[BZ,#23668] Default to the new format for ld.so.cache

Message ID 20180919014833.GA18964@localhost
State New
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Series
  • [BZ,#23668] Default to the new format for ld.so.cache
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Commit Message

Josh Triplett Sept. 19, 2018, 1:48 a.m.
glibc has supported this format for 18+ years.

Reorder conditionals to look for the new format first.

	[BZ #23668]
	* 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.
---
 NEWS           |  3 +++
 elf/dl-cache.c | 16 ++++++++--------
 elf/ldconfig.c |  4 ++--
 3 files changed, 13 insertions(+), 10 deletions(-)

Comments

Florian Weimer Sept. 19, 2018, 7:35 p.m. | #1
Josh Triplett <josh@joshtriplett.org> writes:

> glibc has supported this format for 18+ years.
>
> Reorder conditionals to look for the new format first.
>
> 	[BZ #23668]
> 	* 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.

Josh, do you know if any distribution has been using this format by
default?

Thanks,
Florian
Josh Triplett Sept. 19, 2018, 8:37 p.m. | #2
On Wed, Sep 19, 2018 at 09:35:57PM +0200, Florian Weimer wrote:
> Josh Triplett <josh@joshtriplett.org> writes:
> 
> > glibc has supported this format for 18+ years.
> >
> > Reorder conditionals to look for the new format first.
> >
> > 	[BZ #23668]
> > 	* 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.
> 
> Josh, do you know if any distribution has been using this format by
> default?

Clear is using it by default, and I'm currently working on getting
Debian doing so.

Patch

diff --git a/NEWS b/NEWS
index f76ada94d3..95ca9f5888 100644
--- a/NEWS
+++ b/NEWS
@@ -37,6 +37,9 @@  Deprecated and removed features, and other changes affecting compatibility:
   used by the Linux kernel.  This affects the size and layout of those
   structures.
 
+* ldconfig now defaults to the new format for ld.so.cache. glibc has supported
+  this format for 18+ years.
+
 Changes to build and runtime requirements:
 
   [Add changes to build and runtime requirements here]
diff --git a/elf/dl-cache.c b/elf/dl-cache.c
index 6ee5153ff9..75bd9d9536 100644
--- 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)
 	{
 	  size_t offset;
@@ -220,13 +227,6 @@  _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)
diff --git a/elf/ldconfig.c b/elf/ldconfig.c
index fbdd814edf..1ce4a29566 100644
--- 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 }
 };