1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378
|
/*
* Copyright (c) 1989, 1993
* The Regents of the University of California. All rights reserved.
*
* This code is derived from software contributed to Berkeley by
* Jef Poskanzer and Craig Leres of the Lawrence Berkeley Laboratory.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the University of
* California, Berkeley and its contributors.
* 4. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#ifndef lint
static char copyright[] =
"@(#) Copyright (c) 1989, 1993\n\
The Regents of the University of California. All rights reserved.\n";
#endif /* not lint */
#ifndef lint
static char sccsid[] = "@(#)write.c 8.1 (Berkeley) 6/6/93";
#endif /* not lint */
#include <sys/param.h>
#include <sys/signal.h>
#include <sys/stat.h>
#include <sys/file.h>
#include <sys/time.h>
#include <utmp.h>
#include <ctype.h>
#include <pwd.h>
#include <stdio.h>
#include <string.h>
extern int errno;
main(argc, argv)
int argc;
char **argv;
{
register char *cp;
time_t atime;
uid_t myuid;
int msgsok, myttyfd;
char tty[MAXPATHLEN], *mytty, *ttyname();
void done();
/* check that sender has write enabled */
if (isatty(fileno(stdin)))
myttyfd = fileno(stdin);
else if (isatty(fileno(stdout)))
myttyfd = fileno(stdout);
else if (isatty(fileno(stderr)))
myttyfd = fileno(stderr);
else {
(void)fprintf(stderr, "write: can't find your tty\n");
exit(1);
}
if (!(mytty = ttyname(myttyfd))) {
(void)fprintf(stderr, "write: can't find your tty's name\n");
exit(1);
}
if (cp = rindex(mytty, '/'))
mytty = cp + 1;
if (term_chk(mytty, &msgsok, &atime, 1))
exit(1);
myuid = getuid();
if (!msgsok) {
if (myuid != 0) {
(void)fprintf(stderr,
"write: you have write permission turned off.\n");
exit(1);
} else {
(void)fprintf(stderr,
"write: warning: you have write permission turned off.\n");
}
}
/* check args */
switch (argc) {
case 2:
search_utmp(argv[1], tty, mytty, myuid);
do_write(tty, mytty, myuid);
break;
case 3:
if (!strncmp(argv[2], "/dev/", 5))
argv[2] += 5;
if (utmp_chk(argv[1], argv[2])) {
(void)fprintf(stderr,
"write: %s is not logged in on %s.\n",
argv[1], argv[2]);
exit(1);
}
if (term_chk(argv[2], &msgsok, &atime, 1))
exit(1);
if (myuid && !msgsok) {
(void)fprintf(stderr,
"write: %s has messages disabled on %s\n",
argv[1], argv[2]);
exit(1);
}
do_write(argv[2], mytty, myuid);
break;
default:
(void)fprintf(stderr, "usage: write user [tty]\n");
exit(1);
}
done();
/* NOTREACHED */
}
/*
* utmp_chk - checks that the given user is actually logged in on
* the given tty
*/
utmp_chk(user, tty)
char *user, *tty;
{
struct utmp u;
int ufd;
if ((ufd = open(_PATH_UTMP, O_RDONLY)) < 0)
return(0); /* ignore error, shouldn't happen anyway */
while (read(ufd, (char *) &u, sizeof(u)) == sizeof(u))
if (u.ut_type == USER_PROCESS &&
strncmp(user, u.ut_name, sizeof(u.ut_name)) == 0 &&
strncmp(tty, u.ut_line, sizeof(u.ut_line)) == 0) {
(void)close(ufd);
return(0);
}
(void)close(ufd);
return(1);
}
/*
* search_utmp - search utmp for the "best" terminal to write to
*
* Ignores terminals with messages disabled, and of the rest, returns
* the one with the most recent access time. Returns as value the number
* of the user's terminals with messages enabled, or -1 if the user is
* not logged in at all.
*
* Special case for writing to yourself - ignore the terminal you're
* writing from, unless that's the only terminal with messages enabled.
*/
search_utmp(user, tty, mytty, myuid)
char *user, *tty, *mytty;
uid_t myuid;
{
struct utmp u;
time_t bestatime, atime;
int ufd, nloggedttys, nttys, msgsok, user_is_me;
char atty[UT_LINESIZE + 1];
if ((ufd = open(_PATH_UTMP, O_RDONLY)) < 0) {
perror("utmp");
exit(1);
}
nloggedttys = nttys = 0;
bestatime = 0;
user_is_me = 0;
while (read(ufd, (char *) &u, sizeof(u)) == sizeof(u))
if (u.ut_type == USER_PROCESS &&
strncmp(user, u.ut_name, sizeof(u.ut_name)) == 0) {
++nloggedttys;
(void)strncpy(atty, u.ut_line, UT_LINESIZE);
atty[UT_LINESIZE] = '\0';
if (term_chk(atty, &msgsok, &atime, 0))
continue; /* bad term? skip */
if (myuid && !msgsok)
continue; /* skip ttys with msgs off */
if (strcmp(atty, mytty) == 0) {
user_is_me = 1;
continue; /* don't write to yourself */
}
++nttys;
/* if this is a newly created tty (eg fresh
* xterm), then user will not have typed at
* it, and the atime will be way in the
* past. So, if the atime is < utmp creation
* time, use the utmp time. */
if (atime < u.ut_time)
atime = u.ut_time;
if (atime > bestatime) {
bestatime = atime;
(void)strcpy(tty, atty);
}
}
(void)close(ufd);
if (nloggedttys == 0) {
(void)fprintf(stderr, "write: %s is not logged in\n", user);
exit(1);
}
if (nttys == 0) {
if (user_is_me) { /* ok, so write to yourself! */
(void)strcpy(tty, mytty);
return;
}
(void)fprintf(stderr,
"write: %s has messages disabled\n", user);
exit(1);
} else if (nttys > 1) {
(void)fprintf(stderr,
"write: %s is logged in more than once; writing to %s\n",
user, tty);
}
}
/*
* term_chk - check that a terminal exists, and get the message bit
* and the access time
*/
term_chk(tty, msgsokP, atimeP, showerror)
char *tty;
int *msgsokP, showerror;
time_t *atimeP;
{
struct stat s;
char path[MAXPATHLEN];
(void)sprintf(path, "/dev/%s", tty);
if (stat(path, &s) < 0) {
if (showerror)
(void)fprintf(stderr,
"write: %s: %s\n", path, strerror(errno));
return(1);
}
*msgsokP = (s.st_mode & (S_IWRITE >> 3)) != 0; /* group write bit */
*atimeP = s.st_atime;
return(0);
}
/*
* do_write - actually make the connection
*/
do_write(tty, mytty, myuid)
char *tty, *mytty;
uid_t myuid;
{
register char *login, *nows;
register struct passwd *pwd;
time_t now, time();
char *getlogin(), path[MAXPATHLEN], host[MAXHOSTNAMELEN], line[512];
void done();
#ifndef DEBIAN
/* Determine our login name before the we reopen() stdout */
if ((login = getlogin()) == NULL)
if (pwd = getpwuid(myuid))
login = pwd->pw_name;
else
login = "???";
#else /* DEBIAN */
/* Find a login name and check that it matches the uid */
if ((login = getlogin()) == NULL) {
if (pwd = getpwuid(myuid))
login = pwd->pw_name;
else {
/* uh-oh, no password entry! */
(void)fprintf(stderr, "write: who are you??\n");
exit(1);
}
}
/* got the utmp entry: ensure it matches the uid */
if ((pwd = getpwnam(login)) == NULL) {
/* claimed utmp entry isn't in the password file */
(void)fprintf(stderr,
"write: you're %s, eh? Never heard of you.\n",
login);
exit(1);
}
if (myuid != pwd->pw_uid) {
/* uid of logname in utmp is different from our uid,
eg su'ed in someone else's login */
if (myuid) {
(void)fprintf(stderr,
"write: you are uid %d, but your "
"login is as uid %d\n",
myuid, pwd->pw_uid);
exit(1);
} else {
(void)fprintf(stderr,
"write: warning: write will appear "
"from %s\n", login);
}
}
#endif /* DEBIAN */
(void)sprintf(path, "/dev/%s", tty);
if ((freopen(path, "w", stdout)) == NULL) {
(void)fprintf(stderr, "write: %s: %s\n", path, strerror(errno));
exit(1);
}
(void)signal(SIGINT, done);
(void)signal(SIGHUP, done);
/* print greeting */
if (gethostname(host, sizeof(host)) < 0)
(void)strcpy(host, "???");
now = time((time_t *)NULL);
nows = ctime(&now);
nows[16] = '\0';
(void)printf("\r\n\007\007\007Message from %s@%s on %s at %s ...\r\n",
login, host, mytty, nows + 11);
while (fgets(line, sizeof(line), stdin) != NULL)
wr_fputs(line);
}
/*
* done - cleanup and exit
*/
void
done()
{
(void)printf("EOF\r\n");
exit(0);
}
/*
* wr_fputs - like fputs(), but makes control characters visible and
* turns \n into \r\n
*/
wr_fputs(s)
register char *s;
{
register char c;
#define PUTC(c) if (putchar(c) == EOF) goto err;
for (; *s != '\0'; ++s) {
c = toascii(*s);
if (c == '\n') {
PUTC('\r');
PUTC('\n');
} else if (!isprint(c) && !isspace(c) && c != '\007') {
PUTC('^');
PUTC(c^0x40); /* DEL to ?, others to alpha */
} else
PUTC(c);
}
return;
err: (void)fprintf(stderr, "write: %s\n", strerror(errno));
exit(1);
#undef PUTC
}
|