1 files changed, 221 insertions, 0 deletions
diff --git a/plugin/type_mysql_json/type.cc b/plugin/type_mysql_json/type.cc
new file mode 100644
index 00000000..a39c4ad2
--- /dev/null
+++ b/plugin/type_mysql_json/type.cc
@@ -0,0 +1,221 @@
+/*
+   Copyright (c) 2020 MariaDB Foundation
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; version 2 of the License.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, write to the Free Software
+   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1335  USA */
+
+#include <my_global.h>
+#include <mysql/plugin_data_type.h>
+#include <sql_type.h>
+#include <field.h>
+#include <mysqld_error.h>
+#include "mysql_json.h"
+
+const LEX_CSTRING empty_clex_str= {"", 0};
+
+class Type_handler_mysql_json: public Type_handler_blob
+{
+public:
+  Field *make_conversion_table_field(MEM_ROOT *, TABLE *, uint, const Field *)
+    const override;
+  const Type_collection *type_collection() const override;
+  Field *make_table_field_from_def(TABLE_SHARE *, MEM_ROOT *,
+                                   const LEX_CSTRING *, const Record_addr &,
+                                   const Bit_addr &,
+                                   const Column_definition_attributes *,
+                                   uint32) const override;
+  Field *make_table_field(MEM_ROOT *, const LEX_CSTRING *,
+                          const Record_addr &, const Type_all_attributes &,
+                          TABLE_SHARE *) const override;
+  void Column_definition_reuse_fix_attributes(THD *thd,
+                                              Column_definition *def,
+                                              const Field *field) const override;
+  const Type_handler *type_handler_base() const override
+  {
+    /*
+      Override this method in the same way with what Type_handler_blob_json
+      does, to tell the server that MySQL JSON inherits aggregation behaviour
+      from the LONGBLOB data type.
+      This makes MariaDB JSON column and a MySQL JSON column compatible for
+      assignment, so "ALTER TABLE table_with_mysql_json FORCE" can run without
+      raising ER_ILLEGAL_PARAMETER_DATA_TYPES2_FOR_OPERATION.
+    */
+    return &type_handler_long_blob;
+  }
+};
+
+Type_handler_mysql_json type_handler_mysql_json;
+
+
+class Field_mysql_json: public Field_blob
+{
+public:
+  Field_mysql_json(uchar *ptr_arg, uchar *null_ptr_arg,
+                   uchar null_bit_arg, enum utype unireg_check_arg,
+                   const LEX_CSTRING *field_name_arg, TABLE_SHARE *share,
+                   uint blob_pack_length, const DTCollation &collation)
+    : Field_blob(ptr_arg, null_ptr_arg, null_bit_arg, unireg_check_arg,
+                 field_name_arg, share, blob_pack_length,
+                 &my_charset_utf8mb4_bin)
+  {}
+
+  String *val_str(String *val_buffer, String *val_str);
+  const Type_handler *type_handler() const { return &type_handler_mysql_json; }
+  bool parse_mysql(String *dest, const char *data, size_t length) const;
+  bool send(Protocol *protocol) { return Field::send(protocol); }
+  void sql_type(String &s) const
+  { s.set_ascii(STRING_WITH_LEN("json /* MySQL 5.7 */")); }
+  /* this will make ALTER TABLE to consider it different from built-in field */
+  Compression_method *compression_method() const { return (Compression_method*)1; }
+};
+
+Field *Type_handler_mysql_json::make_conversion_table_field(MEM_ROOT *root,
+                    TABLE *table, uint metadata, const Field *target) const
+{
+  uint pack_length= metadata & 0x00ff;
+  if (pack_length < 1 || pack_length > 4)
+    return NULL; // Broken binary log?
+  return new (root)
+         Field_mysql_json(NULL, (uchar *) "", 1, Field::NONE, &empty_clex_str,
+                          table->s, pack_length, target->charset());
+}
+
+Field *Type_handler_mysql_json::make_table_field_from_def(TABLE_SHARE *share,
+                 MEM_ROOT *root, const LEX_CSTRING *name,
+                 const Record_addr &addr, const Bit_addr &bit,
+                 const Column_definition_attributes *attr, uint32 flags) const
+{
+  return new (root) Field_mysql_json(addr.ptr(), addr.null_ptr(),
+                 addr.null_bit(), attr->unireg_check, name, share,
+                 attr->pack_flag_to_pack_length(), attr->charset);
+}
+
+void Type_handler_mysql_json::
+       Column_definition_reuse_fix_attributes(THD *thd,
+                                              Column_definition *def,
+                                              const Field *field) const
+{
+  Type_handler_blob::Column_definition_reuse_fix_attributes(thd, def, field);
+  def->decimals= 0;
+}
+
+
+
+Field *Type_handler_mysql_json::make_table_field(MEM_ROOT *root,
+                 const LEX_CSTRING *name, const Record_addr &addr,
+                 const Type_all_attributes &attr, TABLE_SHARE *share) const
+{
+  return new (root) Field_mysql_json(addr.ptr(), addr.null_ptr(),
+                 addr.null_bit(), Field::NONE, name, share, 2, attr.collation);
+}
+
+
+String *Field_mysql_json::val_str(String *val_buffer, String *val_ptr)
+{
+  String *raw_value= Field_blob::val_str(val_buffer, val_ptr);
+  String data;
+
+  data.copy(*raw_value);
+
+  val_ptr->length(0);
+  if (parse_mysql(val_ptr, data.ptr(), data.length()))
+  {
+    val_ptr->length(0);
+    my_printf_error(ER_UNKNOWN_ERROR,
+        "Error parsing MySQL JSON format, please dump this table from MySQL "
+        "and then restore it to be able to use it in MariaDB.", MYF(0));
+  }
+  return val_ptr;
+}
+
+bool Field_mysql_json::parse_mysql(String *dest,
+                                   const char *data, size_t length) const
+{
+  if (!data)
+    return false;
+
+  /* Each JSON blob must start with a type specifier. */
+  if (length < 2)
+    return true;
+
+  if (parse_mysql_json_value(dest, static_cast<JSONB_TYPES>(data[0]),
+                             reinterpret_cast<const uchar*>(data) + 1,
+                             length - 1, 0))
+    return true;
+
+  return false;
+}
+
+class Type_collection_mysql_json: public Type_collection
+{
+public:
+  const Type_handler *aggregate_for_result(const Type_handler *a,
+                                           const Type_handler *b)
+                                           const override
+  {
+    if (a == b)
+      return a;
+    return NULL;
+  }
+
+  const Type_handler *aggregate_for_min_max(const Type_handler *a,
+                                            const Type_handler *b)
+                                            const override
+  {
+    return aggregate_for_result(a, b);
+  }
+
+  const Type_handler *aggregate_for_comparison(const Type_handler *a,
+                                               const Type_handler *b)
+                                               const override
+  {
+    return aggregate_for_result(a, b);
+  }
+
+  const Type_handler *aggregate_for_num_op(const Type_handler *a,
+                                           const Type_handler *b)
+                                           const override
+  {
+    return NULL;
+  }
+};
+
+const Type_collection *Type_handler_mysql_json::type_collection() const
+{
+  static Type_collection_mysql_json type_collection_mysql_json;
+  return &type_collection_mysql_json;
+}
+
+static struct st_mariadb_data_type plugin_descriptor_type_mysql_json=
+{
+  MariaDB_DATA_TYPE_INTERFACE_VERSION,
+  &type_handler_mysql_json
+};
+
+maria_declare_plugin(type_mysql_json)
+{
+  MariaDB_DATA_TYPE_PLUGIN,
+  &plugin_descriptor_type_mysql_json,
+  "MYSQL_JSON",
+  "Anel Husaković, Vicențiu Ciorbaru",
+  "Data type MYSQL_JSON",
+  PLUGIN_LICENSE_GPL,
+  0,
+  0,
+  0x0001,
+  NULL,
+  NULL,
+  "0.1",
+  MariaDB_PLUGIN_MATURITY_STABLE
+}
+maria_declare_plugin_end;