nss/nss_db/db-alias.c

   1 /* Mail alias file parser in nss_db module.
   2    Copyright (C) 1996, 1997, 1998 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4    Contributed by Ulrich Drepper <drepper@cygnus.com>, 1996.
   5
   6    The GNU C Library is free software; you can redistribute it and/or
   7    modify it under the terms of the GNU Library General Public License as
   8    published by the Free Software Foundation; either version 2 of the
   9    License, or (at your option) any later version.
  10
  11    The GNU C Library is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14    Library General Public License for more details.
  15
  16    You should have received a copy of the GNU Library General Public
  17    License along with the GNU C Library; see the file COPYING.LIB.  If not,
  18    write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  19    Boston, MA 02111-1307, USA.  */
  20
  21 #include <aliases.h>
  22 #include <alloca.h>
  23 #include <ctype.h>
  24 #include <db.h>
  25 #include <errno.h>
  26 #include <fcntl.h>
  27 #include <bits/libc-lock.h>
  28 #include <paths.h>
  29 #include <string.h>
  30
  31 #include "nsswitch.h"
  32
  33 /* Locks the static variables in this file.  */
  34 __libc_lock_define_initialized (static, lock)
  35 \f
  36 /* Maintenance of the shared handle open on the database.  */
  37
  38 static DB *db;
  39 static int keep_db;
  40 static unsigned int entidx;     /* Index for `getaliasent_r'. */
  41
  42 /* Open database file if not already opened.  */
  43 static enum nss_status
  44 internal_setent (int stayopen)
  45 {
  46   enum nss_status status = NSS_STATUS_SUCCESS;
  47   int err;
  48
  49   if (db == NULL)
  50     {
  51       err = __nss_db_open (_PATH_VARDB "aliases.db", DB_BTREE, DB_RDONLY, 0,
  52                            NULL, NULL, &db);
  53
  54       if (err != 0)
  55         {
  56           __set_errno (err);
  57           status = NSS_STATUS_UNAVAIL;
  58         }
  59       else
  60         {
  61           /* We have to make sure the file is  `closed on exec'.  */
  62           int fd;
  63           int result, flags;
  64
  65           err = db->fd (db, &fd);
  66           if (err != 0)
  67             {
  68               __set_errno (err);
  69               result = -1;
  70             }
  71           else
  72             result = flags = fcntl (fd, F_GETFD, 0);
  73           if (result >= 0)
  74             {
  75               flags |= FD_CLOEXEC;
  76               result = fcntl (fd, F_SETFD, flags);
  77             }
  78           if (result < 0)
  79             {
  80               /* Something went wrong.  Close the stream and return a
  81                  failure.  */
  82               db->close (db, 0);
  83               db = NULL;
  84               status = NSS_STATUS_UNAVAIL;
  85             }
  86         }
  87     }
  88
  89   /* Remember STAYOPEN flag.  */
  90   if (db != NULL)
  91     keep_db |= stayopen;
  92
  93   return status;
  94 }
  95
  96
  97 /* Thread-safe, exported version of that.  */
  98 enum nss_status
  99 _nss_db_setaliasent (int stayopen)
 100 {
 101   enum nss_status status;
 102
 103   __libc_lock_lock (lock);
 104
 105   status = internal_setent (stayopen);
 106
 107   /* Reset the sequential index.  */
 108   entidx = 0;
 109
 110   __libc_lock_unlock (lock);
 111
 112   return status;
 113 }
 114
 115
 116 /* Close the database file.  */
 117 static void
 118 internal_endent (void)
 119 {
 120   if (db != NULL)
 121     {
 122       db->close (db, 0);
 123       db = NULL;
 124     }
 125 }
 126
 127
 128 /* Thread-safe, exported version of that.  */
 129 enum nss_status
 130 _nss_db_endaliasent (void)
 131 {
 132   __libc_lock_lock (lock);
 133
 134   internal_endent ();
 135
 136   /* Reset STAYOPEN flag.  */
 137   keep_db = 0;
 138
 139   __libc_lock_unlock (lock);
 140
 141   return NSS_STATUS_SUCCESS;
 142 }
 143 \f
 144 /* We provide the parse function here.  The parser in libnss_files
 145    cannot be used.  The generation of the db file already resolved all
 146    :include: statements so we simply have to parse the list and store
 147    the result.  */
 148 static enum nss_status
 149 lookup (DBT *key, struct aliasent *result, char *buffer,
 150         size_t buflen, int *errnop)
 151 {
 152   enum nss_status status;
 153   DBT value;
 154
 155   /* Open the database.  */
 156   status = internal_setent (keep_db);
 157   if (status != NSS_STATUS_SUCCESS)
 158     {
 159       *errnop = errno;
 160       return status;
 161     }
 162
 163   value.flags = 0;
 164   if (db->get (db, NULL, key, &value, 0) == 0)
 165     {
 166       const char *src = value.data;
 167
 168       result->alias_members_len = 0;
 169
 170       /* We now have to fill the BUFFER with all the information. */
 171       if (buflen < key->size + 1)
 172         {
 173         no_more_room:
 174           *errnop = ERANGE;
 175           return NSS_STATUS_TRYAGAIN;
 176         }
 177
 178       if (status == NSS_STATUS_SUCCESS)
 179         {
 180           char *cp;
 181           size_t cnt;
 182
 183           buffer = stpncpy (buffer, key->data, key->size) + 1;
 184           buflen -= key->size + 1;
 185
 186           while (*src != '\0')
 187             {
 188               const char *end, *upto;
 189               while (isspace (*src))
 190                 ++src;
 191
 192               end = strchr (src, ',');
 193               if (end == NULL)
 194                 end = strchr (src, '\0');
 195               for (upto = end; upto > src && isspace (upto[-1]); --upto);
 196
 197               if (upto != src)
 198                 {
 199                   if ((upto - src) + __alignof__ (char *) > buflen)
 200                     goto no_more_room;
 201                   buffer = stpncpy (buffer, src, upto - src) + 1;
 202                   buflen -= (upto - src) + __alignof (char *);
 203                   ++result->alias_members_len;
 204                 }
 205               src = end + (*end != '\0');
 206             }
 207
 208           /* Now prepare the return.  Provide string pointers for the
 209              currently selected aliases.  */
 210
 211           /* Adjust the pointer so it is aligned for storing pointers.  */
 212           buffer += __alignof__ (char *) - 1;
 213           buffer -= ((buffer - (char *) 0) % __alignof__ (char *));
 214           result->alias_members = (char **) buffer;
 215
 216           /* Compute addresses of alias entry strings.  */
 217           cp = result->alias_name;
 218           for (cnt = 0; cnt < result->alias_members_len; ++cnt)
 219             {
 220               cp = strchr (cp, '\0') + 1;
 221               result->alias_members[cnt] = cp;
 222             }
 223
 224           status = (result->alias_members_len == 0
 225                     ? NSS_STATUS_RETURN : NSS_STATUS_SUCCESS);
 226         }
 227     }
 228   else
 229     status = NSS_STATUS_NOTFOUND;
 230
 231   if (! keep_db)
 232     internal_endent ();
 233
 234   return status;
 235 }
 236 \f
 237 enum nss_status
 238 _nss_db_getaliasent_r (struct aliasent *result, char *buffer, size_t buflen,
 239                        int *errnop)
 240 {
 241   /* Return next entry in alias file.  */
 242   enum nss_status status;
 243   char buf[20];
 244   DBT key;
 245
 246   __libc_lock_lock (lock);
 247   key.size = snprintf (key.data = buf, sizeof buf, "0%u", entidx++);
 248   key.flags = 0;
 249   status = lookup (&key, result, buffer, buflen, errnop);
 250   if (status == NSS_STATUS_TRYAGAIN && *errnop == ERANGE)
 251     /* Give the user a chance to get the same entry with a larger buffer.  */
 252     --entidx;
 253   __libc_lock_unlock (lock);
 254
 255   return status;
 256 }
 257
 258
 259 enum nss_status
 260 _nss_db_getaliasbyname_r (const char *name, struct aliasent *result,
 261                           char *buffer, size_t buflen, int *errnop)
 262 {
 263   DBT key;
 264   enum nss_status status;
 265
 266   key.size = 1 + strlen (name);
 267
 268   key.data = __alloca (key.size);
 269   ((char *) key.data)[0] = '.';
 270   memcpy (&((char *) key.data)[1], name, key.size - 1);
 271   key.flags = 0;
 272
 273   __libc_lock_lock (lock);
 274   status = lookup (&key, result, buffer, buflen, errnop);
 275   __libc_lock_unlock (lock);
 276
 277   return status;
 278 }