Update //third_party/protobuf to version 3.

third_party/protobuf/ruby/ext/google/protobuf_c/encode_decode.c

+// Protocol Buffers - Google's data interchange format
+// Copyright 2014 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#include "protobuf.h"
+
+// This function is equivalent to rb_str_cat(), but unlike the real
+// rb_str_cat(), it doesn't leak memory in some versions of Ruby.
+// For more information, see:
+//   https://bugs.ruby-lang.org/issues/11328
+VALUE noleak_rb_str_cat(VALUE rb_str, const char *str, long len) {
+  char *p;
+  size_t oldlen = RSTRING_LEN(rb_str);
+  rb_str_modify_expand(rb_str, len);
+  p = RSTRING_PTR(rb_str);
+  memcpy(p + oldlen, str, len);
+  rb_str_set_len(rb_str, oldlen + len);
+  return rb_str;
+}
+
+// -----------------------------------------------------------------------------
+// Parsing.
+// -----------------------------------------------------------------------------
+
+#define DEREF(msg, ofs, type) *(type*)(((uint8_t *)msg) + ofs)
+
+// Creates a handlerdata that simply contains the offset for this field.
+static const void* newhandlerdata(upb_handlers* h, uint32_t ofs) {
+  size_t* hd_ofs = ALLOC(size_t);
+  *hd_ofs = ofs;
+  upb_handlers_addcleanup(h, hd_ofs, free);
+  return hd_ofs;
+}
+
+typedef struct {
+  size_t ofs;
+  const upb_msgdef *md;
+} submsg_handlerdata_t;
+
+// Creates a handlerdata that contains offset and submessage type information.
+static const void *newsubmsghandlerdata(upb_handlers* h, uint32_t ofs,
+                                        const upb_fielddef* f) {
+  submsg_handlerdata_t *hd = ALLOC(submsg_handlerdata_t);
+  hd->ofs = ofs;
+  hd->md = upb_fielddef_msgsubdef(f);
+  upb_handlers_addcleanup(h, hd, free);
+  return hd;
+}
+
+typedef struct {
+  size_t ofs;              // union data slot
+  size_t case_ofs;         // oneof_case field
+  uint32_t oneof_case_num; // oneof-case number to place in oneof_case field
+  const upb_msgdef *md;    // msgdef, for oneof submessage handler
+} oneof_handlerdata_t;
+
+static const void *newoneofhandlerdata(upb_handlers *h,
+                                       uint32_t ofs,
+                                       uint32_t case_ofs,
+                                       const upb_fielddef *f) {
+  oneof_handlerdata_t *hd = ALLOC(oneof_handlerdata_t);
+  hd->ofs = ofs;
+  hd->case_ofs = case_ofs;
+  // We reuse the field tag number as a oneof union discriminant tag. Note that
+  // we don't expose these numbers to the user, so the only requirement is that
+  // we have some unique ID for each union case/possibility. The field tag
+  // numbers are already present and are easy to use so there's no reason to
+  // create a separate ID space. In addition, using the field tag number here
+  // lets us easily look up the field in the oneof accessor.
+  hd->oneof_case_num = upb_fielddef_number(f);
+  if (upb_fielddef_type(f) == UPB_TYPE_MESSAGE) {
+    hd->md = upb_fielddef_msgsubdef(f);
+  } else {
+    hd->md = NULL;
+  }
+  upb_handlers_addcleanup(h, hd, free);
+  return hd;
+}
+
+// A handler that starts a repeated field.  Gets the Repeated*Field instance for
+// this field (such an instance always exists even in an empty message).
+static void *startseq_handler(void* closure, const void* hd) {
+  MessageHeader* msg = closure;
+  const size_t *ofs = hd;
+  return (void*)DEREF(msg, *ofs, VALUE);
+}
+
+// Handlers that append primitive values to a repeated field.
+#define DEFINE_APPEND_HANDLER(type, ctype)                 \
+  static bool append##type##_handler(void *closure, const void *hd, \
+                                     ctype val) {                   \
+    VALUE ary = (VALUE)closure;                                     \
+    RepeatedField_push_native(ary, &val);                           \
+    return true;                                                    \
+  }
+
+DEFINE_APPEND_HANDLER(bool,   bool)
+DEFINE_APPEND_HANDLER(int32,  int32_t)
+DEFINE_APPEND_HANDLER(uint32, uint32_t)
+DEFINE_APPEND_HANDLER(float,  float)
+DEFINE_APPEND_HANDLER(int64,  int64_t)
+DEFINE_APPEND_HANDLER(uint64, uint64_t)
+DEFINE_APPEND_HANDLER(double, double)
+
+// Appends a string to a repeated field.
+static void* appendstr_handler(void *closure,
+                               const void *hd,
+                               size_t size_hint) {
+  VALUE ary = (VALUE)closure;
+  VALUE str = rb_str_new2("");
+  rb_enc_associate(str, kRubyStringUtf8Encoding);
+  RepeatedField_push(ary, str);
+  return (void*)str;
+}
+
+// Appends a 'bytes' string to a repeated field.
+static void* appendbytes_handler(void *closure,
+                                 const void *hd,
+                                 size_t size_hint) {
+  VALUE ary = (VALUE)closure;
+  VALUE str = rb_str_new2("");
+  rb_enc_associate(str, kRubyString8bitEncoding);
+  RepeatedField_push(ary, str);
+  return (void*)str;
+}
+
+// Sets a non-repeated string field in a message.
+static void* str_handler(void *closure,
+                         const void *hd,
+                         size_t size_hint) {
+  MessageHeader* msg = closure;
+  const size_t *ofs = hd;
+  VALUE str = rb_str_new2("");
+  rb_enc_associate(str, kRubyStringUtf8Encoding);
+  DEREF(msg, *ofs, VALUE) = str;
+  return (void*)str;
+}
+
+// Sets a non-repeated 'bytes' field in a message.
+static void* bytes_handler(void *closure,
+                           const void *hd,
+                           size_t size_hint) {
+  MessageHeader* msg = closure;
+  const size_t *ofs = hd;
+  VALUE str = rb_str_new2("");
+  rb_enc_associate(str, kRubyString8bitEncoding);
+  DEREF(msg, *ofs, VALUE) = str;
+  return (void*)str;
+}
+
+static size_t stringdata_handler(void* closure, const void* hd,
+                                 const char* str, size_t len,
+                                 const upb_bufhandle* handle) {
+  VALUE rb_str = (VALUE)closure;
+  noleak_rb_str_cat(rb_str, str, len);
+  return len;
+}
+
+// Appends a submessage to a repeated field (a regular Ruby array for now).
+static void *appendsubmsg_handler(void *closure, const void *hd) {
+  VALUE ary = (VALUE)closure;
+  const submsg_handlerdata_t *submsgdata = hd;
+  VALUE subdesc =
+      get_def_obj((void*)submsgdata->md);
+  VALUE subklass = Descriptor_msgclass(subdesc);
+  MessageHeader* submsg;
+
+  VALUE submsg_rb = rb_class_new_instance(0, NULL, subklass);
+  RepeatedField_push(ary, submsg_rb);
+
+  TypedData_Get_Struct(submsg_rb, MessageHeader, &Message_type, submsg);
+  return submsg;
+}
+
+// Sets a non-repeated submessage field in a message.
+static void *submsg_handler(void *closure, const void *hd) {
+  MessageHeader* msg = closure;
+  const submsg_handlerdata_t* submsgdata = hd;
+  VALUE subdesc =
+      get_def_obj((void*)submsgdata->md);
+  VALUE subklass = Descriptor_msgclass(subdesc);
+  VALUE submsg_rb;
+  MessageHeader* submsg;
+
+  if (DEREF(msg, submsgdata->ofs, VALUE) == Qnil) {
+    DEREF(msg, submsgdata->ofs, VALUE) =
+        rb_class_new_instance(0, NULL, subklass);
+  }
+
+  submsg_rb = DEREF(msg, submsgdata->ofs, VALUE);
+  TypedData_Get_Struct(submsg_rb, MessageHeader, &Message_type, submsg);
+  return submsg;
+}
+
+// Handler data for startmap/endmap handlers.
+typedef struct {
+  size_t ofs;
+  upb_fieldtype_t key_field_type;
+  upb_fieldtype_t value_field_type;
+
+  // We know that we can hold this reference because the handlerdata has the
+  // same lifetime as the upb_handlers struct, and the upb_handlers struct holds
+  // a reference to the upb_msgdef, which in turn has references to its subdefs.
+  const upb_def* value_field_subdef;
+} map_handlerdata_t;
+
+// Temporary frame for map parsing: at the beginning of a map entry message, a
+// submsg handler allocates a frame to hold (i) a reference to the Map object
+// into which this message will be inserted and (ii) storage slots to
+// temporarily hold the key and value for this map entry until the end of the
+// submessage. When the submessage ends, another handler is called to insert the
+// value into the map.
+typedef struct {
+  VALUE map;
+  char key_storage[NATIVE_SLOT_MAX_SIZE];
+  char value_storage[NATIVE_SLOT_MAX_SIZE];
+} map_parse_frame_t;
+
+// Handler to begin a map entry: allocates a temporary frame. This is the
+// 'startsubmsg' handler on the msgdef that contains the map field.
+static void *startmapentry_handler(void *closure, const void *hd) {
+  MessageHeader* msg = closure;
+  const map_handlerdata_t* mapdata = hd;
+  VALUE map_rb = DEREF(msg, mapdata->ofs, VALUE);
+
+  map_parse_frame_t* frame = ALLOC(map_parse_frame_t);
+  frame->map = map_rb;
+
+  native_slot_init(mapdata->key_field_type, &frame->key_storage);
+  native_slot_init(mapdata->value_field_type, &frame->value_storage);
+
+  return frame;
+}
+
+// Handler to end a map entry: inserts the value defined during the message into
+// the map. This is the 'endmsg' handler on the map entry msgdef.
+static bool endmap_handler(void *closure, const void *hd, upb_status* s) {
+  map_parse_frame_t* frame = closure;
+  const map_handlerdata_t* mapdata = hd;
+
+  VALUE key = native_slot_get(
+      mapdata->key_field_type, Qnil,
+      &frame->key_storage);
+
+  VALUE value_field_typeclass = Qnil;
+  VALUE value;
+
+  if (mapdata->value_field_type == UPB_TYPE_MESSAGE ||
+      mapdata->value_field_type == UPB_TYPE_ENUM) {
+    value_field_typeclass = get_def_obj(mapdata->value_field_subdef);
+  }
+
+  value = native_slot_get(
+      mapdata->value_field_type, value_field_typeclass,
+      &frame->value_storage);
+
+  Map_index_set(frame->map, key, value);
+  free(frame);
+
+  return true;
+}
+
+// Allocates a new map_handlerdata_t given the map entry message definition. If
+// the offset of the field within the parent message is also given, that is
+// added to the handler data as well. Note that this is called *twice* per map
+// field: once in the parent message handler setup when setting the startsubmsg
+// handler and once in the map entry message handler setup when setting the
+// key/value and endmsg handlers. The reason is that there is no easy way to
+// pass the handlerdata down to the sub-message handler setup.
+static map_handlerdata_t* new_map_handlerdata(
+    size_t ofs,
+    const upb_msgdef* mapentry_def,
+    Descriptor* desc) {
+  const upb_fielddef* key_field;
+  const upb_fielddef* value_field;
+  map_handlerdata_t* hd = ALLOC(map_handlerdata_t);
+  hd->ofs = ofs;
+  key_field = upb_msgdef_itof(mapentry_def, MAP_KEY_FIELD);
+  assert(key_field != NULL);
+  hd->key_field_type = upb_fielddef_type(key_field);
+  value_field = upb_msgdef_itof(mapentry_def, MAP_VALUE_FIELD);
+  assert(value_field != NULL);
+  hd->value_field_type = upb_fielddef_type(value_field);
+  hd->value_field_subdef = upb_fielddef_subdef(value_field);
+
+  return hd;
+}
+
+// Handlers that set primitive values in oneofs.
+#define DEFINE_ONEOF_HANDLER(type, ctype)                           \
+  static bool oneof##type##_handler(void *closure, const void *hd,  \
+                                     ctype val) {                   \
+    const oneof_handlerdata_t *oneofdata = hd;                      \
+    DEREF(closure, oneofdata->case_ofs, uint32_t) =                 \
+        oneofdata->oneof_case_num;                                  \
+    DEREF(closure, oneofdata->ofs, ctype) = val;                    \
+    return true;                                                    \
+  }
+
+DEFINE_ONEOF_HANDLER(bool,   bool)
+DEFINE_ONEOF_HANDLER(int32,  int32_t)
+DEFINE_ONEOF_HANDLER(uint32, uint32_t)
+DEFINE_ONEOF_HANDLER(float,  float)
+DEFINE_ONEOF_HANDLER(int64,  int64_t)
+DEFINE_ONEOF_HANDLER(uint64, uint64_t)
+DEFINE_ONEOF_HANDLER(double, double)
+
+#undef DEFINE_ONEOF_HANDLER
+
+// Handlers for strings in a oneof.
+static void *oneofstr_handler(void *closure,
+                              const void *hd,
+                              size_t size_hint) {
+  MessageHeader* msg = closure;
+  const oneof_handlerdata_t *oneofdata = hd;
+  VALUE str = rb_str_new2("");
+  rb_enc_associate(str, kRubyStringUtf8Encoding);
+  DEREF(msg, oneofdata->case_ofs, uint32_t) =
+      oneofdata->oneof_case_num;
+  DEREF(msg, oneofdata->ofs, VALUE) = str;
+  return (void*)str;
+}
+
+static void *oneofbytes_handler(void *closure,
+                                const void *hd,
+                                size_t size_hint) {
+  MessageHeader* msg = closure;
+  const oneof_handlerdata_t *oneofdata = hd;
+  VALUE str = rb_str_new2("");
+  rb_enc_associate(str, kRubyString8bitEncoding);
+  DEREF(msg, oneofdata->case_ofs, uint32_t) =
+      oneofdata->oneof_case_num;
+  DEREF(msg, oneofdata->ofs, VALUE) = str;
+  return (void*)str;
+}
+
+// Handler for a submessage field in a oneof.
+static void *oneofsubmsg_handler(void *closure,
+                                 const void *hd) {
+  MessageHeader* msg = closure;
+  const oneof_handlerdata_t *oneofdata = hd;
+  uint32_t oldcase = DEREF(msg, oneofdata->case_ofs, uint32_t);
+
+  VALUE subdesc =
+      get_def_obj((void*)oneofdata->md);
+  VALUE subklass = Descriptor_msgclass(subdesc);
+  VALUE submsg_rb;
+  MessageHeader* submsg;
+
+  if (oldcase != oneofdata->oneof_case_num ||
+      DEREF(msg, oneofdata->ofs, VALUE) == Qnil) {
+    DEREF(msg, oneofdata->ofs, VALUE) =
+        rb_class_new_instance(0, NULL, subklass);
+  }
+  // Set the oneof case *after* allocating the new class instance -- otherwise,
+  // if the Ruby GC is invoked as part of a call into the VM, it might invoke
+  // our mark routines, and our mark routines might see the case value
+  // indicating a VALUE is present and expect a valid VALUE. See comment in
+  // layout_set() for more detail: basically, the change to the value and the
+  // case must be atomic w.r.t. the Ruby VM.
+  DEREF(msg, oneofdata->case_ofs, uint32_t) =
+      oneofdata->oneof_case_num;
+
+  submsg_rb = DEREF(msg, oneofdata->ofs, VALUE);
+  TypedData_Get_Struct(submsg_rb, MessageHeader, &Message_type, submsg);
+  return submsg;
+}
+
+// Set up handlers for a repeated field.
+static void add_handlers_for_repeated_field(upb_handlers *h,
+                                            const upb_fielddef *f,
+                                            size_t offset) {
+  upb_handlerattr attr = UPB_HANDLERATTR_INITIALIZER;
+  upb_handlerattr_sethandlerdata(&attr, newhandlerdata(h, offset));
+  upb_handlers_setstartseq(h, f, startseq_handler, &attr);
+  upb_handlerattr_uninit(&attr);
+
+  switch (upb_fielddef_type(f)) {
+
+#define SET_HANDLER(utype, ltype)                                 \
+  case utype:                                                     \
+    upb_handlers_set##ltype(h, f, append##ltype##_handler, NULL); \
+    break;
+
+    SET_HANDLER(UPB_TYPE_BOOL,   bool);
+    SET_HANDLER(UPB_TYPE_INT32,  int32);
+    SET_HANDLER(UPB_TYPE_UINT32, uint32);
+    SET_HANDLER(UPB_TYPE_ENUM,   int32);
+    SET_HANDLER(UPB_TYPE_FLOAT,  float);
+    SET_HANDLER(UPB_TYPE_INT64,  int64);
+    SET_HANDLER(UPB_TYPE_UINT64, uint64);
+    SET_HANDLER(UPB_TYPE_DOUBLE, double);
+
+#undef SET_HANDLER
+
+    case UPB_TYPE_STRING:
+    case UPB_TYPE_BYTES: {
+      bool is_bytes = upb_fielddef_type(f) == UPB_TYPE_BYTES;
+      upb_handlers_setstartstr(h, f, is_bytes ?
+                               appendbytes_handler : appendstr_handler,
+                               NULL);
+      upb_handlers_setstring(h, f, stringdata_handler, NULL);
+      break;
+    }
+    case UPB_TYPE_MESSAGE: {
+      upb_handlerattr attr = UPB_HANDLERATTR_INITIALIZER;
+      upb_handlerattr_sethandlerdata(&attr, newsubmsghandlerdata(h, 0, f));
+      upb_handlers_setstartsubmsg(h, f, appendsubmsg_handler, &attr);
+      upb_handlerattr_uninit(&attr);
+      break;
+    }
+  }
+}
+
+// Set up handlers for a singular field.
+static void add_handlers_for_singular_field(upb_handlers *h,
+                                            const upb_fielddef *f,
+                                            size_t offset) {
+  switch (upb_fielddef_type(f)) {
+    case UPB_TYPE_BOOL:
+    case UPB_TYPE_INT32:
+    case UPB_TYPE_UINT32:
+    case UPB_TYPE_ENUM:
+    case UPB_TYPE_FLOAT:
+    case UPB_TYPE_INT64:
+    case UPB_TYPE_UINT64:
+    case UPB_TYPE_DOUBLE:
+      upb_shim_set(h, f, offset, -1);
+      break;
+    case UPB_TYPE_STRING:
+    case UPB_TYPE_BYTES: {
+      bool is_bytes = upb_fielddef_type(f) == UPB_TYPE_BYTES;
+      upb_handlerattr attr = UPB_HANDLERATTR_INITIALIZER;
+      upb_handlerattr_sethandlerdata(&attr, newhandlerdata(h, offset));
+      upb_handlers_setstartstr(h, f,
+                               is_bytes ? bytes_handler : str_handler,
+                               &attr);
+      upb_handlers_setstring(h, f, stringdata_handler, &attr);
+      upb_handlerattr_uninit(&attr);
+      break;
+    }
+    case UPB_TYPE_MESSAGE: {
+      upb_handlerattr attr = UPB_HANDLERATTR_INITIALIZER;
+      upb_handlerattr_sethandlerdata(&attr, newsubmsghandlerdata(h, offset, f));
+      upb_handlers_setstartsubmsg(h, f, submsg_handler, &attr);
+      upb_handlerattr_uninit(&attr);
+      break;
+    }
+  }
+}
+
+// Adds handlers to a map field.
+static void add_handlers_for_mapfield(upb_handlers* h,
+                                      const upb_fielddef* fielddef,
+                                      size_t offset,
+                                      Descriptor* desc) {
+  const upb_msgdef* map_msgdef = upb_fielddef_msgsubdef(fielddef);
+  map_handlerdata_t* hd = new_map_handlerdata(offset, map_msgdef, desc);
+  upb_handlerattr attr = UPB_HANDLERATTR_INITIALIZER;
+
+  upb_handlers_addcleanup(h, hd, free);
+  upb_handlerattr_sethandlerdata(&attr, hd);
+  upb_handlers_setstartsubmsg(h, fielddef, startmapentry_handler, &attr);
+  upb_handlerattr_uninit(&attr);
+}
+
+// Adds handlers to a map-entry msgdef.
+static void add_handlers_for_mapentry(const upb_msgdef* msgdef,
+                                      upb_handlers* h,
+                                      Descriptor* desc) {
+  const upb_fielddef* key_field = map_entry_key(msgdef);
+  const upb_fielddef* value_field = map_entry_value(msgdef);
+  map_handlerdata_t* hd = new_map_handlerdata(0, msgdef, desc);
+  upb_handlerattr attr = UPB_HANDLERATTR_INITIALIZER;
+
+  upb_handlers_addcleanup(h, hd, free);
+  upb_handlerattr_sethandlerdata(&attr, hd);
+  upb_handlers_setendmsg(h, endmap_handler, &attr);
+
+  add_handlers_for_singular_field(
+      h, key_field,
+      offsetof(map_parse_frame_t, key_storage));
+  add_handlers_for_singular_field(
+      h, value_field,
+      offsetof(map_parse_frame_t, value_storage));
+}
+
+// Set up handlers for a oneof field.
+static void add_handlers_for_oneof_field(upb_handlers *h,
+                                         const upb_fielddef *f,
+                                         size_t offset,
+                                         size_t oneof_case_offset) {
+
+  upb_handlerattr attr = UPB_HANDLERATTR_INITIALIZER;
+  upb_handlerattr_sethandlerdata(
+      &attr, newoneofhandlerdata(h, offset, oneof_case_offset, f));
+
+  switch (upb_fielddef_type(f)) {
+
+#define SET_HANDLER(utype, ltype)                                 \
+  case utype:                                                     \
+    upb_handlers_set##ltype(h, f, oneof##ltype##_handler, &attr); \
+    break;
+
+    SET_HANDLER(UPB_TYPE_BOOL,   bool);
+    SET_HANDLER(UPB_TYPE_INT32,  int32);
+    SET_HANDLER(UPB_TYPE_UINT32, uint32);
+    SET_HANDLER(UPB_TYPE_ENUM,   int32);
+    SET_HANDLER(UPB_TYPE_FLOAT,  float);
+    SET_HANDLER(UPB_TYPE_INT64,  int64);
+    SET_HANDLER(UPB_TYPE_UINT64, uint64);
+    SET_HANDLER(UPB_TYPE_DOUBLE, double);
+
+#undef SET_HANDLER
+
+    case UPB_TYPE_STRING:
+    case UPB_TYPE_BYTES: {
+      bool is_bytes = upb_fielddef_type(f) == UPB_TYPE_BYTES;
+      upb_handlers_setstartstr(h, f, is_bytes ?
+                               oneofbytes_handler : oneofstr_handler,
+                               &attr);
+      upb_handlers_setstring(h, f, stringdata_handler, NULL);
+      break;
+    }
+    case UPB_TYPE_MESSAGE: {
+      upb_handlers_setstartsubmsg(h, f, oneofsubmsg_handler, &attr);
+      break;
+    }
+  }
+
+  upb_handlerattr_uninit(&attr);
+}
+
+
+static void add_handlers_for_message(const void *closure, upb_handlers *h) {
+  const upb_msgdef* msgdef = upb_handlers_msgdef(h);
+  Descriptor* desc = ruby_to_Descriptor(get_def_obj((void*)msgdef));
+  upb_msg_field_iter i;
+
+  // If this is a mapentry message type, set up a special set of handlers and
+  // bail out of the normal (user-defined) message type handling.
+  if (upb_msgdef_mapentry(msgdef)) {
+    add_handlers_for_mapentry(msgdef, h, desc);
+    return;
+  }
+
+  // Ensure layout exists. We may be invoked to create handlers for a given
+  // message if we are included as a submsg of another message type before our
+  // class is actually built, so to work around this, we just create the layout
+  // (and handlers, in the class-building function) on-demand.
+  if (desc->layout == NULL) {
+    desc->layout = create_layout(desc->msgdef);
+  }
+
+  for (upb_msg_field_begin(&i, desc->msgdef);
+       !upb_msg_field_done(&i);
+       upb_msg_field_next(&i)) {
+    const upb_fielddef *f = upb_msg_iter_field(&i);
+    size_t offset = desc->layout->fields[upb_fielddef_index(f)].offset +
+        sizeof(MessageHeader);
+
+    if (upb_fielddef_containingoneof(f)) {
+      size_t oneof_case_offset =
+          desc->layout->fields[upb_fielddef_index(f)].case_offset +
+          sizeof(MessageHeader);
+      add_handlers_for_oneof_field(h, f, offset, oneof_case_offset);
+    } else if (is_map_field(f)) {
+      add_handlers_for_mapfield(h, f, offset, desc);
+    } else if (upb_fielddef_isseq(f)) {
+      add_handlers_for_repeated_field(h, f, offset);
+    } else {
+      add_handlers_for_singular_field(h, f, offset);
+    }
+  }
+}
+
+// Creates upb handlers for populating a message.
+static const upb_handlers *new_fill_handlers(Descriptor* desc,
+                                             const void* owner) {
+  // TODO(cfallin, haberman): once upb gets a caching/memoization layer for
+  // handlers, reuse subdef handlers so that e.g. if we already parse
+  // B-with-field-of-type-C, we don't have to rebuild the whole hierarchy to
+  // parse A-with-field-of-type-B-with-field-of-type-C.
+  return upb_handlers_newfrozen(desc->msgdef, owner,
+                                add_handlers_for_message, NULL);
+}
+
+// Constructs the handlers for filling a message's data into an in-memory
+// object.
+const upb_handlers* get_fill_handlers(Descriptor* desc) {
+  if (!desc->fill_handlers) {
+    desc->fill_handlers =
+        new_fill_handlers(desc, &desc->fill_handlers);
+  }
+  return desc->fill_handlers;
+}
+
+// Constructs the upb decoder method for parsing messages of this type.
+// This is called from the message class creation code.
+const upb_pbdecodermethod *new_fillmsg_decodermethod(Descriptor* desc,
+                                                     const void* owner) {
+  const upb_handlers* handlers = get_fill_handlers(desc);
+  upb_pbdecodermethodopts opts;
+  upb_pbdecodermethodopts_init(&opts, handlers);
+
+  return upb_pbdecodermethod_new(&opts, owner);
+}
+
+static const upb_pbdecodermethod *msgdef_decodermethod(Descriptor* desc) {
+  if (desc->fill_method == NULL) {
+    desc->fill_method = new_fillmsg_decodermethod(
+        desc, &desc->fill_method);
+  }
+  return desc->fill_method;
+}
+
+
+// Stack-allocated context during an encode/decode operation. Contains the upb
+// environment and its stack-based allocator, an initial buffer for allocations
+// to avoid malloc() when possible, and a template for Ruby exception messages
+// if any error occurs.
+#define STACK_ENV_STACKBYTES 4096
+typedef struct {
+  upb_env env;
+  upb_seededalloc alloc;
+  const char* ruby_error_template;
+  char allocbuf[STACK_ENV_STACKBYTES];
+} stackenv;
+
+static void stackenv_init(stackenv* se, const char* errmsg);
+static void stackenv_uninit(stackenv* se);
+
+// Callback invoked by upb if any error occurs during parsing or serialization.
+static bool env_error_func(void* ud, const upb_status* status) {
+  stackenv* se = ud;
+  // Free the env -- rb_raise will longjmp up the stack past the encode/decode
+  // function so it would not otherwise have been freed.
+  stackenv_uninit(se);
+
+  // TODO(haberman): have a way to verify that this is actually a parse error,
+  // instead of just throwing "parse error" unconditionally.
+  rb_raise(cParseError, se->ruby_error_template, upb_status_errmsg(status));
+  // Never reached: rb_raise() always longjmp()s up the stack, past all of our
+  // code, back to Ruby.
+  return false;
+}
+
+static void stackenv_init(stackenv* se, const char* errmsg) {
+  se->ruby_error_template = errmsg;
+  upb_env_init(&se->env);
+  upb_seededalloc_init(&se->alloc, &se->allocbuf, STACK_ENV_STACKBYTES);
+  upb_env_setallocfunc(
+      &se->env, upb_seededalloc_getallocfunc(&se->alloc), &se->alloc);
+  upb_env_seterrorfunc(&se->env, env_error_func, se);
+}
+
+static void stackenv_uninit(stackenv* se) {
+  upb_env_uninit(&se->env);
+  upb_seededalloc_uninit(&se->alloc);
+}
+
+/*
+ * call-seq:
+ *     MessageClass.decode(data) => message
+ *
+ * Decodes the given data (as a string containing bytes in protocol buffers wire
+ * format) under the interpretration given by this message class's definition
+ * and returns a message object with the corresponding field values.
+ */
+VALUE Message_decode(VALUE klass, VALUE data) {
+  VALUE descriptor = rb_ivar_get(klass, descriptor_instancevar_interned);
+  Descriptor* desc = ruby_to_Descriptor(descriptor);
+  VALUE msgklass = Descriptor_msgclass(descriptor);
+  VALUE msg_rb;
+  MessageHeader* msg;
+
+  if (TYPE(data) != T_STRING) {
+    rb_raise(rb_eArgError, "Expected string for binary protobuf data.");
+  }
+
+  msg_rb = rb_class_new_instance(0, NULL, msgklass);
+  TypedData_Get_Struct(msg_rb, MessageHeader, &Message_type, msg);
+
+  {
+    const upb_pbdecodermethod* method = msgdef_decodermethod(desc);
+    const upb_handlers* h = upb_pbdecodermethod_desthandlers(method);
+    stackenv se;
+    upb_sink sink;
+    upb_pbdecoder* decoder;
+    stackenv_init(&se, "Error occurred during parsing: %s");
+
+    upb_sink_reset(&sink, h, msg);
+    decoder = upb_pbdecoder_create(&se.env, method, &sink);
+    upb_bufsrc_putbuf(RSTRING_PTR(data), RSTRING_LEN(data),
+                      upb_pbdecoder_input(decoder));
+
+    stackenv_uninit(&se);
+  }
+
+  return msg_rb;
+}
+
+/*
+ * call-seq:
+ *     MessageClass.decode_json(data) => message
+ *
+ * Decodes the given data (as a string containing bytes in protocol buffers wire
+ * format) under the interpretration given by this message class's definition
+ * and returns a message object with the corresponding field values.
+ */
+VALUE Message_decode_json(VALUE klass, VALUE data) {
+  VALUE descriptor = rb_ivar_get(klass, descriptor_instancevar_interned);
+  Descriptor* desc = ruby_to_Descriptor(descriptor);
+  VALUE msgklass = Descriptor_msgclass(descriptor);
+  VALUE msg_rb;
+  MessageHeader* msg;
+
+  if (TYPE(data) != T_STRING) {
+    rb_raise(rb_eArgError, "Expected string for JSON data.");
+  }
+  // TODO(cfallin): Check and respect string encoding. If not UTF-8, we need to
+  // convert, because string handlers pass data directly to message string
+  // fields.
+
+  msg_rb = rb_class_new_instance(0, NULL, msgklass);
+  TypedData_Get_Struct(msg_rb, MessageHeader, &Message_type, msg);
+
+  {
+    stackenv se;
+    upb_sink sink;
+    upb_json_parser* parser;
+    stackenv_init(&se, "Error occurred during parsing: %s");
+
+    upb_sink_reset(&sink, get_fill_handlers(desc), msg);
+    parser = upb_json_parser_create(&se.env, &sink);
+    upb_bufsrc_putbuf(RSTRING_PTR(data), RSTRING_LEN(data),
+                      upb_json_parser_input(parser));
+
+    stackenv_uninit(&se);
+  }
+
+  return msg_rb;
+}
+
+// -----------------------------------------------------------------------------
+// Serializing.
+// -----------------------------------------------------------------------------
+//
+// The code below also comes from upb's prototype Ruby binding, developed by
+// haberman@.
+
+/* stringsink *****************************************************************/
+
+// This should probably be factored into a common upb component.
+
+typedef struct {
+  upb_byteshandler handler;
+  upb_bytessink sink;
+  char *ptr;
+  size_t len, size;
+} stringsink;
+
+static void *stringsink_start(void *_sink, const void *hd, size_t size_hint) {
+  stringsink *sink = _sink;
+  sink->len = 0;
+  return sink;
+}
+
+static size_t stringsink_string(void *_sink, const void *hd, const char *ptr,
+                                size_t len, const upb_bufhandle *handle) {
+  stringsink *sink = _sink;
+  size_t new_size = sink->size;
+
+  UPB_UNUSED(hd);
+  UPB_UNUSED(handle);
+
+  while (sink->len + len > new_size) {
+    new_size *= 2;
+  }
+
+  if (new_size != sink->size) {
+    sink->ptr = realloc(sink->ptr, new_size);
+    sink->size = new_size;
+  }
+
+  memcpy(sink->ptr + sink->len, ptr, len);
+  sink->len += len;
+
+  return len;
+}
+
+void stringsink_init(stringsink *sink) {
+  upb_byteshandler_init(&sink->handler);
+  upb_byteshandler_setstartstr(&sink->handler, stringsink_start, NULL);
+  upb_byteshandler_setstring(&sink->handler, stringsink_string, NULL);
+
+  upb_bytessink_reset(&sink->sink, &sink->handler, sink);
+
+  sink->size = 32;
+  sink->ptr = malloc(sink->size);
+  sink->len = 0;
+}
+
+void stringsink_uninit(stringsink *sink) {
+  free(sink->ptr);
+}
+
+/* msgvisitor *****************************************************************/
+
+// TODO: If/when we support proto2 semantics in addition to the current proto3
+// semantics, which means that we have true field presence, we will want to
+// modify msgvisitor so that it emits all present fields rather than all
+// non-default-value fields.
+//
+// Likewise, when implementing JSON serialization, we may need to have a
+// 'verbose' mode that outputs all fields and a 'concise' mode that outputs only
+// those with non-default values.
+
+static void putmsg(VALUE msg, const Descriptor* desc,
+                   upb_sink *sink, int depth);
+
+static upb_selector_t getsel(const upb_fielddef *f, upb_handlertype_t type) {
+  upb_selector_t ret;
+  bool ok = upb_handlers_getselector(f, type, &ret);
+  UPB_ASSERT_VAR(ok, ok);
+  return ret;
+}
+
+static void putstr(VALUE str, const upb_fielddef *f, upb_sink *sink) {
+  upb_sink subsink;
+
+  if (str == Qnil) return;
+
+  assert(BUILTIN_TYPE(str) == RUBY_T_STRING);
+
+  // Ensure that the string has the correct encoding. We also check at field-set
+  // time, but the user may have mutated the string object since then.
+  native_slot_validate_string_encoding(upb_fielddef_type(f), str);
+
+  upb_sink_startstr(sink, getsel(f, UPB_HANDLER_STARTSTR), RSTRING_LEN(str),
+                    &subsink);
+  upb_sink_putstring(&subsink, getsel(f, UPB_HANDLER_STRING), RSTRING_PTR(str),
+                     RSTRING_LEN(str), NULL);
+  upb_sink_endstr(sink, getsel(f, UPB_HANDLER_ENDSTR));
+}
+
+static void putsubmsg(VALUE submsg, const upb_fielddef *f, upb_sink *sink,
+                      int depth) {
+  upb_sink subsink;
+  VALUE descriptor;
+  Descriptor* subdesc;
+
+  if (submsg == Qnil) return;
+
+  descriptor = rb_ivar_get(submsg, descriptor_instancevar_interned);
+  subdesc = ruby_to_Descriptor(descriptor);
+
+  upb_sink_startsubmsg(sink, getsel(f, UPB_HANDLER_STARTSUBMSG), &subsink);
+  putmsg(submsg, subdesc, &subsink, depth + 1);
+  upb_sink_endsubmsg(sink, getsel(f, UPB_HANDLER_ENDSUBMSG));
+}
+
+static void putary(VALUE ary, const upb_fielddef *f, upb_sink *sink,
+                   int depth) {
+  upb_sink subsink;
+  upb_fieldtype_t type = upb_fielddef_type(f);
+  upb_selector_t sel = 0;
+  int size;
+
+  if (ary == Qnil) return;
+
+  upb_sink_startseq(sink, getsel(f, UPB_HANDLER_STARTSEQ), &subsink);
+
+  if (upb_fielddef_isprimitive(f)) {
+    sel = getsel(f, upb_handlers_getprimitivehandlertype(f));
+  }
+
+  size = NUM2INT(RepeatedField_length(ary));
+  for (int i = 0; i < size; i++) {
+    void* memory = RepeatedField_index_native(ary, i);
+    switch (type) {
+#define T(upbtypeconst, upbtype, ctype)                         \
+  case upbtypeconst:                                            \
+    upb_sink_put##upbtype(&subsink, sel, *((ctype *)memory));   \
+    break;
+
+      T(UPB_TYPE_FLOAT,  float,  float)
+      T(UPB_TYPE_DOUBLE, double, double)
+      T(UPB_TYPE_BOOL,   bool,   int8_t)
+      case UPB_TYPE_ENUM:
+      T(UPB_TYPE_INT32,  int32,  int32_t)
+      T(UPB_TYPE_UINT32, uint32, uint32_t)
+      T(UPB_TYPE_INT64,  int64,  int64_t)
+      T(UPB_TYPE_UINT64, uint64, uint64_t)
+
+      case UPB_TYPE_STRING:
+      case UPB_TYPE_BYTES:
+        putstr(*((VALUE *)memory), f, &subsink);
+        break;
+      case UPB_TYPE_MESSAGE:
+        putsubmsg(*((VALUE *)memory), f, &subsink, depth);
+        break;
+
+#undef T
+
+    }
+  }
+  upb_sink_endseq(sink, getsel(f, UPB_HANDLER_ENDSEQ));
+}
+
+static void put_ruby_value(VALUE value,
+                           const upb_fielddef *f,
+                           VALUE type_class,
+                           int depth,
+                           upb_sink *sink) {
+  upb_selector_t sel = 0;
+  if (upb_fielddef_isprimitive(f)) {
+    sel = getsel(f, upb_handlers_getprimitivehandlertype(f));
+  }
+
+  switch (upb_fielddef_type(f)) {
+    case UPB_TYPE_INT32:
+      upb_sink_putint32(sink, sel, NUM2INT(value));
+      break;
+    case UPB_TYPE_INT64:
+      upb_sink_putint64(sink, sel, NUM2LL(value));
+      break;
+    case UPB_TYPE_UINT32:
+      upb_sink_putuint32(sink, sel, NUM2UINT(value));
+      break;
+    case UPB_TYPE_UINT64:
+      upb_sink_putuint64(sink, sel, NUM2ULL(value));
+      break;
+    case UPB_TYPE_FLOAT:
+      upb_sink_putfloat(sink, sel, NUM2DBL(value));
+      break;
+    case UPB_TYPE_DOUBLE:
+      upb_sink_putdouble(sink, sel, NUM2DBL(value));
+      break;
+    case UPB_TYPE_ENUM: {
+      if (TYPE(value) == T_SYMBOL) {
+        value = rb_funcall(type_class, rb_intern("resolve"), 1, value);
+      }
+      upb_sink_putint32(sink, sel, NUM2INT(value));
+      break;
+    }
+    case UPB_TYPE_BOOL:
+      upb_sink_putbool(sink, sel, value == Qtrue);
+      break;
+    case UPB_TYPE_STRING:
+    case UPB_TYPE_BYTES:
+      putstr(value, f, sink);
+      break;
+    case UPB_TYPE_MESSAGE:
+      putsubmsg(value, f, sink, depth);
+  }
+}
+
+static void putmap(VALUE map, const upb_fielddef *f, upb_sink *sink,
+                   int depth) {
+  Map* self;
+  upb_sink subsink;
+  const upb_fielddef* key_field;
+  const upb_fielddef* value_field;
+  Map_iter it;
+
+  if (map == Qnil) return;
+  self = ruby_to_Map(map);
+
+  upb_sink_startseq(sink, getsel(f, UPB_HANDLER_STARTSEQ), &subsink);
+
+  assert(upb_fielddef_type(f) == UPB_TYPE_MESSAGE);
+  key_field = map_field_key(f);
+  value_field = map_field_value(f);
+
+  for (Map_begin(map, &it); !Map_done(&it); Map_next(&it)) {
+    VALUE key = Map_iter_key(&it);
+    VALUE value = Map_iter_value(&it);
+    upb_status status;
+
+    upb_sink entry_sink;
+    upb_sink_startsubmsg(&subsink, getsel(f, UPB_HANDLER_STARTSUBMSG),
+                         &entry_sink);
+    upb_sink_startmsg(&entry_sink);
+
+    put_ruby_value(key, key_field, Qnil, depth + 1, &entry_sink);
+    put_ruby_value(value, value_field, self->value_type_class, depth + 1,
+                   &entry_sink);
+
+    upb_sink_endmsg(&entry_sink, &status);
+    upb_sink_endsubmsg(&subsink, getsel(f, UPB_HANDLER_ENDSUBMSG));
+  }
+
+  upb_sink_endseq(sink, getsel(f, UPB_HANDLER_ENDSEQ));
+}
+
+static void putmsg(VALUE msg_rb, const Descriptor* desc,
+                   upb_sink *sink, int depth) {
+  MessageHeader* msg;
+  upb_msg_field_iter i;
+  upb_status status;
+
+  upb_sink_startmsg(sink);
+
+  // Protect against cycles (possible because users may freely reassign message
+  // and repeated fields) by imposing a maximum recursion depth.
+  if (depth > ENCODE_MAX_NESTING) {
+    rb_raise(rb_eRuntimeError,
+             "Maximum recursion depth exceeded during encoding.");
+  }
+
+  TypedData_Get_Struct(msg_rb, MessageHeader, &Message_type, msg);
+
+  for (upb_msg_field_begin(&i, desc->msgdef);
+       !upb_msg_field_done(&i);
+       upb_msg_field_next(&i)) {
+    upb_fielddef *f = upb_msg_iter_field(&i);
+    uint32_t offset =
+        desc->layout->fields[upb_fielddef_index(f)].offset +
+        sizeof(MessageHeader);
+
+    if (upb_fielddef_containingoneof(f)) {
+      uint32_t oneof_case_offset =
+          desc->layout->fields[upb_fielddef_index(f)].case_offset +
+          sizeof(MessageHeader);
+      // For a oneof, check that this field is actually present -- skip all the
+      // below if not.
+      if (DEREF(msg, oneof_case_offset, uint32_t) !=
+          upb_fielddef_number(f)) {
+        continue;
+      }
+      // Otherwise, fall through to the appropriate singular-field handler
+      // below.
+    }
+
+    if (is_map_field(f)) {
+      VALUE map = DEREF(msg, offset, VALUE);
+      if (map != Qnil) {
+        putmap(map, f, sink, depth);
+      }
+    } else if (upb_fielddef_isseq(f)) {
+      VALUE ary = DEREF(msg, offset, VALUE);
+      if (ary != Qnil) {
+        putary(ary, f, sink, depth);
+      }
+    } else if (upb_fielddef_isstring(f)) {
+      VALUE str = DEREF(msg, offset, VALUE);
+      if (RSTRING_LEN(str) > 0) {
+        putstr(str, f, sink);
+      }
+    } else if (upb_fielddef_issubmsg(f)) {
+      putsubmsg(DEREF(msg, offset, VALUE), f, sink, depth);
+    } else {
+      upb_selector_t sel = getsel(f, upb_handlers_getprimitivehandlertype(f));
+
+#define T(upbtypeconst, upbtype, ctype, default_value)                \
+  case upbtypeconst: {                                                \
+      ctype value = DEREF(msg, offset, ctype);                        \
+      if (value != default_value) {                                   \
+        upb_sink_put##upbtype(sink, sel, value);                      \
+      }                                                               \
+    }                                                                 \
+    break;
+
+      switch (upb_fielddef_type(f)) {
+        T(UPB_TYPE_FLOAT,  float,  float, 0.0)
+        T(UPB_TYPE_DOUBLE, double, double, 0.0)
+        T(UPB_TYPE_BOOL,   bool,   uint8_t, 0)
+        case UPB_TYPE_ENUM:
+        T(UPB_TYPE_INT32,  int32,  int32_t, 0)
+        T(UPB_TYPE_UINT32, uint32, uint32_t, 0)
+        T(UPB_TYPE_INT64,  int64,  int64_t, 0)
+        T(UPB_TYPE_UINT64, uint64, uint64_t, 0)
+
+        case UPB_TYPE_STRING:
+        case UPB_TYPE_BYTES:
+        case UPB_TYPE_MESSAGE: rb_raise(rb_eRuntimeError, "Internal error.");
+      }
+
+#undef T
+
+    }
+  }
+
+  upb_sink_endmsg(sink, &status);
+}
+
+static const upb_handlers* msgdef_pb_serialize_handlers(Descriptor* desc) {
+  if (desc->pb_serialize_handlers == NULL) {
+    desc->pb_serialize_handlers =
+        upb_pb_encoder_newhandlers(desc->msgdef, &desc->pb_serialize_handlers);
+  }
+  return desc->pb_serialize_handlers;
+}
+
+static const upb_handlers* msgdef_json_serialize_handlers(Descriptor* desc) {
+  if (desc->json_serialize_handlers == NULL) {
+    desc->json_serialize_handlers =
+        upb_json_printer_newhandlers(
+            desc->msgdef, &desc->json_serialize_handlers);
+  }
+  return desc->json_serialize_handlers;
+}
+
+/*
+ * call-seq:
+ *     MessageClass.encode(msg) => bytes
+ *
+ * Encodes the given message object to its serialized form in protocol buffers
+ * wire format.
+ */
+VALUE Message_encode(VALUE klass, VALUE msg_rb) {
+  VALUE descriptor = rb_ivar_get(klass, descriptor_instancevar_interned);
+  Descriptor* desc = ruby_to_Descriptor(descriptor);
+
+  stringsink sink;
+  stringsink_init(&sink);
+
+  {
+    const upb_handlers* serialize_handlers =
+        msgdef_pb_serialize_handlers(desc);
+
+    stackenv se;
+    upb_pb_encoder* encoder;
+    VALUE ret;
+
+    stackenv_init(&se, "Error occurred during encoding: %s");
+    encoder = upb_pb_encoder_create(&se.env, serialize_handlers, &sink.sink);
+
+    putmsg(msg_rb, desc, upb_pb_encoder_input(encoder), 0);
+
+    ret = rb_str_new(sink.ptr, sink.len);
+
+    stackenv_uninit(&se);
+    stringsink_uninit(&sink);
+
+    return ret;
+  }
+}
+
+/*
+ * call-seq:
+ *     MessageClass.encode_json(msg) => json_string
+ *
+ * Encodes the given message object into its serialized JSON representation.
+ */
+VALUE Message_encode_json(VALUE klass, VALUE msg_rb) {
+  VALUE descriptor = rb_ivar_get(klass, descriptor_instancevar_interned);
+  Descriptor* desc = ruby_to_Descriptor(descriptor);
+
+  stringsink sink;
+  stringsink_init(&sink);
+
+  {
+    const upb_handlers* serialize_handlers =
+        msgdef_json_serialize_handlers(desc);
+    upb_json_printer* printer;
+    stackenv se;
+    VALUE ret;
+
+    stackenv_init(&se, "Error occurred during encoding: %s");
+    printer = upb_json_printer_create(&se.env, serialize_handlers, &sink.sink);
+
+    putmsg(msg_rb, desc, upb_json_printer_input(printer), 0);
+
+    ret = rb_str_new(sink.ptr, sink.len);
+
+    stackenv_uninit(&se);
+    stringsink_uninit(&sink);
+
+    return ret;
+  }
+}
+