Annotation of src/usr.bin/write/write.c, Revision 1.21
1.21 ! deraadt 1: /* $OpenBSD: write.c,v 1.20 2003/06/03 02:56:24 millert 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.
1.20 millert 19: * 3. Neither the name of the University nor the names of its contributors
1.1 deraadt 20: * may be used to endorse or promote products derived from this software
21: * without specific prior written permission.
22: *
23: * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
24: * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
25: * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
26: * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
27: * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
28: * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
29: * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
30: * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
31: * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
32: * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
33: * SUCH DAMAGE.
34: */
35:
36: #ifndef lint
37: static char copyright[] =
38: "@(#) Copyright (c) 1989, 1993\n\
39: The Regents of the University of California. All rights reserved.\n";
40: #endif /* not lint */
41:
42: #ifndef lint
43: #if 0
44: static char sccsid[] = "@(#)write.c 8.2 (Berkeley) 4/27/95";
45: #endif
1.21 ! deraadt 46: static char *rcsid = "$OpenBSD: write.c,v 1.20 2003/06/03 02:56:24 millert Exp $";
1.1 deraadt 47: #endif /* not lint */
48:
49: #include <sys/param.h>
50: #include <sys/stat.h>
51: #include <ctype.h>
52: #include <stdio.h>
53: #include <string.h>
54: #include <signal.h>
55: #include <time.h>
56: #include <fcntl.h>
1.7 downsj 57: #include <paths.h>
1.1 deraadt 58: #include <pwd.h>
59: #include <unistd.h>
60: #include <utmp.h>
61: #include <err.h>
1.5 deraadt 62: #include <vis.h>
1.1 deraadt 63:
1.15 millert 64: void done(int sig);
65: void do_write(char *, char *, uid_t);
66: void wr_fputs(char *);
1.19 deraadt 67: void search_utmp(char *, char *, int, char *, uid_t);
1.15 millert 68: int term_chk(char *, int *, time_t *, int);
69: int utmp_chk(char *, char *);
1.1 deraadt 70:
71: int
1.21 ! deraadt 72: main(int argc, char *argv[])
1.1 deraadt 73: {
1.17 deraadt 74: char tty[MAXPATHLEN], *mytty, *cp;
75: int msgsok, myttyfd;
1.1 deraadt 76: time_t atime;
77: uid_t myuid;
78:
79: /* check that sender has write enabled */
80: if (isatty(fileno(stdin)))
81: myttyfd = fileno(stdin);
82: else if (isatty(fileno(stdout)))
83: myttyfd = fileno(stdout);
84: else if (isatty(fileno(stderr)))
85: myttyfd = fileno(stderr);
86: else
87: errx(1, "can't find your tty");
88: if (!(mytty = ttyname(myttyfd)))
89: errx(1, "can't find your tty's name");
1.12 jasoni 90: if ((cp = strrchr(mytty, '/')))
1.1 deraadt 91: mytty = cp + 1;
92: if (term_chk(mytty, &msgsok, &atime, 1))
93: exit(1);
94: if (!msgsok)
1.2 deraadt 95: warnx("you have write permission turned off");
1.1 deraadt 96:
97: myuid = getuid();
98:
99: /* check args */
100: switch (argc) {
101: case 2:
1.19 deraadt 102: search_utmp(argv[1], tty, sizeof tty, mytty, myuid);
1.1 deraadt 103: do_write(tty, mytty, myuid);
104: break;
105: case 3:
1.16 fgsch 106: if (!strncmp(argv[2], _PATH_DEV, sizeof(_PATH_DEV) - 1))
107: argv[2] += sizeof(_PATH_DEV) - 1;
1.1 deraadt 108: if (utmp_chk(argv[1], argv[2]))
109: errx(1, "%s is not logged in on %s",
110: argv[1], argv[2]);
111: if (term_chk(argv[2], &msgsok, &atime, 1))
112: exit(1);
113: if (myuid && !msgsok)
114: errx(1, "%s has messages disabled on %s",
115: argv[1], argv[2]);
116: do_write(argv[2], mytty, myuid);
117: break;
118: default:
119: (void)fprintf(stderr, "usage: write user [tty]\n");
120: exit(1);
121: }
1.11 deraadt 122: done(0);
1.12 jasoni 123:
1.1 deraadt 124: /* NOTREACHED */
1.12 jasoni 125: return (0);
1.1 deraadt 126: }
127:
128: /*
129: * utmp_chk - checks that the given user is actually logged in on
130: * the given tty
131: */
132: int
1.17 deraadt 133: utmp_chk(char *user, char *tty)
1.1 deraadt 134: {
135: struct utmp u;
136: int ufd;
137:
138: if ((ufd = open(_PATH_UTMP, O_RDONLY)) < 0)
139: return(0); /* ignore error, shouldn't happen anyway */
140:
141: while (read(ufd, (char *) &u, sizeof(u)) == sizeof(u))
142: if (strncmp(user, u.ut_name, sizeof(u.ut_name)) == 0 &&
143: strncmp(tty, u.ut_line, sizeof(u.ut_line)) == 0) {
144: (void)close(ufd);
145: return(0);
146: }
147:
148: (void)close(ufd);
149: return(1);
150: }
151:
152: /*
153: * search_utmp - search utmp for the "best" terminal to write to
154: *
155: * Ignores terminals with messages disabled, and of the rest, returns
156: * the one with the most recent access time. Returns as value the number
157: * of the user's terminals with messages enabled, or -1 if the user is
158: * not logged in at all.
159: *
160: * Special case for writing to yourself - ignore the terminal you're
161: * writing from, unless that's the only terminal with messages enabled.
162: */
163: void
1.19 deraadt 164: search_utmp(char *user, char *tty, int ttyl, char *mytty, uid_t myuid)
1.1 deraadt 165: {
166: struct utmp u;
167: time_t bestatime, atime;
168: int ufd, nloggedttys, nttys, msgsok, user_is_me;
169: char atty[UT_LINESIZE + 1];
170:
171: if ((ufd = open(_PATH_UTMP, O_RDONLY)) < 0)
172: err(1, "%s", _PATH_UTMP);
173:
174: nloggedttys = nttys = 0;
175: bestatime = 0;
176: user_is_me = 0;
177: while (read(ufd, (char *) &u, sizeof(u)) == sizeof(u))
178: if (strncmp(user, u.ut_name, sizeof(u.ut_name)) == 0) {
179: ++nloggedttys;
180: (void)strncpy(atty, u.ut_line, UT_LINESIZE);
181: atty[UT_LINESIZE] = '\0';
182: if (term_chk(atty, &msgsok, &atime, 0))
183: continue; /* bad term? skip */
184: if (myuid && !msgsok)
185: continue; /* skip ttys with msgs off */
186: if (strcmp(atty, mytty) == 0) {
187: user_is_me = 1;
188: continue; /* don't write to yourself */
189: }
190: ++nttys;
191: if (atime > bestatime) {
192: bestatime = atime;
1.19 deraadt 193: (void)strlcpy(tty, atty, ttyl);
1.1 deraadt 194: }
195: }
196:
197: (void)close(ufd);
198: if (nloggedttys == 0)
199: errx(1, "%s is not logged in", user);
200: if (nttys == 0) {
201: if (user_is_me) { /* ok, so write to yourself! */
1.19 deraadt 202: (void)strlcpy(tty, mytty, ttyl);
1.1 deraadt 203: return;
204: }
205: errx(1, "%s has messages disabled", user);
206: } else if (nttys > 1)
207: warnx("%s is logged in more than once; writing to %s",
208: user, tty);
209: }
210:
211: /*
212: * term_chk - check that a terminal exists, and get the message bit
213: * and the access time
214: */
215: int
1.17 deraadt 216: term_chk(char *tty, int *msgsokP, time_t *atimeP, int showerror)
1.1 deraadt 217: {
218: struct stat s;
219: char path[MAXPATHLEN];
220:
1.7 downsj 221: (void)snprintf(path, sizeof(path), "%s%s", _PATH_DEV, tty);
1.1 deraadt 222: if (stat(path, &s) < 0) {
223: if (showerror)
224: warn("%s", path);
225: return(1);
226: }
1.9 deraadt 227: *msgsokP = (s.st_mode & S_IWGRP) != 0; /* group write bit */
1.1 deraadt 228: *atimeP = s.st_atime;
229: return(0);
230: }
231:
232: /*
233: * do_write - actually make the connection
234: */
235: void
1.17 deraadt 236: do_write(char *tty, char *mytty, uid_t myuid)
1.1 deraadt 237: {
1.14 mpech 238: char *login, *nows;
239: struct passwd *pwd;
1.1 deraadt 240: time_t now;
241: char path[MAXPATHLEN], host[MAXHOSTNAMELEN], line[512];
242:
243: /* Determine our login name before the we reopen() stdout */
1.12 jasoni 244: if ((login = getlogin()) == NULL) {
245: if ((pwd = getpwuid(myuid)))
1.1 deraadt 246: login = pwd->pw_name;
247: else
248: login = "???";
1.12 jasoni 249: }
1.1 deraadt 250:
1.7 downsj 251: (void)snprintf(path, sizeof(path), "%s%s", _PATH_DEV, tty);
1.1 deraadt 252: if ((freopen(path, "w", stdout)) == NULL)
253: err(1, "%s", path);
254:
1.17 deraadt 255: /* revoke privs, now that we have opened the tty */
256: setegid(getgid());
257: setgid(getgid());
258:
1.1 deraadt 259: (void)signal(SIGINT, done);
260: (void)signal(SIGHUP, done);
261:
262: /* print greeting */
263: if (gethostname(host, sizeof(host)) < 0)
1.19 deraadt 264: (void)strlcpy(host, "???", sizeof host);
1.1 deraadt 265: now = time((time_t *)NULL);
266: nows = ctime(&now);
267: nows[16] = '\0';
268: (void)printf("\r\n\007\007\007Message from %s@%s on %s at %s ...\r\n",
269: login, host, mytty, nows + 11);
270:
271: while (fgets(line, sizeof(line), stdin) != NULL)
272: wr_fputs(line);
273: }
274:
275: /*
276: * done - cleanup and exit
277: */
278: void
1.11 deraadt 279: done(int sig)
1.1 deraadt 280: {
1.13 deraadt 281: (void)write(STDOUT_FILENO, "EOF\r\n", 5);
1.11 deraadt 282: if (sig)
283: _exit(0);
284: else
285: exit(0);
1.1 deraadt 286: }
287:
288: /*
289: * wr_fputs - like fputs(), but makes control characters visible and
290: * turns \n into \r\n
291: */
292: void
1.17 deraadt 293: wr_fputs(char *s)
1.1 deraadt 294: {
1.14 mpech 295: u_char c;
1.10 deraadt 296: char visout[5], *s2;
1.1 deraadt 297:
298: #define PUTC(c) if (putchar(c) == EOF) goto err;
299:
300: for (; *s != '\0'; ++s) {
301: c = toascii(*s);
302: if (c == '\n') {
303: PUTC('\r');
1.5 deraadt 304: PUTC('\n');
305: continue;
1.3 deraadt 306: }
1.6 deraadt 307: vis(visout, c, VIS_SAFE|VIS_NOSLASH, s[1]);
1.5 deraadt 308: for (s2 = visout; *s2; s2++)
309: PUTC(*s2);
1.1 deraadt 310: }
311: return;
312:
313: err: err(1, NULL);
314: #undef PUTC
315: }
![[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