nss/nss_files/files-XXX.c

   1 /* Common code for file-based databases in nss_files module.
   2    Copyright (C) 1996-2023 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, see
  17    <https://www.gnu.org/licenses/>.  */
  18
  19 #include <stdio.h>
  20 #include <ctype.h>
  21 #include <errno.h>
  22 #include <fcntl.h>
  23 #include <libc-lock.h>
  24 #include "nsswitch.h"
  25 #include <nss_files.h>
  26
  27 #include <kernel-features.h>
  28
  29 /* These symbols are defined by the including source file:
  30
  31    ENTNAME -- database name of the structure and functions (hostent, pwent).
  32    STRUCTURE -- struct name, define only if not ENTNAME (passwd, group).
  33    DATABASE -- string of the database file's name ("hosts", "passwd").
  34
  35    NEED_H_ERRNO - defined iff an arg `int *herrnop' is used.
  36
  37    Also see files-parse.c.
  38 */
  39
  40 #define ENTNAME_r       CONCAT(ENTNAME,_r)
  41
  42 #define DATAFILE        "/etc/" DATABASE
  43
  44 #ifdef NEED_H_ERRNO
  45 # include <netdb.h>
  46 # define H_ERRNO_PROTO  , int *herrnop
  47 # define H_ERRNO_ARG    , herrnop
  48 # define H_ERRNO_ARG_OR_NULL herrnop
  49 # define H_ERRNO_SET(val) (*herrnop = (val))
  50 #else
  51 # define H_ERRNO_PROTO
  52 # define H_ERRNO_ARG
  53 # define H_ERRNO_ARG_OR_NULL NULL
  54 # define H_ERRNO_SET(val) ((void) 0)
  55 #endif
  56
  57 #ifndef EXTRA_ARGS
  58 # define EXTRA_ARGS
  59 # define EXTRA_ARGS_DECL
  60 # define EXTRA_ARGS_VALUE
  61 #endif
  62
  63 \f
  64 /* Maintenance of the stream open on the database file.  For getXXent
  65    operations the stream needs to be held open across calls, the other
  66    getXXbyYY operations all use their own stream.  */
  67
  68 /* Open database file if not already opened.  */
  69 static enum nss_status
  70 internal_setent (FILE **stream)
  71 {
  72   enum nss_status status = NSS_STATUS_SUCCESS;
  73
  74   if (*stream == NULL)
  75     {
  76       *stream = __nss_files_fopen (DATAFILE);
  77
  78       if (*stream == NULL)
  79         status = errno == EAGAIN ? NSS_STATUS_TRYAGAIN : NSS_STATUS_UNAVAIL;
  80     }
  81   else
  82     rewind (*stream);
  83
  84   return status;
  85 }
  86
  87
  88 /* Thread-safe, exported version of that.  */
  89 enum nss_status
  90 CONCAT(_nss_files_set,ENTNAME) (int stayopen)
  91 {
  92   return __nss_files_data_setent (CONCAT (nss_file_, ENTNAME), DATAFILE);
  93 }
  94 libc_hidden_def (CONCAT (_nss_files_set,ENTNAME))
  95
  96 enum nss_status
  97 CONCAT(_nss_files_end,ENTNAME) (void)
  98 {
  99   return __nss_files_data_endent (CONCAT (nss_file_, ENTNAME));
 100 }
 101 libc_hidden_def (CONCAT (_nss_files_end,ENTNAME))
 102 \f
 103
 104 /* Parsing the database file into `struct STRUCTURE' data structures.  */
 105 static enum nss_status
 106 internal_getent (FILE *stream, struct STRUCTURE *result,
 107                  char *buffer, size_t buflen, int *errnop H_ERRNO_PROTO
 108                  EXTRA_ARGS_DECL)
 109 {
 110   struct parser_data *data = (void *) buffer;
 111   size_t linebuflen = buffer + buflen - data->linebuffer;
 112   int saved_errno = errno;      /* Do not clobber errno on success.  */
 113
 114   if (buflen < sizeof *data + 2)
 115     {
 116       *errnop = ERANGE;
 117       H_ERRNO_SET (NETDB_INTERNAL);
 118       return NSS_STATUS_TRYAGAIN;
 119     }
 120
 121   while (true)
 122     {
 123       off64_t original_offset;
 124       int ret = __nss_readline (stream, data->linebuffer, linebuflen,
 125                                 &original_offset);
 126       if (ret == ENOENT)
 127         {
 128           /* End of file.  */
 129           H_ERRNO_SET (HOST_NOT_FOUND);
 130           __set_errno (saved_errno);
 131           return NSS_STATUS_NOTFOUND;
 132         }
 133       else if (ret == 0)
 134         {
 135           ret = __nss_parse_line_result (stream, original_offset,
 136                                          parse_line (data->linebuffer,
 137                                                      result, data, buflen,
 138                                                      errnop EXTRA_ARGS));
 139           if (ret == 0)
 140             {
 141               /* Line has been parsed successfully.  */
 142               __set_errno (saved_errno);
 143               return NSS_STATUS_SUCCESS;
 144             }
 145           else if (ret == EINVAL)
 146             /* If it is invalid, loop to get the next line of the file
 147                to parse.  */
 148             continue;
 149         }
 150
 151       *errnop = ret;
 152       H_ERRNO_SET (NETDB_INTERNAL);
 153       if (ret == ERANGE)
 154         /* Request larger buffer.  */
 155         return NSS_STATUS_TRYAGAIN;
 156       else
 157         /* Other read failure.  */
 158         return NSS_STATUS_UNAVAIL;
 159     }
 160 }
 161
 162
 163 /* Return the next entry from the database file, doing locking.  */
 164 enum nss_status
 165 CONCAT(_nss_files_get,ENTNAME_r) (struct STRUCTURE *result, char *buffer,
 166                                   size_t buflen, int *errnop H_ERRNO_PROTO)
 167 {
 168   /* Return next entry in host file.  */
 169
 170   struct nss_files_per_file_data *data;
 171   enum nss_status status = __nss_files_data_open (&data,
 172                                                   CONCAT (nss_file_, ENTNAME),
 173                                                   DATAFILE,
 174                                                   errnop, H_ERRNO_ARG_OR_NULL);
 175   if (status != NSS_STATUS_SUCCESS)
 176     return status;
 177
 178   status = internal_getent (data->stream, result, buffer, buflen, errnop
 179                             H_ERRNO_ARG EXTRA_ARGS_VALUE);
 180
 181   __nss_files_data_put (data);
 182   return status;
 183 }
 184 libc_hidden_def (CONCAT (_nss_files_get,ENTNAME_r))
 185 \f
 186 /* Macro for defining lookup functions for this file-based database.
 187
 188    NAME is the name of the lookup; e.g. `hostbyname'.
 189
 190    DB_CHAR, KEYPATTERN, KEYSIZE are ignored here but used by db-XXX.c
 191    e.g. `1 + sizeof (id) * 4'.
 192
 193    PROTO is the potentially empty list of other parameters.
 194
 195    BREAK_IF_MATCH is a block of code which compares `struct STRUCTURE *result'
 196    to the lookup key arguments and does `break;' if they match.  */
 197
 198 #define DB_LOOKUP(name, db_char, keysize, keypattern, break_if_match, proto...)\
 199 enum nss_status                                                               \
 200 _nss_files_get##name##_r (proto,                                              \
 201                           struct STRUCTURE *result, char *buffer,             \
 202                           size_t buflen, int *errnop H_ERRNO_PROTO)           \
 203 {                                                                             \
 204   enum nss_status status;                                                     \
 205   FILE *stream = NULL;                                                        \
 206                                                                               \
 207   /* Open file.  */                                                           \
 208   status = internal_setent (&stream);                                         \
 209                                                                               \
 210   if (status == NSS_STATUS_SUCCESS)                                           \
 211     {                                                                         \
 212       while ((status = internal_getent (stream, result, buffer, buflen, errnop \
 213                                         H_ERRNO_ARG EXTRA_ARGS_VALUE))        \
 214              == NSS_STATUS_SUCCESS)                                           \
 215         { break_if_match }                                                    \
 216                                                                               \
 217       fclose (stream);                                                        \
 218     }                                                                         \
 219                                                                               \
 220   return status;                                                              \
 221 }                                                                             \
 222 libc_hidden_def (_nss_files_get##name##_r)