usr/src/usr.bin/wall/wall.c

/*
 * Copyright (c) 1988 Regents of the University of California.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms are permitted
 * provided that the above copyright notice and this paragraph are
 * duplicated in all such forms and that any documentation,
 * advertising materials, and other materials related to such
 * distribution and use acknowledge that the software was developed
 * by the University of California, Berkeley.  The name of the
 * University may not be used to endorse or promote products derived
 * from this software without specific prior written permission.
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
 * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 */

#ifndef lint
char copyright[] =
"@(#) Copyright (c) 1988 Regents of the University of California.\n\
 All rights reserved.\n";
#endif /* not lint */

#ifndef lint
static char sccsid[] = "@(#)wall.c      5.5 (Berkeley) %G%";
#endif /* not lint */

/*
 * This program is not related to David Wall, whose Stanford Ph.D. thesis
 * is entitled "Mechanisms for Broadcast and Selective Broadcast".
 */

#include <sys/param.h>
#include <sys/time.h>
#include <sys/signal.h>
#include <sys/stat.h>
#include <sys/dir.h>
#include <fcntl.h>
#include <utmp.h>
#include <pwd.h>
#include <errno.h>
#include <stdio.h>

#define IGNOREUSER      "sleeper"
#define UTMP            "/etc/utmp"

static int mbufsize;
static char *mbuf;

/* ARGSUSED */
main(argc, argv)
        int argc;
        char **argv;
{
        struct utmp utmp;
        FILE *fp;

        if (argc > 2) {
                fprintf(stderr, "usage: wall [file]\n");
                exit(1);
        }
        makemsg(argv);

        if (!(fp = fopen(UTMP, "r"))) {
                fprintf(stderr, "wall: cannot read /etc/utmp.\n");
                exit(1);
        }
        /* NOSTRICT */
        while (fread((char *)&utmp, sizeof(utmp), 1, fp) == 1) {
                if (!utmp.ut_name[0] ||
                    !strncmp(utmp.ut_name, IGNOREUSER, sizeof(utmp.ut_name)))
                        continue;
                sendmsg(utmp.ut_line);
        }
        exit(0);
}

makemsg(argv)
        char **argv;
{
        register int ch, cnt;
        struct tm *lt;
        struct passwd *pw, *getpwuid();
        struct stat sbuf;
        time_t now, time();
        FILE *fp;
        int fd;
        char *p, *whom, hostname[MAXHOSTNAMELEN], lbuf[100], tmpname[15];
        char *getlogin(), *malloc(), *strcpy(), *ttyname();

        (void)strcpy(tmpname, "/tmp/wall.XXX");
        if (!(fd = mkstemp(tmpname)) || !(fp = fdopen(fd, "r+"))) {
                fprintf(stderr, "wall: can't open temporary file.\n");
                exit(1);
        }
        (void)unlink(tmpname);

        if (!(whom = getlogin()))
                whom = (pw = getpwuid(getuid())) ? pw->pw_name : "???";
        (void)gethostname(hostname, sizeof(hostname));
        (void)time(&now);
        lt = localtime(&now);

        /*
         * all this stuff is to blank out a square for the message; we
         * limit message lines to 75 characters, and blank out to 79.
         * Not 80 'cause some terminals do weird stuff then.
         */
        fprintf(fp, "\r%79s\r\n", " ");
        (void)sprintf(lbuf, "Broadcast Message from %s@%s", whom, hostname);
        fprintf(fp, "%-79.79s\007\007\r\n", lbuf);
        (void)sprintf(lbuf, "        (%s) at %d:%02d ...", ttyname(2),
            lt->tm_hour, lt->tm_min);
        fprintf(fp, "%-79.79s\r\n", lbuf);
        fprintf(fp, "%79s\r\n", " ");

        if (*++argv && !(freopen(*argv, "r", stdin))) {
                fprintf(stderr, "wall: can't read %s.\n", *argv);
                exit(1);
        }
        while (fgets(lbuf, sizeof(lbuf), stdin))
                for (cnt = 0, p = lbuf; ch = *p; ++p, ++cnt)
                        if (cnt == 75 || ch == '\n') {
                                for (; cnt < 79; ++cnt)
                                        putc(' ', fp);
                                putc('\r', fp);
                                putc('\n', fp);
                                cnt = 1;
                        } else
                                putc(ch, fp);
        fprintf(fp, "%79s\r\n", " ");
        rewind(fp);

        if (fstat(fd, &sbuf)) {
                fprintf(stderr, "wall: can't stat temporary file.\n");
                exit(1);
        }
        mbufsize = sbuf.st_size;
        if (!(mbuf = malloc((u_int)mbufsize))) {
                fprintf(stderr, "wall: out of memory.\n");
                exit(1);
        }
        (void)fread(mbuf, sizeof(*mbuf), mbufsize, fp);
        (void)close(fd);
}

sendmsg(line)
        char *line;
{
        extern int errno;
        static char device[MAXNAMLEN] = "/dev/";
        register int fd, flags, nread;
        char *lp, *strcpy();

        (void)strcpy(device + 5, line);
        if ((fd = open(device, O_WRONLY, 0)) < 0) {
                fprintf(stderr, "wall: %s: ", device);
                perror((char *)NULL);
        }
        flags = fcntl(fd, F_GETFL, 0);
        if (!(flags & FNDELAY)) {
                /* NDELAY bit not set; if can't set, fork instead */
                if (fcntl(fd, F_SETFL, flags|FNDELAY) == -1) {
                        flags = 0;
                        goto forkit;
                }
        }
        else
                flags = 0;
        lp = mbuf;
        while ((nread = write(fd, lp, mbufsize)) != mbufsize) {
                if (mbufsize > 0) {
                        mbufsize -= nread;
                        lp += nread;
                } else if (errno == EWOULDBLOCK) {
                        /* child resets FNDELAY if necessary; parent leaves */
forkit:                 if (fork()) {
                                (void)close(fd);
                                return;
                        }
                        if (flags)
                                (void)fcntl(fd, F_SETFL, flags);
                        /* wait 5 minutes and then quit */
                        (void)alarm((u_int)(60 * 5));
                        (void)write(fd, mbuf, mbufsize);
                        exit(0);
                } else {
                        fprintf(stderr, "wall: %s: ", device);
                        perror((char *)NULL);
                        break;
                }
        }
        /* write was successful, or error != EWOULDBLOCK; cleanup */
        if (flags)
                (void)fcntl(fd, F_SETFL, flags);
        (void)close(fd);
}