Annotation of src/usr.bin/write/write.c, Revision 1.8
1.8 ! downsj 1: /* $OpenBSD: write.c,v 1.7 1996/10/25 06:15:03 downsj Exp $ */
1.1 deraadt 2: /* $NetBSD: write.c,v 1.5 1995/08/31 21:48:32 jtc Exp $ */
3:
4: /*
5: * Copyright (c) 1989, 1993
6: * The Regents of the University of California. All rights reserved.
7: *
8: * This code is derived from software contributed to Berkeley by
9: * Jef Poskanzer and Craig Leres of the Lawrence Berkeley Laboratory.
10: *
11: * Redistribution and use in source and binary forms, with or without
12: * modification, are permitted provided that the following conditions
13: * are met:
14: * 1. Redistributions of source code must retain the above copyright
15: * notice, this list of conditions and the following disclaimer.
16: * 2. Redistributions in binary form must reproduce the above copyright
17: * notice, this list of conditions and the following disclaimer in the
18: * documentation and/or other materials provided with the distribution.
19: * 3. All advertising materials mentioning features or use of this software
20: * must display the following acknowledgement:
21: * This product includes software developed by the University of
22: * California, Berkeley and its contributors.
23: * 4. Neither the name of the University nor the names of its contributors
24: * may be used to endorse or promote products derived from this software
25: * without specific prior written permission.
26: *
27: * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
28: * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
29: * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
30: * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
31: * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
32: * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
33: * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
34: * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
35: * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
36: * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
37: * SUCH DAMAGE.
38: */
39:
40: #ifndef lint
41: static char copyright[] =
42: "@(#) Copyright (c) 1989, 1993\n\
43: The Regents of the University of California. All rights reserved.\n";
44: #endif /* not lint */
45:
46: #ifndef lint
47: #if 0
48: static char sccsid[] = "@(#)write.c 8.2 (Berkeley) 4/27/95";
49: #endif
1.8 ! downsj 50: static char *rcsid = "$OpenBSD: write.c,v 1.7 1996/10/25 06:15:03 downsj Exp $";
1.1 deraadt 51: #endif /* not lint */
52:
53: #include <sys/types.h>
54: #include <sys/param.h>
55: #include <sys/stat.h>
56: #include <ctype.h>
57: #include <stdio.h>
58: #include <string.h>
59: #include <signal.h>
60: #include <time.h>
61: #include <fcntl.h>
1.7 downsj 62: #include <paths.h>
1.1 deraadt 63: #include <pwd.h>
64: #include <unistd.h>
65: #include <utmp.h>
66: #include <err.h>
1.5 deraadt 67: #include <vis.h>
1.1 deraadt 68:
69: void done();
70: void do_write __P((char *, char *, uid_t));
71: void wr_fputs __P((char *));
72: void search_utmp __P((char *, char *, char *, uid_t));
73: int term_chk __P((char *, int *, time_t *, int));
74: int utmp_chk __P((char *, char *));
75:
76: int
77: main(argc, argv)
78: int argc;
79: char **argv;
80: {
81: register char *cp;
82: time_t atime;
83: uid_t myuid;
84: int msgsok, myttyfd;
85: char tty[MAXPATHLEN], *mytty;
86:
87: /* check that sender has write enabled */
88: if (isatty(fileno(stdin)))
89: myttyfd = fileno(stdin);
90: else if (isatty(fileno(stdout)))
91: myttyfd = fileno(stdout);
92: else if (isatty(fileno(stderr)))
93: myttyfd = fileno(stderr);
94: else
95: errx(1, "can't find your tty");
96: if (!(mytty = ttyname(myttyfd)))
97: errx(1, "can't find your tty's name");
98: if (cp = strrchr(mytty, '/'))
99: mytty = cp + 1;
100: if (term_chk(mytty, &msgsok, &atime, 1))
101: exit(1);
102: if (!msgsok)
1.2 deraadt 103: warnx("you have write permission turned off");
1.1 deraadt 104:
105: myuid = getuid();
106:
107: /* check args */
108: switch (argc) {
109: case 2:
110: search_utmp(argv[1], tty, mytty, myuid);
111: do_write(tty, mytty, myuid);
112: break;
113: case 3:
1.7 downsj 114: if (!strncmp(argv[2], _PATH_DEV, strlen(_PATH_DEV)))
1.8 ! downsj 115: argv[2] += strlen(_PATH_DEV);
1.1 deraadt 116: if (utmp_chk(argv[1], argv[2]))
117: errx(1, "%s is not logged in on %s",
118: argv[1], argv[2]);
119: if (term_chk(argv[2], &msgsok, &atime, 1))
120: exit(1);
121: if (myuid && !msgsok)
122: errx(1, "%s has messages disabled on %s",
123: argv[1], argv[2]);
124: do_write(argv[2], mytty, myuid);
125: break;
126: default:
127: (void)fprintf(stderr, "usage: write user [tty]\n");
128: exit(1);
129: }
130: done();
131: /* NOTREACHED */
132: }
133:
134: /*
135: * utmp_chk - checks that the given user is actually logged in on
136: * the given tty
137: */
138: int
139: utmp_chk(user, tty)
140: char *user, *tty;
141: {
142: struct utmp u;
143: int ufd;
144:
145: if ((ufd = open(_PATH_UTMP, O_RDONLY)) < 0)
146: return(0); /* ignore error, shouldn't happen anyway */
147:
148: while (read(ufd, (char *) &u, sizeof(u)) == sizeof(u))
149: if (strncmp(user, u.ut_name, sizeof(u.ut_name)) == 0 &&
150: strncmp(tty, u.ut_line, sizeof(u.ut_line)) == 0) {
151: (void)close(ufd);
152: return(0);
153: }
154:
155: (void)close(ufd);
156: return(1);
157: }
158:
159: /*
160: * search_utmp - search utmp for the "best" terminal to write to
161: *
162: * Ignores terminals with messages disabled, and of the rest, returns
163: * the one with the most recent access time. Returns as value the number
164: * of the user's terminals with messages enabled, or -1 if the user is
165: * not logged in at all.
166: *
167: * Special case for writing to yourself - ignore the terminal you're
168: * writing from, unless that's the only terminal with messages enabled.
169: */
170: void
171: search_utmp(user, tty, mytty, myuid)
172: char *user, *tty, *mytty;
173: uid_t myuid;
174: {
175: struct utmp u;
176: time_t bestatime, atime;
177: int ufd, nloggedttys, nttys, msgsok, user_is_me;
178: char atty[UT_LINESIZE + 1];
179:
180: if ((ufd = open(_PATH_UTMP, O_RDONLY)) < 0)
181: err(1, "%s", _PATH_UTMP);
182:
183: nloggedttys = nttys = 0;
184: bestatime = 0;
185: user_is_me = 0;
186: while (read(ufd, (char *) &u, sizeof(u)) == sizeof(u))
187: if (strncmp(user, u.ut_name, sizeof(u.ut_name)) == 0) {
188: ++nloggedttys;
189: (void)strncpy(atty, u.ut_line, UT_LINESIZE);
190: atty[UT_LINESIZE] = '\0';
191: if (term_chk(atty, &msgsok, &atime, 0))
192: continue; /* bad term? skip */
193: if (myuid && !msgsok)
194: continue; /* skip ttys with msgs off */
195: if (strcmp(atty, mytty) == 0) {
196: user_is_me = 1;
197: continue; /* don't write to yourself */
198: }
199: ++nttys;
200: if (atime > bestatime) {
201: bestatime = atime;
202: (void)strcpy(tty, atty);
203: }
204: }
205:
206: (void)close(ufd);
207: if (nloggedttys == 0)
208: errx(1, "%s is not logged in", user);
209: if (nttys == 0) {
210: if (user_is_me) { /* ok, so write to yourself! */
211: (void)strcpy(tty, mytty);
212: return;
213: }
214: errx(1, "%s has messages disabled", user);
215: } else if (nttys > 1)
216: warnx("%s is logged in more than once; writing to %s",
217: user, tty);
218: }
219:
220: /*
221: * term_chk - check that a terminal exists, and get the message bit
222: * and the access time
223: */
224: int
225: term_chk(tty, msgsokP, atimeP, showerror)
226: char *tty;
227: int *msgsokP, showerror;
228: time_t *atimeP;
229: {
230: struct stat s;
231: char path[MAXPATHLEN];
232:
1.7 downsj 233: (void)snprintf(path, sizeof(path), "%s%s", _PATH_DEV, tty);
1.1 deraadt 234: if (stat(path, &s) < 0) {
235: if (showerror)
236: warn("%s", path);
237: return(1);
238: }
239: *msgsokP = (s.st_mode & (S_IWRITE >> 3)) != 0; /* group write bit */
240: *atimeP = s.st_atime;
241: return(0);
242: }
243:
244: /*
245: * do_write - actually make the connection
246: */
247: void
248: do_write(tty, mytty, myuid)
249: char *tty, *mytty;
250: uid_t myuid;
251: {
252: register char *login, *nows;
253: register struct passwd *pwd;
254: time_t now;
255: char path[MAXPATHLEN], host[MAXHOSTNAMELEN], line[512];
256:
257: /* Determine our login name before the we reopen() stdout */
258: if ((login = getlogin()) == NULL)
259: if (pwd = getpwuid(myuid))
260: login = pwd->pw_name;
261: else
262: login = "???";
263:
1.7 downsj 264: (void)snprintf(path, sizeof(path), "%s%s", _PATH_DEV, tty);
1.1 deraadt 265: if ((freopen(path, "w", stdout)) == NULL)
266: err(1, "%s", path);
267:
268: (void)signal(SIGINT, done);
269: (void)signal(SIGHUP, done);
270:
271: /* print greeting */
272: if (gethostname(host, sizeof(host)) < 0)
273: (void)strcpy(host, "???");
274: now = time((time_t *)NULL);
275: nows = ctime(&now);
276: nows[16] = '\0';
277: (void)printf("\r\n\007\007\007Message from %s@%s on %s at %s ...\r\n",
278: login, host, mytty, nows + 11);
279:
280: while (fgets(line, sizeof(line), stdin) != NULL)
281: wr_fputs(line);
282: }
283:
284: /*
285: * done - cleanup and exit
286: */
287: void
288: done()
289: {
290: (void)printf("EOF\r\n");
291: exit(0);
292: }
293:
294: /*
295: * wr_fputs - like fputs(), but makes control characters visible and
296: * turns \n into \r\n
297: */
298: void
299: wr_fputs(s)
300: register char *s;
301: {
1.5 deraadt 302: register u_char c;
303: char visout[4], *s2;
1.1 deraadt 304:
305: #define PUTC(c) if (putchar(c) == EOF) goto err;
306:
307: for (; *s != '\0'; ++s) {
308: c = toascii(*s);
309: if (c == '\n') {
310: PUTC('\r');
1.5 deraadt 311: PUTC('\n');
312: continue;
1.3 deraadt 313: }
1.6 deraadt 314: vis(visout, c, VIS_SAFE|VIS_NOSLASH, s[1]);
1.5 deraadt 315: for (s2 = visout; *s2; s2++)
316: PUTC(*s2);
1.1 deraadt 317: }
318: return;
319:
320: err: err(1, NULL);
321: #undef PUTC
322: }
![[BACK]](/icons/back.gif){kind=icon}
Return to write.c CVS log ![[TXT]](/icons/text.gif){kind=icon}
![[DIR]](/icons/dir.gif){kind=icon}
Up to [local] / src / usr.bin / write