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who.c

/* GNU's who.
   Copyright (C) 1992-2007 Free Software Foundation, Inc.

   This program is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation, either version 3 of the License, or
   (at your option) any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */

/* Written by jla; revised by djm; revised again by mstone */

/* Output format:
   name [state] line time [activity] [pid] [comment] [exit]
   state: -T
   name, line, time: not -q
   idle: -u
*/

#include <config.h>
#include <getopt.h>
#include <stdio.h>

#include <sys/types.h>
#include "system.h"

#include "canon-host.h"
#include "readutmp.h"
#include "error.h"
#include "hard-locale.h"
#include "inttostr.h"
#include "quote.h"

/* The official name of this program (e.g., no `g' prefix).  */
#define PROGRAM_NAME "who"

#define AUTHORS "Joseph Arceneaux", "David MacKenzie", "Michael Stone"

#ifndef MAXHOSTNAMELEN
# define MAXHOSTNAMELEN 64
#endif

#ifdef RUN_LVL
# define UT_TYPE_RUN_LVL(U) UT_TYPE_EQ (U, RUN_LVL)
#else
# define UT_TYPE_RUN_LVL(U) false
#endif

#ifdef INIT_PROCESS
# define UT_TYPE_INIT_PROCESS(U) UT_TYPE_EQ (U, INIT_PROCESS)
#else
# define UT_TYPE_INIT_PROCESS(U) false
#endif

#ifdef LOGIN_PROCESS
# define UT_TYPE_LOGIN_PROCESS(U) UT_TYPE_EQ (U, LOGIN_PROCESS)
#else
# define UT_TYPE_LOGIN_PROCESS(U) false
#endif

#ifdef DEAD_PROCESS
# define UT_TYPE_DEAD_PROCESS(U) UT_TYPE_EQ (U, DEAD_PROCESS)
#else
# define UT_TYPE_DEAD_PROCESS(U) false
#endif

#ifdef NEW_TIME
# define UT_TYPE_NEW_TIME(U) UT_TYPE_EQ (U, NEW_TIME)
#else
# define UT_TYPE_NEW_TIME(U) false
#endif

#define IDLESTR_LEN 6

#if HAVE_STRUCT_XTMP_UT_PID
# define PIDSTR_DECL_AND_INIT(Var, Utmp_ent) \
  char Var[INT_STRLEN_BOUND (Utmp_ent->ut_pid) + 1]; \
  sprintf (Var, "%ld", (long int) (Utmp_ent->ut_pid))
#else
# define PIDSTR_DECL_AND_INIT(Var, Utmp_ent) \
  const char *Var = ""
#endif

#if HAVE_STRUCT_XTMP_UT_ID
# define UT_ID(U) ((U)->ut_id)
#else
# define UT_ID(U) "??"
#endif

char *ttyname ();

/* The name this program was run with. */
char *program_name;

/* If true, attempt to canonicalize hostnames via a DNS lookup. */
static bool do_lookup;

/* If true, display only a list of usernames and count of
   the users logged on.
   Ignored for `who am i'.  */
static bool short_list;

/* If true, display only name, line, and time fields.  */
static bool short_output;

/* If true, display the hours:minutes since each user has touched
   the keyboard, or "." if within the last minute, or "old" if
   not within the last day.  */
static bool include_idle;

/* If true, display a line at the top describing each field.  */
static bool include_heading;

/* If true, display a `+' for each user if mesg y, a `-' if mesg n,
   or a `?' if their tty cannot be statted. */
static bool include_mesg;

/* If true, display process termination & exit status.  */
static bool include_exit;

/* If true, display the last boot time.  */
static bool need_boottime;

/* If true, display dead processes.  */
static bool need_deadprocs;

/* If true, display processes waiting for user login.  */
static bool need_login;

/* If true, display processes started by init.  */
static bool need_initspawn;

/* If true, display the last clock change.  */
static bool need_clockchange;

/* If true, display the current runlevel.  */
static bool need_runlevel;

/* If true, display user processes.  */
static bool need_users;

/* If true, display info only for the controlling tty.  */
static bool my_line_only;

/* The strftime format to use for login times, and its expected
   output width.  */
static char const *time_format;
static int time_format_width;

/* for long options with no corresponding short option, use enum */
enum
{
  LOOKUP_OPTION = CHAR_MAX + 1
};

static struct option const longopts[] = {
  {"all", no_argument, NULL, 'a'},
  {"boot", no_argument, NULL, 'b'},
  {"count", no_argument, NULL, 'q'},
  {"dead", no_argument, NULL, 'd'},
  {"heading", no_argument, NULL, 'H'},
  {"login", no_argument, NULL, 'l'},
  {"lookup", no_argument, NULL, LOOKUP_OPTION},
  {"message", no_argument, NULL, 'T'},
  {"mesg", no_argument, NULL, 'T'},
  {"process", no_argument, NULL, 'p'},
  {"runlevel", no_argument, NULL, 'r'},
  {"short", no_argument, NULL, 's'},
  {"time", no_argument, NULL, 't'},
  {"users", no_argument, NULL, 'u'},
  {"writable", no_argument, NULL, 'T'},
  {GETOPT_HELP_OPTION_DECL},
  {GETOPT_VERSION_OPTION_DECL},
  {NULL, 0, NULL, 0}
};

/* Return a string representing the time between WHEN and now.
   BOOTTIME is the time of last reboot.
   FIXME: locale? */
static const char *
idle_string (time_t when, time_t boottime)
{
  static time_t now = TYPE_MINIMUM (time_t);

  if (now == TYPE_MINIMUM (time_t))
    time (&now);

  if (boottime < when && now - 24 * 60 * 60 < when && when <= now)
    {
      int seconds_idle = now - when;
      if (seconds_idle < 60)
      return "  .  ";
      else
      {
        static char idle_hhmm[IDLESTR_LEN];
        sprintf (idle_hhmm, "%02d:%02d",
               seconds_idle / (60 * 60),
               (seconds_idle % (60 * 60)) / 60);
        return idle_hhmm;
      }
    }

  return _(" old ");
}

/* Return a time string.  */
static const char *
time_string (const STRUCT_UTMP *utmp_ent)
{
  static char buf[INT_STRLEN_BOUND (intmax_t) + sizeof "-%m-%d %H:%M"];

  /* Don't take the address of UT_TIME_MEMBER directly.
     Ulrich Drepper wrote:
     ``... GNU libc (and perhaps other libcs as well) have extended
     utmp file formats which do not use a simple time_t ut_time field.
     In glibc, ut_time is a macro which selects for backward compatibility
     the tv_sec member of a struct timeval value.''  */
  time_t t = UT_TIME_MEMBER (utmp_ent);
  struct tm *tmp = localtime (&t);

  if (tmp)
    {
      strftime (buf, sizeof buf, time_format, tmp);
      return buf;
    }
  else
    return TYPE_SIGNED (time_t) ? imaxtostr (t, buf) : umaxtostr (t, buf);
}

/* Print formatted output line. Uses mostly arbitrary field sizes, probably
   will need tweaking if any of the localization stuff is done, or for 64 bit
   pids, etc. */
static void
print_line (int userlen, const char *user, const char state,
          int linelen, const char *line,
          const char *time_str, const char *idle, const char *pid,
          const char *comment, const char *exitstr)
{
  static char mesg[3] = { ' ', 'x', '\0' };
  char *buf;
  char x_idle[1 + IDLESTR_LEN + 1];
  char x_pid[1 + INT_STRLEN_BOUND (pid_t) + 1];
  char *x_exitstr;
  int err;

  mesg[1] = state;

  if (include_idle && !short_output && strlen (idle) < sizeof x_idle - 1)
    sprintf (x_idle, " %-6s", idle);
  else
    *x_idle = '\0';

  if (!short_output && strlen (pid) < sizeof x_pid - 1)
    sprintf (x_pid, " %10s", pid);
  else
    *x_pid = '\0';

  x_exitstr = xmalloc (include_exit ? 1 + MAX (12, strlen (exitstr)) + 1 : 1);
  if (include_exit)
    sprintf (x_exitstr, " %-12s", exitstr);
  else
    *x_exitstr = '\0';

  err = asprintf (&buf,
              "%-8.*s"
              "%s"
              " %-12.*s"
              " %-*s"
              "%s"
              "%s"
              " %-8s"
              "%s"
              ,
              userlen, user ? user : "   .",
              include_mesg ? mesg : "",
              linelen, line,
              time_format_width,
              time_str,
              x_idle,
              x_pid,
              /* FIXME: it's not really clear whether the following
                 field should be in the short_output.  A strict reading
                 of SUSv2 would suggest not, but I haven't seen any
                 implementations that actually work that way... */
              comment,
              x_exitstr
              );
  if (err == -1)
    xalloc_die ();

  {
    /* Remove any trailing spaces.  */
    char *p = buf + strlen (buf);
    while (*--p == ' ')
      /* empty */;
    *(p + 1) = '\0';
  }

  puts (buf);
  free (buf);
  free (x_exitstr);
}

/* Send properly parsed USER_PROCESS info to print_line.  The most
   recent boot time is BOOTTIME. */
static void
print_user (const STRUCT_UTMP *utmp_ent, time_t boottime)
{
  struct stat stats;
  time_t last_change;
  char mesg;
  char idlestr[IDLESTR_LEN + 1];
  static char *hoststr;
#if HAVE_UT_HOST
  static size_t hostlen;
#endif

#define DEV_DIR_WITH_TRAILING_SLASH "/dev/"
#define DEV_DIR_LEN (sizeof (DEV_DIR_WITH_TRAILING_SLASH) - 1)

  char line[sizeof (utmp_ent->ut_line) + DEV_DIR_LEN + 1];
  PIDSTR_DECL_AND_INIT (pidstr, utmp_ent);

  /* Copy ut_line into LINE, prepending `/dev/' if ut_line is not
     already an absolute file name.  Some systems may put the full,
     absolute file name in ut_line.  */
  if (utmp_ent->ut_line[0] == '/')
    {
      strncpy (line, utmp_ent->ut_line, sizeof (utmp_ent->ut_line));
      line[sizeof (utmp_ent->ut_line)] = '\0';
    }
  else
    {
      strcpy (line, DEV_DIR_WITH_TRAILING_SLASH);
      strncpy (line + DEV_DIR_LEN, utmp_ent->ut_line,
             sizeof (utmp_ent->ut_line));
      line[DEV_DIR_LEN + sizeof (utmp_ent->ut_line)] = '\0';
    }

  if (stat (line, &stats) == 0)
    {
      mesg = (stats.st_mode & S_IWGRP) ? '+' : '-';
      last_change = stats.st_atime;
    }
  else
    {
      mesg = '?';
      last_change = 0;
    }

  if (last_change)
    sprintf (idlestr, "%.*s", IDLESTR_LEN, idle_string (last_change, boottime));
  else
    sprintf (idlestr, "  ?");

#if HAVE_UT_HOST
  if (utmp_ent->ut_host[0])
    {
      char ut_host[sizeof (utmp_ent->ut_host) + 1];
      char *host = NULL;
      char *display = NULL;

      /* Copy the host name into UT_HOST, and ensure it's nul terminated. */
      strncpy (ut_host, utmp_ent->ut_host, sizeof (utmp_ent->ut_host));
      ut_host[sizeof (utmp_ent->ut_host)] = '\0';

      /* Look for an X display.  */
      display = strchr (ut_host, ':');
      if (display)
      *display++ = '\0';

      if (*ut_host && do_lookup)
      {
        /* See if we can canonicalize it.  */
        host = canon_host (ut_host);
      }

      if (! host)
      host = ut_host;

      if (display)
      {
        if (hostlen < strlen (host) + strlen (display) + 4)
          {
            hostlen = strlen (host) + strlen (display) + 4;
            hoststr = xrealloc (hoststr, hostlen);
          }
        sprintf (hoststr, "(%s:%s)", host, display);
      }
      else
      {
        if (hostlen < strlen (host) + 3)
          {
            hostlen = strlen (host) + 3;
            hoststr = xrealloc (hoststr, hostlen);
          }
        sprintf (hoststr, "(%s)", host);
      }

      if (host != ut_host)
      free (host);
    }
  else
    {
      if (hostlen < 1)
      {
        hostlen = 1;
        hoststr = xrealloc (hoststr, hostlen);
      }
      *hoststr = '\0';
    }
#endif

  print_line (sizeof UT_USER (utmp_ent), UT_USER (utmp_ent), mesg,
            sizeof utmp_ent->ut_line, utmp_ent->ut_line,
            time_string (utmp_ent), idlestr, pidstr,
            hoststr ? hoststr : "", "");
}

static void
print_boottime (const STRUCT_UTMP *utmp_ent)
{
  print_line (-1, "", ' ', -1, "system boot",
            time_string (utmp_ent), "", "", "", "");
}

static char *
make_id_equals_comment (STRUCT_UTMP const *utmp_ent)
{
  char *comment = xmalloc (strlen (_("id=")) + sizeof UT_ID (utmp_ent) + 1);

  strcpy (comment, _("id="));
  strncat (comment, UT_ID (utmp_ent), sizeof UT_ID (utmp_ent));
  return comment;
}

static void
print_deadprocs (const STRUCT_UTMP *utmp_ent)
{
  static char *exitstr;
  char *comment = make_id_equals_comment (utmp_ent);
  PIDSTR_DECL_AND_INIT (pidstr, utmp_ent);

  if (!exitstr)
    exitstr = xmalloc (strlen (_("term="))
                   + INT_STRLEN_BOUND (UT_EXIT_E_TERMINATION (utmp_ent)) + 1
                   + strlen (_("exit="))
                   + INT_STRLEN_BOUND (UT_EXIT_E_EXIT (utmp_ent))
                   + 1);
  sprintf (exitstr, "%s%d %s%d", _("term="), UT_EXIT_E_TERMINATION (utmp_ent),
         _("exit="), UT_EXIT_E_EXIT (utmp_ent));

  /* FIXME: add idle time? */

  print_line (-1, "", ' ', sizeof utmp_ent->ut_line, utmp_ent->ut_line,
            time_string (utmp_ent), "", pidstr, comment, exitstr);
  free (comment);
}

static void
print_login (const STRUCT_UTMP *utmp_ent)
{
  char *comment = make_id_equals_comment (utmp_ent);
  PIDSTR_DECL_AND_INIT (pidstr, utmp_ent);

  /* FIXME: add idle time? */

  print_line (-1, "LOGIN", ' ', sizeof utmp_ent->ut_line, utmp_ent->ut_line,
            time_string (utmp_ent), "", pidstr, comment, "");
  free (comment);
}

static void
print_initspawn (const STRUCT_UTMP *utmp_ent)
{
  char *comment = make_id_equals_comment (utmp_ent);
  PIDSTR_DECL_AND_INIT (pidstr, utmp_ent);

  print_line (-1, "", ' ', sizeof utmp_ent->ut_line, utmp_ent->ut_line,
            time_string (utmp_ent), "", pidstr, comment, "");
  free (comment);
}

static void
print_clockchange (const STRUCT_UTMP *utmp_ent)
{
  /* FIXME: handle NEW_TIME & OLD_TIME both */
  print_line (-1, "", ' ', -1, _("clock change"),
            time_string (utmp_ent), "", "", "", "");
}

static void
print_runlevel (const STRUCT_UTMP *utmp_ent)
{
  static char *runlevline, *comment;
  unsigned char last = UT_PID (utmp_ent) / 256;
  unsigned char curr = UT_PID (utmp_ent) % 256;

  if (!runlevline)
    runlevline = xmalloc (strlen (_("run-level")) + 3);
  sprintf (runlevline, "%s %c", _("run-level"), curr);

  if (!comment)
    comment = xmalloc (strlen (_("last=")) + 2);
  sprintf (comment, "%s%c", _("last="), (last == 'N') ? 'S' : last);

  print_line (-1, "", ' ', -1, runlevline, time_string (utmp_ent),
            "", "", comment, "");

  return;
}

/* Print the username of each valid entry and the number of valid entries
   in UTMP_BUF, which should have N elements. */
static void
list_entries_who (size_t n, const STRUCT_UTMP *utmp_buf)
{
  unsigned long int entries = 0;
  char const *separator = "";

  while (n--)
    {
      if (IS_USER_PROCESS (utmp_buf))
      {
        char *trimmed_name;

        trimmed_name = extract_trimmed_name (utmp_buf);

        printf ("%s%s", separator, trimmed_name);
        free (trimmed_name);
        separator = " ";
        entries++;
      }
      utmp_buf++;
    }
  printf (_("\n# users=%lu\n"), entries);
}

static void
print_heading (void)
{
  print_line (-1, _("NAME"), ' ', -1, _("LINE"), _("TIME"), _("IDLE"),
            _("PID"), _("COMMENT"), _("EXIT"));
}

/* Display UTMP_BUF, which should have N entries. */
static void
scan_entries (size_t n, const STRUCT_UTMP *utmp_buf)
{
  char *ttyname_b IF_LINT ( = NULL);
  time_t boottime = TYPE_MINIMUM (time_t);

  if (include_heading)
    print_heading ();

  if (my_line_only)
    {
      ttyname_b = ttyname (STDIN_FILENO);
      if (!ttyname_b)
      return;
      if (strncmp (ttyname_b, DEV_DIR_WITH_TRAILING_SLASH, DEV_DIR_LEN) == 0)
      ttyname_b += DEV_DIR_LEN;     /* Discard /dev/ prefix.  */
    }

  while (n--)
    {
      if (!my_line_only ||
        strncmp (ttyname_b, utmp_buf->ut_line,
               sizeof (utmp_buf->ut_line)) == 0)
      {
        if (need_users && IS_USER_PROCESS (utmp_buf))
          print_user (utmp_buf, boottime);
        else if (need_runlevel && UT_TYPE_RUN_LVL (utmp_buf))
          print_runlevel (utmp_buf);
        else if (need_boottime && UT_TYPE_BOOT_TIME (utmp_buf))
          print_boottime (utmp_buf);
        /* I've never seen one of these, so I don't know what it should
           look like :^)
           FIXME: handle OLD_TIME also, perhaps show the delta? */
        else if (need_clockchange && UT_TYPE_NEW_TIME (utmp_buf))
          print_clockchange (utmp_buf);
        else if (need_initspawn && UT_TYPE_INIT_PROCESS (utmp_buf))
          print_initspawn (utmp_buf);
        else if (need_login && UT_TYPE_LOGIN_PROCESS (utmp_buf))
          print_login (utmp_buf);
        else if (need_deadprocs && UT_TYPE_DEAD_PROCESS (utmp_buf))
          print_deadprocs (utmp_buf);
      }

      if (UT_TYPE_BOOT_TIME (utmp_buf))
      boottime = UT_TIME_MEMBER (utmp_buf);

      utmp_buf++;
    }
}

/* Display a list of who is on the system, according to utmp file FILENAME.
   Use read_utmp OPTIONS to read the file.  */
static void
who (const char *filename, int options)
{
  size_t n_users;
  STRUCT_UTMP *utmp_buf;

  if (read_utmp (filename, &n_users, &utmp_buf, options) != 0)
    error (EXIT_FAILURE, errno, "%s", filename);

  if (short_list)
    list_entries_who (n_users, utmp_buf);
  else
    scan_entries (n_users, utmp_buf);

  free (utmp_buf);
}

void
usage (int status)
{
  if (status != EXIT_SUCCESS)
    fprintf (stderr, _("Try `%s --help' for more information.\n"),
           program_name);
  else
    {
      printf (_("Usage: %s [OPTION]... [ FILE | ARG1 ARG2 ]\n"), program_name);
      fputs (_("\
\n\
  -a, --all         same as -b -d --login -p -r -t -T -u\n\
  -b, --boot        time of last system boot\n\
  -d, --dead        print dead processes\n\
  -H, --heading     print line of column headings\n\
"), stdout);
      fputs (_("\
  -l, --login       print system login processes\n\
"), stdout);
      fputs (_("\
      --lookup      attempt to canonicalize hostnames via DNS\n\
  -m                only hostname and user associated with stdin\n\
  -p, --process     print active processes spawned by init\n\
"), stdout);
      fputs (_("\
  -q, --count       all login names and number of users logged on\n\
  -r, --runlevel    print current runlevel\n\
  -s, --short       print only name, line, and time (default)\n\
  -t, --time        print last system clock change\n\
"), stdout);
      fputs (_("\
  -T, -w, --mesg    add user's message status as +, - or ?\n\
  -u, --users       list users logged in\n\
      --message     same as -T\n\
      --writable    same as -T\n\
"), stdout);
      fputs (HELP_OPTION_DESCRIPTION, stdout);
      fputs (VERSION_OPTION_DESCRIPTION, stdout);
      printf (_("\
\n\
If FILE is not specified, use %s.  %s as FILE is common.\n\
If ARG1 ARG2 given, -m presumed: `am i' or `mom likes' are usual.\n\
"), UTMP_FILE, WTMP_FILE);
      emit_bug_reporting_address ();
    }
  exit (status);
}

int
main (int argc, char **argv)
{
  int optc;
  bool assumptions = true;

  initialize_main (&argc, &argv);
  program_name = argv[0];
  setlocale (LC_ALL, "");
  bindtextdomain (PACKAGE, LOCALEDIR);
  textdomain (PACKAGE);

  atexit (close_stdout);

  while ((optc = getopt_long (argc, argv, "abdlmpqrstuwHT", longopts, NULL))
       != -1)
    {
      switch (optc)
      {
      case 'a':
        need_boottime = true;
        need_deadprocs = true;
        need_login = true;
        need_initspawn = true;
        need_runlevel = true;
        need_clockchange = true;
        need_users = true;
        include_mesg = true;
        include_idle = true;
        include_exit = true;
        assumptions = false;
        break;

      case 'b':
        need_boottime = true;
        assumptions = false;
        break;

      case 'd':
        need_deadprocs = true;
        include_idle = true;
        include_exit = true;
        assumptions = false;
        break;

      case 'H':
        include_heading = true;
        break;

      case 'l':
        need_login = true;
        include_idle = true;
        assumptions = false;
        break;

      case 'm':
        my_line_only = true;
        break;

      case 'p':
        need_initspawn = true;
        assumptions = false;
        break;

      case 'q':
        short_list = true;
        break;

      case 'r':
        need_runlevel = true;
        include_idle = true;
        assumptions = false;
        break;

      case 's':
        short_output = true;
        break;

      case 't':
        need_clockchange = true;
        assumptions = false;
        break;

      case 'T':
      case 'w':
        include_mesg = true;
        break;

      case 'u':
        need_users = true;
        include_idle = true;
        assumptions = false;
        break;

      case LOOKUP_OPTION:
        do_lookup = true;
        break;

        case_GETOPT_HELP_CHAR;

        case_GETOPT_VERSION_CHAR (PROGRAM_NAME, AUTHORS);

      default:
        usage (EXIT_FAILURE);
      }
    }

  if (assumptions)
    {
      need_users = true;
      short_output = true;
    }

  if (include_exit)
    {
      short_output = false;
    }

  if (hard_locale (LC_TIME))
    {
      time_format = "%Y-%m-%d %H:%M";
      time_format_width = 4 + 1 + 2 + 1 + 2 + 1 + 2 + 1 + 2;
    }
  else
    {
      time_format = "%b %e %H:%M";
      time_format_width = 3 + 1 + 2 + 1 + 2 + 1 + 2;
    }

  switch (argc - optind)
    {
    case 2:             /* who <blurf> <glop> */
      my_line_only = true;
      /* Fall through.  */
    case -1:
    case 0:             /* who */
      who (UTMP_FILE, READ_UTMP_CHECK_PIDS);
      break;

    case 1:             /* who <utmp file> */
      who (argv[optind], 0);
      break;

    default:                  /* lose */
      error (0, 0, _("extra operand %s"), quote (argv[optind + 2]));
      usage (EXIT_FAILURE);
    }

  exit (EXIT_SUCCESS);
}

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