[glib] gmodule – Don't use RTLD_DEFAULT on Android for g_module_self() on Android 64 bit

[Sebastian Dröge <sdroege src gnome org>]

commit 0d81bb4e318b97780c70a55605cacf7e5b3fcaf7
Author: Sebastian Dröge <sebastian centricular com>
Date:   Wed Feb 8 16:27:34 2017 +0200

    gmodule – Don't use RTLD_DEFAULT on Android for g_module_self() on Android 64 bit
    
    On 64 bit Android this is #defined to 0, which is considered an invalid
    library handle in all other cases. RTLD_DEFAULT is only supposed to be
    used with dlsym() it seems, and the usage here was just an
    "optimization" before.
    
    By dlopen'ing NULL, we get the same on all 64 bit Android variants and it
    actually works instead of erroring out. On 32 bit Android, dlopen() of
    NULL unfortunately usually gives us something useless that finds no
    symbols whatsoever.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=776876

 gmodule/gmodule-dl.c |   18 +++++++++++++++---
 1 files changed, 15 insertions(+), 3 deletions(-)
---
diff --git a/gmodule/gmodule-dl.c b/gmodule/gmodule-dl.c
index e452e34..80ef80c 100644
--- a/gmodule/gmodule-dl.c
+++ b/gmodule/gmodule-dl.c
@@ -111,8 +111,14 @@ _g_module_self (void)
   /* to query symbols from the program itself, special link options
    * are required on some systems.
    */
-  
-#ifdef __BIONIC__
+
+  /* On Android 32 bit (i.e. not __LP64__), dlopen(NULL)
+   * does not work reliable and generally no symbols are found
+   * at all. RTLD_DEFAULT works though.
+   * On Android 64 bit, dlopen(NULL) seems to work but RTLD_DEFAULT
+   * is NULL, which is considered an invalid module.
+   */
+#if defined(__BIONIC__) && !defined(__LP64__)
   handle = RTLD_DEFAULT;
 #else
   handle = dlopen (NULL, RTLD_GLOBAL | RTLD_LAZY);
@@ -129,9 +135,15 @@ _g_module_close (gpointer handle,
 {
   /* are there any systems out there that have dlopen()/dlclose()
    * without a reference count implementation?
+   *
+   * See above for the Android special case
    */
+#if defined(__BIONIC__) && !defined(__LP64__)
+  is_unref = (handle != RTLD_DEFAULT);
+#else
   is_unref |= 1;
-  
+#endif
+
   if (is_unref)
     {
       if (dlclose (handle) != 0)