summaryrefslogtreecommitdiff
path: root/nss/makedb.c
blob: 8cee92f891b25e16b99f5b3c229913116f7d13db (plain)
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
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
/* Create simple DB database from textual input.
   Copyright (C) 1996-2000, 2011 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, write to the Free
   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
   02111-1307 USA.  */

#include <argp.h>
#include <assert.h>
#include <ctype.h>
#include <errno.h>
#include <error.h>
#include <fcntl.h>
#include <inttypes.h>
#include <libintl.h>
#include <locale.h>
#include <search.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include "nss_db/nss_db.h"

/* Get libc version number.  */
#include "../version.h"

/* The hashing function we use.  */
#include "../intl/hash-string.h"

/* SELinux support.  */
#ifdef HAVE_SELINUX
# include <selinux/selinux.h>
#endif

#define PACKAGE _libc_intl_domainname

/* List of data bases.  */
struct database
{
  char dbid;
  bool extra_string;
  struct database *next;
  void *entries;
  size_t nentries;
  size_t nhashentries;
  stridx_t *hashtable;
  size_t keystrlen;
  stridx_t *keyidxtab;
  char *keystrtab;
} *databases;
static size_t ndatabases;
static size_t nhashentries_total;
static size_t valstrlen;
static void *valstrtree;
static char *valstrtab;
static size_t extrastrlen;

/* Database entry.  */
struct dbentry
{
  stridx_t validx;
  uint32_t hashval;
  char str[0];
};

/* Stored string entry.  */
struct valstrentry
{
  stridx_t idx;
  bool extra_string;
  char str[0];
};


/* True if any entry has been added.  */
static bool any_dbentry;

/* If non-zero convert key to lower case.  */
static int to_lowercase;

/* If non-zero print content of input file, one entry per line.  */
static int do_undo;

/* If non-zero do not print informational messages.  */
static int be_quiet;

/* Name of output file.  */
static const char *output_name;

/* Name and version of program.  */
static void print_version (FILE *stream, struct argp_state *state);
void (*argp_program_version_hook) (FILE *, struct argp_state *) = print_version;

/* Definitions of arguments for argp functions.  */
static const struct argp_option options[] =
{
  { "fold-case", 'f', NULL, 0, N_("Convert key to lower case") },
  { "output", 'o', N_("NAME"), 0, N_("Write output to file NAME") },
  { "quiet", 'q', NULL, 0,
    N_("Do not print messages while building database") },
  { "undo", 'u', NULL, 0,
    N_("Print content of database file, one entry a line") },
  { "generated", 'g', N_("CHAR"), 0,
    N_("Generated line not part of iteration") },
  { NULL, 0, NULL, 0, NULL }
};

/* Short description of program.  */
static const char doc[] = N_("Create simple database from textual input.");

/* Strings for arguments in help texts.  */
static const char args_doc[] = N_("\
INPUT-FILE OUTPUT-FILE\n-o OUTPUT-FILE INPUT-FILE\n-u INPUT-FILE");

/* Prototype for option handler.  */
static error_t parse_opt (int key, char *arg, struct argp_state *state);

/* Function to print some extra text in the help message.  */
static char *more_help (int key, const char *text, void *input);

/* Data structure to communicate with argp functions.  */
static struct argp argp =
{
  options, parse_opt, args_doc, doc, NULL, more_help
};


/* List of databases which are not part of the iteration table.  */
static struct db_option
{
  char dbid;
  struct db_option *next;
} *db_options;


/* Prototypes for local functions.  */
static int process_input (FILE *input, const char *inname,
			  int to_lowercase, int be_quiet);
static int print_database (int fd);
static void compute_tables (void);
static int write_output (int fd);

/* SELinux support.  */
#ifdef HAVE_SELINUX
/* Set the SELinux file creation context for the given file. */
static void set_file_creation_context (const char *outname, mode_t mode);
static void reset_file_creation_context (void);
#else
# define set_file_creation_context(_outname,_mode)
# define reset_file_creation_context()
#endif


/* External functions.  */
extern void *xmalloc (size_t n) __attribute_malloc__;
extern void *xcalloc (size_t n, size_t m) __attribute_malloc__;


int
main (int argc, char *argv[])
{
  const char *input_name;
  FILE *input_file;
  int remaining;
  int mode = 0644;

  /* Set locale via LC_ALL.  */
  setlocale (LC_ALL, "");

  /* Set the text message domain.  */
  textdomain (_libc_intl_domainname);

  /* Initialize local variables.  */
  input_name = NULL;

  /* Parse and process arguments.  */
  argp_parse (&argp, argc, argv, 0, &remaining, NULL);

  /* Determine file names.  */
  if (do_undo || output_name != NULL)
    {
      if (remaining + 1 != argc)
	{
	wrong_arguments:
	  error (0, 0, gettext ("wrong number of arguments"));
	  argp_help (&argp, stdout, ARGP_HELP_SEE,
		     program_invocation_short_name);
	  exit (1);
	}
      input_name = argv[remaining];
    }
  else
    {
      if (remaining + 2 != argc)
	goto wrong_arguments;

      input_name = argv[remaining++];
      output_name = argv[remaining];
    }

  /* Special handling if we are asked to print the database.  */
  if (do_undo)
    {
      int fd = open (input_name, O_RDONLY);
      if (fd == -1)
	error (EXIT_FAILURE, errno, gettext ("cannot open database file `%s'"),
	       input_name);

      int status = print_database (fd);

      close (fd);

      return status;
    }

  /* Open input file.  */
  if (strcmp (input_name, "-") == 0 || strcmp (input_name, "/dev/stdin") == 0)
    input_file = stdin;
  else
    {
      struct stat64 st;

      input_file = fopen64 (input_name, "r");
      if (input_file == NULL)
	error (EXIT_FAILURE, errno, gettext ("cannot open input file `%s'"),
	       input_name);

      /* Get the access rights from the source file.  The output file should
	 have the same.  */
      if (fstat64 (fileno (input_file), &st) >= 0)
	mode = st.st_mode & ACCESSPERMS;
    }

  /* Start the real work.  */
  int status = process_input (input_file, input_name, to_lowercase, be_quiet);

  /* Close files.  */
  if (input_file != stdin)
    fclose (input_file);

  /* No need to continue when we did not read the file successfully.  */
  if (status != EXIT_SUCCESS)
    return status;

  /* Bail out if nothing is to be done.  */
  if (!any_dbentry)
    {
      if (be_quiet)
	return EXIT_SUCCESS;
      else
	error (EXIT_SUCCESS, 0, gettext ("no entries to be processed"));
    }

  /* Compute hash and string tables.  */
  compute_tables ();

  /* Open output file.  This must not be standard output so we don't
     handle "-" and "/dev/stdout" special.  */
  char *tmp_output_name;
  if (asprintf (&tmp_output_name, "%s.XXXXXX", output_name) == -1)
    error (EXIT_FAILURE, errno, gettext ("cannot create temporary file name"));

  set_file_creation_context (output_name, mode);
  int fd = mkstemp (tmp_output_name);
  reset_file_creation_context ();
  if (fd == -1)
    error (EXIT_FAILURE, errno, gettext ("cannot create temporary file"));

  status = write_output (fd);

  if (status == EXIT_SUCCESS)
    {
      struct stat64 st;

      if (fstat64 (fd, &st) == 0)
	{
	  if ((st.st_mode & ACCESSPERMS) != mode)
	    /* We ignore problems with changing the mode.  */
	    fchmod (fd, mode);
	}
      else
	{
	  error (0, errno, gettext ("cannot stat newly created file"));
	  status = EXIT_FAILURE;
	}
    }

  close (fd);

  if (status == EXIT_SUCCESS)
    {
      if (rename (tmp_output_name, output_name) != 0)
	{
	  error (0, errno, gettext ("cannot rename temporary file"));
	  status = EXIT_FAILURE;
	  goto do_unlink;
	}
    }
  else
  do_unlink:
    unlink (tmp_output_name);

  return status;
}


/* Handle program arguments.  */
static error_t
parse_opt (int key, char *arg, struct argp_state *state)
{
  struct db_option *newp;

  switch (key)
    {
    case 'f':
      to_lowercase = 1;
      break;
    case 'o':
      output_name = arg;
      break;
    case 'q':
      be_quiet = 1;
      break;
    case 'u':
      do_undo = 1;
      break;
    case 'g':
      newp = xmalloc (sizeof (*newp));
      newp->dbid = arg[0];
      newp->next = db_options;
      db_options = newp;
      break;
    default:
      return ARGP_ERR_UNKNOWN;
    }
  return 0;
}


static char *
more_help (int key, const char *text, void *input)
{
  switch (key)
    {
    case ARGP_KEY_HELP_EXTRA:
      /* We print some extra information.  */
      return strdup (gettext ("\
For bug reporting instructions, please see:\n\
<http://www.gnu.org/software/libc/bugs.html>.\n"));
    default:
      break;
    }
  return (char *) text;
}

/* Print the version information.  */
static void
print_version (FILE *stream, struct argp_state *state)
{
  fprintf (stream, "makedb (GNU %s) %s\n", PACKAGE, VERSION);
  fprintf (stream, gettext ("\
Copyright (C) %s Free Software Foundation, Inc.\n\
This is free software; see the source for copying conditions.  There is NO\n\
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.\n\
"), "2011");
  fprintf (stream, gettext ("Written by %s.\n"), "Ulrich Drepper");
}


static int
dbentry_compare (const void *p1, const void *p2)
{
  const struct dbentry *d1 = (const struct dbentry *) p1;
  const struct dbentry *d2 = (const struct dbentry *) p2;

  if (d1->hashval != d2->hashval)
    return d1->hashval < d2->hashval ? -1 : 1;

  return strcmp (d1->str, d2->str);
}


static int
valstr_compare (const void *p1, const void *p2)
{
  const struct valstrentry *d1 = (const struct valstrentry *) p1;
  const struct valstrentry *d2 = (const struct valstrentry *) p2;

  return strcmp (d1->str, d2->str);
}


static int
process_input (input, inname, to_lowercase, be_quiet)
     FILE *input;
     const char *inname;
     int to_lowercase;
     int be_quiet;
{
  char *line;
  size_t linelen;
  int status;
  size_t linenr;

  line = NULL;
  linelen = 0;
  status = EXIT_SUCCESS;
  linenr = 0;

  struct database *last_database = NULL;

  while (!feof_unlocked (input))
    {
      ssize_t n = getline (&line, &linelen, input);
      if (n < 0)
	/* This means end of file or some bug.  */
	break;
      if (n == 0)
	/* Short read.  Probably interrupted system call. */
	continue;

      ++linenr;

      if (line[n - 1] == '\n')
	/* Remove trailing newline.  */
	line[--n] = '\0';

      char *cp = line;
      while (isspace (*cp))
	++cp;

      if (*cp == '#' || *cp == '\0')
	/* First non-space character in line '#': it's a comment.
	   Also go to the next line if it is empty except for whitespaces. */
	continue;

      /* Skip over the character indicating the database so that it is not
	 affected by TO_LOWERCASE.  */
      char *key = cp++;
      while (*cp != '\0' && !isspace (*cp))
	{
	  if (to_lowercase)
	    *cp = tolower (*cp);
	  ++cp;
	}

      if (*cp == '\0')
	/* It's a line without a value field.  */
	continue;

      *cp++ = '\0';
      size_t keylen = cp - key;

      while (isspace (*cp))
	++cp;

      char *data = cp;
      size_t datalen = (&line[n] - cp) + 1;

      /* Find the database.  */
      if (last_database == NULL || last_database->dbid != key[0])
	{
	  last_database = databases;
	  while (last_database != NULL && last_database->dbid != key[0])
	    last_database = last_database->next;

	  if (last_database == NULL)
	    {
	      last_database = xmalloc (sizeof (*last_database));
	      last_database->dbid = key[0];
	      last_database->extra_string = false;
	      last_database->next = databases;
	      last_database->entries = NULL;
	      last_database->nentries = 0;
	      last_database->keystrlen = 0;
	      databases = last_database;

	      struct db_option *runp = db_options;
	      while (runp != NULL)
		if (runp->dbid == key[0])
		  {
		    last_database->extra_string = true;
		    break;
		  }
		else
		  runp = runp->next;
	    }
	}

      /* Skip the database selector.  */
      ++key;
      --keylen;

      /* Store the data.  */
      struct valstrentry *nentry = xmalloc (sizeof (struct valstrentry)
					    + datalen);
      if (last_database->extra_string)
	nentry->idx = extrastrlen;
      else
	nentry->idx = valstrlen;
      nentry->extra_string = last_database->extra_string;
      memcpy (nentry->str, data, datalen);

      struct valstrentry **fdata = tsearch (nentry, &valstrtree,
					    valstr_compare);
      if (fdata == NULL)
	error (EXIT_FAILURE, errno, gettext ("cannot create search tree"));

      if (*fdata != nentry)
	{
	  /* We can reuse a string.  */
	  free (nentry);
	  nentry = *fdata;
	}
      else
	if (last_database->extra_string)
	  extrastrlen += datalen;
	else
	  valstrlen += datalen;

      /* Store the key.  */
      struct dbentry *newp = xmalloc (sizeof (struct dbentry) + keylen);
      newp->validx = nentry->idx;
      newp->hashval = __hash_string (key);
      memcpy (newp->str, key, keylen);

      struct dbentry **found = tsearch (newp, &last_database->entries,
					dbentry_compare);
      if (found == NULL)
	error (EXIT_FAILURE, errno, gettext ("cannot create search tree"));

      if (*found != newp)
	{
	  free (newp);
	  if (!be_quiet)
	    error_at_line (0, 0, inname, linenr, gettext ("duplicate key"));
	  continue;
	}

      ++last_database->nentries;
      last_database->keystrlen += keylen;

      any_dbentry = true;
    }

  if (ferror_unlocked (input))
    {
      error (0, 0, gettext ("problems while reading `%s'"), inname);
      status = EXIT_FAILURE;
    }

  return status;
}


static void
copy_valstr (const void *nodep, const VISIT which, const int depth)
{
  if (which != leaf && which != postorder)
    return;

  const struct valstrentry *p = *(const struct valstrentry **) nodep;

  strcpy (valstrtab + (p->extra_string ? valstrlen : 0) + p->idx, p->str);
}


static int
is_prime (size_t candidate)
{
  /* No even number and none less than 10 will be passed here.  */
  size_t divn = 3;
  size_t sq = divn * divn;

  while (sq < candidate && candidate % divn != 0)
    {
      ++divn;
      sq += 4 * divn;
      ++divn;
    }

  return candidate % divn != 0;
}


static size_t
next_prime (size_t seed)
{
  /* Make it definitely odd.  */
  seed |= 1;

  while (!is_prime (seed))
    seed += 2;

  return seed;
}


static void
compute_tables (void)
{
  valstrtab = xmalloc (roundup (valstrlen + extrastrlen, sizeof (stridx_t)));
  while ((valstrlen + extrastrlen) % sizeof (stridx_t) != 0)
    valstrtab[valstrlen++] = '\0';
  twalk (valstrtree, copy_valstr);

  static struct database *db;
  for (db = databases; db != NULL; db = db->next)
    if (db->nentries != 0)
      {
	++ndatabases;

	/* We simply use an odd number large than twice the number of
	   elements to store in the hash table for the size.  This gives
	   enough efficiency.  */
#define TEST_RANGE 30
	size_t nhashentries_min = next_prime (db->nentries < TEST_RANGE
					      ? db->nentries
					      : db->nentries * 2 - TEST_RANGE);
	size_t nhashentries_max = MAX (nhashentries_min, db->nentries * 4);
	size_t nhashentries_best = nhashentries_min;
	size_t chainlength_best = db->nentries;

	db->hashtable = xmalloc (2 * nhashentries_max * sizeof (stridx_t)
				 + db->keystrlen);
	db->keyidxtab = db->hashtable + nhashentries_max;
	db->keystrtab = (char *) (db->keyidxtab + nhashentries_max);

	static size_t max_chainlength;
	static char *wp;
	static size_t nhashentries;
	static bool copy_string;

	void add_key(const void *nodep, const VISIT which, const int depth)
	{
	  if (which != leaf && which != postorder)
	    return;

	  const struct dbentry *dbe = *(const struct dbentry **) nodep;

	  ptrdiff_t stridx;
	  if (copy_string)
	    {
	      stridx = wp - db->keystrtab;
	      wp = stpcpy (wp, dbe->str) + 1;
	    }
	  else
	    stridx = 0;

	  size_t hidx = dbe->hashval % nhashentries;
	  size_t hval2 = 1 + dbe->hashval % (nhashentries - 2);
	  size_t chainlength = 0;

	  while (db->hashtable[hidx] != ~((stridx_t) 0))
	    {
	      ++chainlength;
	      if ((hidx += hval2) >= nhashentries)
		hidx -= nhashentries;
	    }

	  db->hashtable[hidx] = ((db->extra_string ? valstrlen : 0)
				 + dbe->validx);
	  db->keyidxtab[hidx] = stridx;

	  max_chainlength = MAX (max_chainlength, chainlength);
	}

	copy_string = false;
	nhashentries = nhashentries_min;
	for (size_t cnt = 0; cnt < TEST_RANGE; ++cnt)
	  {
	    memset (db->hashtable, '\xff', nhashentries * sizeof (stridx_t));

	    max_chainlength = 0;
	    wp = db->keystrtab;

	    twalk (db->entries, add_key);

	    if (max_chainlength == 0)
	      {
		/* No need to look further, this is as good as it gets.  */
		nhashentries_best = nhashentries;
		break;
	      }

	    if (max_chainlength < chainlength_best)
	      {
		chainlength_best = max_chainlength;
		nhashentries_best = nhashentries;
	      }

	    nhashentries = next_prime (nhashentries + 1);
	    if (nhashentries > nhashentries_max)
	      break;
	  }

	/* Recompute the best table again, this time fill in the strings.  */
	nhashentries = nhashentries_best;
	memset (db->hashtable, '\xff',
		2 * nhashentries_max * sizeof (stridx_t));
	copy_string = true;
	wp = db->keystrtab;

	twalk (db->entries, add_key);

	db->nhashentries = nhashentries_best;
	nhashentries_total += nhashentries_best;
    }
}


static int
write_output (int fd)
{
  struct nss_db_header *header;
  uint64_t file_offset = (sizeof (struct nss_db_header)
			  + (ndatabases * sizeof (header->dbs[0])));
  header = alloca (file_offset);

  header->magic = NSS_DB_MAGIC;
  header->ndbs = ndatabases;
  header->valstroffset = file_offset;
  header->valstrlen = valstrlen;

  size_t filled_dbs = 0;
  struct iovec iov[2 + ndatabases * 3];
  iov[0].iov_base = header;
  iov[0].iov_len = file_offset;

  iov[1].iov_base = valstrtab;
  iov[1].iov_len = valstrlen + extrastrlen;
  file_offset += iov[1].iov_len;

  size_t keydataoffset = file_offset + nhashentries_total * sizeof (stridx_t);
  for (struct database *db = databases; db != NULL; db = db->next)
    if (db->entries != NULL)
      {
	assert (file_offset % sizeof (stridx_t) == 0);
	assert (filled_dbs < ndatabases);

	header->dbs[filled_dbs].id = db->dbid;
	memset (header->dbs[filled_dbs].pad, '\0',
		sizeof (header->dbs[0].pad));
	header->dbs[filled_dbs].hashsize = db->nhashentries;

	iov[2 + filled_dbs].iov_base = db->hashtable;
	iov[2 + filled_dbs].iov_len = db->nhashentries * sizeof (stridx_t);
	header->dbs[filled_dbs].hashoffset = file_offset;
	file_offset += iov[2 + filled_dbs].iov_len;

	iov[2 + ndatabases + filled_dbs * 2].iov_base = db->keyidxtab;
	iov[2 + ndatabases + filled_dbs * 2].iov_len
	  = db->nhashentries * sizeof (stridx_t);
	header->dbs[filled_dbs].keyidxoffset = keydataoffset;
	keydataoffset += iov[2 + ndatabases + filled_dbs * 2].iov_len;

	iov[3 + ndatabases + filled_dbs * 2].iov_base = db->keystrtab;
	iov[3 + ndatabases + filled_dbs * 2].iov_len = db->keystrlen;
	header->dbs[filled_dbs].keystroffset = keydataoffset;
	keydataoffset += iov[3 + ndatabases + filled_dbs * 2].iov_len;

	++filled_dbs;
      }

  assert (filled_dbs == ndatabases);
  assert (file_offset == (iov[0].iov_len + iov[1].iov_len
			  + nhashentries_total * sizeof (stridx_t)));
  header->allocate = file_offset;

  if (writev (fd, iov, 2 + ndatabases * 3) != keydataoffset)
    {
      error (0, errno, gettext ("failed to write new database file"));
      return EXIT_FAILURE;
    }

  return EXIT_SUCCESS;
}


static int
print_database (int fd)
{
  struct stat64 st;
  if (fstat64 (fd, &st) != 0)
    error (EXIT_FAILURE, errno, gettext ("cannot stat database file"));

  const struct nss_db_header *header = mmap (NULL, st.st_size, PROT_READ,
					     MAP_PRIVATE|MAP_POPULATE, fd, 0);
  if (header == MAP_FAILED)
    error (EXIT_FAILURE, errno, gettext ("cannot map database file"));

  if (header->magic != NSS_DB_MAGIC)
    error (EXIT_FAILURE, 0, gettext ("file not a database file"));

  const char *valstrtab = (const char *) header + header->valstroffset;

  for (unsigned int dbidx = 0; dbidx < header->ndbs; ++dbidx)
    {
      const stridx_t *stridxtab
	= ((const stridx_t *) ((const char *) header
			       + header->dbs[dbidx].keyidxoffset));
      const char *keystrtab
	= (const char *) header + header->dbs[dbidx].keystroffset;
      const stridx_t *hashtab
	= (const stridx_t *) ((const char *) header
			      + header->dbs[dbidx].hashoffset);

      for (uint32_t hidx = 0; hidx < header->dbs[dbidx].hashsize; ++hidx)
	if (hashtab[hidx] != ~((stridx_t) 0))
	  printf ("%c%s %s\n",
		  header->dbs[dbidx].id,
		  keystrtab + stridxtab[hidx],
		  valstrtab + hashtab[hidx]);
    }

  return EXIT_SUCCESS;
}


#ifdef HAVE_SELINUX
static void
set_file_creation_context (const char *outname, mode_t mode)
{
  static int enabled;
  static int enforcing;
  security_context_t ctx;

  /* Check if SELinux is enabled, and remember. */
  if (enabled == 0)
    enabled = is_selinux_enabled ();
  if (enabled < 0)
    return;

  /* Check if SELinux is enforcing, and remember. */
  if (enforcing == 0)
    enforcing = security_getenforce () ? 1 : -1;

  /* Determine the context which the file should have. */
  ctx = NULL;
  if (matchpathcon (outname, S_IFREG | mode, &ctx) == 0 && ctx != NULL)
    {
      if (setfscreatecon (ctx) != 0)
	error (enforcing > 0 ? EXIT_FAILURE : 0, 0,
	       gettext ("cannot set file creation context for `%s'"),
	       outname);

      freecon (ctx);
    }
}

static void
reset_file_creation_context (void)
{
  setfscreatecon (NULL);
}
#endif