Update upb to fix two bugs in the Ruby library.

Fixes:
  https://github.com/google/protobuf/issues/502
  https://github.com/google/protobuf/issues/425

ruby/ext/google/protobuf_c/upb.c

@@ -1770,6 +1770,7 @@ static void *default_alloc(void *_ud, void *ptr, size_t oldsize, size_t size) {
        * updated to its new location. */
       if (block->next) block->next->prev = block;
       if (block->prev) block->prev->next = block;
+      if (ud->head == from) ud->head = block;
     }
   } else {
     /* Insert at head of linked list. */
@@ -1798,7 +1799,7 @@ static void default_alloc_cleanup(void *_ud) {
 
 static bool default_err(void *ud, const upb_status *status) {
   UPB_UNUSED(ud);
-  fprintf(stderr, "upb error: %s\n", upb_status_errmsg(status));
+  UPB_UNUSED(status);
   return false;
 }
 
@@ -1919,7 +1920,6 @@ static size_t align_up(size_t size) {
 UPB_FORCEINLINE static void *seeded_alloc(void *ud, void *ptr, size_t oldsize,
                                           size_t size) {
   upb_seededalloc *a = ud;
-  UPB_UNUSED(ptr);
 
   size = align_up(size);
 
@@ -1937,7 +1937,11 @@ UPB_FORCEINLINE static void *seeded_alloc(void *ud, void *ptr, size_t oldsize,
     /* Is `ptr` part of the user-provided initial block? Don't pass it to the
      * default allocator if so; otherwise, it may try to realloc() the block. */
     if (chptr >= a->mem_base && chptr < a->mem_limit) {
-      return a->alloc(a->alloc_ud, NULL, 0, size);
+      void *ret;
+      assert(chptr + oldsize <= a->mem_limit);
+      ret = a->alloc(a->alloc_ud, NULL, 0, size);
+      if (ret) memcpy(ret, ptr, oldsize);
+      return ret;
     } else {
       return a->alloc(a->alloc_ud, ptr, oldsize, size);
     }
@@ -3692,24 +3696,48 @@ const upb_def *upb_symtab_resolve(const upb_symtab *s, const char *base,
   return ret;
 }
 
-/* Searches def and its children to find defs that have the same name as any
- * def in "addtab."  Returns true if any where found, and as a side-effect adds
- * duplicates of these defs into addtab.
+/* Starts a depth-first traversal at "def", recursing into any subdefs
+ * (ie. submessage types).  Adds duplicates of existing defs to addtab
+ * wherever necessary, so that the resulting symtab will be consistent once
+ * addtab is added.
+ *
+ * More specifically, if any def D is found in the DFS that:
+ *
+ *   1. can reach a def that is being replaced by something in addtab, AND
+ *
+ *   2. is not itself being replaced already (ie. this name doesn't already
+ *      exist in addtab)
+ *
+ * ...then a duplicate (new copy) of D will be added to addtab.
+ *
+ * Returns true if this happened for any def reachable from "def."
+ *
+ * It is slightly tricky to do this correctly in the presence of cycles.  If we
+ * detect that our DFS has hit a cycle, we might not yet know if any SCCs on
+ * our stack can reach a def in addtab or not.  Once we figure this out, that
+ * answer needs to apply to *all* defs in these SCCs, even if we visited them
+ * already.  So a straight up one-pass cycle-detecting DFS won't work.
  *
- * We use a modified depth-first traversal that traverses each SCC (which we
- * already computed) as if it were a single node.  This allows us to traverse
- * the possibly-cyclic graph as if it were a DAG and to dup the correct set of
- * nodes with O(n) time. */
+ * To work around this problem, we traverse each SCC (which we already
+ * computed, since these defs are frozen) as a single node.  We first compute
+ * whether the SCC as a whole can reach any def in addtab, then we dup (or not)
+ * the entire SCC.  This requires breaking the encapsulation of upb_refcounted,
+ * since that is where we get the data about what SCC we are in. */
 static bool upb_resolve_dfs(const upb_def *def, upb_strtable *addtab,
                             const void *new_owner, upb_inttable *seen,
                             upb_status *s) {
-  /* Memoize results of this function for efficiency (since we're traversing a
-   * DAG this is not needed to limit the depth of the search). */
   upb_value v;
   bool need_dup;
   const upb_def *base;
+  const void* memoize_key;
+
+  /* Memoize results of this function for efficiency (since we're traversing a
+   * DAG this is not needed to limit the depth of the search).
+   *
+   * We memoize by SCC instead of by individual def. */
+  memoize_key = def->base.group;
 
-  if (upb_inttable_lookup(seen, (uintptr_t)def, &v))
+  if (upb_inttable_lookupptr(seen, memoize_key, &v))
     return upb_value_getbool(v);
 
   /* Visit submessages for all messages in the SCC. */
@@ -3725,7 +3753,8 @@ static bool upb_resolve_dfs(const upb_def *def, upb_strtable *addtab,
       need_dup = true;
     }
 
-    /* For messages, continue the recursion by visiting all subdefs. */
+    /* For messages, continue the recursion by visiting all subdefs, but only
+     * ones in different SCCs. */
     m = upb_dyncast_msgdef(def);
     if (m) {
       upb_msg_field_iter i;
@@ -3733,17 +3762,23 @@ static bool upb_resolve_dfs(const upb_def *def, upb_strtable *addtab,
           !upb_msg_field_done(&i);
           upb_msg_field_next(&i)) {
         upb_fielddef *f = upb_msg_iter_field(&i);
+        const upb_def *subdef;
+
         if (!upb_fielddef_hassubdef(f)) continue;
+        subdef = upb_fielddef_subdef(f);
+
+        /* Skip subdefs in this SCC. */
+        if (def->base.group == subdef->base.group) continue;
+
         /* |= to avoid short-circuit; we need its side-effects. */
-        need_dup |= upb_resolve_dfs(
-            upb_fielddef_subdef(f), addtab, new_owner, seen, s);
+        need_dup |= upb_resolve_dfs(subdef, addtab, new_owner, seen, s);
         if (!upb_ok(s)) return false;
       }
     }
   } while ((def = (upb_def*)def->base.next) != base);
 
   if (need_dup) {
-    /* Dup any defs that don't already have entries in addtab. */
+    /* Dup all defs in this SCC that don't already have entries in addtab. */
     def = base;
     do {
       const char *name;
@@ -3760,7 +3795,7 @@ static bool upb_resolve_dfs(const upb_def *def, upb_strtable *addtab,
     } while ((def = (upb_def*)def->base.next) != base);
   }
 
-  upb_inttable_insert(seen, (uintptr_t)def, upb_value_bool(need_dup));
+  upb_inttable_insertptr(seen, memoize_key, upb_value_bool(need_dup));
   return need_dup;
 
 oom:

ruby/ext/google/protobuf_c/upb.h

@@ -7928,7 +7928,7 @@ class upb::pb::Encoder {
   static const size_t kSize = UPB_PB_ENCODER_SIZE;
 
  private:
-  UPB_DISALLOW_POD_OPS(Encoder, upb::pb::Encoder);
+  UPB_DISALLOW_POD_OPS(Encoder, upb::pb::Encoder)
 };
 
 #endif