fix JSON datatype string value truncated by '\0' (#5482)

Author: dingxiaobo

dbsync/src/main/java/com/taobao/tddl/dbsync/binlog/JsonConversion.java

@@ -158,7 +158,7 @@ private static Json_Value parse_scalar(int type, LogBuffer buffer, long len, Cha
                     throw new IllegalArgumentException("illegal json data");
                 }
                 return new Json_Value(Json_enum_type.STRING,
-                    buffer.rewind().forward((int) n).getFixString((int) str_len, charset));
+                    buffer.rewind().forward((int) n).getFixStringIgnore0000((int) str_len, charset));
             case JSONB_TYPE_OPAQUE:
                 /*
                  * There should always be at least one byte, which tells the field type of the
@@ -257,7 +257,7 @@ public String key(int i, Charset charset) {
             // entry, always two
             // bytes.
             long key_length = m_data.getUint16();
-            return m_data.rewind().forward((int) key_offset).getFixString((int) key_length, charset);
+            return m_data.rewind().forward((int) key_offset).getFixStringIgnore0000((int) key_length, charset);
         }
 
         public Json_Value element(int i, Charset charset) {
@@ -400,7 +400,7 @@ public StringBuilder toJsonString(StringBuilder buf, Charset charset) {
                                    }
                                    buf.append('"').append(text).append('"');
                                } else {
-                                   text = m_data.getFixString((int) m_length, charset);
+                                   text = m_data.getFixStringIgnore0000((int) m_length, charset);
                                    buf.append('"').append(escapse(text)).append('"');
                                }
 

dbsync/src/main/java/com/taobao/tddl/dbsync/binlog/LogBuffer.java

@@ -1156,6 +1156,22 @@ public final String getFixString(final int len, Charset charset) {
         return string;
     }
 
+    /**
+     * Return next fix length string from buffer. ignore \0
+     */
+    public final String getFixStringIgnore0000(final int len, Charset charset) {
+        if (position + len > origin + limit) {
+            throw new IllegalArgumentException("limit excceed: " + (position + len - origin));
+        }
+
+        final int from = position;
+        byte[] buf = buffer;
+
+        String string = new String(buf, from, len, charset);
+        position += len;
+        return string;
+    }
+
     public final String getFixName(final int len, Charset charset) {
         if (position + len > origin + limit) {
             throw new IllegalArgumentException("limit excceed: " + (position + len - origin));