nss/nss_files/files-XXX.c

   1 /* Common code for file-based databases in nss_files module.
   2    Copyright (C) 1996 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 <stdio.h>
  21 #include <ctype.h>
  22 #include <assert.h>
  23 #include <errno.h>
  24 #include <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 /* Locks the static variables in this file.  */
  54 __libc_lock_define_initialized (static, lock)
  55 \f
  56 /* Maintenance of the shared stream open on the database file.  */
  57
  58 static FILE *stream;
  59 static fpos_t position;
  60 static enum { none, getent, getby } last_use;
  61 static int keep_stream;
  62
  63 /* Open database file if not already opened.  */
  64 static enum nss_status
  65 internal_setent (int stayopen)
  66 {
  67   enum nss_status status = NSS_STATUS_SUCCESS;
  68
  69   if (stream == NULL)
  70     {
  71       stream = fopen (DATAFILE, "r");
  72
  73       if (stream == NULL)
  74         status = NSS_STATUS_UNAVAIL;
  75     }
  76   else
  77     rewind (stream);
  78
  79   /* Remember STAYOPEN flag.  */
  80   if (stream != NULL)
  81     keep_stream |= stayopen;
  82
  83   return status;
  84 }
  85
  86
  87 /* Thread-safe, exported version of that.  */
  88 enum nss_status
  89 CONCAT(_nss_files_set,ENTNAME) (int stayopen)
  90 {
  91   enum nss_status status;
  92
  93   __libc_lock_lock (lock);
  94
  95   status = internal_setent (stayopen);
  96
  97   if (status == NSS_STATUS_SUCCESS && fgetpos (stream, &position) < 0)
  98     {
  99       fclose (stream);
 100       stream = NULL;
 101       status = NSS_STATUS_UNAVAIL;
 102     }
 103
 104   last_use = getent;
 105
 106   __libc_lock_unlock (lock);
 107
 108   return status;
 109 }
 110
 111
 112 /* Close the database file.  */
 113 static void
 114 internal_endent (void)
 115 {
 116   if (stream != NULL)
 117     {
 118       fclose (stream);
 119       stream = NULL;
 120     }
 121 }
 122
 123
 124 /* Thread-safe, exported version of that.  */
 125 enum nss_status
 126 CONCAT(_nss_files_end,ENTNAME) (void)
 127 {
 128   __libc_lock_lock (lock);
 129
 130   internal_endent ();
 131
 132   /* Reset STAYOPEN flag.  */
 133   keep_stream = 0;
 134
 135   __libc_lock_unlock (lock);
 136
 137   return NSS_STATUS_SUCCESS;
 138 }
 139 \f
 140 /* Parsing the database file into `struct STRUCTURE' data structures.  */
 141
 142 static enum nss_status
 143 internal_getent (struct STRUCTURE *result,
 144                  char *buffer, int buflen H_ERRNO_PROTO)
 145 {
 146   char *p;
 147   struct parser_data *data = (void *) buffer;
 148   int linebuflen = buffer + buflen - data->linebuffer;
 149
 150   if (buflen < (int) sizeof *data + 1)
 151     {
 152       __set_errno (ERANGE);
 153       H_ERRNO_SET (NETDB_INTERNAL);
 154       return NSS_STATUS_TRYAGAIN;
 155     }
 156
 157   do
 158     {
 159       /* Terminate the line so that we can test for overflow.  */
 160       data->linebuffer[linebuflen - 1] = '\0';
 161
 162       p = fgets (data->linebuffer, linebuflen, stream);
 163       if (p == NULL)
 164         {
 165           /* End of file or read error.  */
 166           H_ERRNO_SET (HOST_NOT_FOUND);
 167           return NSS_STATUS_NOTFOUND;
 168         }
 169       else if (data->linebuffer[linebuflen - 1] != '\0')
 170         {
 171           /* The line is too long.  Give the user the opportunity to
 172              enlarge the buffer.  */
 173           __set_errno (ERANGE);
 174           H_ERRNO_SET (NETDB_INTERNAL);
 175           return NSS_STATUS_TRYAGAIN;
 176         }
 177
 178       /* Skip leading blanks.  */
 179       while (isspace (*p))
 180         ++p;
 181     }
 182   while (*p == '\0' || *p == '#' /* Ignore empty and comment lines.  */
 183          /* Parse the line.  If it is invalid, loop to get the next
 184             line of the file to parse.  */
 185          || ! parse_line (p, result, data, buflen));
 186
 187   /* Filled in RESULT with the next entry from the database file.  */
 188   return NSS_STATUS_SUCCESS;
 189 }
 190
 191
 192 /* Return the next entry from the database file, doing locking.  */
 193 enum nss_status
 194 CONCAT(_nss_files_get,ENTNAME_r) (struct STRUCTURE *result,
 195                                   char *buffer, size_t buflen H_ERRNO_PROTO)
 196 {
 197   /* Return next entry in host file.  */
 198   enum nss_status status = NSS_STATUS_SUCCESS;
 199
 200   __libc_lock_lock (lock);
 201
 202   /* Be prepared that the set*ent function was not called before.  */
 203   if (stream == NULL)
 204     status = internal_setent (0);
 205
 206   if (status == NSS_STATUS_SUCCESS)
 207     {
 208       /* If the last use was not by the getent function we need the
 209          position the stream.  */
 210       if (last_use != getent)
 211         if (fsetpos (stream, &position) < 0)
 212           status = NSS_STATUS_UNAVAIL;
 213         else
 214           last_use = getent;
 215
 216       if (status == NSS_STATUS_SUCCESS)
 217         {
 218           status = internal_getent (result, buffer, buflen H_ERRNO_ARG);
 219
 220           /* Remember this position if we were successful.  If the
 221              operation failed we give the user a chance to repeat the
 222              operation (perhaps the buffer was too small).  */
 223           if (status == NSS_STATUS_SUCCESS)
 224             fgetpos (stream, &position);
 225           else
 226             /* We must make sure we reposition the stream the next call.  */
 227             last_use = none;
 228         }
 229     }
 230
 231   __libc_lock_unlock (lock);
 232
 233   return status;
 234 }
 235 \f
 236 /* Macro for defining lookup functions for this file-based database.
 237
 238    NAME is the name of the lookup; e.g. `hostbyname'.
 239
 240    KEYSIZE and KEYPATTERN are ignored here but used by ../nss_db/db-XXX.c.
 241
 242    PROTO describes the arguments for the lookup key;
 243    e.g. `const char *hostname'.
 244
 245    BREAK_IF_MATCH is a block of code which compares `struct STRUCTURE *result'
 246    to the lookup key arguments and does `break;' if they match.  */
 247
 248 #define DB_LOOKUP(name, keysize, keypattern, break_if_match, proto...)        \
 249 enum nss_status                                                               \
 250 _nss_files_get##name##_r (proto,                                              \
 251                           struct STRUCTURE *result,                           \
 252                           char *buffer, size_t buflen H_ERRNO_PROTO)          \
 253 {                                                                             \
 254   enum nss_status status;                                                     \
 255                                                                               \
 256   __libc_lock_lock (lock);                                                    \
 257                                                                               \
 258   /* Reset file pointer to beginning or open file.  */                        \
 259   status = internal_setent (keep_stream);                                     \
 260                                                                               \
 261   if (status == NSS_STATUS_SUCCESS)                                           \
 262     {                                                                         \
 263       /* Tell getent function that we have repositioned the file pointer.  */ \
 264       last_use = getby;                                                       \
 265                                                                               \
 266       while ((status = internal_getent (result, buffer, buflen H_ERRNO_ARG))  \
 267              == NSS_STATUS_SUCCESS)                                           \
 268         { break_if_match }                                                    \
 269                                                                               \
 270       if (! keep_stream)                                                      \
 271         internal_endent ();                                                   \
 272     }                                                                         \
 273                                                                               \
 274   __libc_lock_unlock (lock);                                                  \
 275                                                                               \
 276   return status;                                                              \
 277 }