Annotation of src/usr.bin/write/write.c, Revision 1.1
1.1 ! deraadt 1: /* $NetBSD: write.c,v 1.5 1995/08/31 21:48:32 jtc Exp $ */
! 2:
! 3: /*
! 4: * Copyright (c) 1989, 1993
! 5: * The Regents of the University of California. All rights reserved.
! 6: *
! 7: * This code is derived from software contributed to Berkeley by
! 8: * Jef Poskanzer and Craig Leres of the Lawrence Berkeley Laboratory.
! 9: *
! 10: * Redistribution and use in source and binary forms, with or without
! 11: * modification, are permitted provided that the following conditions
! 12: * are met:
! 13: * 1. Redistributions of source code must retain the above copyright
! 14: * notice, this list of conditions and the following disclaimer.
! 15: * 2. Redistributions in binary form must reproduce the above copyright
! 16: * notice, this list of conditions and the following disclaimer in the
! 17: * documentation and/or other materials provided with the distribution.
! 18: * 3. All advertising materials mentioning features or use of this software
! 19: * must display the following acknowledgement:
! 20: * This product includes software developed by the University of
! 21: * California, Berkeley and its contributors.
! 22: * 4. Neither the name of the University nor the names of its contributors
! 23: * may be used to endorse or promote products derived from this software
! 24: * without specific prior written permission.
! 25: *
! 26: * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
! 27: * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
! 28: * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
! 29: * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
! 30: * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
! 31: * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
! 32: * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
! 33: * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
! 34: * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
! 35: * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
! 36: * SUCH DAMAGE.
! 37: */
! 38:
! 39: #ifndef lint
! 40: static char copyright[] =
! 41: "@(#) Copyright (c) 1989, 1993\n\
! 42: The Regents of the University of California. All rights reserved.\n";
! 43: #endif /* not lint */
! 44:
! 45: #ifndef lint
! 46: #if 0
! 47: static char sccsid[] = "@(#)write.c 8.2 (Berkeley) 4/27/95";
! 48: #endif
! 49: static char *rcsid = "$NetBSD: write.c,v 1.5 1995/08/31 21:48:32 jtc Exp $";
! 50: #endif /* not lint */
! 51:
! 52: #include <sys/types.h>
! 53: #include <sys/param.h>
! 54: #include <sys/stat.h>
! 55: #include <ctype.h>
! 56: #include <stdio.h>
! 57: #include <string.h>
! 58: #include <signal.h>
! 59: #include <time.h>
! 60: #include <fcntl.h>
! 61: #include <pwd.h>
! 62: #include <unistd.h>
! 63: #include <utmp.h>
! 64: #include <err.h>
! 65:
! 66: void done();
! 67: void do_write __P((char *, char *, uid_t));
! 68: void wr_fputs __P((char *));
! 69: void search_utmp __P((char *, char *, char *, uid_t));
! 70: int term_chk __P((char *, int *, time_t *, int));
! 71: int utmp_chk __P((char *, char *));
! 72:
! 73: int
! 74: main(argc, argv)
! 75: int argc;
! 76: char **argv;
! 77: {
! 78: register char *cp;
! 79: time_t atime;
! 80: uid_t myuid;
! 81: int msgsok, myttyfd;
! 82: char tty[MAXPATHLEN], *mytty;
! 83:
! 84: /* check that sender has write enabled */
! 85: if (isatty(fileno(stdin)))
! 86: myttyfd = fileno(stdin);
! 87: else if (isatty(fileno(stdout)))
! 88: myttyfd = fileno(stdout);
! 89: else if (isatty(fileno(stderr)))
! 90: myttyfd = fileno(stderr);
! 91: else
! 92: errx(1, "can't find your tty");
! 93: if (!(mytty = ttyname(myttyfd)))
! 94: errx(1, "can't find your tty's name");
! 95: if (cp = strrchr(mytty, '/'))
! 96: mytty = cp + 1;
! 97: if (term_chk(mytty, &msgsok, &atime, 1))
! 98: exit(1);
! 99: if (!msgsok)
! 100: errx(1, "you have write permission turned off");
! 101:
! 102: myuid = getuid();
! 103:
! 104: /* check args */
! 105: switch (argc) {
! 106: case 2:
! 107: search_utmp(argv[1], tty, mytty, myuid);
! 108: do_write(tty, mytty, myuid);
! 109: break;
! 110: case 3:
! 111: if (!strncmp(argv[2], "/dev/", 5))
! 112: argv[2] += 5;
! 113: if (utmp_chk(argv[1], argv[2]))
! 114: errx(1, "%s is not logged in on %s",
! 115: argv[1], argv[2]);
! 116: if (term_chk(argv[2], &msgsok, &atime, 1))
! 117: exit(1);
! 118: if (myuid && !msgsok)
! 119: errx(1, "%s has messages disabled on %s",
! 120: argv[1], argv[2]);
! 121: do_write(argv[2], mytty, myuid);
! 122: break;
! 123: default:
! 124: (void)fprintf(stderr, "usage: write user [tty]\n");
! 125: exit(1);
! 126: }
! 127: done();
! 128: /* NOTREACHED */
! 129: }
! 130:
! 131: /*
! 132: * utmp_chk - checks that the given user is actually logged in on
! 133: * the given tty
! 134: */
! 135: int
! 136: utmp_chk(user, tty)
! 137: char *user, *tty;
! 138: {
! 139: struct utmp u;
! 140: int ufd;
! 141:
! 142: if ((ufd = open(_PATH_UTMP, O_RDONLY)) < 0)
! 143: return(0); /* ignore error, shouldn't happen anyway */
! 144:
! 145: while (read(ufd, (char *) &u, sizeof(u)) == sizeof(u))
! 146: if (strncmp(user, u.ut_name, sizeof(u.ut_name)) == 0 &&
! 147: strncmp(tty, u.ut_line, sizeof(u.ut_line)) == 0) {
! 148: (void)close(ufd);
! 149: return(0);
! 150: }
! 151:
! 152: (void)close(ufd);
! 153: return(1);
! 154: }
! 155:
! 156: /*
! 157: * search_utmp - search utmp for the "best" terminal to write to
! 158: *
! 159: * Ignores terminals with messages disabled, and of the rest, returns
! 160: * the one with the most recent access time. Returns as value the number
! 161: * of the user's terminals with messages enabled, or -1 if the user is
! 162: * not logged in at all.
! 163: *
! 164: * Special case for writing to yourself - ignore the terminal you're
! 165: * writing from, unless that's the only terminal with messages enabled.
! 166: */
! 167: void
! 168: search_utmp(user, tty, mytty, myuid)
! 169: char *user, *tty, *mytty;
! 170: uid_t myuid;
! 171: {
! 172: struct utmp u;
! 173: time_t bestatime, atime;
! 174: int ufd, nloggedttys, nttys, msgsok, user_is_me;
! 175: char atty[UT_LINESIZE + 1];
! 176:
! 177: if ((ufd = open(_PATH_UTMP, O_RDONLY)) < 0)
! 178: err(1, "%s", _PATH_UTMP);
! 179:
! 180: nloggedttys = nttys = 0;
! 181: bestatime = 0;
! 182: user_is_me = 0;
! 183: while (read(ufd, (char *) &u, sizeof(u)) == sizeof(u))
! 184: if (strncmp(user, u.ut_name, sizeof(u.ut_name)) == 0) {
! 185: ++nloggedttys;
! 186: (void)strncpy(atty, u.ut_line, UT_LINESIZE);
! 187: atty[UT_LINESIZE] = '\0';
! 188: if (term_chk(atty, &msgsok, &atime, 0))
! 189: continue; /* bad term? skip */
! 190: if (myuid && !msgsok)
! 191: continue; /* skip ttys with msgs off */
! 192: if (strcmp(atty, 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)strcpy(tty, atty);
! 200: }
! 201: }
! 202:
! 203: (void)close(ufd);
! 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)strcpy(tty, mytty);
! 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",
! 214: user, tty);
! 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(tty, msgsokP, atimeP, showerror)
! 223: char *tty;
! 224: int *msgsokP, showerror;
! 225: time_t *atimeP;
! 226: {
! 227: struct stat s;
! 228: char path[MAXPATHLEN];
! 229:
! 230: (void)sprintf(path, "/dev/%s", tty);
! 231: if (stat(path, &s) < 0) {
! 232: if (showerror)
! 233: warn("%s", path);
! 234: return(1);
! 235: }
! 236: *msgsokP = (s.st_mode & (S_IWRITE >> 3)) != 0; /* group write bit */
! 237: *atimeP = s.st_atime;
! 238: return(0);
! 239: }
! 240:
! 241: /*
! 242: * do_write - actually make the connection
! 243: */
! 244: void
! 245: do_write(tty, mytty, myuid)
! 246: char *tty, *mytty;
! 247: uid_t myuid;
! 248: {
! 249: register char *login, *nows;
! 250: register struct passwd *pwd;
! 251: time_t now;
! 252: char path[MAXPATHLEN], host[MAXHOSTNAMELEN], line[512];
! 253:
! 254: /* Determine our login name before the we reopen() stdout */
! 255: if ((login = getlogin()) == NULL)
! 256: if (pwd = getpwuid(myuid))
! 257: login = pwd->pw_name;
! 258: else
! 259: login = "???";
! 260:
! 261: (void)sprintf(path, "/dev/%s", tty);
! 262: if ((freopen(path, "w", stdout)) == NULL)
! 263: err(1, "%s", path);
! 264:
! 265: (void)signal(SIGINT, done);
! 266: (void)signal(SIGHUP, done);
! 267:
! 268: /* print greeting */
! 269: if (gethostname(host, sizeof(host)) < 0)
! 270: (void)strcpy(host, "???");
! 271: now = time((time_t *)NULL);
! 272: nows = ctime(&now);
! 273: nows[16] = '\0';
! 274: (void)printf("\r\n\007\007\007Message from %s@%s on %s at %s ...\r\n",
! 275: login, host, mytty, nows + 11);
! 276:
! 277: while (fgets(line, sizeof(line), stdin) != NULL)
! 278: wr_fputs(line);
! 279: }
! 280:
! 281: /*
! 282: * done - cleanup and exit
! 283: */
! 284: void
! 285: done()
! 286: {
! 287: (void)printf("EOF\r\n");
! 288: exit(0);
! 289: }
! 290:
! 291: /*
! 292: * wr_fputs - like fputs(), but makes control characters visible and
! 293: * turns \n into \r\n
! 294: */
! 295: void
! 296: wr_fputs(s)
! 297: register char *s;
! 298: {
! 299: register char c;
! 300:
! 301: #define PUTC(c) if (putchar(c) == EOF) goto err;
! 302:
! 303: for (; *s != '\0'; ++s) {
! 304: c = toascii(*s);
! 305: if (c == '\n') {
! 306: PUTC('\r');
! 307: PUTC('\n');
! 308: } else if (!isprint(c) && !isspace(c) && c != '\007') {
! 309: PUTC('^');
! 310: PUTC(c^0x40); /* DEL to ?, others to alpha */
! 311: } else
! 312: PUTC(c);
! 313: }
! 314: return;
! 315:
! 316: err: err(1, NULL);
! 317: #undef PUTC
! 318: }
![[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