_Py_HashSeed basics (3.3)

$ hg diff
diff --git a/Include/object.h b/Include/object.h
--- a/Include/object.h
+++ b/Include/object.h
@@ -51,6 +51,14 @@
 whose size is determined when the object is allocated.
 */

+/* Used to make bytes and unicode hashes unpredictable. */
+#define Py_HASH_SEED_SUPPORTED  /* TODO(gregory.p.smith): make this a configure
+#ifdef Py_HASH_SEED_SUPPORTED
+PyAPI_DATA(Py_hash_t) _Py_HashSeed;
+#else
+#define _Py_HashSeed 0
+#endif
+
 /* Py_DEBUG implies Py_TRACE_REFS. */
 #if defined(Py_DEBUG) && !defined(Py_TRACE_REFS)
 #define Py_TRACE_REFS
diff --git a/Objects/object.c b/Objects/object.c
--- a/Objects/object.c
+++ b/Objects/object.c
@@ -8,6 +8,10 @@
 extern "C" {
 #endif

+#ifdef Py_HASH_SEED_SUPPORTED
+Py_hash_t _Py_HashSeed;
+#endif
+
 #ifdef Py_REF_DEBUG
 Py_ssize_t _Py_RefTotal;

@@ -759,7 +763,7 @@
     Py_uhash_t x;
     Py_ssize_t i;

-    x = (Py_uhash_t) *p << 7;
+    x = _Py_HashSeed ^ ((Py_uhash_t) *p << 7);
     for (i = 0; i < len; i++)
         x = (1000003U * x) ^ (Py_uhash_t) *p++;
     x ^= (Py_uhash_t) len;
diff --git a/Objects/unicodeobject.c b/Objects/unicodeobject.c
--- a/Objects/unicodeobject.c
+++ b/Objects/unicodeobject.c
@@ -11162,7 +11162,7 @@

     /* The hash function as a macro, gets expanded three times below. */
 #define HASH(P) \
-    x = (Py_uhash_t)*P << 7; \
+    x = _Py_HashSeed ^ ((Py_uhash_t)*P << 7); \
     while (--len >= 0) \
         x = (1000003*x) ^ (Py_uhash_t)*P++;

diff --git a/Python/pythonrun.c b/Python/pythonrun.c
--- a/Python/pythonrun.c
+++ b/Python/pythonrun.c
@@ -203,6 +203,12 @@
     initialized = 1;
     _Py_Finalizing = NULL;

+#ifdef Py_HASH_SEED_SUPPORTED
+    _Py_HashSeed = 0; /* TODO(gregory.p.smith): Init from a random source. */
+    /* pid combined with highest resolution time possible at a minimum if
+     * a /dev/urandom or equivalent API is not available.  */
+#endif
+
 #if defined(HAVE_LANGINFO_H) && defined(HAVE_SETLOCALE)
     /* Set up the LC_CTYPE locale, so we can obtain
        the locale's charset without having to switch