Move libc_freeres_ptrs and libc_subfreeres to hidden/weak functions

They are both used by __libc_freeres to free all library malloc
allocated resources to help tooling like mtrace or valgrind with
memory leak tracking.

The current scheme uses assembly markers and linker script entries
to consolidate the free routine function pointers in the RELRO segment
and to be freed buffers in BSS.

This patch changes it to use specific free functions for
libc_freeres_ptrs buffers and call the function pointer array directly
with call_function_static_weak.

It allows the removal of both the internal macros and the linker
script sections.

Checked on x86_64-linux-gnu, i686-linux-gnu, and aarch64-linux-gnu.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>

6 files changed, 26 insertions, 17 deletions

diff --git a/resolv/gai_misc.c b/resolv/gai_misc.c
index dda9b47..9e3b1d2 100644
--- a/resolv/gai_misc.c
+++ b/resolv/gai_misc.c
@@ -434,7 +434,11 @@ handle_requests (void *arg)
 
 
 /* Free allocated resources.  */
-libc_freeres_fn (free_res)
+#if !PTHREAD_IN_LIBC
+__attribute__ ((__destructor__)) static
+#endif
+void
+__gai_freemem (void)
 {
   size_t row;
 
diff --git a/resolv/res-close.c b/resolv/res-close.c
index 936fd3d..8d54677 100644
--- a/resolv/res-close.c
+++ b/resolv/res-close.c
@@ -140,5 +140,3 @@ __res_thread_freeres (void)
   /* Make sure we do a full re-initialization the next time.  */
   _res.options = 0;
 }
-/* Also must be called when the main thread exits.  */
-text_set_element (__libc_subfreeres, __res_thread_freeres);
diff --git a/resolv/res_hconf.c b/resolv/res_hconf.c
index 2c4e12b..89bd20b 100644
--- a/resolv/res_hconf.c
+++ b/resolv/res_hconf.c
@@ -42,6 +42,7 @@
 #include "res_hconf.h"
 #include <wchar.h>
 #include <atomic.h>
+#include <set-freeres.h>
 
 #if IS_IN (libc)
 # define fgets_unlocked __fgets_unlocked
@@ -330,19 +331,8 @@ _res_hconf_init (void)
 #if IS_IN (libc)
 # if defined SIOCGIFCONF && defined SIOCGIFNETMASK
 /* List of known interfaces.  */
-libc_freeres_ptr (
-static struct netaddr
-{
-  int addrtype;
-  union
-  {
-    struct
-    {
-      uint32_t	addr;
-      uint32_t	mask;
-    } ipv4;
-  } u;
-} *ifaddrs);
+static struct netaddr *ifaddrs;
+weak_alias (ifaddrs, __libc_resolv_res_hconf_freemem_ptr)
 # endif
 
 /* Reorder addresses returned in a hostent such that the first address
diff --git a/resolv/resolv-internal.h b/resolv/resolv-internal.h
index 97812eb..c55f3c0 100644
--- a/resolv/resolv-internal.h
+++ b/resolv/resolv-internal.h
@@ -34,6 +34,20 @@
    loads and stores.  */
 typedef HEADER __attribute__ ((__aligned__(1))) UHEADER;
 
+/* List of known interfaces.  */
+struct netaddr
+{
+  int addrtype;
+  union
+  {
+    struct
+    {
+      uint32_t	addr;
+      uint32_t	mask;
+    } ipv4;
+  } u;
+};
+
 /* Legacy function.  This needs to be removed once all NSS modules
    have been adjusted.  */
 static inline bool
diff --git a/resolv/resolv_conf.c b/resolv/resolv_conf.c
index 2e561c8..0ef66d4 100644
--- a/resolv/resolv_conf.c
+++ b/resolv/resolv_conf.c
@@ -654,7 +654,8 @@ __resolv_conf_detach (struct __res_state *resp)
 }
 
 /* Deallocate the global data.  */
-libc_freeres_fn (freeres)
+void
+__libc_resolv_conf_freemem (void)
 {
   /* No locking because this function is supposed to be called when
      the process has turned single-threaded.  */
diff --git a/resolv/tst-leaks2.c b/resolv/tst-leaks2.c
index 3851ea0..50a8054 100644
--- a/resolv/tst-leaks2.c
+++ b/resolv/tst-leaks2.c
@@ -23,6 +23,8 @@
 #include <resolv.h>
 #include <support/check.h>
 
+void __libc_freeres (void);
+
 static int
 do_test (void)
 {