nss/nsswitch.c

   1 /* Copyright (C) 1996-2022 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 <ctype.h>
  19 #include <dlfcn.h>
  20 #include <errno.h>
  21 #include <netdb.h>
  22 #include <libc-lock.h>
  23 #include <search.h>
  24 #include <stdio.h>
  25 #include <stdio_ext.h>
  26 #include <stdlib.h>
  27 #include <string.h>
  28
  29 #include <aliases.h>
  30 #include <grp.h>
  31 #include <netinet/ether.h>
  32 #include <pwd.h>
  33 #include <shadow.h>
  34 #include <unistd.h>
  35
  36 #if !defined DO_STATIC_NSS || defined SHARED
  37 # include <gnu/lib-names.h>
  38 #endif
  39
  40 #include "nsswitch.h"
  41 #include "../nscd/nscd_proto.h"
  42 #include <sysdep.h>
  43 #include <config.h>
  44
  45 /* Declare external database variables.  */
  46 #define DEFINE_DATABASE(name)                                                 \
  47   nss_action_list __nss_##name##_database attribute_hidden;                   \
  48   weak_extern (__nss_##name##_database)
  49 #include "databases.def"
  50 #undef DEFINE_DATABASE
  51
  52
  53 #ifdef USE_NSCD
  54 /* Flags whether custom rules for database is set.  */
  55 bool __nss_database_custom[NSS_DBSIDX_max];
  56 #endif
  57
  58 /*__libc_lock_define_initialized (static, lock)*/
  59
  60 /* -1 == not found
  61     0 == function found
  62     1 == finished */
  63 int
  64 __nss_lookup (nss_action_list *ni, const char *fct_name, const char *fct2_name,
  65               void **fctp)
  66 {
  67   *fctp = __nss_lookup_function (*ni, fct_name);
  68   if (*fctp == NULL && fct2_name != NULL)
  69     *fctp = __nss_lookup_function (*ni, fct2_name);
  70
  71   while (*fctp == NULL
  72          && nss_next_action (*ni, NSS_STATUS_UNAVAIL) == NSS_ACTION_CONTINUE
  73          && (*ni)[1].module != NULL)
  74     {
  75       ++(*ni);
  76
  77       *fctp = __nss_lookup_function (*ni, fct_name);
  78       if (*fctp == NULL && fct2_name != NULL)
  79         *fctp = __nss_lookup_function (*ni, fct2_name);
  80     }
  81
  82   return *fctp != NULL ? 0 : (*ni)[1].module == NULL ? 1 : -1;
  83 }
  84 libc_hidden_def (__nss_lookup)
  85
  86
  87 /* -1 == not found
  88     0 == adjusted for next function
  89     1 == finished */
  90 int
  91 __nss_next2 (nss_action_list *ni, const char *fct_name, const char *fct2_name,
  92              void **fctp, int status, int all_values)
  93 {
  94   if (all_values)
  95     {
  96       if (nss_next_action (*ni, NSS_STATUS_TRYAGAIN) == NSS_ACTION_RETURN
  97           && nss_next_action (*ni, NSS_STATUS_UNAVAIL) == NSS_ACTION_RETURN
  98           && nss_next_action (*ni, NSS_STATUS_NOTFOUND) == NSS_ACTION_RETURN
  99           && nss_next_action (*ni, NSS_STATUS_SUCCESS) == NSS_ACTION_RETURN)
 100         return 1;
 101     }
 102   else
 103     {
 104       /* This is really only for debugging.  */
 105       if (__builtin_expect (NSS_STATUS_TRYAGAIN > status
 106                             || status > NSS_STATUS_RETURN, 0))
 107          __libc_fatal ("Illegal status in __nss_next.\n");
 108
 109        if (nss_next_action (*ni, status) == NSS_ACTION_RETURN)
 110          return 1;
 111     }
 112
 113   if ((*ni)[1].module == NULL)
 114     return -1;
 115
 116   do
 117     {
 118       ++(*ni);
 119
 120       *fctp = __nss_lookup_function (*ni, fct_name);
 121       if (*fctp == NULL && fct2_name != NULL)
 122         *fctp = __nss_lookup_function (*ni, fct2_name);
 123     }
 124   while (*fctp == NULL
 125          && nss_next_action (*ni, NSS_STATUS_UNAVAIL) == NSS_ACTION_CONTINUE
 126          && (*ni)[1].module != NULL);
 127
 128   return *fctp != NULL ? 0 : -1;
 129 }
 130 libc_hidden_def (__nss_next2)
 131
 132 void *
 133 __nss_lookup_function (nss_action_list ni, const char *fct_name)
 134 {
 135   if (ni->module == NULL)
 136     return NULL;
 137   return __nss_module_get_function (ni->module, fct_name);
 138 }
 139 libc_hidden_def (__nss_lookup_function)