1  /* NSS actions, elements in a nsswitch.conf configuration line.
       2     Copyright (c) 2020-2023 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  #ifndef _NSS_ACTION_H
      20  #define _NSS_ACTION_H
      21  
      22  #include <stddef.h>
      23  
      24  /* See nss_database.h for a summary of how this relates.  */
      25  
      26  #include "nsswitch.h" /* For lookup_actions.  */
      27  
      28  struct nss_module;
      29  
      30  /* A NSS action pairs a service module with the action for each result
      31     state.  */
      32  struct nss_action
      33  {
      34    /* The service module that provides the functionality (potentially
      35       not yet loaded).  */
      36    struct nss_module *module;
      37  
      38    /* Action according to result.  Two bits for each lookup_actions
      39       value (from nsswitch.h), indexed by enum nss_status (from nss.h).  */
      40    unsigned int action_bits;
      41  };
      42  
      43  /* Value to add to first nss_status value to get zero.  */
      44  #define NSS_STATUS_BIAS 2
      45  /* Number of bits per lookup action.  */
      46  #define NSS_BPL 2
      47  #define NSS_BPL_MASK ((1 << NSS_BPL) - 1)
      48  
      49  /* Index in actions of an NSS status.  Note that in nss/nss.h the
      50     status starts at -2, and we shift that up to zero by adding 2.
      51     Thus for example NSS_STATUS_TRYAGAIN, which is -2, would index into
      52     the 0th bit place as expected.  */
      53  static inline int
      54  nss_actions_bits_index (enum nss_status status)
      55  {
      56    return NSS_BPL * (NSS_STATUS_BIAS + status);
      57  }
      58  
      59  /* Returns the lookup_action value for STATUS in ACTION.  */
      60  static inline lookup_actions
      61  nss_action_get (const struct nss_action *action, enum nss_status status)
      62  {
      63    return ((action->action_bits >> nss_actions_bits_index (status))
      64  	  & NSS_BPL_MASK);
      65  }
      66  
      67  /* Sets the lookup_action value for STATUS in ACTION.  */
      68  static inline void
      69  nss_action_set (struct nss_action *action,
      70                  enum nss_status status, lookup_actions actions)
      71  {
      72    int offset = nss_actions_bits_index (status);
      73    unsigned int mask = NSS_BPL_MASK << offset;
      74    action->action_bits = ((action->action_bits & ~mask)
      75                           | ((unsigned int) actions << offset));
      76  }
      77  
      78  static inline void
      79  nss_action_set_all (struct nss_action *action, lookup_actions actions)
      80  {
      81    unsigned int bits = actions & NSS_BPL_MASK;
      82    action->action_bits = (   bits
      83  			 | (bits << (NSS_BPL * 1))
      84  			 | (bits << (NSS_BPL * 2))
      85  			 | (bits << (NSS_BPL * 3))
      86  			 | (bits << (NSS_BPL * 4))
      87  			 );
      88  }
      89  
      90  /* A list of struct nss_action objects in array terminated by an
      91     action with a NULL module.  */
      92  typedef struct nss_action *nss_action_list;
      93  
      94  /* Returns a pointer to an allocated NSS action list that has COUNT
      95     actions that matches the array at ACTIONS.  */
      96  nss_action_list __nss_action_allocate (struct nss_action *actions,
      97                                         size_t count) attribute_hidden;
      98  
      99  /* Returns a pointer to a list allocated by __nss_action_allocate, or
     100     NULL on error.  ENOMEM means a (temporary) memory allocation error,
     101     EINVAL means that LINE is syntactically invalid.  */
     102  nss_action_list __nss_action_parse (const char *line);
     103  
     104  
     105  #endif /* _NSS_ACTION_H */