From 209f09d5e9310b7c8b857f24690795cb0998dfc4 Mon Sep 17 00:00:00 2001
From: Alain Jobart <alainjobart@google.com>
Date: Mon, 1 May 2017 07:37:42 -0700
Subject: [PATCH] Stopping the parsing for unsupported json opaques.

---
 go/mysqlconn/replication/binlog_event_json.go | 20 +++++++---------
 .../replication/binlog_event_json_test.go     | 23 ++++++++++---------
 2 files changed, 20 insertions(+), 23 deletions(-)

diff --git a/go/mysqlconn/replication/binlog_event_json.go b/go/mysqlconn/replication/binlog_event_json.go
index f0a25422b67..8273091e700 100644
--- a/go/mysqlconn/replication/binlog_event_json.go
+++ b/go/mysqlconn/replication/binlog_event_json.go
@@ -72,7 +72,7 @@ func printJSONValue(typ byte, data []byte, toplevel bool, result *bytes.Buffer)
 	case jsonTypeString:
 		printJSONString(data, toplevel, result)
 	case jsonTypeOpaque:
-		printJSONOpaque(data, toplevel, result)
+		return printJSONOpaque(data, toplevel, result)
 	default:
 		return fmt.Errorf("unknown object type in JSON: %v", typ)
 	}
@@ -345,17 +345,13 @@ func printJSONOpaque(data []byte, toplevel bool, result *bytes.Buffer) error {
 		return printJSONDecimal(data[pos:pos+size], toplevel, result)
 	}
 
-	// FIXME(alainjobart) this is broken for now. The lack of metadata
-	// makes the parsing fail. The MySQL source code is too obscure
-	// to make any sense of this.
-	val, pos, err := CellValue(data, pos, typ, 0, querypb.Type_INT8)
-	if err != nil {
-		return err
-	}
-	result.WriteString("CAST(")
-	val.EncodeSQL(result)
-	result.WriteString(" AS JSON)")
-	return nil
+	// Other types are encoded in somewhat weird ways. Since we
+	// have no metadata, it seems some types first provide the
+	// metadata, and then the values. But even that metadata is
+	// not straightforward (for instance, a bit field seems to
+	// have one byte as metadata, not two as would be expected).
+	// To be on the safer side, we just reject these cases for now.
+	return fmt.Errorf("opaque type %v is not supported yet, with data %v", typ, data[1:])
 }
 
 func printJSONDate(data []byte, toplevel bool, result *bytes.Buffer) error {
diff --git a/go/mysqlconn/replication/binlog_event_json_test.go b/go/mysqlconn/replication/binlog_event_json_test.go
index 2c47e6220de..71bdfe8fe04 100644
--- a/go/mysqlconn/replication/binlog_event_json_test.go
+++ b/go/mysqlconn/replication/binlog_event_json_test.go
@@ -1,6 +1,9 @@
 package replication
 
-import "testing"
+import (
+	"fmt"
+	"testing"
+)
 
 func TestJSON(t *testing.T) {
 	testcases := []struct {
@@ -99,23 +102,21 @@ func TestJSON(t *testing.T) {
 		data:     []byte{15, 246, 8, 13, 4, 135, 91, 205, 21, 4, 210},
 		expected: `CAST(CAST('123456789.1234' AS DECIMAL(13,4)) AS JSON)`,
 	}, {
-		// opaque, bit field.
-		// FIXME(alainjobart) this is broken. It seems the '2'
-		// is the number of bytes (needed because there is no
-		// metadata), but I can't find how this works.
-		// So the parsing for now will produce an invalid string.
+		// opaque, bit field. Not yet implemented.
 		data:     []byte{15, 16, 2, 202, 254},
-		expected: `CAST('' AS JSON)`,
+		expected: `ERROR: opaque type 16 is not supported yet, with data [2 202 254]`,
 	}}
 
 	for _, tcase := range testcases {
 		r, err := printJSONData(tcase.data)
+		got := ""
 		if err != nil {
-			t.Errorf("unexpected error for %v: %v", tcase.data, err)
-			continue
+			got = fmt.Sprintf("ERROR: %v", err)
+		} else {
+			got = string(r)
 		}
-		if string(r) != tcase.expected {
-			t.Errorf("unexpected output for %v: got %v expected %v", tcase.data, string(r), tcase.expected)
+		if got != tcase.expected {
+			t.Errorf("unexpected output for %v: got %v expected %v", tcase.data, got, tcase.expected)
 		}
 	}
 }