LXR busybox/libbb/utmp.c

   1/* vi: set sw=4 ts=4: */
   2/*
   3 * utmp/wtmp support routines.
   4 *
   5 * Copyright (C) 2010 Denys Vlasenko
   6 *
   7 * Licensed under GPL version 2, see file LICENSE in this tarball for details.
   8 */
   9#include "libbb.h"
  10#include <utmp.h>
  11
  12static void touch(const char *filename)
  13{
  14        if (access(filename, R_OK | W_OK) == -1)
  15                close(open(filename, O_WRONLY | O_CREAT, 0664));
  16}
  17
  18void FAST_FUNC write_new_utmp(pid_t pid, int new_type, const char *tty_name, const char *username, const char *hostname)
  19{
  20        struct utmp utent;
  21        char *id;
  22        unsigned width;
  23
  24        memset(&utent, 0, sizeof(utent));
  25        utent.ut_pid = pid;
  26        utent.ut_type = new_type;
  27        tty_name = skip_dev_pfx(tty_name);
  28        safe_strncpy(utent.ut_line, tty_name, sizeof(utent.ut_line));
  29        if (username)
  30                safe_strncpy(utent.ut_user, username, sizeof(utent.ut_user));
  31        if (hostname)
  32                safe_strncpy(utent.ut_host, hostname, sizeof(utent.ut_host));
  33        utent.ut_tv.tv_sec = time(NULL);
  34
  35        /* Invent our own ut_id. ut_id is only 4 chars wide.
  36         * Try to fit something remotely meaningful... */
  37        id = utent.ut_id;
  38        width = sizeof(utent.ut_id);
  39        if (tty_name[0] == 'p') {
  40                /* if "ptyXXX", map to "pXXX" */
  41                /* if "pts/XX", map to "p/XX" */
  42                *id++ = 'p';
  43                width--;
  44        } /* else: usually it's "ttyXXXX", map to "XXXX" */
  45        if (strlen(tty_name) > 3)
  46                tty_name += 3;
  47        strncpy(id, tty_name, width);
  48
  49        touch(_PATH_UTMP);
  50        //utmpname(_PATH_UTMP);
  51        setutent();
  52        /* Append new one (hopefully, unless we collide on ut_id) */
  53        pututline(&utent);
  54        endutent();
  55
  56#if ENABLE_FEATURE_WTMP
  57        /* "man utmp" says wtmp file should *not* be created automagically */
  58        /*touch(bb_path_wtmp_file);*/
  59        updwtmp(bb_path_wtmp_file, &utent);
  60#endif
  61}
  62
  63/*
  64 * Read "man utmp" to make sense out of it.
  65 */
  66void FAST_FUNC update_utmp(pid_t pid, int new_type, const char *tty_name, const char *username, const char *hostname)
  67{
  68        struct utmp utent;
  69        struct utmp *utp;
  70
  71        touch(_PATH_UTMP);
  72        //utmpname(_PATH_UTMP);
  73        setutent();
  74
  75        /* Did init/getty/telnetd/sshd/... create an entry for us?
  76         * It should be (new_type-1), but we'd also reuse
  77         * any other potentially stale xxx_PROCESS entry */
  78        while ((utp = getutent()) != NULL) {
  79                if (utp->ut_pid == pid
  80                // && ut->ut_line[0]
  81                 && utp->ut_id[0] /* must have nonzero id */
  82                 && (  utp->ut_type == INIT_PROCESS
  83                    || utp->ut_type == LOGIN_PROCESS
  84                    || utp->ut_type == USER_PROCESS
  85                    || utp->ut_type == DEAD_PROCESS
  86                    )
  87                ) {
  88                        if (utp->ut_type >= new_type) {
  89                                /* Stale record. Nuke hostname */
  90                                memset(utp->ut_host, 0, sizeof(utp->ut_host));
  91                        }
  92                        /* NB: pututline (see later) searches for matching utent
  93                         * using getutid(utent) - we must not change ut_id
  94                         * if we want *exactly this* record to be overwritten!
  95                         */
  96                        break;
  97                }
  98        }
  99        //endutent(); - no need, pututline can deal with (and actually likes)
 100        //the situation when utmp file is positioned on found record
 101
 102        if (!utp) {
 103                if (new_type != DEAD_PROCESS)
 104                        write_new_utmp(pid, new_type, tty_name, username, hostname);
 105                else
 106                        endutent();
 107                return;
 108        }
 109
 110        /* Make a copy. We can't use *utp, pututline's internal getutid
 111         * will overwrite it before it is used! */
 112        utent = *utp;
 113
 114        utent.ut_type = new_type;
 115        if (tty_name)
 116                safe_strncpy(utent.ut_line, skip_dev_pfx(tty_name), sizeof(utent.ut_line));
 117        if (username)
 118                safe_strncpy(utent.ut_user, username, sizeof(utent.ut_user));
 119        if (hostname)
 120                safe_strncpy(utent.ut_host, hostname, sizeof(utent.ut_host));
 121        utent.ut_tv.tv_sec = time(NULL);
 122
 123        /* Update, or append new one */
 124        //setutent();
 125        pututline(&utent);
 126        endutent();
 127
 128#if ENABLE_FEATURE_WTMP
 129        /* "man utmp" says wtmp file should *not* be created automagically */
 130        /*touch(bb_path_wtmp_file);*/
 131        updwtmp(bb_path_wtmp_file, &utent);
 132#endif
 133}
 134