2018-09-16  Josh Triplett  <josh@joshtriplett.org>

        * elf/ldconfig.c: Default to the new format for ld.so.cache. glibc has
        supported this format for 18+ years.
        * elf/dl-cache.c (_dl_load_cache_lookup): Reorder conditionals to look
        for the new format first.

--- a/elf/dl-cache.c
+++ b/elf/dl-cache.c
@@ -203,7 +203,14 @@ _dl_load_cache_lookup (const char *name)
 	 - the old format with the new format in it
 	 - only the new format
 	 The following checks if the cache contains any of these formats.  */
-      if (file != MAP_FAILED && cachesize > sizeof *cache
+      if (file != MAP_FAILED && cachesize > sizeof *cache_new
+	       && memcmp (file, CACHEMAGIC_VERSION_NEW,
+			  sizeof CACHEMAGIC_VERSION_NEW - 1) == 0)
+	{
+	  cache_new = file;
+	  cache = file;
+	}
+      else if (file != MAP_FAILED && cachesize > sizeof *cache
 	  && memcmp (file, CACHEMAGIC, sizeof CACHEMAGIC - 1) == 0
 	  /* Check for corruption, avoiding overflow.  */
 	  && ((cachesize - sizeof *cache) / sizeof (struct file_entry)
@@ -223,13 +230,6 @@ _dl_load_cache_lookup (const char *name)
 			 sizeof CACHEMAGIC_VERSION_NEW - 1) != 0)
 	    cache_new = (void *) -1;
 	}
-      else if (file != MAP_FAILED && cachesize > sizeof *cache_new
-	       && memcmp (file, CACHEMAGIC_VERSION_NEW,
-			  sizeof CACHEMAGIC_VERSION_NEW - 1) == 0)
-	{
-	  cache_new = file;
-	  cache = file;
-	}
       else
 	{
 	  if (file != MAP_FAILED)
--- a/elf/ldconfig.c
+++ b/elf/ldconfig.c
@@ -95,7 +95,7 @@ int opt_verbose;

 /* Format to support.  */
 /* 0: only libc5/glibc2; 1: both; 2: only glibc 2.2.  */
-int opt_format = 1;
+int opt_format = 2;

 /* Build cache.  */
 static int opt_build_cache = 1;
@@ -148,7 +148,7 @@ static const struct argp_option options[] =
   { NULL, 'f', N_("CONF"), 0, N_("Use CONF as configuration file"), 0},
   { NULL, 'n', NULL, 0, N_("Only process directories specified on the command line.  Don't build cache."), 0},
   { NULL, 'l', NULL, 0, N_("Manually link individual libraries."), 0},
-  { "format", 'c', N_("FORMAT"), 0, N_("Format to use: new, old or compat (default)"), 0},
+  { "format", 'c', N_("FORMAT"), 0, N_("Format to use: new (default), old, or compat"), 0},
   { "ignore-aux-cache", 'i', NULL, 0, N_("Ignore auxiliary cache file"), 0},
   { NULL, 0, NULL, 0, NULL, 0 }
 };