login/utmpname.c

   1 /* Copyright (C) 1997-2022 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3
   4    The GNU C Library is free software; you can redistribute it and/or
   5    modify it under the terms of the GNU Lesser General Public
   6    License as published by the Free Software Foundation; either
   7    version 2.1 of the License, or (at your option) any later version.
   8
   9    The GNU C Library is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12    Lesser General Public License for more details.
  13
  14    You should have received a copy of the GNU Lesser General Public
  15    License along with the GNU C Library; if not, see
  16    <https://www.gnu.org/licenses/>.  */
  17
  18 #include <libc-lock.h>
  19 #include <stdlib.h>
  20 #include <string.h>
  21 #include <utmp.h>
  22
  23 #include "utmp-private.h"
  24
  25
  26 /* This is the default name.  */
  27 static const char default_file_name[] = _PATH_UTMP;
  28
  29 /* Current file name.  */
  30 const char *__libc_utmp_file_name = (const char *) default_file_name;
  31
  32 /* We have to use the lock in getutent_r.c.  */
  33 __libc_lock_define (extern, __libc_utmp_lock attribute_hidden)
  34
  35
  36 int
  37 __utmpname (const char *file)
  38 {
  39   int result = -1;
  40
  41   __libc_lock_lock (__libc_utmp_lock);
  42
  43   /* Close the old file.  */
  44   __libc_endutent ();
  45
  46   if (strcmp (file, __libc_utmp_file_name) != 0)
  47     {
  48       if (strcmp (file, default_file_name) == 0)
  49         {
  50           free ((char *) __libc_utmp_file_name);
  51
  52           __libc_utmp_file_name = default_file_name;
  53         }
  54       else
  55         {
  56           char *file_name = __strdup (file);
  57           if (file_name == NULL)
  58             /* Out of memory.  */
  59             goto done;
  60
  61           if (__libc_utmp_file_name != default_file_name)
  62             free ((char *) __libc_utmp_file_name);
  63
  64           __libc_utmp_file_name = file_name;
  65         }
  66     }
  67
  68   result = 0;
  69
  70 done:
  71   __libc_lock_unlock (__libc_utmp_lock);
  72   return result;
  73 }
  74 libc_hidden_def (__utmpname)
  75 weak_alias (__utmpname, utmpname)