include problems

[unix-history] / usr / src / usr.bin / write / write.c

static char *sccsid = "@(#)write.c      4.8 %G%";
/*
* write to another user
*/

#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <signal.h>
#include <utmp.h>
#include <sys/time.h>

#define NMAX    sizeof(ubuf.ut_name)
#define LMAX    sizeof(ubuf.ut_line)

char    *strcat();
char    *strcpy();
struct  utmp ubuf;
int     signum[] = {SIGHUP, SIGINT, SIGQUIT, 0};
char    me[10]  = "???";
char    *him;
char    *mytty;
char    histty[32];
char    *histtya;
char    *ttyname();
char    *rindex();
int     logcnt;
int     eof();
int     timout();
FILE    *tf;
char    *getenv();

main(argc, argv)
       int argc;
       char *argv[];
{
       struct stat stbuf;
       register i;
       register FILE *uf;
       int c1, c2;
       long clock = time(0);
       struct tm *localtime();
       struct tm *localclock = localtime( &clock );

       if (argc < 2) {
               printf("usage: write user [ttyname]\n");
               exit(1);
       }
       him = argv[1];
       if (argc > 2)
               histtya = argv[2];
       if ((uf = fopen("/etc/utmp", "r")) == NULL) {
               printf("cannot open /etc/utmp\n");
               goto cont;
       }
       mytty = ttyname(2);
       if (mytty == NULL) {
               printf("Can't find your tty\n");
               exit(1);
       }
       if (stat(mytty, &stbuf) < 0) {
               printf("Can't stat your tty\n");
               exit(1);
       }
       if ((stbuf.st_mode&02) == 0) {
               printf("You have write permission turned off.\n");
               exit(1);
       }
       mytty = rindex(mytty, '/') + 1;
       if (histtya) {
               strcpy(histty, "/dev/");
               strcat(histty, histtya);
       }
       while (fread((char *)&ubuf, sizeof(ubuf), 1, uf) == 1) {
               if (ubuf.ut_name[0] == '\0')
                       continue;
               if (strcmp(ubuf.ut_line, mytty)==0) {
                       for (i=0; i<NMAX; i++) {
                               c1 = ubuf.ut_name[i];
                               if (c1 == ' ')
                                       c1 = 0;
                               me[i] = c1;
                               if (c1 == 0)
                                       break;
                       }
               }
               if (him[0] != '-' || him[1] != 0)
               for (i=0; i<NMAX; i++) {
                       c1 = him[i];
                       c2 = ubuf.ut_name[i];
                       if (c1 == 0)
                               if (c2 == 0 || c2 == ' ')
                                       break;
                       if (c1 != c2)
                               goto nomat;
               }
               logcnt++;
               if (histty[0]==0) {
                       strcpy(histty, "/dev/");
                       strcat(histty, ubuf.ut_line);
               }
       nomat:
               ;
       }
cont:
       if (logcnt==0 && histty[0]=='\0') {
               printf("%s not logged in.\n", him);
               exit(1);
       }
       fclose(uf);
       if (histtya==0 && logcnt > 1) {
               printf("%s logged more than once\nwriting to %s\n", him, histty+5);
       }
       if (histty[0] == 0) {
               printf(him);
               if (logcnt)
                       printf(" not on that tty\n"); else
                       printf(" not logged in\n");
               exit(1);
       }
       if (access(histty, 0) < 0) {
               printf("No such tty\n");
               exit(1);
       }
       signal(SIGALRM, timout);
       alarm(5);
       if ((tf = fopen(histty, "w")) == NULL)
               goto perm;
       alarm(0);
       if (fstat(fileno(tf), &stbuf) < 0)
               goto perm;
       if ((stbuf.st_mode&02) == 0)
               goto perm;
       sigs(eof);
       { char hostname[32];
         gethostname(hostname, sizeof (hostname));
         fprintf(tf, "\r\nMessage from ");
         fprintf(tf, "%s!%s on %s at %d:%02d ...\r\n\007\007\007",
             hostname, me, mytty, localclock->tm_hour, localclock->tm_min);
       }
       fflush(tf);
       for (;;) {
               char buf[128];
               i = read(0, buf, 128);
               if (i <= 0)
                       eof();
               if (buf[0] == '!') {
                       buf[i] = 0;
                       ex(buf);
                       continue;
               }
               if (write(fileno(tf), buf, i) != i) {
                       printf("\n\007Write failed (%s logged out?)\n", him);
                       exit(1);
               }
               if (buf[i-1] == '\n')
                       write(fileno(tf), "\r", 1);
       }
perm:
       printf("Permission denied\n");
       exit(1);
}

timout()
{

       printf("Timeout opening their tty\n");
       exit(1);
}

eof()
{

       fprintf(tf, "EOF\r\n");
       exit(0);
}

ex(bp)
       char *bp;
{
       register i;

       sigs(SIG_IGN);
       i = fork();
       if (i < 0) {
               printf("Try again\n");
               goto out;
       }
       if (i == 0) {
               sigs((int (*)())0);
               execl(getenv("SHELL") ?
                   getenv("SHELL") : "/bin/sh", "sh", "-c", bp+1, 0);
               exit(0);
       }
       while (wait((int *)NULL) != i)
               ;
       printf("!\n");
out:
       sigs(eof);
}

sigs(sig)
       int (*sig)();
{
       register i;

       for (i=0; signum[i]; i++)
               signal(signum[i], sig);
}