about summary refs log tree commit diff
path: root/nss/nss_files/files-alias.c
blob: 53088f6a8b1e9140e97372073440438db0883641 (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
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
/* Mail alias file parser in nss_files module.
   Copyright (C) 1996-2014 Free Software Foundation, Inc.
   This file is part of the GNU C Library.
   Contributed by Ulrich Drepper <drepper@cygnus.com>, 1996.

   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, see
   <http://www.gnu.org/licenses/>.  */

#include <aliases.h>
#include <ctype.h>
#include <errno.h>
#include <fcntl.h>
#include <bits/libc-lock.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>

#include <kernel-features.h>

#include "nsswitch.h"

/* 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 enum nss_status
internal_setent (void)
{
  enum nss_status status = NSS_STATUS_SUCCESS;

  if (stream == NULL)
    {
      stream = fopen ("/etc/aliases", "rce");

      if (stream == NULL)
	status = errno == EAGAIN ? NSS_STATUS_TRYAGAIN : NSS_STATUS_UNAVAIL;
      else
	{
#if !defined O_CLOEXEC || !defined __ASSUME_O_CLOEXEC
# ifdef O_CLOEXEC
	  if (__have_o_cloexec <= 0)
# endif
	    {
	      /* We have to make sure the file is  `closed on exec'.  */
	      int result;
	      int flags;

	      result = flags = fcntl (fileno (stream), F_GETFD, 0);
	      if (result >= 0)
		{
# ifdef O_CLOEXEC
		  if (__have_o_cloexec == 0)
		    __have_o_cloexec = (flags & FD_CLOEXEC) == 0 ? -1 : 1;
		  if (__have_o_cloexec < 0)
# endif
		    {
		      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;
		}
	    }
#endif
	}
    }
  else
    rewind (stream);

  return status;
}


/* Thread-safe, exported version of that.  */
enum nss_status
_nss_files_setaliasent (void)
{
  enum nss_status status;

  __libc_lock_lock (lock);

  status = internal_setent ();

  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
_nss_files_endaliasent (void)
{
  __libc_lock_lock (lock);

  internal_endent ();

  __libc_lock_unlock (lock);

  return NSS_STATUS_SUCCESS;
}

/* Parsing the database file into `struct aliasent' data structures.  */
static enum nss_status
get_next_alias (const char *match, struct aliasent *result,
		char *buffer, size_t buflen, int *errnop)
{
  enum nss_status status = NSS_STATUS_NOTFOUND;
  int ignore = 0;

  result->alias_members_len = 0;

  while (1)
    {
      /* Now we are ready to process the input.  We have to read a
	 line and all its continuations and construct the array of
	 string pointers.  This pointers and the names itself have to
	 be placed in BUFFER.  */
      char *first_unused = buffer;
      size_t room_left = buflen - (buflen % __alignof__ (char *));
      char *line;

      /* Check whether the buffer is large enough for even trying to
	 read something.  */
      if (room_left < 2)
	goto no_more_room;

      /* Read the first line.  It must contain the alias name and
	 possibly some alias names.  */
      first_unused[room_left - 1] = '\xff';
      line = fgets_unlocked (first_unused, room_left, stream);
      if (line == NULL)
	/* Nothing to read.  */
	break;
      else if (first_unused[room_left - 1] != '\xff')
	{
	  /* The line is too long for our buffer.  */
	no_more_room:
	  *errnop = ERANGE;
	  status = NSS_STATUS_TRYAGAIN;
	  break;
	}
      else
	{
	  char *cp;

	  /* If we are in IGNORE mode and the first character in the
	     line is a white space we ignore the line and start
	     reading the next.  */
	  if (ignore && isspace (*first_unused))
	    continue;

	  /* Terminate the line for any case.  */
	  cp = strpbrk (first_unused, "#\n");
	  if (cp != NULL)
	    *cp = '\0';

	  /* Skip leading blanks.  */
	  while (isspace (*line))
	    ++line;

	  result->alias_name = first_unused;
	  while (*line != '\0' && *line != ':')
	    *first_unused++ = *line++;
	  if (*line == '\0' || result->alias_name == first_unused)
	    /* No valid name.  Ignore the line.  */
	    continue;

	  *first_unused++ = '\0';
	  if (room_left < (size_t) (first_unused - result->alias_name))
	    goto no_more_room;
	  room_left -= first_unused - result->alias_name;
	  ++line;

	  /* When we search for a specific alias we can avoid all the
	     difficult parts and compare now with the name we are
	     looking for.  If it does not match we simply ignore all
	     lines until the next line containing the start of a new
	     alias is found.  */
	  ignore = (match != NULL
		    && __strcasecmp (result->alias_name, match) != 0);

	  while (! ignore)
	    {
	      while (isspace (*line))
		++line;

	      cp = first_unused;
	      while (*line != '\0' && *line != ',')
		*first_unused++ = *line++;

	      if (first_unused != cp)
		{
		  /* OK, we can have a regular entry or an include
		     request.  */
		  if (*line != '\0')
		    ++line;
		  *first_unused++ = '\0';

		  if (strncmp (cp, ":include:", 9) != 0)
		    {
		      if (room_left < (first_unused - cp) + sizeof (char *))
			goto no_more_room;
		      room_left -= (first_unused - cp) + sizeof (char *);

		      ++result->alias_members_len;
		    }
		  else
		    {
		      /* Oh well, we have to read the addressed file.  */
		      FILE *listfile;
		      char *old_line = NULL;

		      first_unused = cp;

		      listfile = fopen (&cp[9], "rce");
		      /* If the file does not exist we simply ignore
			 the statement.  */
		      if (listfile != NULL
			  && (old_line = strdup (line)) != NULL)
			{
			  while (! feof_unlocked (listfile))
			    {
			      first_unused[room_left - 1] = '\xff';
			      line = fgets_unlocked (first_unused, room_left,
						     listfile);
			      if (line == NULL)
				break;
			      if (first_unused[room_left - 1] != '\xff')
				{
				  free (old_line);
				  goto no_more_room;
				}

			      /* Parse the line.  */
			      cp = strpbrk (line, "#\n");
			      if (cp != NULL)
				*cp = '\0';

			      do
				{
				  while (isspace (*line))
				    ++line;

				  cp = first_unused;
				  while (*line != '\0' && *line != ',')
				    *first_unused++ = *line++;

				  if (*line != '\0')
				    ++line;

				  if (first_unused != cp)
				    {
				      *first_unused++ = '\0';
				      if (room_left < ((first_unused - cp)
						       + __alignof__ (char *)))
					{
					  free (old_line);
					  goto no_more_room;
					}
				      room_left -= ((first_unused - cp)
						    + __alignof__ (char *));
				      ++result->alias_members_len;
				    }
				}
			      while (*line != '\0');
			    }
			  fclose (listfile);

			  first_unused[room_left - 1] = '\0';
			  strncpy (first_unused, old_line, room_left);

			  free (old_line);
			  line = first_unused;

			  if (first_unused[room_left - 1] != '\0')
			    goto no_more_room;
			}
		    }
		}

	      if (*line == '\0')
		{
		  /* Get the next line.  But we must be careful.  We
		     must not read the whole line at once since it
		     might belong to the current alias.  Simply read
		     the first character.  If it is a white space we
		     have a continuation line.  Otherwise it is the
		     beginning of a new alias and we can push back the
		     just read character.  */
		  int ch;

		  ch = fgetc_unlocked (stream);
		  if (ch == EOF || ch == '\n' || !isspace (ch))
		    {
		      size_t cnt;

		      /* Now prepare the return.  Provide string
			 pointers for the currently selected aliases.  */
		      if (ch != EOF)
			ungetc (ch, stream);

		      /* Adjust the pointer so it is aligned for
			 storing pointers.  */
		      first_unused += __alignof__ (char *) - 1;
		      first_unused -= ((first_unused - (char *) 0)
				       % __alignof__ (char *));
		      result->alias_members = (char **) first_unused;

		      /* Compute addresses of alias entry strings.  */
		      cp = result->alias_name;
		      for (cnt = 0; cnt < result->alias_members_len; ++cnt)
			{
			  cp = strchr (cp, '\0') + 1;
			  result->alias_members[cnt] = cp;
			}

		      status = (result->alias_members_len == 0
				? NSS_STATUS_RETURN : NSS_STATUS_SUCCESS);
		      break;
		    }

		  /* The just read character is a white space and so
		     can be ignored.  */
		  first_unused[room_left - 1] = '\xff';
		  line = fgets_unlocked (first_unused, room_left, stream);
		  if (first_unused[room_left - 1] != '\xff')
		    goto no_more_room;
		  cp = strpbrk (line, "#\n");
		  if (cp != NULL)
		    *cp = '\0';
		}
	    }
	}

      if (status != NSS_STATUS_NOTFOUND)
	/* We read something.  In any case break here.  */
	break;
    }

  return status;
}


enum nss_status
_nss_files_getaliasent_r (struct aliasent *result, char *buffer, size_t buflen,
			  int *errnop)
{
  /* 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 ();

  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)
	{
	  result->alias_local = 1;

	  /* Read lines until we get a definite result.  */
	  do
	    status = get_next_alias (NULL, result, buffer, buflen, errnop);
	  while (status == NSS_STATUS_RETURN);

	  /* If we successfully read an entry remember this position.  */
	  if (status == NSS_STATUS_SUCCESS)
	    fgetpos (stream, &position);
	  else
	    last_use = nouse;
	}
    }

  __libc_lock_unlock (lock);

  return status;
}


enum nss_status
_nss_files_getaliasbyname_r (const char *name, struct aliasent *result,
			     char *buffer, size_t buflen, int *errnop)
{
  /* Return next entry in host file.  */
  enum nss_status status = NSS_STATUS_SUCCESS;

  if (name == NULL)
    {
      __set_errno (EINVAL);
      return NSS_STATUS_UNAVAIL;
    }

  __libc_lock_lock (lock);

  /* Open the stream or rest it.  */
  status = internal_setent ();
  last_use = getby;

  if (status == NSS_STATUS_SUCCESS)
    {
      result->alias_local = 1;

      /* Read lines until we get a definite result.  */
      do
	status = get_next_alias (name, result, buffer, buflen, errnop);
      while (status == NSS_STATUS_RETURN);
    }

  internal_endent ();

  __libc_lock_unlock (lock);

  return status;
}