CSvax:cak (10/09/82)
/*
* on/off -- enable/disable ttys for login
*
* usage -- on [-n] [-f] [ttyname]
*
* on with a ttyname will enable that tty for login, by modifying
* /etc/ttys, and signalling /etc/init.
*
* off will turn the tty off. If someone is logged in, as shown in
* /etc/utmp, /etc/ttys will be changed, but /etc/init will
* not be signalled, allowing the user to finish. (A message
* to that effect is printed.) The -f flag will force a logoff.
*
* -n in either case will cause on/off to modify /etc/ttys, but
* not signal /etc/init.
*
* in all cases, ttyname is the full device name, stripped of the
* leading /dev/.
*
* Invoking the program with no arguments signals /etc/init.
*
* The same object performs both functions, thus there should be
* two links to it. The function is determined by the last
* character of argv[0].
*
* Chris Kent, University of Cincinnati, 9/13/81
*/
#include <utmp.h>
#include <stdio.h>
#include <signal.h>
#define INITPID 1 /* the pid assumed for /etc/init */
#define STARTSIG SIGHUP /* signal to make /etc/init restart */
#define UTMP "/etc/utmp" /* record of who is on */
#define TTYS "/etc/ttys" /* the ttys file */
#define TEMPLATE "/tmp/onXXXXXX" /* template for temporary file */
#define ENABLED 1
#define DISABLED 0
#define ON 1
#define OFF 0
#define OFFMODE 0666 /* mode to reset tty to */
struct utmp u_entry;
main(argc, argv)
char *argv[];
{
register FILE *ufd, *ttysfd, *tempfd;
char *ttyname;
char *tempname;
char *mktemp(), ctime();
short onoff;
short force, nosig;
short turkey;
short found;
char name[9];
char combuf[128];
char login, getty;
if(argc > 3){
fprintf(stderr, "usage: %s [-n] [-f] [ttyname]\n", argv[0]);
exit(-1);
}
if(argc == 1){
kill(INITPID, STARTSIG);
exit(0);
}
if(argv[0][strlen(argv[0])-1] == 'f')
onoff = OFF;
else
onoff = ON;
while(--argc)
switch((*++argv)[0]){
case '-':
switch(argv[0][1]){
case 'n':
nosig = 1;
break;
case 'f':
force = 1;
break;
default:
fprintf(stderr, "bad flag %s\n", *argv);
}
break;
default:
ttyname = argv[0];
}
ufd = fopen(UTMP, "r");
ttysfd = fopen(TTYS, "r");
tempname = mktemp(TEMPLATE);
if((tempfd = fopen(tempname, "w")) == NULL){
fprintf(stderr, "Can't create temp file");
exit(-2);
}
/*
* read in TTYS, modify the proper record, copy to temp file
*/
found = 0;
while(fscanf(ttysfd, "%c%c%s\n", &login, &getty, name) != EOF){
if(strncmp(name, ttyname, 8)){
fprintf(tempfd, "%c%c%s\n", login, getty, name);
continue;
}
found = 1;
fprintf(tempfd, "%1d%c%s\n", onoff, getty, name);
}
if(!found){
fprintf(stderr, "No line in %s for %s\n", TTYS, ttyname);
unlink(tempname);
exit(-1);
}
fflush(tempfd);
/*
* copy new version into place
*/
tempfd = fopen(tempname, "r");
ttysfd = fopen(TTYS, "w");
if(ttysfd == NULL){
fprintf(stderr, "Can't rewrite %s: ", TTYS);
perror("");
unlink(tempname);
exit(-1);
}
while(fgets(combuf, sizeof(combuf), tempfd) != NULL)
fputs(combuf, ttysfd);
fclose(ttysfd);
fclose(tempfd);
unlink(tempname);
/*
* see if someone is logged in
*/
turkey = 0;
while(fread(&u_entry, sizeof (struct utmp), 1, ufd) != NULL)
if(!strncmp(u_entry.ut_line, ttyname, 8) && *u_entry.ut_name){
fprintf(stderr, "%s logged in on /dev/%s since %s",
u_entry.ut_name, ttyname, ctime(&u_entry.ut_time));
turkey = 1;
}
/*
* restart init
*/
if((force || !turkey) && !nosig)
kill(INITPID, STARTSIG);
if(onoff == OFF){
sprintf(combuf, "/dev/%s", ttyname);
chmod(combuf, OFFMODE);
}
exit(turkey);
}