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 <utmp.h>
  60 #include <getopt.h>
  61
  62 #include "nls.h"
  63 #include "xalloc.h"
  64 #include "strutils.h"
  65 #include "ttymsg.h"
  66 #include "pathnames.h"
  67 #include "carefulputc.h"
  68 #include "c.h"
  69 #include "fileutils.h"
  70 #include "closestream.h"
  71
  72 #define TERM_WIDTH      79
  73 #define WRITE_TIME_OUT  300             /* in seconds */
  74
  75 /* Function prototypes */
  76 static char *makemsg(char *fname, char **mvec, int mvecsz,
  77                     size_t *mbufsize, int print_banner);
  78
  79 static void __attribute__((__noreturn__)) usage(FILE *out)
  80 {
  81         fputs(USAGE_HEADER, out);
  82         fprintf(out,
  83               _(" %s [options] [<file> | <message>]\n"), program_invocation_short_name);
  84
  85         fputs(USAGE_SEPARATOR, out);
  86         fputs(_("Write a message to all users.\n"), out);
  87
  88         fputs(USAGE_OPTIONS, out);
  89         fputs(_(" -n, --nobanner          do not print banner, works only for root\n"), out);
  90         fputs(_(" -t, --timeout <timeout> write timeout in seconds\n"), out);
  91         fputs(USAGE_SEPARATOR, out);
  92         fputs(USAGE_HELP, out);
  93         fputs(USAGE_VERSION, out);
  94         fprintf(out, USAGE_MAN_TAIL("wall(1)"));
  95
  96         exit(out == stderr ? EXIT_FAILURE : EXIT_SUCCESS);
  97 }
  98
  99 int main(int argc, char **argv)
 100 {
 101         int ch;
 102         struct iovec iov;
 103         struct utmp *utmpptr;
 104         char *p;
 105         char line[sizeof(utmpptr->ut_line) + 1];
 106         int print_banner = TRUE;
 107         char *mbuf, *fname = NULL;
 108         size_t mbufsize;
 109         unsigned timeout = WRITE_TIME_OUT;
 110         char **mvec = NULL;
 111         int mvecsz = 0;
 112
 113         static const struct option longopts[] = {
 114                 { "nobanner",   no_argument,            0, 'n' },
 115                 { "timeout",    required_argument,      0, 't' },
 116                 { "version",    no_argument,            0, 'V' },
 117                 { "help",       no_argument,            0, 'h' },
 118                 { NULL, 0, 0, 0 }
 119         };
 120
 121         setlocale(LC_ALL, "");
 122         bindtextdomain(PACKAGE, LOCALEDIR);
 123         textdomain(PACKAGE);
 124         atexit(close_stdout);
 125
 126         while ((ch = getopt_long(argc, argv, "nt:Vh", longopts, NULL)) != -1) {
 127                 switch (ch) {
 128                 case 'n':
 129                         if (geteuid() == 0)
 130                                 print_banner = FALSE;
 131                         else
 132                                 warnx(_("--nobanner is available only for root"));
 133                         break;
 134                 case 't':
 135                         timeout = strtou32_or_err(optarg, _("invalid timeout argument"));
 136                         if (timeout < 1)
 137                                 errx(EXIT_FAILURE, _("invalid timeout argument: %s"), optarg);
 138                         break;
 139                 case 'V':
 140                         printf(UTIL_LINUX_VERSION);
 141                         exit(EXIT_SUCCESS);
 142                 case 'h':
 143                         usage(stdout);
 144                 default:
 145                         usage(stderr);
 146                 }
 147         }
 148         argc -= optind;
 149         argv += optind;
 150
 151         if (argc == 1 && access(argv[0], F_OK) == 0)
 152                 fname = argv[0];
 153         else if (argc >= 1) {
 154                 mvec = argv;
 155                 mvecsz = argc;
 156         }
 157
 158         mbuf = makemsg(fname, mvec, mvecsz, &mbufsize, print_banner);
 159
 160         iov.iov_base = mbuf;
 161         iov.iov_len = mbufsize;
 162         while((utmpptr = getutent())) {
 163                 if (!utmpptr->ut_user[0])
 164                         continue;
 165 #ifdef USER_PROCESS
 166                 if (utmpptr->ut_type != USER_PROCESS)
 167                         continue;
 168 #endif
 169                 /* Joey Hess reports that use-sessreg in /etc/X11/wdm/
 170                    produces ut_line entries like :0, and a write
 171                    to /dev/:0 fails. */
 172                 if (utmpptr->ut_line[0] == ':')
 173                         continue;
 174
 175                 xstrncpy(line, utmpptr->ut_line, sizeof(utmpptr->ut_line));
 176                 if ((p = ttymsg(&iov, 1, line, timeout)) != NULL)
 177                         warnx("%s", p);
 178         }
 179         endutent();
 180         free(mbuf);
 181         exit(EXIT_SUCCESS);
 182 }
 183
 184 struct buffer {
 185         size_t  sz;
 186         size_t  used;
 187         char    *data;
 188 };
 189
 190 static void buf_enlarge(struct buffer *bs, size_t len)
 191 {
 192         if (bs->sz == 0 || len > bs->sz - bs->used) {
 193                 bs->sz += len < 128 ? 128 : len;
 194                 bs->data = xrealloc(bs->data, bs->sz);
 195         }
 196 }
 197
 198 static void buf_puts(struct buffer *bs, const char *s)
 199 {
 200         size_t len = strlen(s);
 201
 202         buf_enlarge(bs, len + 1);
 203         memcpy(bs->data + bs->used, s, len + 1);
 204         bs->used += len;
 205 }
 206
 207 static void buf_printf(struct buffer *bs, const char *fmt, ...)
 208 {
 209         int rc;
 210         va_list ap;
 211         size_t limit;
 212
 213         buf_enlarge(bs, 0);     /* default size */
 214         limit = bs->sz - bs->used;
 215
 216         va_start(ap, fmt);
 217         rc = vsnprintf(bs->data + bs->used, limit, fmt, ap);
 218         va_end(ap);
 219
 220         if (rc >= 0 && (size_t) rc >= limit) {  /* not enoght, enlarge */
 221                 buf_enlarge(bs, (size_t)rc + 1);
 222                 limit = bs->sz - bs->used;
 223                 va_start(ap, fmt);
 224                 rc = vsnprintf(bs->data  + bs->used, limit, fmt, ap);;
 225                 va_end(ap);
 226         }
 227
 228         if (rc > 0)
 229                 bs->used += rc;
 230 }
 231
 232 static void buf_putc_careful(struct buffer *bs, int c)
 233 {
 234         if (isprint(c) || c == '\a' || c == '\t' || c == '\r' || c == '\n') {
 235                 buf_enlarge(bs, 1);
 236                 bs->data[bs->used++] = c;
 237         } else if (!isascii(c))
 238                 buf_printf(bs, "\\%3o", (unsigned char)c);
 239         else {
 240                 char tmp[] = { '^', c ^ 0x40, '\0' };
 241                 buf_puts(bs, tmp);
 242         }
 243 }
 244
 245 static char *makemsg(char *fname, char **mvec, int mvecsz,
 246                      size_t *mbufsize, int print_banner)
 247 {
 248         struct buffer _bs = {.used = 0}, *bs = &_bs;
 249         register int ch, cnt;
 250         char *p, *lbuf;
 251         long line_max;
 252
 253         line_max = sysconf(_SC_LINE_MAX);
 254         if (line_max <= 0)
 255                 line_max = 512;
 256
 257         lbuf = xmalloc(line_max);
 258
 259         if (print_banner == TRUE) {
 260                 char *hostname = xgethostname();
 261                 char *whom, *where, *date;
 262                 struct passwd *pw;
 263                 time_t now;
 264
 265                 if (!(whom = getlogin()) || !*whom)
 266                         whom = (pw = getpwuid(getuid())) ? pw->pw_name : "???";
 267                 if (!whom) {
 268                         whom = "someone";
 269                         warn(_("cannot get passwd uid"));
 270                 }
 271                 where = ttyname(STDOUT_FILENO);
 272                 if (!where) {
 273                         where = "somewhere";
 274                         warn(_("cannot get tty name"));
 275                 } else if (strncmp(where, "/dev/", 5) == 0)
 276                         where += 5;
 277
 278                 time(&now);
 279                 date = xstrdup(ctime(&now));
 280                 date[strlen(date) - 1] = '\0';
 281
 282                 /*
 283                  * all this stuff is to blank out a square for the message;
 284                  * we wrap message lines at column 79, not 80, because some
 285                  * terminals wrap after 79, some do not, and we can't tell.
 286                  * Which means that we may leave a non-blank character
 287                  * in column 80, but that can't be helped.
 288                  */
 289                 /* snprintf is not always available, but the sprintf's here
 290                    will not overflow as long as %d takes at most 100 chars */
 291                 buf_printf(bs, "\r%*s\r\n", TERM_WIDTH, " ");
 292
 293                 snprintf(lbuf, line_max,
 294                                 _("Broadcast message from %s@%s (%s) (%s):"),
 295                                 whom, hostname, where, date);
 296                 buf_printf(bs, "%-*.*s\007\007\r\n", TERM_WIDTH, TERM_WIDTH, lbuf);
 297                 free(hostname);
 298                 free(date);
 299         }
 300         buf_printf(bs, "%*s\r\n", TERM_WIDTH, " ");
 301
 302          if (mvec) {
 303                 /*
 304                  * Read message from argv[]
 305                  */
 306                 int i;
 307
 308                 for (i = 0; i < mvecsz; i++) {
 309                         buf_puts(bs, mvec[i]);
 310                         if (i < mvecsz - 1)
 311                                 buf_puts(bs, " ");
 312                 }
 313                 buf_puts(bs, "\r\n");
 314         } else {
 315                 /*
 316                  * read message from <file>
 317                  */
 318                 if (fname) {
 319                         /*
 320                          * When we are not root, but suid or sgid, refuse to read files
 321                          * (e.g. device files) that the user may not have access to.
 322                          * After all, our invoker can easily do "wall < file"
 323                          * instead of "wall file".
 324                          */
 325                         uid_t uid = getuid();
 326                         if (uid && (uid != geteuid() || getgid() != getegid()))
 327                                 errx(EXIT_FAILURE, _("will not read %s - use stdin."),
 328                                      fname);
 329
 330                         if (!freopen(fname, "r", stdin))
 331                                 err(EXIT_FAILURE, _("cannot open %s"), fname);
 332
 333                 }
 334
 335                 /*
 336                  * Read message from stdin.
 337                  */
 338                 while (fgets(lbuf, line_max, stdin)) {
 339                         for (cnt = 0, p = lbuf; (ch = *p) != '\0'; ++p, ++cnt) {
 340                                 if (cnt == TERM_WIDTH || ch == '\n') {
 341                                         for (; cnt < TERM_WIDTH; ++cnt)
 342                                                 buf_puts(bs, " ");
 343                                         buf_puts(bs, "\r\n");
 344                                         cnt = 0;
 345                                 }
 346                                 if (ch == '\t')
 347                                         cnt += (7 - (cnt % 8));
 348                                 if (ch != '\n')
 349                                         buf_putc_careful(bs, ch);
 350                         }
 351                 }
 352         }
 353         buf_printf(bs, "%*s\r\n", TERM_WIDTH, " ");
 354
 355         free(lbuf);
 356
 357         bs->data[bs->used] = '\0';      /* be paranoid */
 358         *mbufsize = bs->used;
 359         return bs->data;
 360 }