nss/nss_files/files-XXX.c

   1 /* Common code for file-based databases in nss_files module.
   2    Copyright (C) 1996, 1997, 1998, 1999, 2001 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, write to the Free
  17    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  18    02111-1307 USA.  */
  19
  20 #include <stdio.h>
  21 #include <ctype.h>
  22 #include <errno.h>
  23 #include <fcntl.h>
  24 #include <bits/libc-lock.h>
  25 #include "nsswitch.h"
  26
  27 /* These symbols are defined by the including source file:
  28
  29    ENTNAME -- database name of the structure and functions (hostent, pwent).
  30    STRUCTURE -- struct name, define only if not ENTNAME (passwd, group).
  31    DATABASE -- string of the database file's name ("hosts", "passwd").
  32
  33    NEED_H_ERRNO - defined iff an arg `int *herrnop' is used.
  34
  35    Also see files-parse.c.
  36 */
  37
  38 #define ENTNAME_r       CONCAT(ENTNAME,_r)
  39
  40 #define DATAFILE        "/etc/" DATABASE
  41
  42 #ifdef NEED_H_ERRNO
  43 # include <netdb.h>
  44 # define H_ERRNO_PROTO  , int *herrnop
  45 # define H_ERRNO_ARG    , herrnop
  46 # define H_ERRNO_SET(val) (*herrnop = (val))
  47 #else
  48 # define H_ERRNO_PROTO
  49 # define H_ERRNO_ARG
  50 # define H_ERRNO_SET(val) ((void) 0)
  51 #endif
  52
  53 #ifndef EXTRA_ARGS
  54 # define EXTRA_ARGS
  55 # define EXTRA_ARGS_DECL
  56 # define EXTRA_ARGS_VALUE
  57 #endif
  58
  59 /* Locks the static variables in this file.  */
  60 __libc_lock_define_initialized (static, lock)
  61 \f
  62 /* Maintenance of the shared stream open on the database file.  */
  63
  64 static FILE *stream;
  65 static fpos_t position;
  66 static enum { none, getent, getby } last_use;
  67 static int keep_stream;
  68
  69 /* Open database file if not already opened.  */
  70 static enum nss_status
  71 internal_setent (int stayopen)
  72 {
  73   enum nss_status status = NSS_STATUS_SUCCESS;
  74
  75   if (stream == NULL)
  76     {
  77       stream = fopen (DATAFILE, "r");
  78
  79       if (stream == NULL)
  80         status = errno == EAGAIN ? NSS_STATUS_TRYAGAIN : NSS_STATUS_UNAVAIL;
  81       else
  82         {
  83           /* We have to make sure the file is  `closed on exec'.  */
  84           int result, flags;
  85
  86           result = flags = fcntl (fileno (stream), F_GETFD, 0);
  87           if (result >= 0)
  88             {
  89               flags |= FD_CLOEXEC;
  90               result = fcntl (fileno (stream), F_SETFD, flags);
  91             }
  92           if (result < 0)
  93             {
  94               /* Something went wrong.  Close the stream and return a
  95                  failure.  */
  96               fclose (stream);
  97               stream = NULL;
  98               status = NSS_STATUS_UNAVAIL;
  99             }
 100         }
 101     }
 102   else
 103     rewind (stream);
 104
 105   /* Remember STAYOPEN flag.  */
 106   if (stream != NULL)
 107     keep_stream |= stayopen;
 108
 109   return status;
 110 }
 111
 112
 113 /* Thread-safe, exported version of that.  */
 114 enum nss_status
 115 CONCAT(_nss_files_set,ENTNAME) (int stayopen)
 116 {
 117   enum nss_status status;
 118
 119   __libc_lock_lock (lock);
 120
 121   status = internal_setent (stayopen);
 122
 123   if (status == NSS_STATUS_SUCCESS && fgetpos (stream, &position) < 0)
 124     {
 125       fclose (stream);
 126       stream = NULL;
 127       status = NSS_STATUS_UNAVAIL;
 128     }
 129
 130   last_use = getent;
 131
 132   __libc_lock_unlock (lock);
 133
 134   return status;
 135 }
 136
 137
 138 /* Close the database file.  */
 139 static void
 140 internal_endent (void)
 141 {
 142   if (stream != NULL)
 143     {
 144       fclose (stream);
 145       stream = NULL;
 146     }
 147 }
 148
 149
 150 /* Thread-safe, exported version of that.  */
 151 enum nss_status
 152 CONCAT(_nss_files_end,ENTNAME) (void)
 153 {
 154   __libc_lock_lock (lock);
 155
 156   internal_endent ();
 157
 158   /* Reset STAYOPEN flag.  */
 159   keep_stream = 0;
 160
 161   __libc_lock_unlock (lock);
 162
 163   return NSS_STATUS_SUCCESS;
 164 }
 165 \f
 166 /* Parsing the database file into `struct STRUCTURE' data structures.  */
 167
 168 static enum nss_status
 169 internal_getent (struct STRUCTURE *result,
 170                  char *buffer, size_t buflen, int *errnop H_ERRNO_PROTO
 171                  EXTRA_ARGS_DECL)
 172 {
 173   char *p;
 174   struct parser_data *data = (void *) buffer;
 175   int linebuflen = buffer + buflen - data->linebuffer;
 176   int parse_result;
 177
 178   if (buflen < sizeof *data + 2)
 179     {
 180       *errnop = ERANGE;
 181       H_ERRNO_SET (NETDB_INTERNAL);
 182       return NSS_STATUS_TRYAGAIN;
 183     }
 184
 185   do
 186     {
 187       /* Terminate the line so that we can test for overflow.  */
 188       ((unsigned char *) data->linebuffer)[linebuflen - 1] = '\xff';
 189
 190       p = fgets_unlocked (data->linebuffer, linebuflen, stream);
 191       if (p == NULL)
 192         {
 193           /* End of file or read error.  */
 194           *errnop = ENOENT;
 195           H_ERRNO_SET (HOST_NOT_FOUND);
 196           return NSS_STATUS_NOTFOUND;
 197         }
 198       else if (((unsigned char *) data->linebuffer)[linebuflen - 1] != 0xff)
 199         {
 200           /* The line is too long.  Give the user the opportunity to
 201              enlarge the buffer.  */
 202           *errnop = ERANGE;
 203           H_ERRNO_SET (NETDB_INTERNAL);
 204           return NSS_STATUS_TRYAGAIN;
 205         }
 206
 207       /* Skip leading blanks.  */
 208       while (isspace (*p))
 209         ++p;
 210     }
 211   while (*p == '\0' || *p == '#' /* Ignore empty and comment lines.  */
 212          /* Parse the line.  If it is invalid, loop to get the next
 213             line of the file to parse.  */
 214          || ! (parse_result = parse_line (p, result, data, buflen, errnop
 215                                           EXTRA_ARGS)));
 216
 217   /* Filled in RESULT with the next entry from the database file.  */
 218   return parse_result == -1 ? NSS_STATUS_TRYAGAIN : NSS_STATUS_SUCCESS;
 219 }
 220
 221
 222 /* Return the next entry from the database file, doing locking.  */
 223 enum nss_status
 224 CONCAT(_nss_files_get,ENTNAME_r) (struct STRUCTURE *result, char *buffer,
 225                                   size_t buflen, int *errnop H_ERRNO_PROTO)
 226 {
 227   /* Return next entry in host file.  */
 228   enum nss_status status = NSS_STATUS_SUCCESS;
 229
 230   __libc_lock_lock (lock);
 231
 232   /* Be prepared that the set*ent function was not called before.  */
 233   if (stream == NULL)
 234     {
 235       status = internal_setent (0);
 236
 237       if (status == NSS_STATUS_SUCCESS && fgetpos (stream, &position) < 0)
 238         {
 239           fclose (stream);
 240           stream = NULL;
 241           status = NSS_STATUS_UNAVAIL;
 242         }
 243     }
 244
 245   if (status == NSS_STATUS_SUCCESS)
 246     {
 247       /* If the last use was not by the getent function we need the
 248          position the stream.  */
 249       if (last_use != getent)
 250         {
 251           if (fsetpos (stream, &position) < 0)
 252             status = NSS_STATUS_UNAVAIL;
 253           else
 254             last_use = getent;
 255         }
 256
 257       if (status == NSS_STATUS_SUCCESS)
 258         {
 259           status = internal_getent (result, buffer, buflen, errnop
 260                                     H_ERRNO_ARG EXTRA_ARGS_VALUE);
 261
 262           /* Remember this position if we were successful.  If the
 263              operation failed we give the user a chance to repeat the
 264              operation (perhaps the buffer was too small).  */
 265           if (status == NSS_STATUS_SUCCESS)
 266             fgetpos (stream, &position);
 267           else
 268             /* We must make sure we reposition the stream the next call.  */
 269             last_use = none;
 270         }
 271     }
 272
 273   __libc_lock_unlock (lock);
 274
 275   return status;
 276 }
 277 \f
 278 /* Macro for defining lookup functions for this file-based database.
 279
 280    NAME is the name of the lookup; e.g. `hostbyname'.
 281
 282    KEYSIZE and KEYPATTERN are ignored here but used by ../nss_db/db-XXX.c.
 283
 284    PROTO describes the arguments for the lookup key;
 285    e.g. `const char *hostname'.
 286
 287    BREAK_IF_MATCH is a block of code which compares `struct STRUCTURE *result'
 288    to the lookup key arguments and does `break;' if they match.  */
 289
 290 #define DB_LOOKUP(name, keysize, keypattern, break_if_match, proto...)        \
 291 enum nss_status                                                               \
 292 _nss_files_get##name##_r (proto,                                              \
 293                           struct STRUCTURE *result, char *buffer,             \
 294                           size_t buflen, int *errnop H_ERRNO_PROTO)           \
 295 {                                                                             \
 296   enum nss_status status;                                                     \
 297                                                                               \
 298   __libc_lock_lock (lock);                                                    \
 299                                                                               \
 300   /* Reset file pointer to beginning or open file.  */                        \
 301   status = internal_setent (keep_stream);                                     \
 302                                                                               \
 303   if (status == NSS_STATUS_SUCCESS)                                           \
 304     {                                                                         \
 305       /* Tell getent function that we have repositioned the file pointer.  */ \
 306       last_use = getby;                                                       \
 307                                                                               \
 308       while ((status = internal_getent (result, buffer, buflen, errnop        \
 309                                         H_ERRNO_ARG EXTRA_ARGS_VALUE))        \
 310              == NSS_STATUS_SUCCESS)                                           \
 311         { break_if_match }                                                    \
 312                                                                               \
 313       if (! keep_stream)                                                      \
 314         internal_endent ();                                                   \
 315     }                                                                         \
 316                                                                               \
 317   __libc_lock_unlock (lock);                                                  \
 318                                                                               \
 319   return status;                                                              \
 320 }