login/utmpname.c

   1 /* Copyright (C) 1997-2018 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    <http://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_utmp_jump_table->endutent) ();
  46   __libc_utmp_jump_table = &__libc_utmp_unknown_functions;
  47
  48   if (strcmp (file, __libc_utmp_file_name) != 0)
  49     {
  50       if (strcmp (file, default_file_name) == 0)
  51         {
  52           free ((char *) __libc_utmp_file_name);
  53
  54           __libc_utmp_file_name = default_file_name;
  55         }
  56       else
  57         {
  58           char *file_name = __strdup (file);
  59           if (file_name == NULL)
  60             /* Out of memory.  */
  61             goto done;
  62
  63           if (__libc_utmp_file_name != default_file_name)
  64             free ((char *) __libc_utmp_file_name);
  65
  66           __libc_utmp_file_name = file_name;
  67         }
  68     }
  69
  70   result = 0;
  71
  72 done:
  73   __libc_lock_unlock (__libc_utmp_lock);
  74   return result;
  75 }
  76 weak_alias (__utmpname, utmpname)