Fixes for the open-source build.

Makefile

@@ -131,6 +131,7 @@ make_objs_cc = $$(patsubst upb/$$(pc).cc,obj/upb/$$(pc).$(1),$$($$(call to_srcs,
 
 upb_SRCS = \
   upb/def.c \
+  upb/env.c \
   upb/handlers.c \
   upb/refcounted.c \
   upb/shim/shim.c \

upb/bindings/lua/upb.c

@@ -1358,7 +1358,7 @@ static size_t align_up(size_t val, size_t align) {
 
 // If we always read/write as a consistent type to each value, this shouldn't
 // violate aliasing.
-#define DEREF(msg, ofs, type) *(type*)(&msg->data[ofs])
+#define DEREF(msg, ofs, type) *(type*)((char*)msg + sizeof(lupb_msg) + ofs)
 
 lupb_msg *lupb_msg_check(lua_State *L, int narg) {
   lupb_msg *msg = luaL_checkudata(L, narg, LUPB_MSG);

upb/bindings/lua/upb/pb.c

@@ -41,13 +41,6 @@ static int lupb_pbdecodermethod_new(lua_State *L) {
   return 1;  // The DecoderMethod wrapper.
 }
 
-// We implement upb's allocation function by allocating a Lua userdata.
-// This is a raw hunk of memory that will be GC'd by Lua.
-static void *lua_alloc(void *ud, size_t size) {
-  lua_State *L = ud;
-  return lua_newuserdata(L, size);
-}
-
 // Unlike most of our exposed Lua functions, this does not correspond to an
 // actual method on the underlying DecoderMethod.  But it's convenient, and
 // important to implement in C because we can do stack allocation and
@@ -77,11 +70,9 @@ static int lupb_pbdecodermethod_parse(lua_State *L) {
   upb_pbdecoder *decoder = upb_pbdecoder_create(&env, method, &sink);
   upb_bufsrc_putbuf(pb, len, upb_pbdecoder_input(decoder));
 
-  // This won't get called in the error case, which longjmp's across us.  But
-  // since we made our alloc function allocate only GC-able memory, that
-  // shouldn't matter.  It *would* matter if the environment had references to
-  // any non-memory resources (ie.  filehandles).  As an alternative to this we
-  // could make the environment itself a userdata.
+  // TODO: This won't get called in the error case, which longjmp's across us.
+  // This will cause the memory to leak.  To remedy this, we should make the
+  // upb_env wrapped in a userdata that guarantees this will get called.
   upb_env_uninit(&env);
 
   lupb_checkstatus(L, &status);

upb/env.c

@@ -43,7 +43,7 @@ static void *default_alloc(void *_ud, void *ptr, size_t oldsize, size_t size) {
   UPB_UNUSED(oldsize);
   default_alloc_ud *ud = _ud;
 
-  mem_block *from = ptr ? ptr - sizeof(mem_block) : NULL;
+  mem_block *from = ptr ? (void*)((char*)ptr - sizeof(mem_block)) : NULL;
 
 #ifndef NDEBUG
   if (from) {
@@ -214,7 +214,9 @@ UPB_FORCEINLINE static void *seeded_alloc(void *ud, void *ptr, size_t oldsize,
   upb_seededalloc *a = ud;
   size = align_up(size);
 
-  if (oldsize == 0 && size <= a->mem_limit - a->mem_ptr) {
+  assert(a->mem_limit >= a->mem_ptr);
+
+  if (oldsize == 0 && size <= (size_t)(a->mem_limit - a->mem_ptr)) {
     // Fast path: we can satisfy from the initial allocation.
     void *ret = a->mem_ptr;
     a->mem_ptr += size;
@@ -229,7 +231,7 @@ UPB_FORCEINLINE static void *seeded_alloc(void *ud, void *ptr, size_t oldsize,
 void upb_seededalloc_init(upb_seededalloc *a, void *mem, size_t len) {
   a->mem_base = mem;
   a->mem_ptr = mem;
-  a->mem_limit = mem + len;
+  a->mem_limit = (char*)mem + len;
   a->need_cleanup = false;
   a->returned_allocfunc = false;
 

upb/env.h

@@ -177,9 +177,9 @@ UPB_DEFINE_STRUCT0(upb_seededalloc,
   void *default_alloc_ud;
 
   // Pointers for the initial memory region.
-  void *mem_base;
-  void *mem_ptr;
-  void *mem_limit;
+  char *mem_base;
+  char *mem_ptr;
+  char *mem_limit;
 
   // For future expansion, since the size of this struct is exposed to users.
   void *future1;

upb/pb/decoder.c

@@ -966,7 +966,9 @@ size_t upb_pbdecoder_maxnesting(const upb_pbdecoder *d) {
 }
 
 bool upb_pbdecoder_setmaxnesting(upb_pbdecoder *d, size_t max) {
-  if (max < d->top - d->stack) {
+  assert(d->top >= d->stack);
+
+  if (max < (size_t)(d->top - d->stack)) {
     // Can't set a limit smaller than what we are currently at.
     return false;
   }