Update upb amalgamation.

2 files changed, 747 insertions, 400 deletions

diff --git a/ruby/ext/google/protobuf_c/upb.c b/ruby/ext/google/protobuf_c/upb.c
index abea7711..571c809f 100644
--- a/ruby/ext/google/protobuf_c/upb.c
+++ b/ruby/ext/google/protobuf_c/upb.c
@@ -3416,6 +3416,8 @@ char *upb_strdup(const char *s) {
 }
 
 char *upb_strdup2(const char *s, size_t len) {
+  // Prevent overflow errors.
+  if (len == SIZE_MAX) return NULL;
   // Always null-terminate, even if binary data; but don't rely on the input to
   // have a null-terminating byte since it may be a raw binary buffer.
   size_t n = len + 1;
@@ -4230,8 +4232,10 @@ static void nullz(upb_status *status) {
 }
 
 void upb_status_clear(upb_status *status) {
-  upb_status blank = UPB_STATUS_INIT;
-  upb_status_copy(status, &blank);
+  if (!status) return;
+  status->ok_ = true;
+  status->code_ = 0;
+  status->msg[0] = '\0';
 }
 
 bool upb_ok(const upb_status *status) { return status->ok_; }
@@ -5998,6 +6002,7 @@ static void putop(compiler *c, opcode op, ...) {
     case OP_SETDELIM:
     case OP_HALT:
     case OP_RET:
+    case OP_DISPATCH:
       put32(c, op);
       break;
     case OP_PARSE_DOUBLE:
@@ -6078,7 +6083,7 @@ const char *upb_pbdecoder_getopname(unsigned int op) {
     OP(ENDSUBMSG), OP(STARTSTR), OP(STRING), OP(ENDSTR), OP(CALL), OP(RET),
     OP(PUSHLENDELIM), OP(PUSHTAGDELIM), OP(SETDELIM), OP(CHECKDELIM),
     OP(BRANCH), OP(TAG1), OP(TAG2), OP(TAGN), OP(SETDISPATCH), OP(POP),
-    OP(SETBIGGROUPNUM), OP(HALT),
+    OP(SETBIGGROUPNUM), OP(DISPATCH), OP(HALT),
   };
   return op > OP_HALT ? names[0] : names[op];
 #undef OP
@@ -6110,6 +6115,7 @@ static void dumpbc(uint32_t *p, uint32_t *end, FILE *f) {
                               upb_handlers_msgdef(method->dest_handlers_)));
         break;
       }
+      case OP_DISPATCH:
       case OP_STARTMSG:
       case OP_ENDMSG:
       case OP_PUSHLENDELIM:
@@ -6455,6 +6461,7 @@ static void compile_method(compiler *c, upb_pbdecodermethod *method) {
   putop(c, OP_SETDISPATCH, &method->dispatch);
   putsel(c, OP_STARTMSG, UPB_STARTMSG_SELECTOR, h);
  label(c, LABEL_FIELD);
+  uint32_t* start_pc = c->pc;
   upb_msg_iter i;
   for(upb_msg_begin(&i, md); !upb_msg_done(&i); upb_msg_next(&i)) {
     const upb_fielddef *f = upb_msg_iter_field(&i);
@@ -6470,8 +6477,18 @@ static void compile_method(compiler *c, upb_pbdecodermethod *method) {
     }
   }
 
+  // If there were no fields, or if no handlers were defined, we need to
+  // generate a non-empty loop body so that we can at least dispatch for unknown
+  // fields and check for the end of the message.
+  if (c->pc == start_pc) {
+    // Check for end-of-message.
+    putop(c, OP_CHECKDELIM, LABEL_ENDMSG);
+    // Unconditionally dispatch.
+    putop(c, OP_DISPATCH, 0);
+  }
+
   // For now we just loop back to the last field of the message (or if none,
-  // the DISPATCH opcode for the message.
+  // the DISPATCH opcode for the message).
   putop(c, OP_BRANCH, -LABEL_FIELD);
 
   // Insert both a label and a dispatch table entry for this end-of-msg.
@@ -7455,6 +7472,9 @@ size_t upb_pbdecoder_decode(void *closure, const void *hd, const char *buf,
         if (result == DECODE_MISMATCH) goto badtag;
         if (result >= 0) return result;
       })
+      VMCASE(OP_DISPATCH, {
+        CHECK_RETURN(dispatch(d));
+      })
       VMCASE(OP_HALT, {
         return size;
       })
@@ -7513,7 +7533,8 @@ bool upb_pbdecoder_end(void *closure, const void *handler_data) {
       // Rewind from OP_TAG* to OP_CHECKDELIM.
       assert(getop(*d->pc) == OP_TAG1 ||
              getop(*d->pc) == OP_TAG2 ||
-             getop(*d->pc) == OP_TAGN);
+             getop(*d->pc) == OP_TAGN ||
+             getop(*d->pc == OP_DISPATCH));
       d->pc = p;
     }
     upb_pbdecoder_decode(closure, handler_data, &dummy, 0, NULL);
@@ -8648,6 +8669,9 @@ upb_decoderet upb_vdecode_max8_wright(upb_decoderet r) {
 
 #define PARSER_CHECK_RETURN(x) if (!(x)) return false
 
+// Used to signal that a capture has been suspended.
+static char suspend_capture;
+
 static upb_selector_t getsel_for_handlertype(upb_json_parser *p,
                                              upb_handlertype_t type) {
   upb_selector_t sel;
@@ -8661,41 +8685,6 @@ static upb_selector_t parser_getsel(upb_json_parser *p) {
       p, upb_handlers_getprimitivehandlertype(p->top->f));
 }
 
-static void start_member(upb_json_parser *p) {
-  assert(!p->top->f);
-  assert(!p->accumulated);
-  p->accumulated_len = 0;
-}
-
-static bool end_member(upb_json_parser *p) {
-  // TODO(haberman): support keys that span buffers or have escape sequences.
-  assert(!p->top->f);
-  assert(p->accumulated);
-  const upb_fielddef *f =
-      upb_msgdef_ntof(p->top->m, p->accumulated, p->accumulated_len);
-
-  if (!f) {
-    // TODO(haberman): Ignore unknown fields if requested/configured to do so.
-    upb_status_seterrf(p->status, "No such field: %.*s\n",
-                       (int)p->accumulated_len, p->accumulated);
-    return false;
-  }
-
-  p->top->f = f;
-  p->accumulated = NULL;
-
-  return true;
-}
-
-static void start_object(upb_json_parser *p) {
-  upb_sink_startmsg(&p->top->sink);
-}
-
-static void end_object(upb_json_parser *p) {
-  upb_status status;
-  upb_sink_endmsg(&p->top->sink, &status);
-}
-
 static bool check_stack(upb_json_parser *p) {
   if ((p->top + 1) == p->limit) {
     upb_status_seterrmsg(p->status, "Nesting too deep");
@@ -8705,83 +8694,28 @@ static bool check_stack(upb_json_parser *p) {
   return true;
 }
 
-static bool start_subobject(upb_json_parser *p) {
-  assert(p->top->f);
-
-  if (!upb_fielddef_issubmsg(p->top->f)) {
-    upb_status_seterrf(p->status,
-                       "Object specified for non-message/group field: %s",
-                       upb_fielddef_name(p->top->f));
-    return false;
-  }
-
-  if (!check_stack(p)) return false;
-
-  upb_jsonparser_frame *inner = p->top + 1;
-
-  upb_selector_t sel = getsel_for_handlertype(p, UPB_HANDLER_STARTSUBMSG);
-  upb_sink_startsubmsg(&p->top->sink, sel, &inner->sink);
-  inner->m = upb_fielddef_msgsubdef(p->top->f);
-  inner->f = NULL;
-  p->top = inner;
+// There are GCC/Clang built-ins for overflow checking which we could start
+// using if there was any performance benefit to it.
 
+static bool checked_add(size_t a, size_t b, size_t *c) {
+  if (SIZE_MAX - a < b) return false;
+  *c = a + b;
   return true;
 }
 
-static void end_subobject(upb_json_parser *p) {
-  p->top--;
-  upb_selector_t sel = getsel_for_handlertype(p, UPB_HANDLER_ENDSUBMSG);
-  upb_sink_endsubmsg(&p->top->sink, sel);
-}
-
-static bool start_array(upb_json_parser *p) {
-  assert(p->top->f);
-
-  if (!upb_fielddef_isseq(p->top->f)) {
-    upb_status_seterrf(p->status,
-                       "Array specified for non-repeated field: %s",
-                       upb_fielddef_name(p->top->f));
-    return false;
+static size_t saturating_multiply(size_t a, size_t b) {
+  // size_t is unsigned, so this is defined behavior even on overflow.
+  size_t ret = a * b;
+  if (b != 0 && ret / b != a) {
+    ret = SIZE_MAX;
   }
-
-  if (!check_stack(p)) return false;
-
-  upb_jsonparser_frame *inner = p->top + 1;
-  upb_selector_t sel = getsel_for_handlertype(p, UPB_HANDLER_STARTSEQ);
-  upb_sink_startseq(&p->top->sink, sel, &inner->sink);
-  inner->m = p->top->m;
-  inner->f = p->top->f;
-  p->top = inner;
-
-  return true;
+  return ret;
 }
 
-static void end_array(upb_json_parser *p) {
-  assert(p->top > p->stack);
-
-  p->top--;
-  upb_selector_t sel = getsel_for_handlertype(p, UPB_HANDLER_ENDSEQ);
-  upb_sink_endseq(&p->top->sink, sel);
-}
 
-static void clear_member(upb_json_parser *p) { p->top->f = NULL; }
+/* Base64 decoding ************************************************************/
 
-static bool parser_putbool(upb_json_parser *p, bool val) {
-  if (upb_fielddef_type(p->top->f) != UPB_TYPE_BOOL) {
-    upb_status_seterrf(p->status,
-                       "Boolean value specified for non-bool field: %s",
-                       upb_fielddef_name(p->top->f));
-    return false;
-  }
-
-  bool ok = upb_sink_putbool(&p->top->sink, parser_getsel(p), val);
-  UPB_ASSERT_VAR(ok, ok);
-  return true;
-}
-
-static void start_text(upb_json_parser *p, const char *ptr) {
-  p->text_begin = ptr;
-}
+// TODO(haberman): make this streaming.
 
 static const signed char b64table[] = {
   -1,      -1,      -1,      -1,      -1,      -1,      -1,      -1,
@@ -8901,89 +8835,326 @@ badpadding:
   return false;
 }
 
-static bool end_text(upb_json_parser *p, const char *ptr, bool is_num) {
-  assert(!p->accumulated);  // TODO: handle this case.
-  p->accumulated = p->text_begin;
-  p->accumulated_len = ptr - p->text_begin;
 
-  if (p->top->f && upb_fielddef_isstring(p->top->f)) {
-    // This is a string field (as opposed to a member name).
-    upb_selector_t sel = getsel_for_handlertype(p, UPB_HANDLER_STRING);
-    if (upb_fielddef_type(p->top->f) == UPB_TYPE_BYTES) {
-      PARSER_CHECK_RETURN(base64_push(p, sel, p->accumulated,
-                                      p->accumulated_len));
-    } else {
-      upb_sink_putstring(&p->top->sink, sel, p->accumulated, p->accumulated_len, NULL);
-    }
-    p->accumulated = NULL;
-  } else if (p->top->f &&
-             upb_fielddef_type(p->top->f) == UPB_TYPE_ENUM &&
-             !is_num) {
-
-    // Enum case: resolve enum symbolic name to integer value.
-    const upb_enumdef *enumdef =
-        (const upb_enumdef*)upb_fielddef_subdef(p->top->f);
-
-    int32_t int_val = 0;
-    if (upb_enumdef_ntoi(enumdef, p->accumulated, p->accumulated_len,
-                         &int_val)) {
-      upb_selector_t sel = parser_getsel(p);
-      upb_sink_putint32(&p->top->sink, sel, int_val);
-    } else {
-      upb_status_seterrmsg(p->status, "Enum value name unknown");
+/* Accumulate buffer **********************************************************/
+
+// Functionality for accumulating a buffer.
+//
+// Some parts of the parser need an entire value as a contiguous string.  For
+// example, to look up a member name in a hash table, or to turn a string into
+// a number, the relevant library routines need the input string to be in
+// contiguous memory, even if the value spanned two or more buffers in the
+// input.  These routines handle that.
+//
+// In the common case we can just point to the input buffer to get this
+// contiguous string and avoid any actual copy.  So we optimistically begin
+// this way.  But there are a few cases where we must instead copy into a
+// separate buffer:
+//
+//   1. The string was not contiguous in the input (it spanned buffers).
+//
+//   2. The string included escape sequences that need to be interpreted to get
+//      the true value in a contiguous buffer.
+
+static void assert_accumulate_empty(upb_json_parser *p) {
+  assert(p->accumulated == NULL);
+  assert(p->accumulated_len == 0);
+}
+
+static void accumulate_clear(upb_json_parser *p) {
+  p->accumulated = NULL;
+  p->accumulated_len = 0;
+}
+
+// Used internally by accumulate_append().
+static bool accumulate_realloc(upb_json_parser *p, size_t need) {
+  size_t new_size = UPB_MAX(p->accumulate_buf_size, 128);
+  while (new_size < need) {
+    new_size = saturating_multiply(new_size, 2);
+  }
+
+  void *mem = realloc(p->accumulate_buf, new_size);
+  if (!mem) {
+    upb_status_seterrmsg(p->status, "Out of memory allocating buffer.");
+    return false;
+  }
+
+  p->accumulate_buf = mem;
+  p->accumulate_buf_size = new_size;
+  return true;
+}
+
+// Logically appends the given data to the append buffer.
+// If "can_alias" is true, we will try to avoid actually copying, but the buffer
+// must be valid until the next accumulate_append() call (if any).
+static bool accumulate_append(upb_json_parser *p, const char *buf, size_t len,
+                              bool can_alias) {
+  if (!p->accumulated && can_alias) {
+    p->accumulated = buf;
+    p->accumulated_len = len;
+    return true;
+  }
+
+  size_t need;
+  if (!checked_add(p->accumulated_len, len, &need)) {
+    upb_status_seterrmsg(p->status, "Integer overflow.");
+    return false;
+  }
+
+  if (need > p->accumulate_buf_size && !accumulate_realloc(p, need)) {
+    return false;
+  }
+
+  if (p->accumulated != p->accumulate_buf) {
+    memcpy(p->accumulate_buf, p->accumulated, p->accumulated_len);
+    p->accumulated = p->accumulate_buf;
+  }
+
+  memcpy(p->accumulate_buf + p->accumulated_len, buf, len);
+  p->accumulated_len += len;
+  return true;
+}
+
+// Returns a pointer to the data accumulated since the last accumulate_clear()
+// call, and writes the length to *len.  This with point either to the input
+// buffer or a temporary accumulate buffer.
+static const char *accumulate_getptr(upb_json_parser *p, size_t *len) {
+  assert(p->accumulated);
+  *len = p->accumulated_len;
+  return p->accumulated;
+}
+
+
+/* Mult-part text data ********************************************************/
+
+// When we have text data in the input, it can often come in multiple segments.
+// For example, there may be some raw string data followed by an escape
+// sequence.  The two segments are processed with different logic.  Also buffer
+// seams in the input can cause multiple segments.
+//
+// As we see segments, there are two main cases for how we want to process them:
+//
+//  1. we want to push the captured input directly to string handlers.
+//
+//  2. we need to accumulate all the parts into a contiguous buffer for further
+//     processing (field name lookup, string->number conversion, etc).
+
+// This is the set of states for p->multipart_state.
+enum {
+  // We are not currently processing multipart data.
+  MULTIPART_INACTIVE = 0,
+
+  // We are processing multipart data by accumulating it into a contiguous
+  // buffer.
+  MULTIPART_ACCUMULATE = 1,
+
+  // We are processing multipart data by pushing each part directly to the
+  // current string handlers.
+  MULTIPART_PUSHEAGERLY = 2
+};
+
+// Start a multi-part text value where we accumulate the data for processing at
+// the end.
+static void multipart_startaccum(upb_json_parser *p) {
+  assert_accumulate_empty(p);
+  assert(p->multipart_state == MULTIPART_INACTIVE);
+  p->multipart_state = MULTIPART_ACCUMULATE;
+}
+
+// Start a multi-part text value where we immediately push text data to a string
+// value with the given selector.
+static void multipart_start(upb_json_parser *p, upb_selector_t sel) {
+  assert_accumulate_empty(p);
+  assert(p->multipart_state == MULTIPART_INACTIVE);
+  p->multipart_state = MULTIPART_PUSHEAGERLY;
+  p->string_selector = sel;
+}
+
+static bool multipart_text(upb_json_parser *p, const char *buf, size_t len,
+                           bool can_alias) {
+  switch (p->multipart_state) {
+    case MULTIPART_INACTIVE:
+      upb_status_seterrmsg(
+          p->status, "Internal error: unexpected state MULTIPART_INACTIVE");
       return false;
+
+    case MULTIPART_ACCUMULATE:
+      if (!accumulate_append(p, buf, len, can_alias)) {
+        return false;
+      }
+      break;
+
+    case MULTIPART_PUSHEAGERLY: {
+      const upb_bufhandle *handle = can_alias ? p->handle : NULL;
+      upb_sink_putstring(&p->top->sink, p->string_selector, buf, len, handle);
+      break;
     }
-    p->accumulated = NULL;
   }
 
   return true;
 }
 
-static bool start_stringval(upb_json_parser *p) {
-  assert(p->top->f);
+// Note: this invalidates the accumulate buffer!  Call only after reading its
+// contents.
+static void multipart_end(upb_json_parser *p) {
+  assert(p->multipart_state != MULTIPART_INACTIVE);
+  p->multipart_state = MULTIPART_INACTIVE;
+  accumulate_clear(p);
+}
 
-  if (upb_fielddef_isstring(p->top->f)) {
-    if (!check_stack(p)) return false;
 
-    // Start a new parser frame: parser frames correspond one-to-one with
-    // handler frames, and string events occur in a sub-frame.
-    upb_jsonparser_frame *inner = p->top + 1;
-    upb_selector_t sel = getsel_for_handlertype(p, UPB_HANDLER_STARTSTR);
-    upb_sink_startstr(&p->top->sink, sel, 0, &inner->sink);
-    inner->m = p->top->m;
-    inner->f = p->top->f;
-    p->top = inner;
+/* Input capture **************************************************************/
 
-    return true;
-  } else if (upb_fielddef_type(p->top->f) == UPB_TYPE_ENUM) {
-    // Do nothing -- symbolic enum names in quotes remain in the
-    // current parser frame.
+// Functionality for capturing a region of the input as text.  Gracefully
+// handles the case where a buffer seam occurs in the middle of the captured
+// region.
+
+static void capture_begin(upb_json_parser *p, const char *ptr) {
+  assert(p->multipart_state != MULTIPART_INACTIVE);
+  assert(p->capture == NULL);
+  p->capture = ptr;
+}
+
+static bool capture_end(upb_json_parser *p, const char *ptr) {
+  assert(p->capture);
+  if (multipart_text(p, p->capture, ptr - p->capture, true)) {
+    p->capture = NULL;
     return true;
   } else {
-    upb_status_seterrf(p->status,
-                       "String specified for non-string/non-enum field: %s",
-                       upb_fielddef_name(p->top->f));
     return false;
   }
+}
+
+// This is called at the end of each input buffer (ie. when we have hit a
+// buffer seam).  If we are in the middle of capturing the input, this
+// processes the unprocessed capture region.
+static void capture_suspend(upb_json_parser *p, const char **ptr) {
+  if (!p->capture) return;
+
+  if (multipart_text(p, p->capture, *ptr - p->capture, false)) {
+    // We use this as a signal that we were in the middle of capturing, and
+    // that capturing should resume at the beginning of the next buffer.
+    //
+    // We can't use *ptr here, because we have no guarantee that this pointer
+    // will be valid when we resume (if the underlying memory is freed, then
+    // using the pointer at all, even to compare to NULL, is likely undefined
+    // behavior).
+    p->capture = &suspend_capture;
+  } else {
+    // Need to back up the pointer to the beginning of the capture, since
+    // we were not able to actually preserve it.
+    *ptr = p->capture;
+  }
+}
 
+static void capture_resume(upb_json_parser *p, const char *ptr) {
+  if (p->capture) {
+    assert(p->capture == &suspend_capture);
+    p->capture = ptr;
+  }
 }
 
-static void end_stringval(upb_json_parser *p) {
-  if (upb_fielddef_isstring(p->top->f)) {
-    upb_selector_t sel = getsel_for_handlertype(p, UPB_HANDLER_ENDSTR);
-    upb_sink_endstr(&p->top->sink, sel);
-    p->top--;
+
+/* Callbacks from the parser **************************************************/
+
+// These are the functions called directly from the parser itself.
+// We define these in the same order as their declarations in the parser.
+
+static char escape_char(char in) {
+  switch (in) {
+    case 'r': return '\r';
+    case 't': return '\t';
+    case 'n': return '\n';
+    case 'f': return '\f';
+    case 'b': return '\b';
+    case '/': return '/';
+    case '"': return '"';
+    case '\\': return '\\';
+    default:
+      assert(0);
+      return 'x';
   }
 }
 
+static bool escape(upb_json_parser *p, const char *ptr) {
+  char ch = escape_char(*ptr);
+  return multipart_text(p, &ch, 1, false);
+}
+
+static void start_hex(upb_json_parser *p) {
+  p->digit = 0;
+}
+
+static void hexdigit(upb_json_parser *p, const char *ptr) {
+  char ch = *ptr;
+
+  p->digit <<= 4;
+
+  if (ch >= '0' && ch <= '9') {
+    p->digit += (ch - '0');
+  } else if (ch >= 'a' && ch <= 'f') {
+    p->digit += ((ch - 'a') + 10);
+  } else {
+    assert(ch >= 'A' && ch <= 'F');
+    p->digit += ((ch - 'A') + 10);
+  }
+}
+
+static bool end_hex(upb_json_parser *p) {
+  uint32_t codepoint = p->digit;
+
+  // emit the codepoint as UTF-8.
+  char utf8[3]; // support \u0000 -- \uFFFF -- need only three bytes.
+  int length = 0;
+  if (codepoint <= 0x7F) {
+    utf8[0] = codepoint;
+    length = 1;
+  } else if (codepoint <= 0x07FF) {
+    utf8[1] = (codepoint & 0x3F) | 0x80;
+    codepoint >>= 6;
+    utf8[0] = (codepoint & 0x1F) | 0xC0;
+    length = 2;
+  } else /* codepoint <= 0xFFFF */ {
+    utf8[2] = (codepoint & 0x3F) | 0x80;
+    codepoint >>= 6;
+    utf8[1] = (codepoint & 0x3F) | 0x80;
+    codepoint >>= 6;
+    utf8[0] = (codepoint & 0x0F) | 0xE0;
+    length = 3;
+  }
+  // TODO(haberman): Handle high surrogates: if codepoint is a high surrogate
+  // we have to wait for the next escape to get the full code point).
+
+  return multipart_text(p, utf8, length, false);
+}
+
+static void start_text(upb_json_parser *p, const char *ptr) {
+  capture_begin(p, ptr);
+}
+
+static bool end_text(upb_json_parser *p, const char *ptr) {
+  return capture_end(p, ptr);
+}
+
 static void start_number(upb_json_parser *p, const char *ptr) {
-  start_text(p, ptr);
-  assert(p->accumulated == NULL);
+  multipart_startaccum(p);
+  capture_begin(p, ptr);
 }
 
-static void end_number(upb_json_parser *p, const char *ptr) {
-  end_text(p, ptr, true);
-  const char *myend = p->accumulated + p->accumulated_len;
+static bool end_number(upb_json_parser *p, const char *ptr) {
+  if (!capture_end(p, ptr)) {
+    return false;
+  }
+
+  // strtol() and friends unfortunately do not support specifying the length of
+  // the input string, so we need to force a copy into a NULL-terminated buffer.
+  if (!multipart_text(p, "\0", 1, false)) {
+    return false;
+  }
+
+  size_t len;
+  const char *buf = accumulate_getptr(p, &len);
+  const char *myend = buf + len - 1;  // One for NULL.
   char *end;
 
   switch (upb_fielddef_type(p->top->f)) {
@@ -8991,7 +9162,7 @@ static void end_number(upb_json_parser *p, const char *ptr) {
     case UPB_TYPE_INT32: {
       long val = strtol(p->accumulated, &end, 0);
       if (val > INT32_MAX || val < INT32_MIN || errno == ERANGE || end != myend)
-        assert(false);
+        goto err;
       else
         upb_sink_putint32(&p->top->sink, parser_getsel(p), val);
       break;
@@ -8999,7 +9170,7 @@ static void end_number(upb_json_parser *p, const char *ptr) {
     case UPB_TYPE_INT64: {
       long long val = strtoll(p->accumulated, &end, 0);
       if (val > INT64_MAX || val < INT64_MIN || errno == ERANGE || end != myend)
-        assert(false);
+        goto err;
       else
         upb_sink_putint64(&p->top->sink, parser_getsel(p), val);
       break;
@@ -9007,7 +9178,7 @@ static void end_number(upb_json_parser *p, const char *ptr) {
     case UPB_TYPE_UINT32: {
       unsigned long val = strtoul(p->accumulated, &end, 0);
       if (val > UINT32_MAX || errno == ERANGE || end != myend)
-        assert(false);
+        goto err;
       else
         upb_sink_putuint32(&p->top->sink, parser_getsel(p), val);
       break;
@@ -9015,7 +9186,7 @@ static void end_number(upb_json_parser *p, const char *ptr) {
     case UPB_TYPE_UINT64: {
       unsigned long long val = strtoull(p->accumulated, &end, 0);
       if (val > UINT64_MAX || errno == ERANGE || end != myend)
-        assert(false);
+        goto err;
       else
         upb_sink_putuint64(&p->top->sink, parser_getsel(p), val);
       break;
@@ -9023,7 +9194,7 @@ static void end_number(upb_json_parser *p, const char *ptr) {
     case UPB_TYPE_DOUBLE: {
       double val = strtod(p->accumulated, &end);
       if (errno == ERANGE || end != myend)
-        assert(false);
+        goto err;
       else
         upb_sink_putdouble(&p->top->sink, parser_getsel(p), val);
       break;
@@ -9031,7 +9202,7 @@ static void end_number(upb_json_parser *p, const char *ptr) {
     case UPB_TYPE_FLOAT: {
       float val = strtof(p->accumulated, &end);
       if (errno == ERANGE || end != myend)
-        assert(false);
+        goto err;
       else
         upb_sink_putfloat(&p->top->sink, parser_getsel(p), val);
       break;
@@ -9040,230 +9211,380 @@ static void end_number(upb_json_parser *p, const char *ptr) {
       assert(false);
   }
 
-  p->accumulated = NULL;
+  multipart_end(p);
+  return true;
+
+err:
+  upb_status_seterrf(p->status, "error parsing number: %s", buf);
+  multipart_end(p);
+  return false;
 }
 
-static char escape_char(char in) {
-  switch (in) {
-    case 'r': return '\r';
-    case 't': return '\t';
-    case 'n': return '\n';
-    case 'f': return '\f';
-    case 'b': return '\b';
-    case '/': return '/';
-    case '"': return '"';
-    case '\\': return '\\';
+static bool parser_putbool(upb_json_parser *p, bool val) {
+  if (upb_fielddef_type(p->top->f) != UPB_TYPE_BOOL) {
+    upb_status_seterrf(p->status,
+                       "Boolean value specified for non-bool field: %s",
+                       upb_fielddef_name(p->top->f));
+    return false;
+  }
+
+  bool ok = upb_sink_putbool(&p->top->sink, parser_getsel(p), val);
+  UPB_ASSERT_VAR(ok, ok);
+  return true;
+}
+
+static bool start_stringval(upb_json_parser *p) {
+  assert(p->top->f);
+
+  if (upb_fielddef_isstring(p->top->f)) {
+    if (!check_stack(p)) return false;
+
+    // Start a new parser frame: parser frames correspond one-to-one with
+    // handler frames, and string events occur in a sub-frame.
+    upb_jsonparser_frame *inner = p->top + 1;
+    upb_selector_t sel = getsel_for_handlertype(p, UPB_HANDLER_STARTSTR);
+    upb_sink_startstr(&p->top->sink, sel, 0, &inner->sink);
+    inner->m = p->top->m;
+    inner->f = p->top->f;
+    p->top = inner;
+
+    if (upb_fielddef_type(p->top->f) == UPB_TYPE_STRING) {
+      // For STRING fields we push data directly to the handlers as it is
+      // parsed.  We don't do this yet for BYTES fields, because our base64
+      // decoder is not streaming.
+      //
+      // TODO(haberman): make base64 decoding streaming also.
+      multipart_start(p, getsel_for_handlertype(p, UPB_HANDLER_STRING));
+      return true;
+    } else {
+      multipart_startaccum(p);
+      return true;
+    }
+  } else if (upb_fielddef_type(p->top->f) == UPB_TYPE_ENUM) {
+    // No need to push a frame -- symbolic enum names in quotes remain in the
+    // current parser frame.
+    //
+    // Enum string values must accumulate so we can look up the value in a table
+    // once it is complete.
+    multipart_startaccum(p);
+    return true;
+  } else {
+    upb_status_seterrf(p->status,
+                       "String specified for non-string/non-enum field: %s",
+                       upb_fielddef_name(p->top->f));
+    return false;
+  }
+}
+
+static bool end_stringval(upb_json_parser *p) {
+  bool ok = true;
+
+  switch (upb_fielddef_type(p->top->f)) {
+    case UPB_TYPE_BYTES:
+      if (!base64_push(p, getsel_for_handlertype(p, UPB_HANDLER_STRING),
+                       p->accumulated, p->accumulated_len)) {
+        return false;
+      }
+      // Fall through.
+
+    case UPB_TYPE_STRING: {
+      upb_selector_t sel = getsel_for_handlertype(p, UPB_HANDLER_ENDSTR);
+      upb_sink_endstr(&p->top->sink, sel);
+      p->top--;
+      break;
+    }
+
+    case UPB_TYPE_ENUM: {
+      // Resolve enum symbolic name to integer value.
+      const upb_enumdef *enumdef =
+          (const upb_enumdef*)upb_fielddef_subdef(p->top->f);
+
+      size_t len;
+      const char *buf = accumulate_getptr(p, &len);
+
+      int32_t int_val = 0;
+      ok = upb_enumdef_ntoi(enumdef, buf, len, &int_val);
+
+      if (ok) {
+        upb_selector_t sel = parser_getsel(p);
+        upb_sink_putint32(&p->top->sink, sel, int_val);
+      } else {
+        upb_status_seterrf(p->status, "Enum value unknown: '%.*s'", len, buf);
+      }
+
+      break;
+    }
+
     default:
-      assert(0);
-      return 'x';
+      assert(false);
+      upb_status_seterrmsg(p->status, "Internal error in JSON decoder");
+      ok = false;
+      break;
   }
+
+  multipart_end(p);
+  return ok;
 }
 
-static void escape(upb_json_parser *p, const char *ptr) {
-  char ch = escape_char(*ptr);
-  upb_selector_t sel = getsel_for_handlertype(p, UPB_HANDLER_STRING);
-  upb_sink_putstring(&p->top->sink, sel, &ch, 1, NULL);
+static void start_member(upb_json_parser *p) {
+  assert(!p->top->f);
+  multipart_startaccum(p);
 }
 
-static uint8_t hexdigit(char ch) {
-  if (ch >= '0' && ch <= '9') {
-    return ch - '0';
-  } else if (ch >= 'a' && ch <= 'f') {
-    return ch - 'a' + 10;
-  } else {
-    assert(ch >= 'A' && ch <= 'F');
-    return ch - 'A' + 10;
+static bool end_member(upb_json_parser *p) {
+  assert(!p->top->f);
+  size_t len;
+  const char *buf = accumulate_getptr(p, &len);
+
+  const upb_fielddef *f = upb_msgdef_ntof(p->top->m, buf, len);
+
+  if (!f) {
+    // TODO(haberman): Ignore unknown fields if requested/configured to do so.
+    upb_status_seterrf(p->status, "No such field: %.*s\n", (int)len, buf);
+    return false;
+  }
+
+  p->top->f = f;
+  multipart_end(p);
+
+  return true;
+}
+
+static void clear_member(upb_json_parser *p) { p->top->f = NULL; }
+
+static bool start_subobject(upb_json_parser *p) {
+  assert(p->top->f);
+
+  if (!upb_fielddef_issubmsg(p->top->f)) {
+    upb_status_seterrf(p->status,
+                       "Object specified for non-message/group field: %s",
+                       upb_fielddef_name(p->top->f));
+    return false;
   }
+
+  if (!check_stack(p)) return false;
+
+  upb_jsonparser_frame *inner = p->top + 1;
+
+  upb_selector_t sel = getsel_for_handlertype(p, UPB_HANDLER_STARTSUBMSG);
+  upb_sink_startsubmsg(&p->top->sink, sel, &inner->sink);
+  inner->m = upb_fielddef_msgsubdef(p->top->f);
+  inner->f = NULL;
+  p->top = inner;
+
+  return true;
 }
 
-static void start_hex(upb_json_parser *p, const char *ptr) {
-  start_text(p, ptr);
+static void end_subobject(upb_json_parser *p) {
+  p->top--;
+  upb_selector_t sel = getsel_for_handlertype(p, UPB_HANDLER_ENDSUBMSG);
+  upb_sink_endsubmsg(&p->top->sink, sel);
 }
 
-static void hex(upb_json_parser *p, const char *end) {
-  const char *start = p->text_begin;
-  UPB_ASSERT_VAR(end, end - start == 4);
-  uint16_t codepoint =
-      (hexdigit(start[0]) << 12) |
-      (hexdigit(start[1]) << 8) |
-      (hexdigit(start[2]) << 4) |
-      hexdigit(start[3]);
-  // emit the codepoint as UTF-8.
-  char utf8[3]; // support \u0000 -- \uFFFF -- need only three bytes.
-  int length = 0;
-  if (codepoint <= 0x7F) {
-    utf8[0] = codepoint;
-    length = 1;
-  } else if (codepoint <= 0x07FF) {
-    utf8[1] = (codepoint & 0x3F) | 0x80;
-    codepoint >>= 6;
-    utf8[0] = (codepoint & 0x1F) | 0xC0;
-    length = 2;
-  } else /* codepoint <= 0xFFFF */ {
-    utf8[2] = (codepoint & 0x3F) | 0x80;
-    codepoint >>= 6;
-    utf8[1] = (codepoint & 0x3F) | 0x80;
-    codepoint >>= 6;
-    utf8[0] = (codepoint & 0x0F) | 0xE0;
-    length = 3;
+static bool start_array(upb_json_parser *p) {
+  assert(p->top->f);
+
+  if (!upb_fielddef_isseq(p->top->f)) {
+    upb_status_seterrf(p->status,
+                       "Array specified for non-repeated field: %s",
+                       upb_fielddef_name(p->top->f));
+    return false;
   }
-  // TODO(haberman): Handle high surrogates: if codepoint is a high surrogate
-  // we have to wait for the next escape to get the full code point).
 
-  upb_selector_t sel = getsel_for_handlertype(p, UPB_HANDLER_STRING);
-  upb_sink_putstring(&p->top->sink, sel, utf8, length, NULL);
+  if (!check_stack(p)) return false;
+
+  upb_jsonparser_frame *inner = p->top + 1;
+  upb_selector_t sel = getsel_for_handlertype(p, UPB_HANDLER_STARTSEQ);
+  upb_sink_startseq(&p->top->sink, sel, &inner->sink);
+  inner->m = p->top->m;
+  inner->f = p->top->f;
+  p->top = inner;
+
+  return true;
+}
+
+static void end_array(upb_json_parser *p) {
+  assert(p->top > p->stack);
+
+  p->top--;
+  upb_selector_t sel = getsel_for_handlertype(p, UPB_HANDLER_ENDSEQ);
+  upb_sink_endseq(&p->top->sink, sel);
+}
+
+static void start_object(upb_json_parser *p) {
+  upb_sink_startmsg(&p->top->sink);
+}
+
+static void end_object(upb_json_parser *p) {
+  upb_status status;
+  upb_sink_endmsg(&p->top->sink, &status);
 }
 
+
 #define CHECK_RETURN_TOP(x) if (!(x)) goto error
 
+
+/* The actual parser **********************************************************/
+
 // What follows is the Ragel parser itself.  The language is specified in Ragel
 // and the actions call our C functions above.
+//
+// Ragel has an extensive set of functionality, and we use only a small part of
+// it.  There are many action types but we only use a few:
+//
+//   ">" -- transition into a machine
+//   "%" -- transition out of a machine
+//   "@" -- transition into a final state of a machine.
+//
+// "@" transitions are tricky because a machine can transition into a final
+// state repeatedly.  But in some cases we know this can't happen, for example
+// a string which is delimited by a final '"' can only transition into its
+// final state once, when the closing '"' is seen.
+
 
-#line 596 "upb/json/parser.rl"
+#line 904 "upb/json/parser.rl"
 
 
 
-#line 514 "upb/json/parser.c"
+#line 816 "upb/json/parser.c"
 static const char _json_actions[] = {
 	0, 1, 0, 1, 2, 1, 3, 1, 
-	4, 1, 5, 1, 6, 1, 7, 1, 
-	9, 1, 11, 1, 12, 1, 13, 1, 
-	14, 1, 15, 1, 16, 1, 24, 1, 
-	26, 2, 3, 7, 2, 5, 2, 2, 
-	5, 7, 2, 10, 8, 2, 12, 14, 
-	2, 13, 14, 2, 17, 1, 2, 18, 
-	26, 2, 19, 8, 2, 20, 26, 2, 
-	21, 26, 2, 22, 26, 2, 23, 26, 
-	2, 25, 26, 3, 13, 10, 8
+	5, 1, 6, 1, 7, 1, 8, 1, 
+	10, 1, 12, 1, 13, 1, 14, 1, 
+	15, 1, 16, 1, 17, 1, 21, 1, 
+	25, 1, 27, 2, 3, 8, 2, 4, 
+	5, 2, 6, 2, 2, 6, 8, 2, 
+	11, 9, 2, 13, 15, 2, 14, 15, 
+	2, 18, 1, 2, 19, 27, 2, 20, 
+	9, 2, 22, 27, 2, 23, 27, 2, 
+	24, 27, 2, 26, 27, 3, 14, 11, 
+	9
 };
 
 static const unsigned char _json_key_offsets[] = {
-	0, 0, 4, 9, 14, 18, 22, 27, 
-	32, 37, 41, 45, 48, 51, 53, 57, 
-	61, 63, 65, 70, 72, 74, 83, 89, 
-	95, 101, 107, 109, 118, 118, 118, 123, 
-	128, 133, 133, 134, 135, 136, 137, 137, 
-	138, 139, 140, 140, 141, 142, 143, 143, 
-	148, 153, 157, 161, 166, 171, 176, 180, 
-	180, 183, 183, 183
+	0, 0, 4, 9, 14, 15, 19, 24, 
+	29, 34, 38, 42, 45, 48, 50, 54, 
+	58, 60, 62, 67, 69, 71, 80, 86, 
+	92, 98, 104, 106, 115, 116, 116, 116, 
+	121, 126, 131, 132, 133, 134, 135, 135, 
+	136, 137, 138, 138, 139, 140, 141, 141, 
+	146, 151, 152, 156, 161, 166, 171, 175, 
+	175, 178, 178, 178
 };
 
 static const char _json_trans_keys[] = {
 	32, 123, 9, 13, 32, 34, 125, 9, 
-	13, 32, 34, 125, 9, 13, 32, 58, 
-	9, 13, 32, 58, 9, 13, 32, 93, 
-	125, 9, 13, 32, 44, 125, 9, 13, 
-	32, 44, 125, 9, 13, 32, 34, 9, 
-	13, 45, 48, 49, 57, 48, 49, 57, 
-	46, 69, 101, 48, 57, 69, 101, 48, 
-	57, 43, 45, 48, 57, 48, 57, 48, 
-	57, 46, 69, 101, 48, 57, 34, 92, 
-	34, 92, 34, 47, 92, 98, 102, 110, 
-	114, 116, 117, 48, 57, 65, 70, 97, 
-	102, 48, 57, 65, 70, 97, 102, 48, 
-	57, 65, 70, 97, 102, 48, 57, 65, 
-	70, 97, 102, 34, 92, 34, 45, 91, 
-	102, 110, 116, 123, 48, 57, 32, 93, 
-	125, 9, 13, 32, 44, 93, 9, 13, 
-	32, 93, 125, 9, 13, 97, 108, 115, 
-	101, 117, 108, 108, 114, 117, 101, 32, 
-	34, 125, 9, 13, 32, 34, 125, 9, 
-	13, 32, 58, 9, 13, 32, 58, 9, 
-	13, 32, 93, 125, 9, 13, 32, 44, 
-	125, 9, 13, 32, 44, 125, 9, 13, 
-	32, 34, 9, 13, 32, 9, 13, 0
+	13, 32, 34, 125, 9, 13, 34, 32, 
+	58, 9, 13, 32, 93, 125, 9, 13, 
+	32, 44, 125, 9, 13, 32, 44, 125, 
+	9, 13, 32, 34, 9, 13, 45, 48, 
+	49, 57, 48, 49, 57, 46, 69, 101, 
+	48, 57, 69, 101, 48, 57, 43, 45, 
+	48, 57, 48, 57, 48, 57, 46, 69, 
+	101, 48, 57, 34, 92, 34, 92, 34, 
+	47, 92, 98, 102, 110, 114, 116, 117, 
+	48, 57, 65, 70, 97, 102, 48, 57, 
+	65, 70, 97, 102, 48, 57, 65, 70, 
+	97, 102, 48, 57, 65, 70, 97, 102, 
+	34, 92, 34, 45, 91, 102, 110, 116, 
+	123, 48, 57, 34, 32, 93, 125, 9, 
+	13, 32, 44, 93, 9, 13, 32, 93, 
+	125, 9, 13, 97, 108, 115, 101, 117, 
+	108, 108, 114, 117, 101, 32, 34, 125, 
+	9, 13, 32, 34, 125, 9, 13, 34, 
+	32, 58, 9, 13, 32, 93, 125, 9, 
+	13, 32, 44, 125, 9, 13, 32, 44, 
+	125, 9, 13, 32, 34, 9, 13, 32, 
+	9, 13, 0
 };
 
 static const char _json_single_lengths[] = {
-	0, 2, 3, 3, 2, 2, 3, 3, 
+	0, 2, 3, 3, 1, 2, 3, 3, 
 	3, 2, 2, 1, 3, 0, 2, 2, 
 	0, 0, 3, 2, 2, 9, 0, 0, 
-	0, 0, 2, 7, 0, 0, 3, 3, 
-	3, 0, 1, 1, 1, 1, 0, 1, 
+	0, 0, 2, 7, 1, 0, 0, 3, 
+	3, 3, 1, 1, 1, 1, 0, 1, 
 	1, 1, 0, 1, 1, 1, 0, 3, 
-	3, 2, 2, 3, 3, 3, 2, 0, 
+	3, 1, 2, 3, 3, 3, 2, 0, 
 	1, 0, 0, 0
 };
 
 static const char _json_range_lengths[] = {
-	0, 1, 1, 1, 1, 1, 1, 1, 
+	0, 1, 1, 1, 0, 1, 1, 1, 
 	1, 1, 1, 1, 0, 1, 1, 1, 
 	1, 1, 1, 0, 0, 0, 3, 3, 
-	3, 3, 0, 1, 0, 0, 1, 1, 
-	1, 0, 0, 0, 0, 0, 0, 0, 
+	3, 3, 0, 1, 0, 0, 0, 1, 
+	1, 1, 0, 0, 0, 0, 0, 0, 
 	0, 0, 0, 0, 0, 0, 0, 1, 
-	1, 1, 1, 1, 1, 1, 1, 0, 
+	1, 0, 1, 1, 1, 1, 1, 0, 
 	1, 0, 0, 0
 };
 
 static const short _json_index_offsets[] = {
-	0, 0, 4, 9, 14, 18, 22, 27, 
-	32, 37, 41, 45, 48, 52, 54, 58, 
-	62, 64, 66, 71, 74, 77, 87, 91, 
-	95, 99, 103, 106, 115, 116, 117, 122, 
-	127, 132, 133, 135, 137, 139, 141, 142, 
-	144, 146, 148, 149, 151, 153, 155, 156, 
-	161, 166, 170, 174, 179, 184, 189, 193, 
-	194, 197, 198, 199
+	0, 0, 4, 9, 14, 16, 20, 25, 
+	30, 35, 39, 43, 46, 50, 52, 56, 
+	60, 62, 64, 69, 72, 75, 85, 89, 
+	93, 97, 101, 104, 113, 115, 116, 117, 
+	122, 127, 132, 134, 136, 138, 140, 141, 
+	143, 145, 147, 148, 150, 152, 154, 155, 
+	160, 165, 167, 171, 176, 181, 186, 190, 
+	191, 194, 195, 196
 };
 
 static const char _json_indicies[] = {
 	0, 2, 0, 1, 3, 4, 5, 3, 
-	1, 6, 7, 8, 6, 1, 9, 10, 
-	9, 1, 11, 12, 11, 1, 12, 1, 
-	1, 12, 13, 14, 15, 16, 14, 1, 
-	17, 18, 8, 17, 1, 18, 7, 18, 
-	1, 19, 20, 21, 1, 20, 21, 1, 
-	23, 24, 24, 22, 25, 1, 24, 24, 
-	25, 22, 26, 26, 27, 1, 27, 1, 
-	27, 22, 23, 24, 24, 21, 22, 29, 
-	30, 28, 32, 33, 31, 34, 34, 34, 
-	34, 34, 34, 34, 34, 35, 1, 36, 
-	36, 36, 1, 37, 37, 37, 1, 38, 
-	38, 38, 1, 39, 39, 39, 1, 41, 
-	42, 40, 43, 44, 45, 46, 47, 48, 
-	49, 44, 1, 50, 51, 53, 54, 1, 
+	1, 6, 7, 8, 6, 1, 9, 1, 
+	10, 11, 10, 1, 11, 1, 1, 11, 
+	12, 13, 14, 15, 13, 1, 16, 17, 
+	8, 16, 1, 17, 7, 17, 1, 18, 
+	19, 20, 1, 19, 20, 1, 22, 23, 
+	23, 21, 24, 1, 23, 23, 24, 21, 
+	25, 25, 26, 1, 26, 1, 26, 21, 
+	22, 23, 23, 20, 21, 28, 29, 27, 
+	31, 32, 30, 33, 33, 33, 33, 33, 
+	33, 33, 33, 34, 1, 35, 35, 35, 
+	1, 36, 36, 36, 1, 37, 37, 37, 
+	1, 38, 38, 38, 1, 40, 41, 39, 
+	42, 43, 44, 45, 46, 47, 48, 43, 
+	1, 49, 1, 50, 51, 53, 54, 1, 
 	53, 52, 55, 56, 54, 55, 1, 56, 
-	1, 1, 56, 52, 57, 58, 1, 59, 
-	1, 60, 1, 61, 1, 62, 63, 1, 
-	64, 1, 65, 1, 66, 67, 1, 68, 
-	1, 69, 1, 70, 71, 72, 73, 71, 
-	1, 74, 75, 76, 74, 1, 77, 78, 
-	77, 1, 79, 80, 79, 1, 80, 1, 
-	1, 80, 81, 82, 83, 84, 82, 1, 
-	85, 86, 76, 85, 1, 86, 75, 86, 
-	1, 87, 88, 88, 1, 1, 1, 1, 
-	0
+	1, 1, 56, 52, 57, 1, 58, 1, 
+	59, 1, 60, 1, 61, 62, 1, 63, 
+	1, 64, 1, 65, 66, 1, 67, 1, 
+	68, 1, 69, 70, 71, 72, 70, 1, 
+	73, 74, 75, 73, 1, 76, 1, 77, 
+	78, 77, 1, 78, 1, 1, 78, 79, 
+	80, 81, 82, 80, 1, 83, 84, 75, 
+	83, 1, 84, 74, 84, 1, 85, 86, 
+	86, 1, 1, 1, 1, 0
 };
 
 static const char _json_trans_targs[] = {
 	1, 0, 2, 3, 4, 56, 3, 4, 
-	56, 5, 6, 5, 6, 7, 8, 9, 
-	56, 8, 9, 11, 12, 18, 57, 13, 
-	15, 14, 16, 17, 20, 58, 21, 20, 
-	58, 21, 19, 22, 23, 24, 25, 26, 
-	20, 58, 21, 28, 29, 30, 34, 39, 
-	43, 47, 59, 59, 31, 30, 33, 31, 
-	32, 59, 35, 36, 37, 38, 59, 40, 
-	41, 42, 59, 44, 45, 46, 59, 48, 
-	49, 55, 48, 49, 55, 50, 51, 50, 
-	51, 52, 53, 54, 55, 53, 54, 59, 
-	56
+	56, 5, 5, 6, 7, 8, 9, 56, 
+	8, 9, 11, 12, 18, 57, 13, 15, 
+	14, 16, 17, 20, 58, 21, 20, 58, 
+	21, 19, 22, 23, 24, 25, 26, 20, 
+	58, 21, 28, 30, 31, 34, 39, 43, 
+	47, 29, 59, 59, 32, 31, 29, 32, 
+	33, 35, 36, 37, 38, 59, 40, 41, 
+	42, 59, 44, 45, 46, 59, 48, 49, 
+	55, 48, 49, 55, 50, 50, 51, 52, 
+	53, 54, 55, 53, 54, 59, 56
 };
 
 static const char _json_trans_actions[] = {
-	0, 0, 0, 21, 75, 48, 0, 42, 
-	23, 17, 17, 0, 0, 15, 19, 19, 
-	45, 0, 0, 0, 0, 0, 1, 0, 
-	0, 0, 0, 0, 3, 13, 0, 0, 
-	33, 5, 11, 0, 7, 0, 0, 0, 
-	36, 39, 9, 57, 51, 25, 0, 0, 
-	0, 29, 60, 54, 15, 0, 27, 0, 
-	0, 31, 0, 0, 0, 0, 66, 0, 
-	0, 0, 69, 0, 0, 0, 63, 21, 
-	75, 48, 0, 42, 23, 17, 17, 0, 
-	0, 15, 19, 19, 45, 0, 0, 72, 
-	0
+	0, 0, 0, 21, 77, 53, 0, 47, 
+	23, 17, 0, 0, 15, 19, 19, 50, 
+	0, 0, 0, 0, 0, 1, 0, 0, 
+	0, 0, 0, 3, 13, 0, 0, 35, 
+	5, 11, 0, 38, 7, 7, 7, 41, 
+	44, 9, 62, 56, 25, 0, 0, 0, 
+	31, 29, 33, 59, 15, 0, 27, 0, 
+	0, 0, 0, 0, 0, 68, 0, 0, 
+	0, 71, 0, 0, 0, 65, 21, 77, 
+	53, 0, 47, 23, 17, 0, 0, 15, 
+	19, 19, 50, 0, 0, 74, 0
 };
 
 static const int json_start = 1;
@@ -9276,13 +9597,14 @@ static const int json_en_value_machine = 27;
 static const int json_en_main = 1;
 
 
-#line 599 "upb/json/parser.rl"
+#line 907 "upb/json/parser.rl"
 
 size_t parse(void *closure, const void *hd, const char *buf, size_t size,
              const upb_bufhandle *handle) {
   UPB_UNUSED(hd);
   UPB_UNUSED(handle);
   upb_json_parser *parser = closure;
+  parser->handle = handle;
 
   // Variables used by Ragel's generated code.
   int cs = parser->current_state;
@@ -9292,8 +9614,10 @@ size_t parse(void *closure, const void *hd, const char *buf, size_t size,
   const char *p = buf;
   const char *pe = buf + size;
 
+  capture_resume(parser, buf);
+
   
-#line 684 "upb/json/parser.c"
+#line 987 "upb/json/parser.c"
 	{
 	int _klen;
 	unsigned int _trans;
@@ -9368,114 +9692,118 @@ _match:
 		switch ( *_acts++ )
 		{
 	case 0:
-#line 517 "upb/json/parser.rl"
+#line 819 "upb/json/parser.rl"
 	{ p--; {cs = stack[--top]; goto _again;} }
 	break;
 	case 1:
-#line 518 "upb/json/parser.rl"
+#line 820 "upb/json/parser.rl"
 	{ p--; {stack[top++] = cs; cs = 10; goto _again;} }
 	break;
 	case 2:
-#line 522 "upb/json/parser.rl"
+#line 824 "upb/json/parser.rl"
 	{ start_text(parser, p); }
 	break;
 	case 3:
-#line 523 "upb/json/parser.rl"
-	{ CHECK_RETURN_TOP(end_text(parser, p, false)); }
+#line 825 "upb/json/parser.rl"
+	{ CHECK_RETURN_TOP(end_text(parser, p)); }
 	break;
 	case 4:
-#line 529 "upb/json/parser.rl"
-	{ start_hex(parser, p); }
+#line 831 "upb/json/parser.rl"
+	{ start_hex(parser); }
 	break;
 	case 5:
-#line 530 "upb/json/parser.rl"
-	{ hex(parser, p); }
+#line 832 "upb/json/parser.rl"
+	{ hexdigit(parser, p); }
 	break;
 	case 6:
-#line 536 "upb/json/parser.rl"
-	{ escape(parser, p); }
+#line 833 "upb/json/parser.rl"
+	{ CHECK_RETURN_TOP(end_hex(parser)); }
 	break;
 	case 7:
-#line 539 "upb/json/parser.rl"
-	{ {cs = stack[--top]; goto _again;} }
+#line 839 "upb/json/parser.rl"
+	{ CHECK_RETURN_TOP(escape(parser, p)); }
 	break;
 	case 8:
-#line 540 "upb/json/parser.rl"
-	{ {stack[top++] = cs; cs = 19; goto _again;} }
+#line 845 "upb/json/parser.rl"
+	{ p--; {cs = stack[--top]; goto _again;} }
 	break;
 	case 9:
-#line 542 "upb/json/parser.rl"
-	{ p--; {stack[top++] = cs; cs = 27; goto _again;} }
+#line 848 "upb/json/parser.rl"
+	{ {stack[top++] = cs; cs = 19; goto _again;} }
 	break;
 	case 10:
-#line 547 "upb/json/parser.rl"
-	{ start_member(parser); }
+#line 850 "upb/json/parser.rl"
+	{ p--; {stack[top++] = cs; cs = 27; goto _again;} }
 	break;
 	case 11:
-#line 548 "upb/json/parser.rl"
-	{ CHECK_RETURN_TOP(end_member(parser)); }
+#line 855 "upb/json/parser.rl"
+	{ start_member(parser); }
 	break;
 	case 12:
-#line 551 "upb/json/parser.rl"
-	{ clear_member(parser); }
+#line 856 "upb/json/parser.rl"
+	{ CHECK_RETURN_TOP(end_member(parser)); }
 	break;
 	case 13:
-#line 557 "upb/json/parser.rl"
-	{ start_object(parser); }
+#line 859 "upb/json/parser.rl"
+	{ clear_member(parser); }
 	break;
 	case 14:
-#line 560 "upb/json/parser.rl"
-	{ end_object(parser); }
+#line 865 "upb/json/parser.rl"
+	{ start_object(parser); }
 	break;
 	case 15:
-#line 566 "upb/json/parser.rl"
-	{ CHECK_RETURN_TOP(start_array(parser)); }
+#line 868 "upb/json/parser.rl"
+	{ end_object(parser); }
 	break;
 	case 16:
-#line 570 "upb/json/parser.rl"
-	{ end_array(parser); }
+#line 874 "upb/json/parser.rl"
+	{ CHECK_RETURN_TOP(start_array(parser)); }
 	break;
 	case 17:
-#line 575 "upb/json/parser.rl"
-	{ start_number(parser, p); }
+#line 878 "upb/json/parser.rl"
+	{ end_array(parser); }
 	break;
 	case 18:
-#line 576 "upb/json/parser.rl"
-	{ end_number(parser, p); }
+#line 883 "upb/json/parser.rl"
+	{ start_number(parser, p); }
 	break;
 	case 19:
-#line 578 "upb/json/parser.rl"
-	{ CHECK_RETURN_TOP(start_stringval(parser)); }
+#line 884 "upb/json/parser.rl"
+	{ CHECK_RETURN_TOP(end_number(parser, p)); }
 	break;
 	case 20:
-#line 579 "upb/json/parser.rl"
-	{ end_stringval(parser); }
+#line 886 "upb/json/parser.rl"
+	{ CHECK_RETURN_TOP(start_stringval(parser)); }
 	break;
 	case 21:
-#line 581 "upb/json/parser.rl"
-	{ CHECK_RETURN_TOP(parser_putbool(parser, true)); }
+#line 887 "upb/json/parser.rl"
+	{ CHECK_RETURN_TOP(end_stringval(parser)); }
 	break;
 	case 22:
-#line 583 "upb/json/parser.rl"
-	{ CHECK_RETURN_TOP(parser_putbool(parser, false)); }
+#line 889 "upb/json/parser.rl"
+	{ CHECK_RETURN_TOP(parser_putbool(parser, true)); }
 	break;
 	case 23:
-#line 585 "upb/json/parser.rl"
-	{ /* null value */ }
+#line 891 "upb/json/parser.rl"
+	{ CHECK_RETURN_TOP(parser_putbool(parser, false)); }
 	break;
 	case 24:
-#line 587 "upb/json/parser.rl"
-	{ CHECK_RETURN_TOP(start_subobject(parser)); }
+#line 893 "upb/json/parser.rl"
+	{ /* null value */ }
 	break;
 	case 25:
-#line 588 "upb/json/parser.rl"
-	{ end_subobject(parser); }
+#line 895 "upb/json/parser.rl"
+	{ CHECK_RETURN_TOP(start_subobject(parser)); }
 	break;
 	case 26:
-#line 593 "upb/json/parser.rl"
+#line 896 "upb/json/parser.rl"
+	{ end_subobject(parser); }
+	break;
+	case 27:
+#line 901 "upb/json/parser.rl"
 	{ p--; {cs = stack[--top]; goto _again;} }
 	break;
-#line 866 "upb/json/parser.c"
+#line 1173 "upb/json/parser.c"
 		}
 	}
 
@@ -9488,10 +9816,12 @@ _again:
 	_out: {}
 	}
 
-#line 615 "upb/json/parser.rl"
+#line 926 "upb/json/parser.rl"
 
   if (p != pe) {
     upb_status_seterrf(parser->status, "Parse error at %s\n", p);
+  } else {
+    capture_suspend(parser, &p);
   }
 
 error:
@@ -9508,8 +9838,13 @@ bool end(void *closure, const void *hd) {
   return true;
 }
 
+
+/* Public API *****************************************************************/
+
 void upb_json_parser_init(upb_json_parser *p, upb_status *status) {
   p->limit = p->stack + UPB_JSON_MAX_DEPTH;
+  p->accumulate_buf = NULL;
+  p->accumulate_buf_size = 0;
   upb_byteshandler_init(&p->input_handler_);
   upb_byteshandler_setstring(&p->input_handler_, parse, NULL);
   upb_byteshandler_setendstr(&p->input_handler_, end, NULL);
@@ -9519,6 +9854,7 @@ void upb_json_parser_init(upb_json_parser *p, upb_status *status) {
 
 void upb_json_parser_uninit(upb_json_parser *p) {
   upb_byteshandler_uninit(&p->input_handler_);
+  free(p->accumulate_buf);
 }
 
 void upb_json_parser_reset(upb_json_parser *p) {
@@ -9529,18 +9865,18 @@ void upb_json_parser_reset(upb_json_parser *p) {
   int top;
   // Emit Ragel initialization of the parser.
   
-#line 920 "upb/json/parser.c"
+#line 1235 "upb/json/parser.c"
 	{
 	cs = json_start;
 	top = 0;
 	}
 
-#line 655 "upb/json/parser.rl"
+#line 974 "upb/json/parser.rl"
   p->current_state = cs;
   p->parser_top = top;
-  p->text_begin = NULL;
-  p->accumulated = NULL;
-  p->accumulated_len = 0;
+  accumulate_clear(p);
+  p->multipart_state = MULTIPART_INACTIVE;
+  p->capture = NULL;
 }
 
 void upb_json_parser_resetoutput(upb_json_parser *p, upb_sink *sink) {
diff --git a/ruby/ext/google/protobuf_c/upb.h b/ruby/ext/google/protobuf_c/upb.h
index 0e98bbab..fbcb8e99 100644
--- a/ruby/ext/google/protobuf_c/upb.h
+++ b/ruby/ext/google/protobuf_c/upb.h
@@ -6662,7 +6662,9 @@ typedef enum {
                            //   | unused (24)         | opc |
                            //   | upb_inttable* (32 or 64)  |
 
-  OP_HALT           = 36,  // No arg.
+  OP_DISPATCH       = 36,  // No arg.
+
+  OP_HALT           = 37,  // No arg.
 } opcode;
 
 #define OP_MAX OP_HALT
@@ -7339,15 +7341,24 @@ UPB_DEFINE_STRUCT0(upb_json_parser,
   int parser_stack[UPB_JSON_MAX_DEPTH];
   int parser_top;
 
-  // A pointer to the beginning of whatever text we are currently parsing.
-  const char *text_begin;
+  // The handle for the current buffer.
+  const upb_bufhandle *handle;
 
-  // We have to accumulate text for member names, integers, unicode escapes, and
-  // base64 partial results.
+  // Accumulate buffer.  See details in parser.rl.
   const char *accumulated;
   size_t accumulated_len;
-  // TODO: add members and code for allocating a buffer when necessary (when the
-  // member spans input buffers or contains escapes).
+  char *accumulate_buf;
+  size_t accumulate_buf_size;
+
+  // Multi-part text data.  See details in parser.rl.
+  int multipart_state;
+  upb_selector_t string_selector;
+
+  // Input capture.  See details in parser.rl.
+  const char *capture;
+
+  // Intermediate result of parsing a unicode escape sequence.
+  uint32_t digit;
 ));
 
 UPB_BEGIN_EXTERN_C