1 /* 2 * Copyright (c) 1989, 1993 3 * The Regents of the University of California. All rights reserved. 4 * 5 * This code is derived from software contributed to Berkeley by 6 * Jef Poskanzer and Craig Leres of the Lawrence Berkeley Laboratory. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 4. Neither the name of the University nor the names of its contributors 17 * may be used to endorse or promote products derived from this software 18 * without specific prior written permission. 19 * 20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30 * SUCH DAMAGE. 31 */ 32 33 #ifndef lint 34 static const char copyright[] = 35 "@(#) Copyright (c) 1989, 1993\n\ 36 The Regents of the University of California. All rights reserved.\n"; 37 #endif 38 39 #if 0 40 #ifndef lint 41 static char sccsid[] = "@(#)write.c 8.1 (Berkeley) 6/6/93"; 42 #endif 43 #endif 44 45 #include <sys/cdefs.h> 46 __FBSDID("$FreeBSD$"); 47 48 #include <sys/param.h> 49 #include <sys/signal.h> 50 #include <sys/stat.h> 51 #include <sys/file.h> 52 #include <sys/time.h> 53 #include <ctype.h> 54 #include <err.h> 55 #include <locale.h> 56 #include <paths.h> 57 #include <pwd.h> 58 #include <stdio.h> 59 #include <stdlib.h> 60 #include <string.h> 61 #include <unistd.h> 62 #include <utmpx.h> 63 #include <wchar.h> 64 #include <wctype.h> 65 66 void done(int); 67 void do_write(char *, char *, uid_t); 68 static void usage(void); 69 int term_chk(char *, int *, time_t *, int); 70 void wr_fputs(wchar_t *s); 71 void search_utmp(char *, char *, char *, uid_t); 72 int utmp_chk(char *, char *); 73 74 int 75 main(int argc, char **argv) 76 { 77 time_t atime; 78 uid_t myuid; 79 int msgsok, myttyfd; 80 char tty[MAXPATHLEN], *mytty; 81 82 (void)setlocale(LC_CTYPE, ""); 83 84 while (getopt(argc, argv, "") != -1) 85 usage(); 86 argc -= optind; 87 argv += optind; 88 89 /* check that sender has write enabled */ 90 if (isatty(fileno(stdin))) 91 myttyfd = fileno(stdin); 92 else if (isatty(fileno(stdout))) 93 myttyfd = fileno(stdout); 94 else if (isatty(fileno(stderr))) 95 myttyfd = fileno(stderr); 96 else 97 errx(1, "can't find your tty"); 98 if (!(mytty = ttyname(myttyfd))) 99 errx(1, "can't find your tty's name"); 100 if (!strncmp(mytty, _PATH_DEV, strlen(_PATH_DEV))) 101 mytty += strlen(_PATH_DEV); 102 if (term_chk(mytty, &msgsok, &atime, 1)) 103 exit(1); 104 if (!msgsok) 105 errx(1, "you have write permission turned off"); 106 107 myuid = getuid(); 108 109 /* check args */ 110 switch (argc) { 111 case 1: 112 search_utmp(argv[0], tty, mytty, myuid); 113 do_write(tty, mytty, myuid); 114 break; 115 case 2: 116 if (!strncmp(argv[1], _PATH_DEV, strlen(_PATH_DEV))) 117 argv[1] += strlen(_PATH_DEV); 118 if (utmp_chk(argv[0], argv[1])) 119 errx(1, "%s is not logged in on %s", argv[0], argv[1]); 120 if (term_chk(argv[1], &msgsok, &atime, 1)) 121 exit(1); 122 if (myuid && !msgsok) 123 errx(1, "%s has messages disabled on %s", argv[0], argv[1]); 124 do_write(argv[1], mytty, myuid); 125 break; 126 default: 127 usage(); 128 } 129 done(0); 130 return (0); 131 } 132 133 static void 134 usage(void) 135 { 136 (void)fprintf(stderr, "usage: write user [tty]\n"); 137 exit(1); 138 } 139 140 /* 141 * utmp_chk - checks that the given user is actually logged in on 142 * the given tty 143 */ 144 int 145 utmp_chk(char *user, char *tty) 146 { 147 struct utmpx lu, *u; 148 149 strncpy(lu.ut_line, tty, sizeof lu.ut_line); 150 setutxent(); 151 while ((u = getutxline(&lu)) != NULL) 152 if (u->ut_type == USER_PROCESS && 153 strcmp(user, u->ut_user) == 0) { 154 endutxent(); 155 return(0); 156 } 157 endutxent(); 158 return(1); 159 } 160 161 /* 162 * search_utmp - search utmp for the "best" terminal to write to 163 * 164 * Ignores terminals with messages disabled, and of the rest, returns 165 * the one with the most recent access time. Returns as value the number 166 * of the user's terminals with messages enabled, or -1 if the user is 167 * not logged in at all. 168 * 169 * Special case for writing to yourself - ignore the terminal you're 170 * writing from, unless that's the only terminal with messages enabled. 171 */ 172 void 173 search_utmp(char *user, char *tty, char *mytty, uid_t myuid) 174 { 175 struct utmpx *u; 176 time_t bestatime, atime; 177 int nloggedttys, nttys, msgsok, user_is_me; 178 179 nloggedttys = nttys = 0; 180 bestatime = 0; 181 user_is_me = 0; 182 183 setutxent(); 184 while ((u = getutxent()) != NULL) 185 if (u->ut_type == USER_PROCESS && 186 strcmp(user, u->ut_user) == 0) { 187 ++nloggedttys; 188 if (term_chk(u->ut_line, &msgsok, &atime, 0)) 189 continue; /* bad term? skip */ 190 if (myuid && !msgsok) 191 continue; /* skip ttys with msgs off */ 192 if (strcmp(u->ut_line, mytty) == 0) { 193 user_is_me = 1; 194 continue; /* don't write to yourself */ 195 } 196 ++nttys; 197 if (atime > bestatime) { 198 bestatime = atime; 199 (void)strlcpy(tty, u->ut_line, MAXPATHLEN); 200 } 201 } 202 endutxent(); 203 204 if (nloggedttys == 0) 205 errx(1, "%s is not logged in", user); 206 if (nttys == 0) { 207 if (user_is_me) { /* ok, so write to yourself! */ 208 (void)strlcpy(tty, mytty, MAXPATHLEN); 209 return; 210 } 211 errx(1, "%s has messages disabled", user); 212 } else if (nttys > 1) { 213 warnx("%s is logged in more than once; writing to %s", user, tty); 214 } 215 } 216 217 /* 218 * term_chk - check that a terminal exists, and get the message bit 219 * and the access time 220 */ 221 int 222 term_chk(char *tty, int *msgsokP, time_t *atimeP, int showerror) 223 { 224 struct stat s; 225 char path[MAXPATHLEN]; 226 227 (void)snprintf(path, sizeof(path), "%s%s", _PATH_DEV, tty); 228 if (stat(path, &s) < 0) { 229 if (showerror) 230 warn("%s", path); 231 return(1); 232 } 233 *msgsokP = (s.st_mode & (S_IWRITE >> 3)) != 0; /* group write bit */ 234 *atimeP = s.st_atime; 235 return(0); 236 } 237 238 /* 239 * do_write - actually make the connection 240 */ 241 void 242 do_write(char *tty, char *mytty, uid_t myuid) 243 { 244 const char *login; 245 char *nows; 246 struct passwd *pwd; 247 time_t now; 248 char path[MAXPATHLEN], host[MAXHOSTNAMELEN]; 249 wchar_t line[512]; 250 251 /* Determine our login name before we reopen() stdout */ 252 if ((login = getlogin()) == NULL) { 253 if ((pwd = getpwuid(myuid))) 254 login = pwd->pw_name; 255 else 256 login = "???"; 257 } 258 259 (void)snprintf(path, sizeof(path), "%s%s", _PATH_DEV, tty); 260 if ((freopen(path, "w", stdout)) == NULL) 261 err(1, "%s", path); 262 263 (void)signal(SIGINT, done); 264 (void)signal(SIGHUP, done); 265 266 /* print greeting */ 267 if (gethostname(host, sizeof(host)) < 0) 268 (void)strcpy(host, "???"); 269 now = time((time_t *)NULL); 270 nows = ctime(&now); 271 nows[16] = '\0'; 272 (void)printf("\r\n\007\007\007Message from %s@%s on %s at %s ...\r\n", 273 login, host, mytty, nows + 11); 274 275 while (fgetws(line, sizeof(line)/sizeof(wchar_t), stdin) != NULL) 276 wr_fputs(line); 277 } 278 279 /* 280 * done - cleanup and exit 281 */ 282 void 283 done(int n __unused) 284 { 285 (void)printf("EOF\r\n"); 286 exit(0); 287 } 288 289 /* 290 * wr_fputs - like fputs(), but makes control characters visible and 291 * turns \n into \r\n 292 */ 293 void 294 wr_fputs(wchar_t *s) 295 { 296 297 #define PUTC(c) if (putwchar(c) == WEOF) err(1, NULL); 298 299 for (; *s != L'\0'; ++s) { 300 if (*s == L'\n') { 301 PUTC(L'\r'); 302 PUTC(L'\n'); 303 } else if (iswprint(*s) || iswspace(*s)) { 304 PUTC(*s); 305 } else { 306 wprintf(L"<0x%X>", *s); 307 } 308 } 309 return; 310 #undef PUTC 311 } 312