login/utmpname.c

   1 /* Copyright (C) 1997-2021 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3    Contributed by Mark Kettenis <kettenis@phys.uva.nl>, 1997.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <https://www.gnu.org/licenses/>.  */
  18
  19 #include <libc-lock.h>
  20 #include <stdlib.h>
  21 #include <string.h>
  22 #include <utmp.h>
  23
  24 #include "utmp-private.h"
  25
  26
  27 /* This is the default name.  */
  28 static const char default_file_name[] = _PATH_UTMP;
  29
  30 /* Current file name.  */
  31 const char *__libc_utmp_file_name = (const char *) default_file_name;
  32
  33 /* We have to use the lock in getutent_r.c.  */
  34 __libc_lock_define (extern, __libc_utmp_lock attribute_hidden)
  35
  36
  37 int
  38 __utmpname (const char *file)
  39 {
  40   int result = -1;
  41
  42   __libc_lock_lock (__libc_utmp_lock);
  43
  44   /* Close the old file.  */
  45   __libc_endutent ();
  46
  47   if (strcmp (file, __libc_utmp_file_name) != 0)
  48     {
  49       if (strcmp (file, default_file_name) == 0)
  50         {
  51           free ((char *) __libc_utmp_file_name);
  52
  53           __libc_utmp_file_name = default_file_name;
  54         }
  55       else
  56         {
  57           char *file_name = __strdup (file);
  58           if (file_name == NULL)
  59             /* Out of memory.  */
  60             goto done;
  61
  62           if (__libc_utmp_file_name != default_file_name)
  63             free ((char *) __libc_utmp_file_name);
  64
  65           __libc_utmp_file_name = file_name;
  66         }
  67     }
  68
  69   result = 0;
  70
  71 done:
  72   __libc_lock_unlock (__libc_utmp_lock);
  73   return result;
  74 }
  75 libc_hidden_def (__utmpname)
  76 weak_alias (__utmpname, utmpname)