 /*
 426                  * Read message from stdin.
 427                  */
 428                 while (fgets(lbuf, line_max, stdin)) {
 429                         for (cnt = 0, p = lbuf; (ch = *p) != '\0'; ++p, ++cnt) {
 430                                 if (cnt == TERM_WIDTH || ch == '\n') {
 431                                         for (; cnt < TERM_WIDTH; ++cnt)
 432                                                 buf_puts(bs, " ");
 433                                         buf_puts(bs, "\r\n");
 434                                         cnt = 0;
 435                                 }
 436                                 if (ch == '\t')
 437                                         cnt += (7 - (cnt % 8));
 438                                 if (ch != '\n')
 439                                         buf_putc_careful(bs, ch);
 440                         }
 441                 }
 442         }
 443         buf_printf(bs, "%*s\r\n", TERM_WIDTH, " ");
 444
 445         free(lbuf);
 446
 447         bs->data[bs->used] = '\0';      /* be paranoid */
 448         *mbufsize = bs->used;
 449         return bs->data;
 450 }