BSD 4_1_snap release

[unix-history] / usr / src / cmd / wall.c

static char *sccsid = "@(#)wall.c       4.5 (Berkeley) 81/06/12";
/*
* wall.c - Broadcast a message to all users.
*
* This program is not related to David Wall, whose Stanford Ph.D. thesis
* is entitled "Mechanisms for Broadcast and Selective Broadcast".
*/

#include <stdio.h>
#include <utmp.h>
#include <time.h>
#include <whoami.h>
#include <signal.h>
#define USERS   128
#define IGNOREUSER      "sleeper"

char    mesg[3000];
int     msize,sline;
struct  utmp utmp[USERS];
char    *strcpy();
char    *strcat();
char who[9] = "???";
long    clock, time();
struct tm *localtime();
struct tm *localclock;

main(argc, argv)
char *argv[];
{
       register i;
       register char c;
       register struct utmp *p;
       FILE *f;
       FILE *mf;

       if((f = fopen("/etc/utmp", "r")) == NULL) {
               fprintf(stderr, "Cannot open /etc/utmp\n");
               exit(1);
       }
       clock = time( 0 );
       localclock = localtime( &clock );
       mf = stdin;
       if(argc >= 2) {
               /* take message from unix file instead of standard input */
               if((mf = fopen(argv[1], "r")) == NULL) {
                       fprintf(stderr,"Cannot open %s\n", argv[1]);
                       exit(1);
               }
       }
       while((i = getc(mf)) != EOF) {
               if (msize >= sizeof mesg) {
                       fprintf(stderr, "Message too long\n");
                       exit(1);
               }
               mesg[msize++] = i;
       }
       fclose(mf);
       sline = ttyslot(2); /* 'utmp' slot no. of sender */
       fread((char *)utmp, sizeof(struct utmp), USERS, f);
       fclose(f);
       if (sline)
               strncpy(who, utmp[sline].ut_name, sizeof(utmp[sline].ut_name));
       for(i=0; i<USERS; i++) {
               p = &utmp[i];
               if ((p->ut_name[0] == 0) ||
                   (strncmp (p->ut_name, IGNOREUSER, sizeof(p->ut_name)) == 0))
                       continue;
       /***            this might be nice, but utmp gets so out of date !!
               sleep(1);
       ***/
               sendmes(p->ut_line);
       }
       exit(0);
}

sendmes(tty)
char *tty;
{
       register i;
       char t[50], buf[BUFSIZ];
       register char *cp;
       register int c, ch;
       FILE *f;

/***                    you can't do this with lots of users & MAXUPROC
       i = fork();
       if(i == -1) {
               fprintf(stderr, "Try again\n");
               return;
       }
***/
       while ((i = fork()) == -1)
               if (wait((int *)0) == -1) {
                       fprintf(stderr, "Try again\n");
                       return;
               }
       if(i)
               return;
       strcpy(t, "/dev/");
       strcat(t, tty);

       signal(SIGALRM, SIG_DFL);       /* blow away if open hangs */
       alarm(10);

       if((f = fopen(t, "w")) == NULL) {
               fprintf(stderr,"cannot open %s\n", t);
               exit(1);
       }
       setbuf(f, buf);
       fprintf(f,
           "\n\a\a\aBroadcast Message from %s!%s (%.*s) at %d:%02d ...\r\n\n"
               , sysname
               , who
               , sizeof(utmp[sline].ut_line)
               , utmp[sline].ut_line
               , localclock -> tm_hour
               , localclock -> tm_min
       );
       /* fwrite(mesg, msize, 1, f); */
       for (cp = mesg, c = msize; c-- > 0; cp++) {
               ch = *cp;
               if (ch == '\n')
                       putc('\r', f);
               putc(ch, f);
       }

       /*
        * Bitchin'.
        */

       exit(0);
}