Fix edge cases when determing Query result packets

fixes #1547

Author: dougwilson

Changes.md

@@ -9,6 +9,7 @@ you spot any mistakes.
 * Accept regular expression as pool cluster pattern #1572
 * Accept wildcard anywhere in pool cluster pattern #1570
 * Add new error codes up to MySQL 5.7.17
+* Fix edge cases when determing Query result packets #1547
 * Fix memory leak when using long-running domains #1619 #1620
 * Update `bignumber.js` to 3.1.2
 

lib/protocol/sequences/Query.js

@@ -29,38 +29,32 @@ Query.prototype.start = function() {
   this.emit('packet', new Packets.ComQueryPacket(this.sql));
 };
 
-Query.prototype.determinePacket = function(firstByte, parser) {
-  if (firstByte === 0) {
-    // If we have a resultSet and got one eofPacket
-    if (this._resultSet && this._resultSet.eofPackets.length === 1) {
-      // Then this is a RowDataPacket with an empty string in the first column.
-      // See: https://github.com/mysqljs/mysql/issues/222
-    } else if (this._resultSet && this._resultSet.resultSetHeaderPacket
-           && this._resultSet.resultSetHeaderPacket.fieldCount !== null) {
-      return Packets.FieldPacket;
-    } else {
-      return undefined;
+Query.prototype.determinePacket = function determinePacket(byte, parser) {
+  var resultSet = this._resultSet;
+
+  if (!resultSet) {
+    switch (byte) {
+      case 0x00: return Packets.OkPacket;
+      case 0xff: return Packets.ErrorPacket;
+      default:   return Packets.ResultSetHeaderPacket;
     }
   }
 
-  if (firstByte === 255) {
-    return undefined;
+  if (resultSet.eofPackets.length === 0) {
+    return (resultSet.fieldPackets.length < resultSet.resultSetHeaderPacket.fieldCount)
+      ? Packets.FieldPacket
+      : Packets.EofPacket;
   }
 
-  // EofPacket's are 5 bytes in mysql >= 4.1
-  // This is the only / best way to differentiate their firstByte from a 9
-  // byte length coded binary.
-  if (firstByte === 0xfe && parser.packetLength() < 9) {
-    return Packets.EofPacket;
+  if (byte === 0xff) {
+    return Packets.ErrorPacket;
   }
 
-  if (!this._resultSet) {
-    return Packets.ResultSetHeaderPacket;
+  if (byte === 0xfe && parser.packetLength() < 9) {
+    return Packets.EofPacket;
   }
 
-  return (this._resultSet.eofPackets.length === 0)
-    ? Packets.FieldPacket
-    : Packets.RowDataPacket;
+  return Packets.RowDataPacket;
 };
 
 Query.prototype['OkPacket'] = function(packet) {
@@ -95,11 +89,10 @@ Query.prototype['ErrorPacket'] = function(packet) {
 };
 
 Query.prototype['ResultSetHeaderPacket'] = function(packet) {
-  this._resultSet = new ResultSet(packet);
-
-  // used by LOAD DATA LOCAL INFILE queries
   if (packet.fieldCount === null) {
     this._sendLocalDataFile(packet.extra);
+  } else {
+    this._resultSet = new ResultSet(packet);
   }
 };