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
  17 not, write to the Free Software Foundation, Inc., 675 Mass Ave,
  18 Cambridge, MA 02139, USA.  */
  19
  20 #include <stdio.h>
  21 #include <ctype.h>
  22 #include <assert.h>
  23 #include <libc-lock.h>
  24 #include "nsswitch.h"
  25
  26 /* These symbols are defined by the including source file:
  27
  28    ENTNAME -- database name of the structure and functions (hostent, pwent).
  29    STRUCTURE -- struct name, define only if not ENTNAME (passwd, group).
  30    DATAFILE -- string of the database file's name.
  31
  32    NEED_H_ERRNO - defined iff an arg `int *herrnop' is used.
  33    MIDLINE_COMMENTS - defined iff # before \n terminates a database line.
  34 */
  35
  36 #define ENTNAME_r CONCAT(ENTNAME,_r)
  37
  38 #ifdef NEED_H_ERRNO
  39 #define H_ERRNO_PROTO   , int *herrnop
  40 #define H_ERRNO_ARG     , herrnop
  41 #define H_ERRNO_SET(val) (*herrnop = (val))
  42 #else
  43 #define H_ERRNO_PROTO
  44 #define H_ERRNO_ARG
  45 #define H_ERRNO_SET(val) ((void) 0)
  46 #endif
  47
  48 /* Locks the static variables in this file.  */
  49 __libc_lock_define_initialized (static, lock);
  50 \f
  51 /* Maintenance of the shared stream open on the database file.  */
  52
  53 static FILE *stream;
  54 static int keep_stream;
  55
  56 /* Open database file if not already opened.  */
  57 static int
  58 internal_setent (int stayopen)
  59 {
  60   int status = NSS_STATUS_SUCCESS;
  61
  62   if (stream == NULL)
  63     {
  64       stream = fopen (DATAFILE, "r");
  65
  66       if (stream == NULL)
  67         status = NSS_STATUS_UNAVAIL;
  68     }
  69   else
  70     rewind (stream);
  71
  72   /* Remember STAYOPEN flag.  */
  73   if (stream != NULL)
  74     keep_stream |= stayopen;
  75
  76   return status;
  77 }
  78
  79
  80 /* Thread-safe, exported version of that.  */
  81 int
  82 CONCAT(_nss_files_set,ENTNAME) (int stayopen)
  83 {
  84   int status;
  85
  86   __libc_lock_lock (lock);
  87
  88   status = internal_setent (stayopen);
  89
  90   __libc_lock_unlock (lock);
  91
  92   return status;
  93 }
  94
  95
  96 /* Close the database file.  */
  97 static void
  98 internal_endent (void)
  99 {
 100   if (stream != NULL)
 101     {
 102       fclose (stream);
 103       stream = NULL;
 104     }
 105 }
 106
 107
 108 /* Thread-safe, exported version of that.  */
 109 int
 110 CONCAT(_nss_files_end,ENTNAME) (void)
 111 {
 112   __libc_lock_lock (lock);
 113
 114   internal_endent ();
 115
 116   /* Reset STAYOPEN flag.  */
 117   keep_stream = 0;
 118
 119   __libc_lock_unlock (lock);
 120
 121   return NSS_STATUS_SUCCESS;
 122 }
 123 \f
 124 /* Parsing the database file into `struct STRUCTURE' data structures.  */
 125
 126 static enum nss_status
 127 internal_getent (struct STRUCTURE *result,
 128                  char *buffer, int buflen H_ERRNO_PROTO)
 129 {
 130   char *p;
 131   struct parser_data *data = (void *) buffer;
 132   int linebuflen = buffer + buflen - data->linebuffer;
 133
 134   /* Be prepared that the set*ent function was not called before.  */
 135   if (stream == NULL)
 136     {
 137       enum nss_status status;
 138
 139       status = internal_setent (0);
 140       if (status != NSS_STATUS_SUCCESS)
 141         return status;
 142     }
 143
 144   if (buflen < (int) sizeof *data + 1)
 145     {
 146       errno = ERANGE;
 147       return NSS_STATUS_NOTFOUND;
 148     }
 149
 150   do
 151     {
 152       p = fgets (data->linebuffer, linebuflen, stream);
 153       if (p == NULL)
 154         {
 155           /* End of file or read error.  */
 156           H_ERRNO_SET (HOST_NOT_FOUND);
 157           return NSS_STATUS_NOTFOUND;
 158         }
 159
 160       /* Terminate the line for any case.  */
 161       data->linebuffer[linebuflen - 1] = '\0';
 162
 163       /* Skip leading blanks.  */
 164       while (isspace (*p))
 165         ++p;
 166     } while (*p == '\0' || *p == '#' || /* Ignore empty and comment lines.  */
 167              /* Parse the line.  If it is invalid, loop to
 168                 get the next line of the file to parse.  */
 169              ! parse_line (p, result, data, buflen));
 170
 171   /* Filled in RESULT with the next entry from the database file.  */
 172   return NSS_STATUS_SUCCESS;
 173 }
 174
 175
 176 /* Return the next entry from the database file, doing locking.  */
 177 int
 178 CONCAT(_nss_files_get,ENTNAME_r) (struct STRUCTURE *result,
 179                                   char *buffer, int buflen H_ERRNO_PROTO)
 180 {
 181   /* Return next entry in host file.  */
 182   int status;
 183
 184   __libc_lock_lock (lock);
 185
 186   status = internal_getent (result, buffer, buflen H_ERRNO_ARG);
 187
 188   __libc_lock_unlock (lock);
 189
 190   return status;
 191 }
 192 \f
 193 /* Macro for defining lookup functions for this file-based database.
 194
 195    NAME is the name of the lookup; e.g. `hostbyname'.
 196
 197    PROTO describes the arguments for the lookup key;
 198    e.g. `const char *hostname'.
 199
 200    BREAK_IF_MATCH is a block of code which compares `struct STRUCTURE *result'
 201    to the lookup key arguments and does `break;' if they match.  */
 202
 203 #define DB_LOOKUP(name, break_if_match, proto...)                             \
 204 enum nss_status                                                               \
 205 _nss_files_get##name##_r (proto,                                              \
 206                           struct STRUCTURE *result,                           \
 207                           char *buffer, int buflen H_ERRNO_PROTO)             \
 208 {                                                                             \
 209   enum nss_status status;                                                     \
 210                                                                               \
 211   __libc_lock_lock (lock);                                                    \
 212                                                                               \
 213   /* Reset file pointer to beginning or open file.  */                        \
 214   internal_setent (keep_stream);                                              \
 215                                                                               \
 216   while ((status = internal_getent (result, buffer, buflen H_ERRNO_ARG))      \
 217          == NSS_STATUS_SUCCESS)                                               \
 218     { break_if_match }                                                        \
 219                                                                               \
 220   if (! keep_stream)                                                          \
 221     internal_endent ();                                                       \
 222                                                                               \
 223   __libc_lock_unlock (lock);                                                  \
 224                                                                               \
 225   return status;                                                              \
 226 }