dynamically configure utmp size

[unix-history] / usr / src / libexec / comsat / comsat.c

#ifndef lint
static  char sccsid[] = "@(#)comsat.c   4.14 (Berkeley) %G%";
#endif

#include <sys/types.h>
#include <sys/socket.h>
#include <sys/stat.h>
#include <sys/wait.h>
#include <sys/file.h>

#include <netinet/in.h>

#include <stdio.h>
#include <sgtty.h>
#include <utmp.h>
#include <signal.h>
#include <errno.h>
#include <netdb.h>
#include <syslog.h>

/*
* comsat
*/
int     debug = 0;
#define dprintf if (debug) printf

struct  sockaddr_in sin = { AF_INET };
extern  errno;

char    hostname[32];
struct  utmp *utmp = NULL;
int     nutmp;
int     uf;
unsigned utmpmtime = 0;                 /* last modification time for utmp */
unsigned utmpsize = 0;                  /* last malloced size for utmp */
int     onalrm();
int     reapchildren();
long    lastmsgtime;
char    *malloc(), *realloc();

#define MAXIDLE 120
#define NAMLEN (sizeof (uts[0].ut_name) + 1)

main(argc, argv)
       int argc;
       char *argv[];
{
       register int cc;
       char buf[BUFSIZ];
       char msgbuf[100];
       struct sockaddr_in from;
       int fromlen;

       /* verify proper invocation */
       fromlen = sizeof (from);
       if (getsockname(0, &from, &fromlen) < 0) {
               fprintf(stderr, "%s: ", argv[0]);
               perror("getsockname");
               _exit(1);
       }
       chdir("/usr/spool/mail");
       if ((uf = open("/etc/utmp",0)) < 0) {
               openlog("comsat", 0, 0);
               syslog(LOG_ERR, "/etc/utmp: %m");
               (void) recv(0, msgbuf, sizeof (msgbuf) - 1, 0);
               exit(1);
       }
       lastmsgtime = time(0);
       gethostname(hostname, sizeof (hostname));
       onalrm();
       signal(SIGALRM, onalrm);
       signal(SIGTTOU, SIG_IGN);
       signal(SIGCHLD, reapchildren);
       for (;;) {
               cc = recv(0, msgbuf, sizeof (msgbuf) - 1, 0);
               if (cc <= 0) {
                       if (errno != EINTR)
                               sleep(1);
                       errno = 0;
                       continue;
               }
               sigblock(1<<SIGALRM);
               msgbuf[cc] = 0;
               lastmsgtime = time(0);
               mailfor(msgbuf);
               sigsetmask(0);
       }
}

reapchildren()
{

       while (wait3((struct wait *)0, WNOHANG, (struct rusage *)0) > 0)
               ;
}

onalrm()
{
       struct stat statbf;

       if (time(0) - lastmsgtime >= MAXIDLE)
               exit(0);
       dprintf("alarm\n");
       alarm(15);
       fstat(uf, &statbf);
       if (statbf.st_mtime > utmpmtime) {
               dprintf(" changed\n");
               utmpmtime = statbf.st_mtime;
               if (statbf.st_size > utmpsize) {
                       utmpsize = statbf.st_size + 10 * sizeof(struct utmp);
                       if (utmp)
                               utmp = (struct utmp *)realloc(utmp, utmpsize);
                       else
                               utmp = (struct utmp *)malloc(utmpsize);
                       if (! utmp) {
                               dprintf("malloc failed\n");
                               exit(1);
                       }
               }
               lseek(uf, 0, 0);
               nutmp = read(uf,utmp,statbf.st_size)/sizeof(struct utmp);
       } else
               dprintf(" ok\n");
}

mailfor(name)
       char *name;
{
       register struct utmp *utp = &utmp[nutmp];
       register char *cp;
       char *rindex();
       int offset;

       dprintf("mailfor %s\n", name);
       cp = name;
       while (*cp && *cp != '@')
               cp++;
       if (*cp == 0) {
               dprintf("bad format\n");
               return;
       }
       *cp = 0;
       offset = atoi(cp+1);
       while (--utp >= utmp)
               if (!strncmp(utp->ut_name, name, sizeof(utmp[0].ut_name)))
                       notify(utp, offset);
}

char    *cr;

notify(utp, offset)
       register struct utmp *utp;
{
       FILE *tp;
       struct sgttyb gttybuf;
       char tty[20], name[sizeof (utmp[0].ut_name) + 1];
       struct stat stb;

       strcpy(tty, "/dev/");
       strncat(tty, utp->ut_line, sizeof(utp->ut_line));
       dprintf("notify %s on %s\n", utp->ut_name, tty);
       if (stat(tty, &stb) == 0 && (stb.st_mode & 0100) == 0) {
               dprintf("wrong mode\n");
               return;
       }
       if (fork())
               return;
       signal(SIGALRM, SIG_DFL);
       alarm(30);
       if ((tp = fopen(tty,"w")) == 0) {
               dprintf("fopen failed\n");
               exit(-1);
       }
       ioctl(fileno(tp), TIOCGETP, &gttybuf);
       cr = (gttybuf.sg_flags & CRMOD) ? "" : "\r";
       strncpy(name, utp->ut_name, sizeof (utp->ut_name));
       name[sizeof (name) - 1] = '\0';
       fprintf(tp,"%s\n\007New mail for %s@%s\007 has arrived:%s\n",
           cr, name, hostname, cr);
       fprintf(tp,"----%s\n", cr);
       jkfprintf(tp, name, offset);
       exit(0);
}

jkfprintf(tp, name, offset)
       register FILE *tp;
{
       register FILE *fi;
       register int linecnt, charcnt;
       char line[BUFSIZ];
       int inheader;

       dprintf("HERE %s's mail starting at %d\n",
           name, offset);
       if ((fi = fopen(name,"r")) == NULL) {
               dprintf("Cant read the mail\n");
               return;
       }
       fseek(fi, offset, L_SET);
       /* 
        * Print the first 7 lines or 560 characters of the new mail
        * (whichever comes first).  Skip header crap other than
        * From, Subject, To, and Date.
        */
       linecnt = 7;
       charcnt = 560;
       inheader = 1;
       while (fgets(line, sizeof (line), fi) != NULL) {
               register char *cp;
               char *index();
               int cnt;

               if (linecnt <= 0 || charcnt <= 0) {  
                       fprintf(tp,"...more...%s\n", cr);
                       return;
               }
               if (strncmp(line, "From ", 5) == 0)
                       continue;
               if (inheader && (line[0] == ' ' || line[0] == '\t'))
                       continue;
               cp = index(line, ':');
               if (cp == 0 || (index(line, ' ') && index(line, ' ') < cp))
                       inheader = 0;
               else
                       cnt = cp - line;
               if (inheader &&
                   strncmp(line, "Date", cnt) &&
                   strncmp(line, "From", cnt) &&
                   strncmp(line, "Subject", cnt) &&
                   strncmp(line, "To", cnt))
                       continue;
               cp = index(line, '\n');
               if (cp)
                       *cp = '\0';
               fprintf(tp,"%s%s\n", line, cr);
               linecnt--, charcnt -= strlen(line);
       }
       fprintf(tp,"----%s\n", cr);
}