nis/nss-default.c

   1 /* Copyright (C) 1996-2018 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    <http://www.gnu.org/licenses/>.  */
  17
  18 #include <ctype.h>
  19 #include <errno.h>
  20 #include <stdio.h>
  21 #include <stdio_ext.h>
  22 #include <stdlib.h>
  23 #include <string.h>
  24 #include <libc-lock.h>
  25
  26 #include <libnsl.h>
  27
  28
  29 /* Path of the file.  */
  30 static const char default_nss[] = "/etc/default/nss";
  31
  32 /* Flags once read from the file.  */
  33 static int default_nss_flags;
  34
  35 /* Code to make sure we call 'init' once.  */
  36 __libc_once_define (static, once);
  37
  38 /* Table of the recognized variables.  */
  39 static const struct
  40 {
  41   char name[23];
  42   unsigned int len;
  43   int flag;
  44 } vars[] =
  45   {
  46 #define STRNLEN(s) s, sizeof (s) - 1
  47     { STRNLEN ("NETID_AUTHORITATIVE"), NSS_FLAG_NETID_AUTHORITATIVE },
  48     { STRNLEN ("SERVICES_AUTHORITATIVE"), NSS_FLAG_SERVICES_AUTHORITATIVE },
  49     { STRNLEN ("SETENT_BATCH_READ"), NSS_FLAG_SETENT_BATCH_READ },
  50     { STRNLEN ("ADJUNCT_AS_SHADOW"), NSS_FLAG_ADJUNCT_AS_SHADOW },
  51   };
  52 #define nvars (sizeof (vars) / sizeof (vars[0]))
  53
  54
  55 static void
  56 init (void)
  57 {
  58   int saved_errno = errno;
  59   FILE *fp = fopen (default_nss, "rce");
  60   if (fp != NULL)
  61     {
  62       char *line = NULL;
  63       size_t linelen = 0;
  64
  65       __fsetlocking (fp, FSETLOCKING_BYCALLER);
  66
  67       while (!feof_unlocked (fp))
  68         {
  69           ssize_t n = getline (&line, &linelen, fp);
  70           if (n <= 0)
  71             break;
  72
  73           /* Recognize only
  74
  75                <THE-VARIABLE> = TRUE
  76
  77              with arbitrary white spaces.  */
  78           char *cp = line;
  79           while (isspace (*cp))
  80             ++cp;
  81
  82           /* Recognize comment lines.  */
  83           if (*cp == '#')
  84             continue;
  85
  86           int idx;
  87           for (idx = 0; idx < nvars; ++idx)
  88             if (strncmp (cp, vars[idx].name, vars[idx].len) == 0)
  89               break;
  90           if (idx == nvars)
  91             continue;
  92
  93           cp += vars[idx].len;
  94           while (isspace (*cp))
  95             ++cp;
  96           if (*cp++ != '=')
  97             continue;
  98           while (isspace (*cp))
  99             ++cp;
 100
 101           if (strncmp (cp, "TRUE", 4) != 0)
 102             continue;
 103           cp += 4;
 104
 105           while (isspace (*cp))
 106             ++cp;
 107
 108           if (*cp == '\0')
 109             default_nss_flags |= vars[idx].flag;
 110         }
 111
 112       free (line);
 113
 114       fclose (fp);
 115     }
 116   __set_errno (saved_errno);
 117 }
 118
 119
 120 int
 121 _nsl_default_nss (void)
 122 {
 123   /* If we have not yet read the file yet do it now.  */
 124   __libc_once (once, init);
 125
 126   return default_nss_flags;
 127 }