nss/nss_action_parse.c

   1 /* Parse a service line from nsswitch.conf.
   2    Copyright (c) 1996-2020 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 "nss_action.h"
  20 #include "nss_module.h"
  21
  22 #include <ctype.h>
  23 #include <string.h>
  24 #include <stdbool.h>
  25
  26 /* Staging area during parsing.  */
  27 #define DYNARRAY_STRUCT action_list
  28 #define DYNARRAY_ELEMENT struct nss_action
  29 #define DYNARRAY_PREFIX action_list_
  30 #include <malloc/dynarray-skeleton.c>
  31
  32 /* Skip whitespace in line[].  */
  33 #define SKIP_WS() \
  34   while (line[0] != '\0' && isspace (line[0]))  \
  35     ++line;
  36
  37 /* Read the source names:
  38         `( <source> ( "[" "!"? (<status> "=" <action> )+ "]" )? )*'
  39    */
  40 static bool
  41 nss_action_parse (const char *line, struct action_list *result)
  42 {
  43   while (1)
  44     {
  45       SKIP_WS ();
  46       if (line[0] == '\0')
  47         /* No more sources specified.  */
  48         return true;
  49
  50       /* Read <source> identifier.  */
  51       const char *name = line;
  52       while (line[0] != '\0' && !isspace (line[0]) && line[0] != '[')
  53         ++line;
  54       if (name == line)
  55         return true;
  56
  57       struct nss_action new_service
  58         = { .module = __nss_module_allocate (name, line - name), };
  59       if (new_service.module == NULL)
  60         {
  61           /* Memory allocation error.  */
  62           action_list_mark_failed (result);
  63           return false;
  64         }
  65       nss_action_set_all (&new_service, NSS_ACTION_CONTINUE);
  66       nss_action_set (&new_service, NSS_STATUS_SUCCESS, NSS_ACTION_RETURN);
  67       nss_action_set (&new_service, NSS_STATUS_RETURN, NSS_ACTION_RETURN);
  68
  69       SKIP_WS ();
  70
  71       if (line[0] == '[')
  72         {
  73           /* Read criterions.  */
  74
  75           /* Skip the '['.  */
  76           ++line;
  77           SKIP_WS ();
  78
  79           do
  80             {
  81               int not;
  82               enum nss_status status;
  83               lookup_actions action;
  84
  85               /* Grok ! before name to mean all statuses but that one.  */
  86               not = line[0] == '!';
  87               if (not)
  88                 ++line;
  89
  90               /* Read status name.  */
  91               name = line;
  92               while (line[0] != '\0' && !isspace (line[0]) && line[0] != '='
  93                      && line[0] != ']')
  94                 ++line;
  95
  96               /* Compare with known statuses.  */
  97               if (line - name == 7)
  98                 {
  99                   if (__strncasecmp (name, "SUCCESS", 7) == 0)
 100                     status = NSS_STATUS_SUCCESS;
 101                   else if (__strncasecmp (name, "UNAVAIL", 7) == 0)
 102                     status = NSS_STATUS_UNAVAIL;
 103                   else
 104                     return false;
 105                 }
 106               else if (line - name == 8)
 107                 {
 108                   if (__strncasecmp (name, "NOTFOUND", 8) == 0)
 109                     status = NSS_STATUS_NOTFOUND;
 110                   else if (__strncasecmp (name, "TRYAGAIN", 8) == 0)
 111                     status = NSS_STATUS_TRYAGAIN;
 112                   else
 113                     return false;
 114                 }
 115               else
 116                 return false;
 117
 118               SKIP_WS ();
 119               if (line[0] != '=')
 120                 return false;
 121
 122               /* Skip the '='.  */
 123               ++line;
 124               SKIP_WS ();
 125               name = line;
 126               while (line[0] != '\0' && !isspace (line[0]) && line[0] != '='
 127                      && line[0] != ']')
 128                 ++line;
 129
 130               if (line - name == 6 && __strncasecmp (name, "RETURN", 6) == 0)
 131                 action = NSS_ACTION_RETURN;
 132               else if (line - name == 8
 133                        && __strncasecmp (name, "CONTINUE", 8) == 0)
 134                 action = NSS_ACTION_CONTINUE;
 135               else if (line - name == 5
 136                        && __strncasecmp (name, "MERGE", 5) == 0)
 137                 action = NSS_ACTION_MERGE;
 138               else
 139                 return false;
 140
 141               if (not)
 142                 {
 143                   /* Save the current action setting for this status,
 144                      set them all to the given action, and reset this one.  */
 145                   const lookup_actions save
 146                     = nss_action_get (&new_service, status);
 147                   nss_action_set_all (&new_service, action);
 148                   nss_action_set (&new_service, status, save);
 149                 }
 150               else
 151                 nss_action_set (&new_service, status, action);
 152
 153               SKIP_WS ();
 154             }
 155           while (line[0] != ']');
 156
 157           /* Skip the ']'.  */
 158           ++line;
 159         }
 160
 161       action_list_add (result, new_service);
 162     }
 163 }
 164
 165 nss_action_list
 166  __nss_action_parse (const char *line)
 167 {
 168   struct action_list list;
 169   action_list_init (&list);
 170   if (nss_action_parse (line, &list))
 171     {
 172       size_t size = action_list_size (&list);
 173       nss_action_list result
 174         = malloc (sizeof (*result) * (size + 1));
 175       if (result == NULL)
 176         {
 177           action_list_free (&list);
 178           return NULL;
 179         }
 180       memcpy (result, action_list_begin (&list), sizeof (*result) * size);
 181       /* Sentinel.  */
 182       result[size].module = NULL;
 183       return result;
 184     }
 185   else if (action_list_has_failed (&list))
 186     {
 187       /* Memory allocation error.  */
 188       __set_errno (ENOMEM);
 189       return NULL;
 190     }
 191   else
 192     {
 193       /* Parse error.  */
 194       __set_errno (EINVAL);
 195       return NULL;
 196     }
 197 }