aboutsummaryrefslogtreecommitdiff
path: root/elf/cache.c
blob: dadab9132b0078049f09a064d19586cc03287204 (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
/* Copyright (C) 1999-2003,2005,2006,2007,2011 Free Software Foundation, Inc.
   This file is part of the GNU C Library.
   Contributed by Andreas Jaeger <aj@suse.de>, 1999.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published
   by the Free Software Foundation; version 2 of the License, or
   (at your option) any later version.

   This program 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 General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, see <http://www.gnu.org/licenses/>.  */

#include <errno.h>
#include <error.h>
#include <dirent.h>
#include <inttypes.h>
#include <libgen.h>
#include <libintl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/fcntl.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <sys/types.h>

#include <ldconfig.h>
#include <dl-cache.h>

struct cache_entry
{
  char *lib;			/* Library name.  */
  char *path;			/* Path to find library.  */
  int flags;			/* Flags to indicate kind of library.  */
  unsigned int osversion;	/* Required OS version.  */
  uint64_t hwcap;		/* Important hardware capabilities.  */
  int bits_hwcap;		/* Number of bits set in hwcap.  */
  struct cache_entry *next;	/* Next entry in list.  */
};

/* List of all cache entries.  */
static struct cache_entry *entries;

static const char *flag_descr[] =
{ "libc4", "ELF", "libc5", "libc6"};

/* Print a single entry.  */
static void
print_entry (const char *lib, int flag, unsigned int osversion,
	     uint64_t hwcap, const char *key)
{
  printf ("\t%s (", lib);
  switch (flag & FLAG_TYPE_MASK)
    {
    case FLAG_LIBC4:
    case FLAG_ELF:
    case FLAG_ELF_LIBC5:
    case FLAG_ELF_LIBC6:
      fputs (flag_descr[flag & FLAG_TYPE_MASK], stdout);
      break;
    default:
      fputs (_("unknown"), stdout);
      break;
    }
  switch (flag & FLAG_REQUIRED_MASK)
    {
    case FLAG_SPARC_LIB64:
      fputs (",64bit", stdout);
      break;
    case FLAG_IA64_LIB64:
      fputs (",IA-64", stdout);
      break;
    case FLAG_X8664_LIB64:
      fputs (",x86-64", stdout);
      break;
    case FLAG_S390_LIB64:
      fputs (",64bit", stdout);
      break;
    case FLAG_POWERPC_LIB64:
      fputs (",64bit", stdout);
      break;
    case FLAG_MIPS64_LIBN32:
      fputs (",N32", stdout);
      break;
    case FLAG_MIPS64_LIBN64:
      fputs (",64bit", stdout);
    case 0:
      break;
    default:
      printf (",%d", flag & FLAG_REQUIRED_MASK);
      break;
    }
  if (hwcap != 0)
    printf (", hwcap: %#.16" PRIx64, hwcap);
  if (osversion != 0)
    {
      static const char *const abi_tag_os[] =
      {
	[0] = "Linux",
	[1] = "Hurd",
	[2] = "Solaris",
	[3] = "FreeBSD",
	[4] = "kNetBSD",
	[5] = "Syllable",
	[6] = N_("Unknown OS")
      };
#define MAXTAG (sizeof abi_tag_os / sizeof abi_tag_os[0] - 1)
      unsigned int os = osversion >> 24;

      printf (_(", OS ABI: %s %d.%d.%d"),
	      _(abi_tag_os[os > MAXTAG ? MAXTAG : os]),
	      (osversion >> 16) & 0xff,
	      (osversion >> 8) & 0xff,
	      osversion & 0xff);
    }
  printf (") => %s\n", key);
}


/* Print the whole cache file, if a file contains the new cache format
   hidden in the old one, print the contents of the new format.  */
void
print_cache (const char *cache_name)
{
  int fd = open (cache_name, O_RDONLY);
  if (fd < 0)
    error (EXIT_FAILURE, errno, _("Can't open cache file %s\n"), cache_name);

  struct stat64 st;
  if (fstat64 (fd, &st) < 0
      /* No need to map the file if it is empty.  */
      || st.st_size == 0)
    {
      close (fd);
      return;
    }

  struct cache_file *cache
    = mmap (NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
  if (cache == MAP_FAILED)
    error (EXIT_FAILURE, errno, _("mmap of cache file failed.\n"));

  size_t cache_size = st.st_size;
  if (cache_size < sizeof (struct cache_file))
    error (EXIT_FAILURE, 0, _("File is not a cache file.\n"));

  struct cache_file_new *cache_new = NULL;
  const char *cache_data;
  int format = 0;

  if (memcmp (cache->magic, CACHEMAGIC, sizeof CACHEMAGIC - 1))
    {
      /* This can only be the new format without the old one.  */
      cache_new = (struct cache_file_new *) cache;

      if (memcmp (cache_new->magic, CACHEMAGIC_NEW, sizeof CACHEMAGIC_NEW - 1)
	  || memcmp (cache_new->version, CACHE_VERSION,
		      sizeof CACHE_VERSION - 1))
	error (EXIT_FAILURE, 0, _("File is not a cache file.\n"));
      format = 1;
      /* This is where the strings start.  */
      cache_data = (const char *) cache_new;
    }
  else
    {
      size_t offset = ALIGN_CACHE (sizeof (struct cache_file)
				   + (cache->nlibs
				      * sizeof (struct file_entry)));
      /* This is where the strings start.  */
      cache_data = (const char *) &cache->libs[cache->nlibs];

      /* Check for a new cache embedded in the old format.  */
      if (cache_size >
	  (offset + sizeof (struct cache_file_new)))
	{

	  cache_new = (struct cache_file_new *) ((void *)cache + offset);

	  if (memcmp (cache_new->magic, CACHEMAGIC_NEW,
		      sizeof CACHEMAGIC_NEW - 1) == 0
	      && memcmp (cache_new->version, CACHE_VERSION,
			 sizeof CACHE_VERSION - 1) == 0)
	    {
	      cache_data = (const char *) cache_new;
	      format = 1;
	    }
	}
    }

  if (format == 0)
    {
      printf (_("%d libs found in cache `%s'\n"), cache->nlibs, cache_name);

      /* Print everything.  */
      for (unsigned int i = 0; i < cache->nlibs; i++)
	print_entry (cache_data + cache->libs[i].key,
		     cache->libs[i].flags, 0, 0,
		     cache_data + cache->libs[i].value);
    }
  else if (format == 1)
    {
      printf (_("%d libs found in cache `%s'\n"),
	      cache_new->nlibs, cache_name);

      /* Print everything.  */
      for (unsigned int i = 0; i < cache_new->nlibs; i++)
	print_entry (cache_data + cache_new->libs[i].key,
		     cache_new->libs[i].flags,
		     cache_new->libs[i].osversion,
		     cache_new->libs[i].hwcap,
		     cache_data + cache_new->libs[i].value);
    }
  /* Cleanup.  */
  munmap (cache, cache_size);
  close (fd);
}

/* Initialize cache data structures.  */
void
init_cache (void)
{
  entries = NULL;
}

static int
compare (const struct cache_entry *e1, const struct cache_entry *e2)
{
  /* We need to swap entries here to get the correct sort order.  */
  int res = _dl_cache_libcmp (e2->lib, e1->lib);
  if (res == 0)
    {
      if (e1->flags < e2->flags)
	return 1;
      else if (e1->flags > e2->flags)
	return -1;
      /* Sort by most specific hwcap.  */
      else if (e2->bits_hwcap > e1->bits_hwcap)
	return 1;
      else if (e2->bits_hwcap < e1->bits_hwcap)
	return -1;
      else if (e2->hwcap > e1->hwcap)
	return 1;
      else if (e2->hwcap < e1->hwcap)
	return -1;
      if (e2->osversion > e1->osversion)
	return 1;
      if (e2->osversion < e1->osversion)
	return -1;
    }
  return res;
}

/* Save the contents of the cache.  */
void
save_cache (const char *cache_name)
{
  /* The cache entries are sorted already, save them in this order. */

  /* Count the length of all strings.  */
  /* The old format doesn't contain hwcap entries and doesn't contain
     libraries in subdirectories with hwcaps entries.  Count therefore
     also all entries with hwcap == 0.  */
  size_t total_strlen = 0;
  struct cache_entry *entry;
  /* Number of cache entries.  */
  int cache_entry_count = 0;
  /* Number of normal cache entries.  */
  int cache_entry_old_count = 0;

  for (entry = entries; entry != NULL; entry = entry->next)
    {
      /* Account the final NULs.  */
      total_strlen += strlen (entry->lib) + strlen (entry->path) + 2;
      ++cache_entry_count;
      if (entry->hwcap == 0)
	++cache_entry_old_count;
    }

  /* Create the on disk cache structure.  */
  struct cache_file *file_entries = NULL;
  size_t file_entries_size = 0;

  if (opt_format != 2)
    {
      /* struct cache_file_new is 64-bit aligned on some arches while
	 only 32-bit aligned on other arches.  Duplicate last old
	 cache entry so that new cache in ld.so.cache can be used by
	 both.  */
      if (opt_format != 0)
	cache_entry_old_count = (cache_entry_old_count + 1) & ~1;

      /* And the list of all entries in the old format.  */
      file_entries_size = sizeof (struct cache_file)
	+ cache_entry_old_count * sizeof (struct file_entry);
      file_entries = xmalloc (file_entries_size);

      /* Fill in the header.  */
      memset (file_entries, '\0', sizeof (struct cache_file));
      memcpy (file_entries->magic, CACHEMAGIC, sizeof CACHEMAGIC - 1);

      file_entries->nlibs = cache_entry_old_count;
    }

  struct cache_file_new *file_entries_new = NULL;
  size_t file_entries_new_size = 0;

  if (opt_format != 0)
    {
      /* And the list of all entries in the new format.  */
      file_entries_new_size = sizeof (struct cache_file_new)
	+ cache_entry_count * sizeof (struct file_entry_new);
      file_entries_new = xmalloc (file_entries_new_size);

      /* Fill in the header.  */
      memset (file_entries_new, '\0', sizeof (struct cache_file_new));
      memcpy (file_entries_new->magic, CACHEMAGIC_NEW,
	      sizeof CACHEMAGIC_NEW - 1);
      memcpy (file_entries_new->version, CACHE_VERSION,
	      sizeof CACHE_VERSION - 1);

      file_entries_new->nlibs = cache_entry_count;
      file_entries_new->len_strings = total_strlen;
    }

  /* Pad for alignment of cache_file_new.  */
  size_t pad = ALIGN_CACHE (file_entries_size) - file_entries_size;

  /* If we have both formats, we hide the new format in the strings
     table, we have to adjust all string indices for this so that
     old libc5/glibc 2 dynamic linkers just ignore them.  */
  unsigned int str_offset;
  if (opt_format != 0)
    str_offset = file_entries_new_size;
  else
    str_offset = 0;

  /* An array for all strings.  */
  char *strings = xmalloc (total_strlen);
  char *str = strings;
  int idx_old;
  int idx_new;

  for (idx_old = 0, idx_new = 0, entry = entries; entry != NULL;
       entry = entry->next, ++idx_new)
    {
      /* First the library.  */
      if (opt_format != 2 && entry->hwcap == 0)
	{
	  file_entries->libs[idx_old].flags = entry->flags;
	  /* XXX: Actually we can optimize here and remove duplicates.  */
	  file_entries->libs[idx_old].key = str_offset + pad;
	}
      if (opt_format != 0)
	{
	  /* We could subtract file_entries_new_size from str_offset -
	     not doing so makes the code easier, the string table
	     always begins at the beginning of the new cache
	     struct.  */
	  file_entries_new->libs[idx_new].flags = entry->flags;
	  file_entries_new->libs[idx_new].osversion = entry->osversion;
	  file_entries_new->libs[idx_new].hwcap = entry->hwcap;
	  file_entries_new->libs[idx_new].key = str_offset;
	}

      size_t len = strlen (entry->lib) + 1;
      str = mempcpy (str, entry->lib, len);
      str_offset += len;
      /* Then the path.  */
      if (opt_format != 2 && entry->hwcap == 0)
	file_entries->libs[idx_old].value = str_offset + pad;
      if (opt_format != 0)
	file_entries_new->libs[idx_new].value = str_offset;
      len = strlen (entry->path) + 1;
      str = mempcpy (str, entry->path, len);
      str_offset += len;
      /* Ignore entries with hwcap for old format.  */
      if (entry->hwcap == 0)
	++idx_old;
    }

  /* Duplicate last old cache entry if needed.  */
  if (opt_format != 2
      && idx_old < cache_entry_old_count)
    file_entries->libs[idx_old] = file_entries->libs[idx_old - 1];

  /* Write out the cache.  */

  /* Write cache first to a temporary file and rename it later.  */
  char *temp_name = xmalloc (strlen (cache_name) + 2);
  sprintf (temp_name, "%s~", cache_name);

  /* Create file.  */
  int fd = open (temp_name, O_CREAT|O_WRONLY|O_TRUNC|O_NOFOLLOW,
		 S_IRUSR|S_IWUSR);
  if (fd < 0)
    error (EXIT_FAILURE, errno, _("Can't create temporary cache file %s"),
	   temp_name);

  /* Write contents.  */
  if (opt_format != 2)
    {
      if (write (fd, file_entries, file_entries_size)
	  != (ssize_t) file_entries_size)
	error (EXIT_FAILURE, errno, _("Writing of cache data failed"));
    }
  if (opt_format != 0)
    {
      /* Align cache.  */
      if (opt_format != 2)
	{
	  char zero[pad];
	  memset (zero, '\0', pad);
	  if (write (fd, zero, pad) != (ssize_t) pad)
	    error (EXIT_FAILURE, errno, _("Writing of cache data failed"));
	}
      if (write (fd, file_entries_new, file_entries_new_size)
	  != (ssize_t) file_entries_new_size)
	error (EXIT_FAILURE, errno, _("Writing of cache data failed"));
    }

  if (write (fd, strings, total_strlen) != (ssize_t) total_strlen
      || close (fd))
    error (EXIT_FAILURE, errno, _("Writing of cache data failed"));

  /* Make sure user can always read cache file */
  if (chmod (temp_name, S_IROTH|S_IRGRP|S_IRUSR|S_IWUSR))
    error (EXIT_FAILURE, errno,
	   _("Changing access rights of %s to %#o failed"), temp_name,
	   S_IROTH|S_IRGRP|S_IRUSR|S_IWUSR);

  /* Move temporary to its final location.  */
  if (rename (temp_name, cache_name))
    error (EXIT_FAILURE, errno, _("Renaming of %s to %s failed"), temp_name,
	   cache_name);

  /* Free all allocated memory.  */
  free (file_entries_new);
  free (file_entries);
  free (strings);

  while (entries)
    {
      entry = entries;
      entries = entries->next;
      free (entry);
    }
}


/* Add one library to the cache.  */
void
add_to_cache (const char *path, const char *lib, int flags,
	      unsigned int osversion, uint64_t hwcap)
{
  size_t liblen = strlen (lib) + 1;
  size_t len = liblen + strlen (path) + 1;
  struct cache_entry *new_entry
    = xmalloc (sizeof (struct cache_entry) + liblen + len);

  new_entry->lib = memcpy ((char *) (new_entry + 1), lib, liblen);
  new_entry->path = new_entry->lib + liblen;
  snprintf (new_entry->path, len, "%s/%s", path, lib);
  new_entry->flags = flags;
  new_entry->osversion = osversion;
  new_entry->hwcap = hwcap;
  new_entry->bits_hwcap = 0;

  /* Count the number of bits set in the masked value.  */
  for (size_t i = 0;
       (~((1ULL << i) - 1) & hwcap) != 0 && i < 8 * sizeof (hwcap); ++i)
    if ((hwcap & (1ULL << i)) != 0)
      ++new_entry->bits_hwcap;


  /* Keep the list sorted - search for right place to insert.  */
  struct cache_entry *ptr = entries;
  struct cache_entry *prev = entries;
  while (ptr != NULL)
    {
      if (compare (ptr, new_entry) > 0)
	break;
      prev = ptr;
      ptr = ptr->next;
    }
  /* Is this the first entry?  */
  if (ptr == entries)
    {
      new_entry->next = entries;
      entries = new_entry;
    }
  else
    {
      new_entry->next = prev->next;
      prev->next = new_entry;
    }
}


/* Auxiliary cache.  */

struct aux_cache_entry_id
{
  uint64_t ino;
  uint64_t ctime;
  uint64_t size;
  uint64_t dev;
};

struct aux_cache_entry
{
  struct aux_cache_entry_id id;
  int flags;
  unsigned int osversion;
  int used;
  char *soname;
  struct aux_cache_entry *next;
};

#define AUX_CACHEMAGIC		"glibc-ld.so.auxcache-1.0"

struct aux_cache_file_entry
{
  struct aux_cache_entry_id id;	/* Unique id of entry.  */
  int32_t flags;		/* This is 1 for an ELF library.  */
  uint32_t soname;		/* String table indice.  */
  uint32_t osversion;		/* Required OS version.	 */
  int32_t pad;
};

/* ldconfig maintains an auxiliary cache file that allows
   only reading those libraries that have changed since the last iteration.
   For this for each library some information is cached in the auxiliary
   cache.  */
struct aux_cache_file
{
  char magic[sizeof AUX_CACHEMAGIC - 1];
  uint32_t nlibs;		/* Number of entries.  */
  uint32_t len_strings;		/* Size of string table. */
  struct aux_cache_file_entry libs[0]; /* Entries describing libraries.  */
  /* After this the string table of size len_strings is found.	*/
};

static const unsigned int primes[] =
{
  1021, 2039, 4093, 8191, 16381, 32749, 65521, 131071, 262139,
  524287, 1048573, 2097143, 4194301, 8388593, 16777213, 33554393,
  67108859, 134217689, 268435399, 536870909, 1073741789, 2147483647
};

static size_t aux_hash_size;
static struct aux_cache_entry **aux_hash;

/* Simplistic hash function for aux_cache_entry_id.  */
static unsigned int
aux_cache_entry_id_hash (struct aux_cache_entry_id *id)
{
  uint64_t ret = ((id->ino * 11 + id->ctime) * 11 + id->size) * 11 + id->dev;
  return ret ^ (ret >> 32);
}

static size_t nextprime (size_t x)
{
  for (unsigned int i = 0; i < sizeof (primes) / sizeof (primes[0]); ++i)
    if (primes[i] >= x)
      return primes[i];
  return x;
}

void
init_aux_cache (void)
{
  aux_hash_size = primes[3];
  aux_hash = xcalloc (aux_hash_size, sizeof (struct aux_cache_entry *));
}

int
search_aux_cache (struct stat64 *stat_buf, int *flags,
		  unsigned int *osversion, char **soname)
{
  struct aux_cache_entry_id id;
  id.ino = (uint64_t) stat_buf->st_ino;
  id.ctime = (uint64_t) stat_buf->st_ctime;
  id.size = (uint64_t) stat_buf->st_size;
  id.dev = (uint64_t) stat_buf->st_dev;

  unsigned int hash = aux_cache_entry_id_hash (&id);
  struct aux_cache_entry *entry;
  for (entry = aux_hash[hash % aux_hash_size]; entry; entry = entry->next)
    if (id.ino == entry->id.ino
	&& id.ctime == entry->id.ctime
	&& id.size == entry->id.size
	&& id.dev == entry->id.dev)
      {
	*flags = entry->flags;
	*osversion = entry->osversion;
	if (entry->soname != NULL)
	  *soname = xstrdup (entry->soname);
	else
	  *soname = NULL;
	entry->used = 1;
	return 1;
      }

  return 0;
}

static void
insert_to_aux_cache (struct aux_cache_entry_id *id, int flags,
		     unsigned int osversion, const char *soname, int used)
{
  size_t hash = aux_cache_entry_id_hash (id) % aux_hash_size;
  struct aux_cache_entry *entry;
  for (entry = aux_hash[hash]; entry; entry = entry->next)
    if (id->ino == entry->id.ino
	&& id->ctime == entry->id.ctime
	&& id->size == entry->id.size
	&& id->dev == entry->id.dev)
      abort ();

  size_t len = soname ? strlen (soname) + 1 : 0;
  entry = xmalloc (sizeof (struct aux_cache_entry) + len);
  entry->id = *id;
  entry->flags = flags;
  entry->osversion = osversion;
  entry->used = used;
  if (soname != NULL)
    entry->soname = memcpy ((char *) (entry + 1), soname, len);
  else
    entry->soname = NULL;
  entry->next = aux_hash[hash];
  aux_hash[hash] = entry;
}

void
add_to_aux_cache (struct stat64 *stat_buf, int flags,
		  unsigned int osversion, const char *soname)
{
  struct aux_cache_entry_id id;
  id.ino = (uint64_t) stat_buf->st_ino;
  id.ctime = (uint64_t) stat_buf->st_ctime;
  id.size = (uint64_t) stat_buf->st_size;
  id.dev = (uint64_t) stat_buf->st_dev;
  insert_to_aux_cache (&id, flags, osversion, soname, 1);
}

/* Load auxiliary cache to search for unchanged entries.   */
void
load_aux_cache (const char *aux_cache_name)
{
  int fd = open (aux_cache_name, O_RDONLY);
  if (fd < 0)
    {
      init_aux_cache ();
      return;
    }

  struct stat64 st;
  if (fstat64 (fd, &st) < 0 || st.st_size < sizeof (struct aux_cache_file))
    {
      close (fd);
      init_aux_cache ();
      return;
    }

  size_t aux_cache_size = st.st_size;
  struct aux_cache_file *aux_cache
    = mmap (NULL, aux_cache_size, PROT_READ, MAP_PRIVATE, fd, 0);
  if (aux_cache == MAP_FAILED
      || aux_cache_size < sizeof (struct aux_cache_file)
      || memcmp (aux_cache->magic, AUX_CACHEMAGIC, sizeof AUX_CACHEMAGIC - 1)
      || aux_cache->nlibs >= aux_cache_size)
    {
      close (fd);
      init_aux_cache ();
      return;
    }

  aux_hash_size = nextprime (aux_cache->nlibs);
  aux_hash = xcalloc (aux_hash_size, sizeof (struct aux_cache_entry *));

  const char *aux_cache_data
    = (const char *) &aux_cache->libs[aux_cache->nlibs];
  for (unsigned int i = 0; i < aux_cache->nlibs; ++i)
    insert_to_aux_cache (&aux_cache->libs[i].id,
			 aux_cache->libs[i].flags,
			 aux_cache->libs[i].osversion,
			 aux_cache->libs[i].soname == 0
			 ? NULL : aux_cache_data + aux_cache->libs[i].soname,
			 0);

  munmap (aux_cache, aux_cache_size);
  close (fd);
}

/* Save the contents of the auxiliary cache.  */
void
save_aux_cache (const char *aux_cache_name)
{
  /* Count the length of all sonames.  We start with empty string.  */
  size_t total_strlen = 1;
  /* Number of cache entries.  */
  int cache_entry_count = 0;

  for (size_t i = 0; i < aux_hash_size; ++i)
    for (struct aux_cache_entry *entry = aux_hash[i];
	 entry != NULL; entry = entry->next)
      if (entry->used)
	{
	  ++cache_entry_count;
	  if (entry->soname != NULL)
	    total_strlen += strlen (entry->soname) + 1;
	}

  /* Auxiliary cache.  */
  size_t file_entries_size
    = sizeof (struct aux_cache_file)
      + cache_entry_count * sizeof (struct aux_cache_file_entry);
  struct aux_cache_file *file_entries
    = xmalloc (file_entries_size + total_strlen);

  /* Fill in the header of the auxiliary cache.  */
  memset (file_entries, '\0', sizeof (struct aux_cache_file));
  memcpy (file_entries->magic, AUX_CACHEMAGIC, sizeof AUX_CACHEMAGIC - 1);

  file_entries->nlibs = cache_entry_count;
  file_entries->len_strings = total_strlen;

  /* Initial String offset for auxiliary cache is always after the
     special empty string.  */
  unsigned int str_offset = 1;

  /* An array for all strings.  */
  char *str = (char *) file_entries + file_entries_size;
  *str++ = '\0';

  size_t idx = 0;
  for (size_t i = 0; i < aux_hash_size; ++i)
    for (struct aux_cache_entry *entry = aux_hash[i];
	 entry != NULL; entry = entry->next)
      if (entry->used)
	{
	  file_entries->libs[idx].id = entry->id;
	  file_entries->libs[idx].flags = entry->flags;
	  if (entry->soname == NULL)
	    file_entries->libs[idx].soname = 0;
	  else
	    {
	      file_entries->libs[idx].soname = str_offset;

	      size_t len = strlen (entry->soname) + 1;
	      str = mempcpy (str, entry->soname, len);
	      str_offset += len;
	    }
	  file_entries->libs[idx].osversion = entry->osversion;
	  file_entries->libs[idx++].pad = 0;
	}

  /* Write out auxiliary cache file.  */
  /* Write auxiliary cache first to a temporary file and rename it later.  */

  char *temp_name = xmalloc (strlen (aux_cache_name) + 2);
  sprintf (temp_name, "%s~", aux_cache_name);

  /* Check that directory exists and create if needed.  */
  char *dir = strdupa (aux_cache_name);
  dir = dirname (dir);

  struct stat64 st;
  if (stat64 (dir, &st) < 0)
    {
      if (mkdir (dir, 0700) < 0)
	goto out_fail;
    }

  /* Create file.  */
  int fd = open (temp_name, O_CREAT|O_WRONLY|O_TRUNC|O_NOFOLLOW,
		 S_IRUSR|S_IWUSR);
  if (fd < 0)
    goto out_fail;

  if (write (fd, file_entries, file_entries_size + total_strlen)
      != (ssize_t) (file_entries_size + total_strlen)
      || close (fd))
    {
      unlink (temp_name);
      goto out_fail;
    }

  /* Move temporary to its final location.  */
  if (rename (temp_name, aux_cache_name))
    unlink (temp_name);

out_fail:
  /* Free allocated memory.  */
  free (temp_name);
  free (file_entries);
}