nss/nss_action_parse.c

   1 /* Parse a service line from nsswitch.conf.
   2    Copyright (c) 1996-2022 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   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 <nsswitch.h>
  20
  21 #include <ctype.h>
  22 #include <string.h>
  23 #include <stdbool.h>
  24
  25 /* Staging area during parsing.  */
  26 #define DYNARRAY_STRUCT action_list
  27 #define DYNARRAY_ELEMENT struct nss_action
  28 #define DYNARRAY_PREFIX action_list_
  29 #include <malloc/dynarray-skeleton.c>
  30
  31 /* Skip whitespace in line[].  */
  32 #define SKIP_WS() \
  33   while (line[0] != '\0' && isspace (line[0]))  \
  34     ++line;
  35
  36 /* Read the source names:
  37         `( <source> ( "[" "!"? (<status> "=" <action> )+ "]" )? )*'
  38    */
  39 static bool
  40 nss_action_parse (const char *line, struct action_list *result)
  41 {
  42   while (1)
  43     {
  44       SKIP_WS ();
  45       if (line[0] == '\0')
  46         /* No more sources specified.  */
  47         return true;
  48
  49       /* Read <source> identifier.  */
  50       const char *name = line;
  51       while (line[0] != '\0' && !isspace (line[0]) && line[0] != '[')
  52         ++line;
  53       if (name == line)
  54         return true;
  55
  56       struct nss_action new_service
  57         = { .module = __nss_module_allocate (name, line - name), };
  58       if (new_service.module == NULL)
  59         {
  60           /* Memory allocation error.  */
  61           action_list_mark_failed (result);
  62           return false;
  63         }
  64       nss_action_set_all (&new_service, NSS_ACTION_CONTINUE);
  65       nss_action_set (&new_service, NSS_STATUS_SUCCESS, NSS_ACTION_RETURN);
  66       nss_action_set (&new_service, NSS_STATUS_RETURN, NSS_ACTION_RETURN);
  67
  68       SKIP_WS ();
  69
  70       if (line[0] == '[')
  71         {
  72           /* Read criterions.  */
  73
  74           /* Skip the '['.  */
  75           ++line;
  76           SKIP_WS ();
  77
  78           do
  79             {
  80               int not;
  81               enum nss_status status;
  82               lookup_actions action;
  83
  84               /* Grok ! before name to mean all statuses but that one.  */
  85               not = line[0] == '!';
  86               if (not)
  87                 ++line;
  88
  89               /* Read status name.  */
  90               name = line;
  91               while (line[0] != '\0' && !isspace (line[0]) && line[0] != '='
  92                      && line[0] != ']')
  93                 ++line;
  94
  95               /* Compare with known statuses.  */
  96               if (line - name == 7)
  97                 {
  98                   if (__strncasecmp (name, "SUCCESS", 7) == 0)
  99                     status = NSS_STATUS_SUCCESS;
 100                   else if (__strncasecmp (name, "UNAVAIL", 7) == 0)
 101                     status = NSS_STATUS_UNAVAIL;
 102                   else
 103                     return false;
 104                 }
 105               else if (line - name == 8)
 106                 {
 107                   if (__strncasecmp (name, "NOTFOUND", 8) == 0)
 108                     status = NSS_STATUS_NOTFOUND;
 109                   else if (__strncasecmp (name, "TRYAGAIN", 8) == 0)
 110                     status = NSS_STATUS_TRYAGAIN;
 111                   else
 112                     return false;
 113                 }
 114               else
 115                 return false;
 116
 117               SKIP_WS ();
 118               if (line[0] != '=')
 119                 return false;
 120
 121               /* Skip the '='.  */
 122               ++line;
 123               SKIP_WS ();
 124               name = line;
 125               while (line[0] != '\0' && !isspace (line[0]) && line[0] != '='
 126                      && line[0] != ']')
 127                 ++line;
 128
 129               if (line - name == 6 && __strncasecmp (name, "RETURN", 6) == 0)
 130                 action = NSS_ACTION_RETURN;
 131               else if (line - name == 8
 132                        && __strncasecmp (name, "CONTINUE", 8) == 0)
 133                 action = NSS_ACTION_CONTINUE;
 134               else if (line - name == 5
 135                        && __strncasecmp (name, "MERGE", 5) == 0)
 136                 action = NSS_ACTION_MERGE;
 137               else
 138                 return false;
 139
 140               if (not)
 141                 {
 142                   /* Save the current action setting for this status,
 143                      set them all to the given action, and reset this one.  */
 144                   const lookup_actions save
 145                     = nss_action_get (&new_service, status);
 146                   nss_action_set_all (&new_service, action);
 147                   nss_action_set (&new_service, status, save);
 148                 }
 149               else
 150                 nss_action_set (&new_service, status, action);
 151
 152               SKIP_WS ();
 153             }
 154           while (line[0] != ']');
 155
 156           /* Skip the ']'.  */
 157           ++line;
 158         }
 159
 160       action_list_add (result, new_service);
 161     }
 162 }
 163
 164 nss_action_list
 165  __nss_action_parse (const char *line)
 166 {
 167   struct action_list list;
 168   action_list_init (&list);
 169   if (nss_action_parse (line, &list))
 170     {
 171       size_t size;
 172       struct nss_action null_service
 173         = { .module = NULL, };
 174
 175       action_list_add (&list, null_service);
 176       size = action_list_size (&list);
 177       return __nss_action_allocate (action_list_begin (&list), size);
 178     }
 179   else if (action_list_has_failed (&list))
 180     {
 181       /* Memory allocation error.  */
 182       __set_errno (ENOMEM);
 183       return NULL;
 184     }
 185   else
 186     {
 187       /* Parse error.  */
 188       __set_errno (EINVAL);
 189       return NULL;
 190     }
 191 }