AArch64: Calculate private_handle_t's numInts

A constant sNumInts with a value of 6 was being assigned to the numInts
attribute in the private_handle_t constructor, and was also used in the
validate method. That constant value is appropriate for 32-bit systems
but is not appropriate for a 64-bit system where uintptr_t used for
base attribute will be 64-bit.

sNumInts is now changed to a static inline function that calculates
numInts.

Change-Id: I482ddb5915c9ff55fb2e2a87887a0ec2dc2299ed
Signed-off-by: Marcus Oakland <marcus.oakland@arm.com>
Signed-off-by: Ashok Bhat <ashok.bhat@arm.com>
diff --git a/modules/gralloc/gralloc_priv.h b/modules/gralloc/gralloc_priv.h
index 9f32d58..22a5715 100644
--- a/modules/gralloc/gralloc_priv.h
+++ b/modules/gralloc/gralloc_priv.h
@@ -79,7 +79,9 @@
     int     pid;
 
 #ifdef __cplusplus
-    static const int sNumInts = 6;
+    static inline int sNumInts() {
+        return (((sizeof(private_handle_t) - sizeof(native_handle_t))/sizeof(int)) - sNumFds);
+    }
     static const int sNumFds = 1;
     static const int sMagic = 0x3141592;
 
@@ -88,7 +90,7 @@
         base(0), pid(getpid())
     {
         version = sizeof(native_handle);
-        numInts = sNumInts;
+        numInts = sNumInts();
         numFds = sNumFds;
     }
     ~private_handle_t() {
@@ -98,7 +100,7 @@
     static int validate(const native_handle* h) {
         const private_handle_t* hnd = (const private_handle_t*)h;
         if (!h || h->version != sizeof(native_handle) ||
-                h->numInts != sNumInts || h->numFds != sNumFds ||
+                h->numInts != sNumInts() || h->numFds != sNumFds ||
                 hnd->magic != sMagic)
         {
             ALOGE("invalid gralloc handle (at %p)", h);