summary refs log tree commit diff
path: root/nss/nss_files/files-XXX.c
blob: fd000bfd9ac1288c39ff2ab9f7a9e90f460e0473 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
/* Common code for file-based databases in nss_files module.
   Copyright (C) 1996,1997,1998,1999,2001,2002 Free Software Foundation, Inc.
   This file is part of the GNU C Library.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with the GNU C Library; if not, write to the Free
   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
   02111-1307 USA.  */

#include <stdio.h>
#include <ctype.h>
#include <errno.h>
#include <fcntl.h>
#include <bits/libc-lock.h>
#include "nsswitch.h"

/* These symbols are defined by the including source file:

   ENTNAME -- database name of the structure and functions (hostent, pwent).
   STRUCTURE -- struct name, define only if not ENTNAME (passwd, group).
   DATABASE -- string of the database file's name ("hosts", "passwd").

   NEED_H_ERRNO - defined iff an arg `int *herrnop' is used.

   Also see files-parse.c.
*/

#define ENTNAME_r	CONCAT(ENTNAME,_r)

#define DATAFILE	"/etc/" DATABASE

#ifdef NEED_H_ERRNO
# include <netdb.h>
# define H_ERRNO_PROTO	, int *herrnop
# define H_ERRNO_ARG	, herrnop
# define H_ERRNO_SET(val) (*herrnop = (val))
#else
# define H_ERRNO_PROTO
# define H_ERRNO_ARG
# define H_ERRNO_SET(val) ((void) 0)
#endif

#ifndef EXTRA_ARGS
# define EXTRA_ARGS
# define EXTRA_ARGS_DECL
# define EXTRA_ARGS_VALUE
#endif

/* Locks the static variables in this file.  */
__libc_lock_define_initialized (static, lock)

/* Maintenance of the shared stream open on the database file.  */

static FILE *stream;
static fpos_t position;
static enum { nouse, getent, getby } last_use;
static int keep_stream;

/* Open database file if not already opened.  */
static enum nss_status
internal_setent (int stayopen)
{
  enum nss_status status = NSS_STATUS_SUCCESS;

  if (stream == NULL)
    {
      stream = fopen (DATAFILE, "r");

      if (stream == NULL)
	status = errno == EAGAIN ? NSS_STATUS_TRYAGAIN : NSS_STATUS_UNAVAIL;
      else
	{
	  /* We have to make sure the file is  `closed on exec'.  */
	  int result, flags;

	  result = flags = fcntl (fileno (stream), F_GETFD, 0);
	  if (result >= 0)
	    {
	      flags |= FD_CLOEXEC;
	      result = fcntl (fileno (stream), F_SETFD, flags);
	    }
	  if (result < 0)
	    {
	      /* Something went wrong.  Close the stream and return a
		 failure.  */
	      fclose (stream);
	      stream = NULL;
	      status = NSS_STATUS_UNAVAIL;
	    }
	}
    }
  else
    rewind (stream);

  /* Remember STAYOPEN flag.  */
  if (stream != NULL)
    keep_stream |= stayopen;

  return status;
}


/* Thread-safe, exported version of that.  */
enum nss_status
CONCAT(_nss_files_set,ENTNAME) (int stayopen)
{
  enum nss_status status;

  __libc_lock_lock (lock);

  status = internal_setent (stayopen);

  if (status == NSS_STATUS_SUCCESS && fgetpos (stream, &position) < 0)
    {
      fclose (stream);
      stream = NULL;
      status = NSS_STATUS_UNAVAIL;
    }

  last_use = getent;

  __libc_lock_unlock (lock);

  return status;
}


/* Close the database file.  */
static void
internal_endent (void)
{
  if (stream != NULL)
    {
      fclose (stream);
      stream = NULL;
    }
}


/* Thread-safe, exported version of that.  */
enum nss_status
CONCAT(_nss_files_end,ENTNAME) (void)
{
  __libc_lock_lock (lock);

  internal_endent ();

  /* Reset STAYOPEN flag.  */
  keep_stream = 0;

  __libc_lock_unlock (lock);

  return NSS_STATUS_SUCCESS;
}

/* Parsing the database file into `struct STRUCTURE' data structures.  */

static enum nss_status
internal_getent (struct STRUCTURE *result,
		 char *buffer, size_t buflen, int *errnop H_ERRNO_PROTO
		 EXTRA_ARGS_DECL)
{
  char *p;
  struct parser_data *data = (void *) buffer;
  int linebuflen = buffer + buflen - data->linebuffer;
  int parse_result;

  if (buflen < sizeof *data + 2)
    {
      *errnop = ERANGE;
      H_ERRNO_SET (NETDB_INTERNAL);
      return NSS_STATUS_TRYAGAIN;
    }

  do
    {
      /* Terminate the line so that we can test for overflow.  */
      ((unsigned char *) data->linebuffer)[linebuflen - 1] = '\xff';

      p = fgets_unlocked (data->linebuffer, linebuflen, stream);
      if (p == NULL)
	{
	  /* End of file or read error.  */
	  H_ERRNO_SET (HOST_NOT_FOUND);
	  return NSS_STATUS_NOTFOUND;
	}
      else if (((unsigned char *) data->linebuffer)[linebuflen - 1] != 0xff)
	{
	  /* The line is too long.  Give the user the opportunity to
	     enlarge the buffer.  */
	  *errnop = ERANGE;
	  H_ERRNO_SET (NETDB_INTERNAL);
	  return NSS_STATUS_TRYAGAIN;
	}

      /* Skip leading blanks.  */
      while (isspace (*p))
	++p;
    }
  while (*p == '\0' || *p == '#' /* Ignore empty and comment lines.  */
	 /* Parse the line.  If it is invalid, loop to get the next
	    line of the file to parse.  */
	 || ! (parse_result = parse_line (p, result, data, buflen, errnop
					  EXTRA_ARGS)));

  /* Filled in RESULT with the next entry from the database file.  */
  return parse_result == -1 ? NSS_STATUS_TRYAGAIN : NSS_STATUS_SUCCESS;
}


/* Return the next entry from the database file, doing locking.  */
enum nss_status
CONCAT(_nss_files_get,ENTNAME_r) (struct STRUCTURE *result, char *buffer,
				  size_t buflen, int *errnop H_ERRNO_PROTO)
{
  /* Return next entry in host file.  */
  enum nss_status status = NSS_STATUS_SUCCESS;

  __libc_lock_lock (lock);

  /* Be prepared that the set*ent function was not called before.  */
  if (stream == NULL)
    {
      status = internal_setent (0);

      if (status == NSS_STATUS_SUCCESS && fgetpos (stream, &position) < 0)
	{
	  fclose (stream);
	  stream = NULL;
	  status = NSS_STATUS_UNAVAIL;
	}
    }

  if (status == NSS_STATUS_SUCCESS)
    {
      /* If the last use was not by the getent function we need the
	 position the stream.  */
      if (last_use != getent)
	{
	  if (fsetpos (stream, &position) < 0)
	    status = NSS_STATUS_UNAVAIL;
	  else
	    last_use = getent;
	}

      if (status == NSS_STATUS_SUCCESS)
	{
	  status = internal_getent (result, buffer, buflen, errnop
				    H_ERRNO_ARG EXTRA_ARGS_VALUE);

	  /* Remember this position if we were successful.  If the
	     operation failed we give the user a chance to repeat the
	     operation (perhaps the buffer was too small).  */
	  if (status == NSS_STATUS_SUCCESS)
	    fgetpos (stream, &position);
	  else
	    /* We must make sure we reposition the stream the next call.  */
	    last_use = nouse;
	}
    }

  __libc_lock_unlock (lock);

  return status;
}

/* Macro for defining lookup functions for this file-based database.

   NAME is the name of the lookup; e.g. `hostbyname'.

   KEYSIZE and KEYPATTERN are ignored here but used by ../nss_db/db-XXX.c.

   PROTO describes the arguments for the lookup key;
   e.g. `const char *hostname'.

   BREAK_IF_MATCH is a block of code which compares `struct STRUCTURE *result'
   to the lookup key arguments and does `break;' if they match.  */

#define DB_LOOKUP(name, keysize, keypattern, break_if_match, proto...)	      \
enum nss_status								      \
_nss_files_get##name##_r (proto,					      \
			  struct STRUCTURE *result, char *buffer,	      \
			  size_t buflen, int *errnop H_ERRNO_PROTO)	      \
{									      \
  enum nss_status status;						      \
									      \
  __libc_lock_lock (lock);						      \
									      \
  /* Reset file pointer to beginning or open file.  */			      \
  status = internal_setent (keep_stream);				      \
									      \
  if (status == NSS_STATUS_SUCCESS)					      \
    {									      \
      /* Tell getent function that we have repositioned the file pointer.  */ \
      last_use = getby;							      \
									      \
      while ((status = internal_getent (result, buffer, buflen, errnop	      \
					H_ERRNO_ARG EXTRA_ARGS_VALUE))	      \
	     == NSS_STATUS_SUCCESS)					      \
	{ break_if_match }						      \
									      \
      if (! keep_stream)						      \
	internal_endent ();						      \
    }									      \
									      \
  __libc_lock_unlock (lock);						      \
									      \
  return status;							      \
}