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utmp.c

/* $Id: utmp.c,v 1.4 1993/08/09 11:54:15 lipka Exp lipka $

 * Revision 1.5 08/09/1993 stempien
 * Something was wrong with the Linux support!
 * I fixed it using the provided utmp manipulation routines.
 * I also surrounded many varables that were not needed for Linux 
 * in the BSD defines to reduce the memory needed to run.
 * I didn't touch the Sun part of the code so it should still work.
 *
 * $Log: utmp.c,v $
 * Revision 1.4  1993/08/09  11:54:15  lipka
 * now works both on Linux and SunOs 4.1.3.
 * Brians clean-ups incorporated
 *
 * Revision 1.3  1993/08/09  07:16:42  lipka
 * nearly correct (running) linux-version.
 * Delete-Window is still a problem
 *
 * Revision 1.1  1993/08/07  18:03:53  lipka
 * Initial revision
 *
 * Clean-ups according to suggestions of Brian Stempien (stempien@cs.wmich.edu)
 *
 *    provides:
 *    int utmp_end(), returns eof(UTMP)
 *    void makeutent(), stamps _current_ process to UTMP
 *    void clean_exit(), to clear a record in utmp
 *        (void) cleanutent(pos)
 *
 *    Bugs: UTMP should be locked from call to utmp_end() 'til
 *          makeutent() (?).
 *          Maybe the child should tell the parent, where the entry is made.
 *          Tested only on Linux.
 *
 *          Gives weird inital idle times. They go away after one uses the 
 *          window, but......
 *
 */
/* There must be a more elegant way than this HUGE ifdef to do this */
#ifdef ALPHA
#define SVR4
#endif
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/time.h>
#include <utmp.h>
#include <unistd.h>
#ifdef BSD
#ifndef FREEBSD
#include <lastlog.h>
#endif
#include <strings.h>
#endif
#include <pwd.h>
#include <string.h>
#include <stdio.h>
#include <memory.h>
#include <signal.h>

void    cleanutent(void);
void    makeutent(char *);
int   kill_process_group(int pid, int sig);

/* for cleanutent, marks whether or not the entry has been made */
char    madeutent = 0;

/****************************************************************************
 * Makes sure that the utmp entry is removed when we exit 
 ***************************************************************************/
void    clean_exit(int r)
{
    extern  comm_pid;

#ifndef SVR4
    extern char ttynam[];
    extern struct stat ttyfd_stat;

    chmod(ttynam, ttyfd_stat.st_mode);

    chown(ttynam, ttyfd_stat.st_uid, ttyfd_stat.st_gid);
#endif
    if (madeutent)
      cleanutent();
    if (comm_pid)
      kill_process_group(comm_pid, SIGKILL);
    exit(r);
}

#ifndef UTMP_SUPPORT
/***************************************************************************
 * Dummy routines to use if utmp support is not wanted/needed 
 **************************************************************************/
void    makeutent(char *ttyname)
{
    return;
}
void    cleanutent()
{
    return;
}

#else                   /* UTMP_SUPPORT */
/**************************************************************************
 *
 * Code to make utmp entries really starts here !
 *
 **************************************************************************/
int     utmp_pos;       /* position of utmp-stamp */


/*
 * on Sparcs login/logouts are logged at /var/adm/wtmp
 * but talk(d)/finger only look at /etc/utmp
 */
#ifndef UTMP
#define UTMP "/var/run/utmp"
#endif

#ifndef USER_PROCESS
#define USER_PROCESS 7
#endif

#ifndef DEAD_PROCESS
#define DEAD_PROCESS 8
#endif

/**************************************************************************
 *
 * The code was pretty ugly when BSD and SYSV style utmp stuff was mixed up,
 * so I just made a huge ifdef for BSD, and another for SYSV
 *
 *************************************************************************/
#ifdef BSD

/**************************************************************************
 * get_tslot() - grabbed from xvt-1.0 - modified by David Perry
 *
 *  Look up the tty name in the etc/ttytab file and return a slot number
 * that can be used to access the utmp file.  We cannot use ttyslot()
 * because the tty name is not that of fd 0.
 *************************************************************************/
int     get_tslot(char *ttynam)
{
    FILE   *fs;
    char    buf[200], name[200];
    int     i;

    if ((fs = fopen(TTYTAB, "r")) == NULL)
      return (-1);
    i = 1;
    while (fgets(buf, 200, fs) != NULL) {
      if (*buf == '#')
          continue;
      if (sscanf(buf, "%s", name) != 1)
          continue;
      if (strcmp(ttynam, name) == 0) {
          fclose(fs);
          return (i);
      }
      i++;
    }
    fclose(fs);
    return (-1);
}

/****************************************************************************
 * write a utmp entry to the utmp file 
 ***************************************************************************/
int     write_utmp(char *ttyname, struct utmp *u)
{
    extern int no_utmp;
    FILE   *utmp;

    if (no_utmp)
      return;
    if ((utmp = fopen(UTMP, "r+")) == NULL)
      return -1;
    utmp_pos = get_tslot(ttyname) * sizeof(struct utmp);

    if (utmp_pos < 0)
      return -1;
    fseek(utmp, utmp_pos, 0);
    fwrite((char *) u, sizeof(struct utmp), 1, utmp);

    fclose(utmp);
    madeutent = 1;
    return (utmp_pos);
}

/****************************************************************************
 * Makes a utmp entry
 ***************************************************************************/
void    makeutent(char *ttyname)
{
    struct passwd *pwent;
    struct utmp u;


    struct timeval tp;
    struct timezone tzp;
    int     l;
    extern char *display_name;

    pwent = getpwuid(getuid());
    memset((char *) &u, 0, sizeof(u));
    /* memset? never heard of it :-) thanks Brian */

#ifndef SVR4
    l = sizeof(u.ut_host);
    strncpy(u.ut_host, display_name, l);
#endif
    /* and now the line: */
    l = sizeof(u.ut_line);
    strncpy(u.ut_line, ttyname, l);
    if (!gettimeofday(&tp, &tzp))
      u.ut_time = tp.tv_sec;
    strncpy(u.ut_name, pwent->pw_name, sizeof(u.ut_name));
    (void) write_utmp(ttyname, &u);
}

/****************************************************************************
 * Removes a utmp entry
 ***************************************************************************/
/*
 * there is a nice function "endutent" defined in <utmp.h>;
 * like "setutent" it takes no arguments, so I think it gets all information
 * from library-calls.
 * That's why "setutent" has to be called by the child-process with
 * file-descriptors 0/1 set to the pty. But that child execs to the
 * application-program and therefore can't clean it's own utmp-entry!(?)
 * The master on the other hand doesn't have the correct process-id
 * and io-channels... I'll do it by hand:
 * (what's the position of the utmp-entry, the child wrote? :-)
 */
void    cleanutent(void)
{
    FILE   *ut;
    struct utmp u;

    if ((ut = fopen(UTMP, "r+")) == NULL)
      return;
    fseek(ut, utmp_pos, 0);
    memset(&u, 0, sizeof(u));
    fwrite((char *) &u, sizeof(struct utmp), 1, ut);

    fclose(ut);
}


/***************************************************************************
 *
 * Here's where we start SYSV style utmp entry code 
 *
 **************************************************************************/
#else                   /* BSD */

/****************************************************************************
 * write a utmp entry to the utmp file 
 ***************************************************************************/
int     write_utmp(struct utmp *u)
{
    int     pos;

    utmpname(UTMP);
    setutent();
    pututline(u);
    endutent();
    pos = (int) NULL;
    madeutent = 1;
    return (pos);
}

/****************************************************************************
 * Makes a utmp entry
 ***************************************************************************/
void    makeutent(char *ttyname)
{
    struct passwd *pwent;
    struct utmp u;

    pwent = getpwuid(getuid());
    memset((char *) &u, 0, sizeof(u));
    /* memset? never heard of it :-) thanks Brian */

#ifndef SVR4
    strcpy(u.ut_host, "\0");  /* Needs to be this way for Linux */
#endif
    /* and now the line: */
    strcpy(u.ut_line, ttyname);     /* This works at the moment. I don't think that 
                           ttyname is NULL terminated, so something 
                           more elaborate may need to be done. */
    time(&u.ut_time);
    strncpy(u.ut_user, pwent->pw_name, sizeof(u.ut_user));
    u.ut_type = USER_PROCESS;
    u.ut_pid = getpid();
    strncpy(u.ut_id, (ttyname + 3), 2);

    (void) write_utmp(&u);
}

/****************************************************************************
 * Removes a utmp entry
 ***************************************************************************/
/*
 * there is a nice function "endutent" defined in <utmp.h>;
 * like "setutent" it takes no arguments, so I think it gets all information
 * from library-calls.
 * That's why "setutent" has to be called by the child-process with
 * file-descriptors 0/1 set to the pty. But that child execs to the
 * application-program and therefore can't clean it's own utmp-entry!(?)
 * The master on the other hand doesn't have the correct process-id
 * and io-channels... I'll do it by hand:
 * (what's the position of the utmp-entry, the child wrote? :-)
 */
void    cleanutent()
{
    int     pid;
    struct utmp *u;

    utmpname(UTMP);
    setutent();
    pid = getpid();
    /* The following 11 lines of code were copied from the 
     * poeigl-1.20 login/init package. Special thanks to 
     * poe for the code examples.
     */
    while ((u = getutent())) {
      if (u->ut_pid == pid) {
          time(&u->ut_time);
#ifdef SVR4
          memset(&u->ut_user, 0, sizeof(u->ut_user));
#else
          memset(&u->ut_user, 0, sizeof(u->ut_user));
          memset(&u->ut_host, 0, sizeof(u->ut_host));
#endif
          u->ut_type = DEAD_PROCESS;
          u->ut_pid = 0;
#if !defined(SVR4) && !defined(AIXV3)
          u->ut_addr = 0;
#endif
          pututline(u); /* Was reversed with in the original */
          endutent();
      }
    }
}

#endif                        /* BSD */
#endif                        /* UTMP_SUPPORT */

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