nss/nss_db/db-XXX.c

   1 /* Common code for DB-based databases in nss_db module.
   2    Copyright (C) 1996, 1997 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 Library General Public License as
   7    published by the Free Software Foundation; either version 2 of the
   8    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    Library General Public License for more details.
  14
  15    You should have received a copy of the GNU Library General Public
  16    License along with the GNU C Library; see the file COPYING.LIB.  If not,
  17    write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  18    Boston, MA 02111-1307, USA.  */
  19
  20 #include <db_185.h>
  21 #include <fcntl.h>
  22 #include <bits/libc-lock.h>
  23 #include "nsswitch.h"
  24
  25 /* These symbols are defined by the including source file:
  26
  27    ENTNAME -- database name of the structure and functions (hostent, pwent).
  28    STRUCTURE -- struct name, define only if not ENTNAME (passwd, group).
  29    DATABASE -- database file name, ("hosts", "passwd")
  30
  31    NEED_H_ERRNO - defined iff an arg `int *herrnop' is used.
  32 */
  33
  34 #define ENTNAME_r       CONCAT(ENTNAME,_r)
  35
  36 #include <paths.h>
  37 #define DBFILE          _PATH_VARDB DATABASE ".db"
  38
  39 #ifdef NEED_H_ERRNO
  40 #define H_ERRNO_PROTO   , int *herrnop
  41 #define H_ERRNO_ARG     , herrnop
  42 #define H_ERRNO_SET(val) (*herrnop = (val))
  43 #else
  44 #define H_ERRNO_PROTO
  45 #define H_ERRNO_ARG
  46 #define H_ERRNO_SET(val) ((void) 0)
  47 #endif
  48
  49 /* Locks the static variables in this file.  */
  50 __libc_lock_define_initialized (static, lock)
  51 \f
  52 /* Maintenance of the shared handle open on the database.  */
  53
  54 static DB *db;
  55 static int keep_db;
  56 static unsigned int entidx;     /* Index for `getENTNAME'. */
  57
  58 /* Open database file if not already opened.  */
  59 static enum nss_status
  60 internal_setent (int stayopen)
  61 {
  62   enum nss_status status = NSS_STATUS_SUCCESS;
  63
  64   if (db == NULL)
  65     {
  66       db = __dbopen (DBFILE, O_RDONLY, 0, DB_BTREE, NULL);
  67
  68       if (db == NULL)
  69         status = errno == EAGAIN ? NSS_STATUS_TRYAGAIN : NSS_STATUS_UNAVAIL;
  70       else
  71         {
  72           /* We have to make sure the file is  `closed on exec'.  */
  73           int result, flags;
  74
  75           result = flags = fcntl ((*db->fd) (db), F_GETFD, 0);
  76           if (result >= 0)
  77             {
  78               flags |= FD_CLOEXEC;
  79               result = fcntl ((*db->fd) (db), F_SETFD, flags);
  80             }
  81           if (result < 0)
  82             {
  83               /* Something went wrong.  Close the stream and return a
  84                  failure.  */
  85               (*db->close) (db);
  86               db = NULL;
  87               status = NSS_STATUS_UNAVAIL;
  88             }
  89         }
  90     }
  91
  92   /* Remember STAYOPEN flag.  */
  93   if (db != NULL)
  94     keep_db |= stayopen;
  95
  96   return status;
  97 }
  98
  99
 100 /* Thread-safe, exported version of that.  */
 101 enum nss_status
 102 CONCAT(_nss_db_set,ENTNAME) (int stayopen)
 103 {
 104   enum nss_status status;
 105
 106   __libc_lock_lock (lock);
 107
 108   status = internal_setent (stayopen);
 109
 110   /* Reset the sequential index.  */
 111   entidx = 0;
 112
 113   __libc_lock_unlock (lock);
 114
 115   return status;
 116 }
 117
 118
 119 /* Close the database file.  */
 120 static void
 121 internal_endent (void)
 122 {
 123   if (db != NULL)
 124     {
 125       (*db->close) (db);
 126       db = NULL;
 127     }
 128 }
 129
 130
 131 /* Thread-safe, exported version of that.  */
 132 enum nss_status
 133 CONCAT(_nss_db_end,ENTNAME) (void)
 134 {
 135   __libc_lock_lock (lock);
 136
 137   internal_endent ();
 138
 139   /* Reset STAYOPEN flag.  */
 140   keep_db = 0;
 141
 142   __libc_lock_unlock (lock);
 143
 144   return NSS_STATUS_SUCCESS;
 145 }
 146 \f
 147 /* Do a database lookup for KEY.  */
 148 static enum nss_status
 149 lookup (const DBT *key, struct STRUCTURE *result,
 150         void *buffer, size_t buflen, int *errnop H_ERRNO_PROTO)
 151 {
 152   char *p;
 153   enum nss_status status;
 154   int err;
 155   DBT value;
 156
 157   /* Open the database.  */
 158   status = internal_setent (keep_db);
 159   if (status != NSS_STATUS_SUCCESS)
 160     {
 161       *errnop = errno;
 162       H_ERRNO_SET (NETDB_INTERNAL);
 163       return status;
 164     }
 165
 166   /* Succeed iff it matches a value that parses correctly.  */
 167   err = (*db->get) (db, key, &value, 0);
 168   if (err < 0)
 169     {
 170       *errnop = errno;
 171       H_ERRNO_SET (NETDB_INTERNAL);
 172       status = NSS_STATUS_UNAVAIL;
 173     }
 174   else if (err != 0)
 175     {
 176       H_ERRNO_SET (HOST_NOT_FOUND);
 177       status = NSS_STATUS_NOTFOUND;
 178     }
 179   else
 180     {
 181       /* Skip leading blanks.  */
 182       p = (char *) value.data;
 183       while (isspace (*p))
 184         ++p;
 185
 186       err = parse_line (p, result, buffer, buflen, errnop);
 187
 188       if (err == 0)
 189         {
 190           /* If the key begins with '0' we are trying to get the next
 191              entry.  We want to ignore unparsable lines in this case.  */
 192           if (((char *) key->data)[0] == '0')
 193             {
 194               /* Super magical return value.  We need to tell our caller
 195                  that it should continue looping.  This value cannot
 196                  happen in other cases.  */
 197               status = NSS_STATUS_RETURN;
 198             }
 199           else
 200             {
 201               H_ERRNO_SET (HOST_NOT_FOUND);
 202               status = NSS_STATUS_NOTFOUND;
 203             }
 204         }
 205       else if (err < 0)
 206         {
 207           H_ERRNO_SET (NETDB_INTERNAL);
 208           status = NSS_STATUS_TRYAGAIN;
 209         }
 210       else
 211         status = NSS_STATUS_SUCCESS;
 212     }
 213
 214   if (! keep_db)
 215     internal_endent ();
 216
 217   return status;
 218 }
 219
 220
 221 /* Macro for defining lookup functions for this DB-based database.
 222
 223    NAME is the name of the lookup; e.g. `pwnam'.
 224
 225    KEYPATTERN gives `printf' args to construct a key string;
 226    e.g. `(".%s", name)'.
 227
 228    KEYSIZE gives the allocation size of a buffer to construct it in;
 229    e.g. `1 + strlen (name)'.
 230
 231    PROTO describes the arguments for the lookup key;
 232    e.g. `const char *name'.
 233
 234    BREAK_IF_MATCH is ignored, but used by ../nss_files/files-XXX.c.  */
 235
 236 #define DB_LOOKUP(name, keysize, keypattern, break_if_match, proto...)        \
 237 enum nss_status                                                               \
 238 _nss_db_get##name##_r (proto,                                                 \
 239                        struct STRUCTURE *result,                              \
 240                        char *buffer, size_t buflen, int *errnop H_ERRNO_PROTO)\
 241 {                                                                             \
 242   DBT key;                                                                    \
 243   enum nss_status status;                                                     \
 244   const size_t size = (keysize) + 1;                                          \
 245   key.data = __alloca (size);                                                 \
 246   key.size = KEYPRINTF keypattern;                                            \
 247   __libc_lock_lock (lock);                                                    \
 248   status = lookup (&key, result, buffer, buflen, errnop H_ERRNO_ARG);         \
 249   __libc_lock_unlock (lock);                                                  \
 250   return status;                                                              \
 251 }
 252
 253 #define KEYPRINTF(pattern, args...) snprintf (key.data, size, pattern ,##args)
 254 \f
 255
 256
 257
 258 /* Return the next entry from the database file, doing locking.  */
 259 enum nss_status
 260 CONCAT(_nss_db_get,ENTNAME_r) (struct STRUCTURE *result, char *buffer,
 261                                size_t buflen, int *errnop H_ERRNO_PROTO)
 262 {
 263   /* Return next entry in host file.  */
 264   enum nss_status status;
 265   char buf[20];
 266   DBT key;
 267
 268   __libc_lock_lock (lock);
 269
 270   /* Loop until we find a valid entry or hit EOF.  See above for the
 271      special meaning of the status value.  */
 272   do
 273     {
 274       key.size = snprintf (key.data = buf, sizeof buf, "0%u", entidx++);
 275       status = lookup (&key, result, buffer, buflen, errnop H_ERRNO_ARG);
 276     }
 277   while (status == NSS_STATUS_RETURN);
 278
 279   __libc_lock_unlock (lock);
 280
 281   return status;
 282 }