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/* cleanutmp.c
chown root.utmp cleanutmp
chmod 2711 cleanutmp
*/
#include <utmp.h>
#include <signal.h>
#include <errno.h>
#include <unistd.h>
#include <fcntl.h>
#include "lib.h"
void ops(int n, const char *s0, const char *s1) {
write(2,s0,str_len(s0));
write(2,s1,str_len(s1));
write(2,"\n",1);
_exit(n);
}
int main() {
int fd,wfd;
struct utmp ut;
off_t pos=0;
if ((fd = open(_PATH_UTMP,O_RDWR)) <0 &&
(fd = open(_PATH_UTMP,O_RDONLY)) <0)
ops(1,"error opening: ", _PATH_UTMP);
while (utmp_io(fd,&ut,F_RDLCK)) {
pos += UTMP_SIZE;
if (ut.ut_type != USER_PROCESS) continue;
if (kill(ut.ut_pid, 0) && errno == ESRCH) {
ut.ut_type = DEAD_PROCESS;
ut.ut_tv.tv_sec = time(0);
pos -= UTMP_SIZE;
if (lseek(fd, pos, SEEK_SET) != pos ||
!utmp_io(fd,&ut,F_WRLCK))
ops(2,"error writing to: ", _PATH_UTMP);
pos += UTMP_SIZE;
wfd=open(_PATH_WTMP, O_WRONLY|O_APPEND);
if (wfd>=0) {
write(fd, &ut, UTMP_SIZE);
close(wfd);
}
}
}
close(fd);
return 0;
}
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