write.c revision 97454
11590Srgrimes/* 21590Srgrimes * Copyright (c) 1989, 1993 31590Srgrimes * The Regents of the University of California. All rights reserved. 41590Srgrimes * 51590Srgrimes * This code is derived from software contributed to Berkeley by 61590Srgrimes * Jef Poskanzer and Craig Leres of the Lawrence Berkeley Laboratory. 71590Srgrimes * 81590Srgrimes * Redistribution and use in source and binary forms, with or without 91590Srgrimes * modification, are permitted provided that the following conditions 101590Srgrimes * are met: 111590Srgrimes * 1. Redistributions of source code must retain the above copyright 121590Srgrimes * notice, this list of conditions and the following disclaimer. 131590Srgrimes * 2. Redistributions in binary form must reproduce the above copyright 141590Srgrimes * notice, this list of conditions and the following disclaimer in the 151590Srgrimes * documentation and/or other materials provided with the distribution. 161590Srgrimes * 3. All advertising materials mentioning features or use of this software 171590Srgrimes * must display the following acknowledgement: 181590Srgrimes * This product includes software developed by the University of 191590Srgrimes * California, Berkeley and its contributors. 201590Srgrimes * 4. Neither the name of the University nor the names of its contributors 211590Srgrimes * may be used to endorse or promote products derived from this software 221590Srgrimes * without specific prior written permission. 231590Srgrimes * 241590Srgrimes * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 251590Srgrimes * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 261590Srgrimes * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 271590Srgrimes * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 281590Srgrimes * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 291590Srgrimes * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 301590Srgrimes * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 311590Srgrimes * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 321590Srgrimes * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 331590Srgrimes * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 341590Srgrimes * SUCH DAMAGE. 351590Srgrimes */ 361590Srgrimes 371590Srgrimes#ifndef lint 3828794Scharnierstatic const char copyright[] = 391590Srgrimes"@(#) Copyright (c) 1989, 1993\n\ 401590Srgrimes The Regents of the University of California. All rights reserved.\n"; 4187682Smarkm#endif 421590Srgrimes 4391378Sdwmalone#if 0 441590Srgrimes#ifndef lint 4591378Sdwmalonestatic char sccsid[] = "@(#)write.c 8.1 (Berkeley) 6/6/93"; 4628794Scharnier#endif 4791378Sdwmalone#endif 481590Srgrimes 4991378Sdwmalone#include <sys/cdefs.h> 5091378Sdwmalone__FBSDID("$FreeBSD: head/usr.bin/write/write.c 97454 2002-05-29 13:14:51Z tjr $"); 5191378Sdwmalone 521590Srgrimes#include <sys/param.h> 531590Srgrimes#include <sys/signal.h> 541590Srgrimes#include <sys/stat.h> 551590Srgrimes#include <sys/file.h> 561590Srgrimes#include <sys/time.h> 571590Srgrimes#include <ctype.h> 5828794Scharnier#include <err.h> 5929430Sache#include <locale.h> 6019190Salex#include <paths.h> 611590Srgrimes#include <pwd.h> 621590Srgrimes#include <stdio.h> 6391378Sdwmalone#include <stdlib.h> 641590Srgrimes#include <string.h> 6528794Scharnier#include <unistd.h> 6628794Scharnier#include <utmp.h> 671590Srgrimes 6892922Simpvoid done(int); 6992922Simpvoid do_write(char *, char *, uid_t); 7092922Simpstatic void usage(void); 7192922Simpint term_chk(char *, int *, time_t *, int); 7292922Simpvoid wr_fputs(unsigned char *s); 7392922Simpvoid search_utmp(char *, char *, char *, uid_t); 7492922Simpint utmp_chk(char *, char *); 751590Srgrimes 7628794Scharnierint 771590Srgrimesmain(argc, argv) 781590Srgrimes int argc; 791590Srgrimes char **argv; 801590Srgrimes{ 811590Srgrimes register char *cp; 821590Srgrimes time_t atime; 831590Srgrimes uid_t myuid; 841590Srgrimes int msgsok, myttyfd; 8528794Scharnier char tty[MAXPATHLEN], *mytty; 861590Srgrimes 8729430Sache (void)setlocale(LC_CTYPE, ""); 8829430Sache 8997454Stjr while (getopt(argc, argv, "") != -1) 9097454Stjr usage(); 9197454Stjr argc -= optind; 9297454Stjr argv += optind; 9397454Stjr 941590Srgrimes /* check that sender has write enabled */ 951590Srgrimes if (isatty(fileno(stdin))) 961590Srgrimes myttyfd = fileno(stdin); 971590Srgrimes else if (isatty(fileno(stdout))) 981590Srgrimes myttyfd = fileno(stdout); 991590Srgrimes else if (isatty(fileno(stderr))) 1001590Srgrimes myttyfd = fileno(stderr); 10128794Scharnier else 10228794Scharnier errx(1, "can't find your tty"); 10328794Scharnier if (!(mytty = ttyname(myttyfd))) 10428794Scharnier errx(1, "can't find your tty's name"); 10528794Scharnier if ((cp = rindex(mytty, '/'))) 1061590Srgrimes mytty = cp + 1; 1071590Srgrimes if (term_chk(mytty, &msgsok, &atime, 1)) 1081590Srgrimes exit(1); 10928794Scharnier if (!msgsok) 11028794Scharnier errx(1, "you have write permission turned off"); 1111590Srgrimes 1121590Srgrimes myuid = getuid(); 1131590Srgrimes 1141590Srgrimes /* check args */ 1151590Srgrimes switch (argc) { 11697454Stjr case 1: 11797454Stjr search_utmp(argv[0], tty, mytty, myuid); 1181590Srgrimes do_write(tty, mytty, myuid); 1191590Srgrimes break; 12097454Stjr case 2: 12197454Stjr if (!strncmp(argv[1], _PATH_DEV, strlen(_PATH_DEV))) 12297454Stjr argv[1] += strlen(_PATH_DEV); 12397454Stjr if (utmp_chk(argv[0], argv[1])) 12497454Stjr errx(1, "%s is not logged in on %s", argv[0], argv[1]); 12597454Stjr if (term_chk(argv[1], &msgsok, &atime, 1)) 1261590Srgrimes exit(1); 12728794Scharnier if (myuid && !msgsok) 12897454Stjr errx(1, "%s has messages disabled on %s", argv[0], argv[1]); 12997454Stjr do_write(argv[1], mytty, myuid); 1301590Srgrimes break; 1311590Srgrimes default: 13228794Scharnier usage(); 1331590Srgrimes } 13429430Sache done(0); 13528794Scharnier return (0); 1361590Srgrimes} 1371590Srgrimes 13828794Scharnierstatic void 13928794Scharnierusage() 14028794Scharnier{ 14128794Scharnier (void)fprintf(stderr, "usage: write user [tty]\n"); 14228794Scharnier exit(1); 14328794Scharnier} 14428794Scharnier 1451590Srgrimes/* 1461590Srgrimes * utmp_chk - checks that the given user is actually logged in on 1471590Srgrimes * the given tty 1481590Srgrimes */ 14928794Scharnierint 1501590Srgrimesutmp_chk(user, tty) 1511590Srgrimes char *user, *tty; 1521590Srgrimes{ 1531590Srgrimes struct utmp u; 1541590Srgrimes int ufd; 1551590Srgrimes 1561590Srgrimes if ((ufd = open(_PATH_UTMP, O_RDONLY)) < 0) 1571590Srgrimes return(0); /* ignore error, shouldn't happen anyway */ 1581590Srgrimes 1591590Srgrimes while (read(ufd, (char *) &u, sizeof(u)) == sizeof(u)) 1601590Srgrimes if (strncmp(user, u.ut_name, sizeof(u.ut_name)) == 0 && 1611590Srgrimes strncmp(tty, u.ut_line, sizeof(u.ut_line)) == 0) { 1621590Srgrimes (void)close(ufd); 1631590Srgrimes return(0); 1641590Srgrimes } 1651590Srgrimes 1661590Srgrimes (void)close(ufd); 1671590Srgrimes return(1); 1681590Srgrimes} 1691590Srgrimes 1701590Srgrimes/* 1711590Srgrimes * search_utmp - search utmp for the "best" terminal to write to 1721590Srgrimes * 1731590Srgrimes * Ignores terminals with messages disabled, and of the rest, returns 1741590Srgrimes * the one with the most recent access time. Returns as value the number 1751590Srgrimes * of the user's terminals with messages enabled, or -1 if the user is 1761590Srgrimes * not logged in at all. 1771590Srgrimes * 1781590Srgrimes * Special case for writing to yourself - ignore the terminal you're 1791590Srgrimes * writing from, unless that's the only terminal with messages enabled. 1801590Srgrimes */ 18128794Scharniervoid 1821590Srgrimessearch_utmp(user, tty, mytty, myuid) 1831590Srgrimes char *user, *tty, *mytty; 1841590Srgrimes uid_t myuid; 1851590Srgrimes{ 1861590Srgrimes struct utmp u; 1871590Srgrimes time_t bestatime, atime; 1881590Srgrimes int ufd, nloggedttys, nttys, msgsok, user_is_me; 1891590Srgrimes char atty[UT_LINESIZE + 1]; 1901590Srgrimes 19128794Scharnier if ((ufd = open(_PATH_UTMP, O_RDONLY)) < 0) 19228794Scharnier err(1, "utmp"); 1931590Srgrimes 1941590Srgrimes nloggedttys = nttys = 0; 1951590Srgrimes bestatime = 0; 1961590Srgrimes user_is_me = 0; 1971590Srgrimes while (read(ufd, (char *) &u, sizeof(u)) == sizeof(u)) 1981590Srgrimes if (strncmp(user, u.ut_name, sizeof(u.ut_name)) == 0) { 1991590Srgrimes ++nloggedttys; 2001590Srgrimes (void)strncpy(atty, u.ut_line, UT_LINESIZE); 2011590Srgrimes atty[UT_LINESIZE] = '\0'; 2021590Srgrimes if (term_chk(atty, &msgsok, &atime, 0)) 2031590Srgrimes continue; /* bad term? skip */ 2041590Srgrimes if (myuid && !msgsok) 2051590Srgrimes continue; /* skip ttys with msgs off */ 2061590Srgrimes if (strcmp(atty, mytty) == 0) { 2071590Srgrimes user_is_me = 1; 2081590Srgrimes continue; /* don't write to yourself */ 2091590Srgrimes } 2101590Srgrimes ++nttys; 2111590Srgrimes if (atime > bestatime) { 2121590Srgrimes bestatime = atime; 2131590Srgrimes (void)strcpy(tty, atty); 2141590Srgrimes } 2151590Srgrimes } 2161590Srgrimes 2171590Srgrimes (void)close(ufd); 21828794Scharnier if (nloggedttys == 0) 21928794Scharnier errx(1, "%s is not logged in", user); 2201590Srgrimes if (nttys == 0) { 2211590Srgrimes if (user_is_me) { /* ok, so write to yourself! */ 2221590Srgrimes (void)strcpy(tty, mytty); 2231590Srgrimes return; 2241590Srgrimes } 22528794Scharnier errx(1, "%s has messages disabled", user); 2261590Srgrimes } else if (nttys > 1) { 22728794Scharnier warnx("%s is logged in more than once; writing to %s", user, tty); 2281590Srgrimes } 2291590Srgrimes} 2301590Srgrimes 2311590Srgrimes/* 2321590Srgrimes * term_chk - check that a terminal exists, and get the message bit 2331590Srgrimes * and the access time 2341590Srgrimes */ 23528794Scharnierint 2361590Srgrimesterm_chk(tty, msgsokP, atimeP, showerror) 2371590Srgrimes char *tty; 2381590Srgrimes int *msgsokP, showerror; 2391590Srgrimes time_t *atimeP; 2401590Srgrimes{ 2411590Srgrimes struct stat s; 2421590Srgrimes char path[MAXPATHLEN]; 2431590Srgrimes 24419190Salex (void)snprintf(path, sizeof(path), "%s%s", _PATH_DEV, tty); 2451590Srgrimes if (stat(path, &s) < 0) { 2461590Srgrimes if (showerror) 24728794Scharnier warn("%s", path); 2481590Srgrimes return(1); 2491590Srgrimes } 2501590Srgrimes *msgsokP = (s.st_mode & (S_IWRITE >> 3)) != 0; /* group write bit */ 2511590Srgrimes *atimeP = s.st_atime; 2521590Srgrimes return(0); 2531590Srgrimes} 2541590Srgrimes 2551590Srgrimes/* 2561590Srgrimes * do_write - actually make the connection 2571590Srgrimes */ 25828794Scharniervoid 2591590Srgrimesdo_write(tty, mytty, myuid) 2601590Srgrimes char *tty, *mytty; 2611590Srgrimes uid_t myuid; 2621590Srgrimes{ 26387682Smarkm const char *login; 26487682Smarkm char *nows; 26587682Smarkm struct passwd *pwd; 26628794Scharnier time_t now; 26728794Scharnier char path[MAXPATHLEN], host[MAXHOSTNAMELEN], line[512]; 2681590Srgrimes 2691590Srgrimes /* Determine our login name before the we reopen() stdout */ 27048566Sbillf if ((login = getlogin()) == NULL) { 27128794Scharnier if ((pwd = getpwuid(myuid))) 2721590Srgrimes login = pwd->pw_name; 2731590Srgrimes else 2741590Srgrimes login = "???"; 27548566Sbillf } 2761590Srgrimes 27719190Salex (void)snprintf(path, sizeof(path), "%s%s", _PATH_DEV, tty); 27828794Scharnier if ((freopen(path, "w", stdout)) == NULL) 27928794Scharnier err(1, "%s", path); 2801590Srgrimes 2811590Srgrimes (void)signal(SIGINT, done); 2821590Srgrimes (void)signal(SIGHUP, done); 2831590Srgrimes 2841590Srgrimes /* print greeting */ 2851590Srgrimes if (gethostname(host, sizeof(host)) < 0) 2861590Srgrimes (void)strcpy(host, "???"); 2871590Srgrimes now = time((time_t *)NULL); 2881590Srgrimes nows = ctime(&now); 2891590Srgrimes nows[16] = '\0'; 2901590Srgrimes (void)printf("\r\n\007\007\007Message from %s@%s on %s at %s ...\r\n", 2911590Srgrimes login, host, mytty, nows + 11); 2921590Srgrimes 2931590Srgrimes while (fgets(line, sizeof(line), stdin) != NULL) 2941590Srgrimes wr_fputs(line); 2951590Srgrimes} 2961590Srgrimes 2971590Srgrimes/* 2981590Srgrimes * done - cleanup and exit 2991590Srgrimes */ 3001590Srgrimesvoid 30129430Sachedone(n) 30287682Smarkm int n __unused; 3031590Srgrimes{ 3041590Srgrimes (void)printf("EOF\r\n"); 3051590Srgrimes exit(0); 3061590Srgrimes} 3071590Srgrimes 3081590Srgrimes/* 3091590Srgrimes * wr_fputs - like fputs(), but makes control characters visible and 3101590Srgrimes * turns \n into \r\n 3111590Srgrimes */ 31228794Scharniervoid 3131590Srgrimeswr_fputs(s) 31487682Smarkm unsigned char *s; 3151590Srgrimes{ 3161590Srgrimes 31728794Scharnier#define PUTC(c) if (putchar(c) == EOF) err(1, NULL); 3181590Srgrimes 3191590Srgrimes for (; *s != '\0'; ++s) { 32011916Sache if (*s == '\n') { 3211590Srgrimes PUTC('\r'); 32229431Sache } else if (((*s & 0x80) && *s < 0xA0) || 32329431Sache /* disable upper controls */ 32429433Sache (!isprint(*s) && !isspace(*s) && 32529433Sache *s != '\a' && *s != '\b') 32629430Sache ) { 32712097Sache if (*s & 0x80) { 32812097Sache *s &= ~0x80; 32912097Sache PUTC('M'); 33012097Sache PUTC('-'); 33112097Sache } 33212097Sache if (iscntrl(*s)) { 33312097Sache *s ^= 0x40; 33412097Sache PUTC('^'); 33512097Sache } 33612097Sache } 33712097Sache PUTC(*s); 3381590Srgrimes } 3391590Srgrimes return; 3401590Srgrimes#undef PUTC 3411590Srgrimes} 342