2007-08-01 Andreas Jaeger <aj@suse.de>

	    Jakub Jelinek  <jakub@redhat.com>

	* elf/ldconfig.c (opt_ignore_aux_cache): Add new option.
	(options): Add option.
	(parse_opt): Handle option.
	(manual_link): Adjust process_file caller.  Call implicit_soname.
	(search_dir): Formatting.  Use and populate auxiliary cache.
	(main): Load and save auxiliary cache.
	* elf/readlib.c (process_file): Add stat_buf argument.  Pass struct
	stat64 from fstat64 to caller.
	(implicit_soname): New function.
	* elf/readelflib.c (process_elf_file): If DT_SONAME is not present,
	leave *soname as NULL.
	* elf/cache.c: Include libgen.h.
	(print_entry, print_cache, compare, save_cache, add_to_cache):
	Formatting and cleanups.
	(aux_cache_entry_id, aux_cache_entry, aux_cache_file_entry,
	aux_cache_file): New structures.
	(AUX_CACHEMAGIC): Define.
	(primes): New array.
	(aux_hash_size, aux_hash): New variables.
	(aux_cache_entry_id_hash, nextprime, init_aux_cache,
	search_aux_cache, insert_to_aux_cache, add_to_aux_cache,
	load_aux_cache, save_aux_cache): New functions.
	* sysdeps/generic/ldconfig.h (_PATH_LDCONFIG_AUX_CACHE): Define.
	(init_aux_cache, search_aux_cache, add_to_aux_cache,
	load_aux_cache, save_aux_cache, implicit_soname): New prototypes.
	(process_file): Adjust prototype.

1 files changed, 370 insertions, 90 deletions

diff --git a/elf/cache.c b/elf/cache.c
index 6dbd5a6..180adea 100644
--- a/elf/cache.c
+++ b/elf/cache.c
@@ -1,4 +1,4 @@
-/* Copyright (C) 1999-2003,2005,2006 Free Software Foundation, Inc.
+/* Copyright (C) 1999-2003,2005,2006,2007 Free Software Foundation, Inc.
    This file is part of the GNU C Library.
    Contributed by Andreas Jaeger <aj@suse.de>, 1999.
 
@@ -20,6 +20,7 @@
 #include <error.h>
 #include <dirent.h>
 #include <inttypes.h>
+#include <libgen.h>
 #include <libintl.h>
 #include <stdio.h>
 #include <stdlib.h>
@@ -80,16 +81,16 @@ print_entry (const char *lib, int flag, unsigned int osversion,
       fputs (",x86-64", stdout);
       break;
     case FLAG_S390_LIB64:
-      fputs(",64bit", stdout);
+      fputs (",64bit", stdout);
       break;
     case FLAG_POWERPC_LIB64:
-      fputs(",64bit", stdout);
+      fputs (",64bit", stdout);
       break;
     case FLAG_MIPS64_LIBN32:
-      fputs(",N32", stdout);
+      fputs (",N32", stdout);
       break;
     case FLAG_MIPS64_LIBN64:
-      fputs(",64bit", stdout);
+      fputs (",64bit", stdout);
     case 0:
       break;
     default:
@@ -128,19 +129,11 @@ print_entry (const char *lib, int flag, unsigned int osversion,
 void
 print_cache (const char *cache_name)
 {
-  size_t cache_size;
-  struct stat64 st;
-  int fd;
-  unsigned int i;
-  struct cache_file *cache;
-  struct cache_file_new *cache_new = NULL;
-  const char *cache_data;
-  int format = 0;
-
-  fd = open (cache_name, O_RDONLY);
+  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)
@@ -149,14 +142,19 @@ print_cache (const char *cache_name)
       return;
     }
 
-  cache = mmap (0, st.st_size, PROT_READ, MAP_SHARED, fd, 0);
+  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"));
-  cache_size = st.st_size;
 
+  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.  */
@@ -201,7 +199,7 @@ print_cache (const char *cache_name)
       printf (_("%d libs found in cache `%s'\n"), cache->nlibs, cache_name);
 
       /* Print everything.  */
-      for (i = 0; i < cache->nlibs; i++)
+      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);
@@ -212,7 +210,7 @@ print_cache (const char *cache_name)
 	      cache_new->nlibs, cache_name);
 
       /* Print everything.  */
-      for (i = 0; i < cache_new->nlibs; i++)
+      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,
@@ -231,15 +229,11 @@ init_cache (void)
   entries = NULL;
 }
 
-
-
-static
-int compare (const struct cache_entry *e1, const struct cache_entry *e2)
+static int
+compare (const struct cache_entry *e1, const struct cache_entry *e2)
 {
-  int res;
-
   /* We need to swap entries here to get the correct sort order.  */
-  res = _dl_cache_libcmp (e2->lib, e1->lib);
+  int res = _dl_cache_libcmp (e2->lib, e1->lib);
   if (res == 0)
     {
       if (e1->flags < e2->flags)
@@ -267,29 +261,19 @@ int compare (const struct cache_entry *e1, const struct cache_entry *e2)
 void
 save_cache (const char *cache_name)
 {
-  struct cache_entry *entry;
-  int fd, idx_old, idx_new;
-  size_t total_strlen, len;
-  char *strings, *str, *temp_name;
-  struct cache_file *file_entries = NULL;
-  struct cache_file_new *file_entries_new = NULL;
-  size_t file_entries_size = 0;
-  size_t file_entries_new_size = 0;
-  unsigned int str_offset;
-  /* Number of cache entries.  */
-  int cache_entry_count = 0;
-  /* Number of normal cache entries.  */
-  int cache_entry_old_count = 0;
-  /* Pad for alignment of cache_file_new.  */
-  size_t pad;
-
   /* 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.  */
-  total_strlen = 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.  */
@@ -300,8 +284,8 @@ save_cache (const char *cache_name)
     }
 
   /* Create the on disk cache structure.  */
-  /* First an array for all strings.  */
-  strings = (char *)xmalloc (total_strlen);
+  struct cache_file *file_entries = NULL;
+  size_t file_entries_size = 0;
 
   if (opt_format != 2)
     {
@@ -315,25 +299,27 @@ save_cache (const char *cache_name)
       /* 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 = (struct cache_file *) xmalloc (file_entries_size);
+      file_entries = xmalloc (file_entries_size);
 
       /* Fill in the header.  */
-      memset (file_entries, 0, sizeof (struct cache_file));
+      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 =
-	(struct cache_file_new *) xmalloc (file_entries_new_size);
+      file_entries_new = xmalloc (file_entries_new_size);
 
       /* Fill in the header.  */
-      memset (file_entries_new, 0, sizeof (struct cache_file_new));
+      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,
@@ -343,17 +329,24 @@ save_cache (const char *cache_name)
       file_entries_new->len_strings = total_strlen;
     }
 
-  pad = ALIGN_CACHE (file_entries_size) - file_entries_size;
+  /* 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;
 
-  str = strings;
+  /* 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)
     {
@@ -375,21 +368,18 @@ save_cache (const char *cache_name)
 	  file_entries_new->libs[idx_new].hwcap = entry->hwcap;
 	  file_entries_new->libs[idx_new].key = str_offset;
 	}
-      len = strlen (entry->lib);
-      str = stpcpy (str, entry->lib);
-      /* Account the final NUL.  */
-      ++str;
-      str_offset += len + 1;
+
+      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);
-      str = stpcpy (str, entry->path);
-      /* Account the final NUL.  */
-      ++str;
-      str_offset += len + 1;
+      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;
@@ -403,16 +393,12 @@ save_cache (const char *cache_name)
   /* Write out the cache.  */
 
   /* Write cache first to a temporary file and rename it later.  */
-  temp_name = xmalloc (strlen (cache_name) + 2);
+  char *temp_name = xmalloc (strlen (cache_name) + 2);
   sprintf (temp_name, "%s~", cache_name);
-  /* First remove an old copy if it exists.  */
-  if (unlink (temp_name) && errno != ENOENT)
-    error (EXIT_FAILURE, errno, _("Can't remove old temporary cache file %s"),
-	   temp_name);
 
   /* Create file.  */
-  fd = open (temp_name, O_CREAT|O_WRONLY|O_TRUNC|O_NOFOLLOW,
-	     S_IROTH|S_IRGRP|S_IRUSR|S_IWUSR);
+  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);
@@ -439,11 +425,10 @@ save_cache (const char *cache_name)
 	error (EXIT_FAILURE, errno, _("Writing of cache data failed"));
     }
 
-  if (write (fd, strings, total_strlen) != (ssize_t) total_strlen)
+  if (write (fd, strings, total_strlen) != (ssize_t) total_strlen
+      || close (fd))
     error (EXIT_FAILURE, errno, _("Writing of cache data failed"));
 
-  close (fd);
-
   /* Make sure user can always read cache file */
   if (chmod (temp_name, S_IROTH|S_IRGRP|S_IRUSR|S_IWUSR))
     error (EXIT_FAILURE, errno,
@@ -463,8 +448,6 @@ save_cache (const char *cache_name)
   while (entries)
     {
       entry = entries;
-      free (entry->path);
-      free (entry->lib);
       entries = entries->next;
       free (entry);
     }
@@ -476,33 +459,29 @@ void
 add_to_cache (const char *path, const char *lib, int flags,
 	      unsigned int osversion, uint64_t hwcap)
 {
-  struct cache_entry *new_entry, *ptr, *prev;
-  char *full_path;
-  size_t len, i;
-
-  new_entry = (struct cache_entry *) xmalloc (sizeof (struct cache_entry));
-
-  len = strlen (lib) + strlen (path) + 2;
-
-  full_path = (char *) xmalloc (len);
-  snprintf (full_path, len, "%s/%s", path, lib);
-
-  new_entry->lib = xstrdup (lib);
-  new_entry->path = full_path;
+  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 (i = 0; (~((1ULL << i) - 1) & hwcap) != 0 && i < 8 * sizeof (hwcap); ++i)
+  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.  */
-  ptr = entries;
-  prev = entries;
+  struct cache_entry *ptr = entries;
+  struct cache_entry *prev = entries;
   while (ptr != NULL)
     {
       if (compare (ptr, new_entry) > 0)
@@ -522,3 +501,304 @@ add_to_cache (const char *path, const char *lib, int flags,
       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 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 < 0
+      || 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 (file_entries);
+}