write.c revision 91378
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 91378 2002-02-27 14:40:09Z dwmalone $"); 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 6829430Sachevoid done __P((int)); 6928794Scharniervoid do_write __P((char *, char *, uid_t)); 7028794Scharnierstatic void usage __P((void)); 7128794Scharnierint term_chk __P((char *, int *, time_t *, int)); 7228794Scharniervoid wr_fputs __P((unsigned char *s)); 7328794Scharniervoid search_utmp __P((char *, char *, char *, uid_t)); 7428794Scharnierint utmp_chk __P((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 891590Srgrimes /* check that sender has write enabled */ 901590Srgrimes if (isatty(fileno(stdin))) 911590Srgrimes myttyfd = fileno(stdin); 921590Srgrimes else if (isatty(fileno(stdout))) 931590Srgrimes myttyfd = fileno(stdout); 941590Srgrimes else if (isatty(fileno(stderr))) 951590Srgrimes myttyfd = fileno(stderr); 9628794Scharnier else 9728794Scharnier errx(1, "can't find your tty"); 9828794Scharnier if (!(mytty = ttyname(myttyfd))) 9928794Scharnier errx(1, "can't find your tty's name"); 10028794Scharnier if ((cp = rindex(mytty, '/'))) 1011590Srgrimes mytty = cp + 1; 1021590Srgrimes if (term_chk(mytty, &msgsok, &atime, 1)) 1031590Srgrimes exit(1); 10428794Scharnier if (!msgsok) 10528794Scharnier errx(1, "you have write permission turned off"); 1061590Srgrimes 1071590Srgrimes myuid = getuid(); 1081590Srgrimes 1091590Srgrimes /* check args */ 1101590Srgrimes switch (argc) { 1111590Srgrimes case 2: 1121590Srgrimes search_utmp(argv[1], tty, mytty, myuid); 1131590Srgrimes do_write(tty, mytty, myuid); 1141590Srgrimes break; 1151590Srgrimes case 3: 11619190Salex if (!strncmp(argv[2], _PATH_DEV, strlen(_PATH_DEV))) 11719193Salex argv[2] += strlen(_PATH_DEV); 11828794Scharnier if (utmp_chk(argv[1], argv[2])) 11928794Scharnier errx(1, "%s is not logged in on %s", argv[1], argv[2]); 1201590Srgrimes if (term_chk(argv[2], &msgsok, &atime, 1)) 1211590Srgrimes exit(1); 12228794Scharnier if (myuid && !msgsok) 12328794Scharnier errx(1, "%s has messages disabled on %s", argv[1], argv[2]); 1241590Srgrimes do_write(argv[2], mytty, myuid); 1251590Srgrimes break; 1261590Srgrimes default: 12728794Scharnier usage(); 1281590Srgrimes } 12929430Sache done(0); 13028794Scharnier return (0); 1311590Srgrimes} 1321590Srgrimes 13328794Scharnierstatic void 13428794Scharnierusage() 13528794Scharnier{ 13628794Scharnier (void)fprintf(stderr, "usage: write user [tty]\n"); 13728794Scharnier exit(1); 13828794Scharnier} 13928794Scharnier 1401590Srgrimes/* 1411590Srgrimes * utmp_chk - checks that the given user is actually logged in on 1421590Srgrimes * the given tty 1431590Srgrimes */ 14428794Scharnierint 1451590Srgrimesutmp_chk(user, tty) 1461590Srgrimes char *user, *tty; 1471590Srgrimes{ 1481590Srgrimes struct utmp u; 1491590Srgrimes int ufd; 1501590Srgrimes 1511590Srgrimes if ((ufd = open(_PATH_UTMP, O_RDONLY)) < 0) 1521590Srgrimes return(0); /* ignore error, shouldn't happen anyway */ 1531590Srgrimes 1541590Srgrimes while (read(ufd, (char *) &u, sizeof(u)) == sizeof(u)) 1551590Srgrimes if (strncmp(user, u.ut_name, sizeof(u.ut_name)) == 0 && 1561590Srgrimes strncmp(tty, u.ut_line, sizeof(u.ut_line)) == 0) { 1571590Srgrimes (void)close(ufd); 1581590Srgrimes return(0); 1591590Srgrimes } 1601590Srgrimes 1611590Srgrimes (void)close(ufd); 1621590Srgrimes return(1); 1631590Srgrimes} 1641590Srgrimes 1651590Srgrimes/* 1661590Srgrimes * search_utmp - search utmp for the "best" terminal to write to 1671590Srgrimes * 1681590Srgrimes * Ignores terminals with messages disabled, and of the rest, returns 1691590Srgrimes * the one with the most recent access time. Returns as value the number 1701590Srgrimes * of the user's terminals with messages enabled, or -1 if the user is 1711590Srgrimes * not logged in at all. 1721590Srgrimes * 1731590Srgrimes * Special case for writing to yourself - ignore the terminal you're 1741590Srgrimes * writing from, unless that's the only terminal with messages enabled. 1751590Srgrimes */ 17628794Scharniervoid 1771590Srgrimessearch_utmp(user, tty, mytty, myuid) 1781590Srgrimes char *user, *tty, *mytty; 1791590Srgrimes uid_t myuid; 1801590Srgrimes{ 1811590Srgrimes struct utmp u; 1821590Srgrimes time_t bestatime, atime; 1831590Srgrimes int ufd, nloggedttys, nttys, msgsok, user_is_me; 1841590Srgrimes char atty[UT_LINESIZE + 1]; 1851590Srgrimes 18628794Scharnier if ((ufd = open(_PATH_UTMP, O_RDONLY)) < 0) 18728794Scharnier err(1, "utmp"); 1881590Srgrimes 1891590Srgrimes nloggedttys = nttys = 0; 1901590Srgrimes bestatime = 0; 1911590Srgrimes user_is_me = 0; 1921590Srgrimes while (read(ufd, (char *) &u, sizeof(u)) == sizeof(u)) 1931590Srgrimes if (strncmp(user, u.ut_name, sizeof(u.ut_name)) == 0) { 1941590Srgrimes ++nloggedttys; 1951590Srgrimes (void)strncpy(atty, u.ut_line, UT_LINESIZE); 1961590Srgrimes atty[UT_LINESIZE] = '\0'; 1971590Srgrimes if (term_chk(atty, &msgsok, &atime, 0)) 1981590Srgrimes continue; /* bad term? skip */ 1991590Srgrimes if (myuid && !msgsok) 2001590Srgrimes continue; /* skip ttys with msgs off */ 2011590Srgrimes if (strcmp(atty, mytty) == 0) { 2021590Srgrimes user_is_me = 1; 2031590Srgrimes continue; /* don't write to yourself */ 2041590Srgrimes } 2051590Srgrimes ++nttys; 2061590Srgrimes if (atime > bestatime) { 2071590Srgrimes bestatime = atime; 2081590Srgrimes (void)strcpy(tty, atty); 2091590Srgrimes } 2101590Srgrimes } 2111590Srgrimes 2121590Srgrimes (void)close(ufd); 21328794Scharnier if (nloggedttys == 0) 21428794Scharnier errx(1, "%s is not logged in", user); 2151590Srgrimes if (nttys == 0) { 2161590Srgrimes if (user_is_me) { /* ok, so write to yourself! */ 2171590Srgrimes (void)strcpy(tty, mytty); 2181590Srgrimes return; 2191590Srgrimes } 22028794Scharnier errx(1, "%s has messages disabled", user); 2211590Srgrimes } else if (nttys > 1) { 22228794Scharnier warnx("%s is logged in more than once; writing to %s", user, tty); 2231590Srgrimes } 2241590Srgrimes} 2251590Srgrimes 2261590Srgrimes/* 2271590Srgrimes * term_chk - check that a terminal exists, and get the message bit 2281590Srgrimes * and the access time 2291590Srgrimes */ 23028794Scharnierint 2311590Srgrimesterm_chk(tty, msgsokP, atimeP, showerror) 2321590Srgrimes char *tty; 2331590Srgrimes int *msgsokP, showerror; 2341590Srgrimes time_t *atimeP; 2351590Srgrimes{ 2361590Srgrimes struct stat s; 2371590Srgrimes char path[MAXPATHLEN]; 2381590Srgrimes 23919190Salex (void)snprintf(path, sizeof(path), "%s%s", _PATH_DEV, tty); 2401590Srgrimes if (stat(path, &s) < 0) { 2411590Srgrimes if (showerror) 24228794Scharnier warn("%s", path); 2431590Srgrimes return(1); 2441590Srgrimes } 2451590Srgrimes *msgsokP = (s.st_mode & (S_IWRITE >> 3)) != 0; /* group write bit */ 2461590Srgrimes *atimeP = s.st_atime; 2471590Srgrimes return(0); 2481590Srgrimes} 2491590Srgrimes 2501590Srgrimes/* 2511590Srgrimes * do_write - actually make the connection 2521590Srgrimes */ 25328794Scharniervoid 2541590Srgrimesdo_write(tty, mytty, myuid) 2551590Srgrimes char *tty, *mytty; 2561590Srgrimes uid_t myuid; 2571590Srgrimes{ 25887682Smarkm const char *login; 25987682Smarkm char *nows; 26087682Smarkm struct passwd *pwd; 26128794Scharnier time_t now; 26228794Scharnier char path[MAXPATHLEN], host[MAXHOSTNAMELEN], line[512]; 2631590Srgrimes 2641590Srgrimes /* Determine our login name before the we reopen() stdout */ 26548566Sbillf if ((login = getlogin()) == NULL) { 26628794Scharnier if ((pwd = getpwuid(myuid))) 2671590Srgrimes login = pwd->pw_name; 2681590Srgrimes else 2691590Srgrimes login = "???"; 27048566Sbillf } 2711590Srgrimes 27219190Salex (void)snprintf(path, sizeof(path), "%s%s", _PATH_DEV, tty); 27328794Scharnier if ((freopen(path, "w", stdout)) == NULL) 27428794Scharnier err(1, "%s", path); 2751590Srgrimes 2761590Srgrimes (void)signal(SIGINT, done); 2771590Srgrimes (void)signal(SIGHUP, done); 2781590Srgrimes 2791590Srgrimes /* print greeting */ 2801590Srgrimes if (gethostname(host, sizeof(host)) < 0) 2811590Srgrimes (void)strcpy(host, "???"); 2821590Srgrimes now = time((time_t *)NULL); 2831590Srgrimes nows = ctime(&now); 2841590Srgrimes nows[16] = '\0'; 2851590Srgrimes (void)printf("\r\n\007\007\007Message from %s@%s on %s at %s ...\r\n", 2861590Srgrimes login, host, mytty, nows + 11); 2871590Srgrimes 2881590Srgrimes while (fgets(line, sizeof(line), stdin) != NULL) 2891590Srgrimes wr_fputs(line); 2901590Srgrimes} 2911590Srgrimes 2921590Srgrimes/* 2931590Srgrimes * done - cleanup and exit 2941590Srgrimes */ 2951590Srgrimesvoid 29629430Sachedone(n) 29787682Smarkm int n __unused; 2981590Srgrimes{ 2991590Srgrimes (void)printf("EOF\r\n"); 3001590Srgrimes exit(0); 3011590Srgrimes} 3021590Srgrimes 3031590Srgrimes/* 3041590Srgrimes * wr_fputs - like fputs(), but makes control characters visible and 3051590Srgrimes * turns \n into \r\n 3061590Srgrimes */ 30728794Scharniervoid 3081590Srgrimeswr_fputs(s) 30987682Smarkm unsigned char *s; 3101590Srgrimes{ 3111590Srgrimes 31228794Scharnier#define PUTC(c) if (putchar(c) == EOF) err(1, NULL); 3131590Srgrimes 3141590Srgrimes for (; *s != '\0'; ++s) { 31511916Sache if (*s == '\n') { 3161590Srgrimes PUTC('\r'); 31729431Sache } else if (((*s & 0x80) && *s < 0xA0) || 31829431Sache /* disable upper controls */ 31929433Sache (!isprint(*s) && !isspace(*s) && 32029433Sache *s != '\a' && *s != '\b') 32129430Sache ) { 32212097Sache if (*s & 0x80) { 32312097Sache *s &= ~0x80; 32412097Sache PUTC('M'); 32512097Sache PUTC('-'); 32612097Sache } 32712097Sache if (iscntrl(*s)) { 32812097Sache *s ^= 0x40; 32912097Sache PUTC('^'); 33012097Sache } 33112097Sache } 33212097Sache PUTC(*s); 3331590Srgrimes } 3341590Srgrimes return; 3351590Srgrimes#undef PUTC 3361590Srgrimes} 337