file reorg, pathnames.h, paths.h

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

#ifndef lint
static char *sccsid = "@(#)write.c      4.15 %G%";
#endif
/*
* write to another user
*/

#include <sys/types.h>
#include <sys/stat.h>
#include <sys/signal.h>
#include <sys/time.h>
#include <utmp.h>
#include <stdio.h>
#include <ctype.h>
#include <paths.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[NMAX + 1]    = "???";
char    *him;
char    *mytty;
char    histty[32];
char    ttybuf[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);
       int suser = getuid() == 0;
       int nomesg = 0;
       struct tm *localtime();
       struct tm *localclock = localtime( &clock );

       if (argc < 2) {
               fprintf(stderr, "Usage: write user [ttyname]\n");
               exit(1);
       }
       him = argv[1];
       if (argc > 2)
               histtya = argv[2];
       if ((uf = fopen(_PATH_UTMP, "r")) == NULL) {
               fprintf(stderr, "write: can't read %s\n", _PATH_UTMP);
               if (histtya == 0)
                       exit(10);
               goto cont;
       }
       mytty = ttyname(2);
       if (mytty == NULL) {
               fprintf(stderr, "write: Can't find your tty\n");
               exit(1);
       }
       if (stat(mytty, &stbuf) < 0) {
               perror("write: Can't stat your tty");
               exit(1);
       }
       if ((stbuf.st_mode&020) == 0) {
               fprintf(stderr,
                       "write: You have write permission turned off\n");
               if (!suser)
                       exit(1);
       }
       mytty = rindex(mytty, '/') + 1;
       if (histtya) {
               strcpy(histty, _PATH_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)
                       goto nomat;
               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;
               }
               if (histtya && strncmp(histtya, ubuf.ut_line,
                   sizeof(ubuf.ut_line)))
                       continue;
               logcnt++;
               if (histty[0]==0 || nomesg && histtya == 0) {
                       strcpy(ttybuf, _PATH_DEV);
                       strcat(ttybuf, ubuf.ut_line);
                       if (histty[0]==0)
                               strcpy(histty, ttybuf);
                       if (access(ttybuf, 0) < 0 || stat(ttybuf, &stbuf) < 0 ||
                           (stbuf.st_mode&020) == 0)
                               nomesg++;
                       else {
                               strcpy(histty, ttybuf);
                               nomesg = 0;
                       }
               }
       nomat:
               ;
       }
       fclose(uf);
       if (logcnt==0) {
               fprintf(stderr, "write: %s not logged in%s\n", him,
                       histtya ? " on that tty" : "");
               exit(1);
       }
       if (histtya==0 && logcnt > 1) {
               fprintf(stderr,
               "write: %s logged in more than once ... writing to %s\n",
                       him, histty+5);
       }
cont:
       if (access(histty, 0) < 0) {
               fprintf(stderr, "write: No such tty\n");
               exit(1);
       }
       signal(SIGALRM, timout);
       alarm(5);
       if ((tf = fopen(histty, "w")) == NULL) {
               fprintf(stderr, "write: Permission denied\n");
               exit(1);
       }
       alarm(0);
       sigs(eof);
       { char hostname[32];
         gethostname(hostname, sizeof (hostname));
         fprintf(tf,
             "\r\nMessage from %s@%s on %s at %d:%02d ...\r\n\007\007\007",
             me, hostname, mytty, localclock->tm_hour, localclock->tm_min);
       fflush(tf);
       }
       for (;;) {
               char buf[BUFSIZ];
               register char *bp;
               i = read(0, buf, sizeof buf);
               if (i <= 0)
                       eof();
               if (buf[0] == '!') {
                       buf[i] = 0;
                       ex(buf);
                       continue;
               }
               for (bp = buf; --i >= 0; bp++) {
                       if (*bp == '\n')
                               putc('\r', tf);

                       if (!isascii(*bp)) {
                               putc('M', tf);
                               putc('-', tf);
                               *bp = toascii(*bp);
                       }

                       if (isprint(*bp) ||
                           *bp == ' ' || *bp == '\t' || *bp == '\n') {
                               putc(*bp, tf);
                       } else {
                               putc('^', tf);
                               putc(*bp ^ 0100, tf);
                       }

                       if (*bp == '\n')
                               fflush(tf);

                       if (ferror(tf) || feof(tf)) {
                               printf("\n\007Write failed (%s logged out?)\n",
                                       him);
                               exit(1);
                       }
               }
       }
}

timout()
{

       fprintf(stderr, "write: 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) {
               fclose(tf);             /* Close his terminal */
               setgid(getgid());       /* Give up effective group privs */
               sigs((int (*)())0);
               execl(getenv("SHELL") ?
                   getenv("SHELL") : _PATH_BSHELL, "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);
}