From a977e40defa5a3c945e46db5cf3cd45f46473ece Mon Sep 17 00:00:00 2001
From: Anel Husakovic <anel@mariadb.org>
Date: Tue, 7 May 2019 07:51:01 -0700
Subject: Add parse_array_or_object()

---
 sql/field.cc | 58 ++++++++++++++++++++++++++++++++++++++++++++++++++++++----
 sql/field.h  | 10 +++++++---
 2 files changed, 61 insertions(+), 7 deletions(-)

diff --git a/sql/field.cc b/sql/field.cc
index 3a234afc719..0d758a08455 100644
--- a/sql/field.cc
+++ b/sql/field.cc
@@ -11226,7 +11226,57 @@ bool Field_mysql_json::val_json (Json_wrapper *wr)
   wr->steal(&w);
   return false;
 }
+/**
+  Read an offset or size field from a buffer. The offset could be either
+  a two byte unsigned integer or a four byte unsigned integer.
+
+  @param data  the buffer to read from
+  @param large tells if the large or small storage format is used; true
+               means read four bytes, false means read two bytes
+*/
+size_t read_offset_or_size(const char *data, bool large)
+{
+  return large ? uint4korr(data) : uint2korr(data);
+}
+
+bool parse_array_or_object(Field_mysql_json::enum_type t, const char *data, size_t len,
+                           bool large)
+{
+  //DBUG_ASSERT(t == Field_mysql_json::ARRAY || t == Field_mysql_json::OBJECT);
+  /*
+    Make sure the document is long enough to contain the two length fields
+    (both number of elements or members, and number of bytes).
+  */
+  const size_t offset_size= large ? LARGE_OFFSET_SIZE : SMALL_OFFSET_SIZE;
+  if (len < 2 * offset_size)
+    return true;
+  const size_t element_count= read_offset_or_size(data, large);
+  const size_t bytes= read_offset_or_size(data + offset_size, large);
+
+  // The value can't have more bytes than what's available in the data buffer.
+  if (bytes > len)
+    return true;
 
+  /*
+    Calculate the size of the header. It consists of:
+    - two length fields
+    - if it is a JSON object, key entries with pointers to where the keys
+      are stored
+    - value entries with pointers to where the actual values are stored
+  */
+  size_t header_size= 2 * offset_size;
+  if (t==Field_mysql_json::OBJECT)
+    header_size+= element_count *
+      (large ? KEY_ENTRY_SIZE_LARGE : KEY_ENTRY_SIZE_SMALL);
+  header_size+= element_count *
+    (large ? VALUE_ENTRY_SIZE_LARGE : VALUE_ENTRY_SIZE_SMALL);
+
+  // The header should not be larger than the full size of the value.
+  if (header_size > bytes)
+    return true;                             /* purecov: inspected */
+  //return Value(t, data, bytes, element_count, large);
+  return 1;
+}
 bool Field_mysql_json::parse_mysql(String *s, bool json_quoted,
                                    const char *func_name) const
 {
@@ -11261,13 +11311,13 @@ bool Field_mysql_json::parse_mysql(String *s, bool json_quoted,
 
   size_t type= data[0];
 
-  //const char* data1=data+1;
-  //size_t len=len-1;
+  const char* data1=data+1;
+  size_t len=length-1;
 
   switch (type)
   {
   case JSONB_TYPE_SMALL_OBJECT:
-    return false; //this->parse_array_or_object(Field_mysql_json::OBJECT, data1, len, false);
+    return parse_array_or_object(Field_mysql_json::OBJECT, data1, len, false);
   case JSONB_TYPE_LARGE_OBJECT:
     return false; //this->parse_array_or_object(Field_mysql_json::OBJECT, data1, len, true);
   case JSONB_TYPE_SMALL_ARRAY:
@@ -11278,8 +11328,8 @@ bool Field_mysql_json::parse_mysql(String *s, bool json_quoted,
     return false;//this->parse_scalar(type, data, len);
   }
 
-
 }
+
  String *Field_mysql_json::val_str(String *buf1_tmp, String *buf2 __attribute__((unused)))
 {
   ASSERT_COLUMN_MARKED_FOR_READ;
diff --git a/sql/field.h b/sql/field.h
index 14e4b104c3e..b50cbc85b7f 100644
--- a/sql/field.h
+++ b/sql/field.h
@@ -4924,7 +4924,7 @@ class Field_mysql_json :public Field_blob
      @param[in,out] buf1 string buffer for converting JSON value to string
     @param[in,out] buf2 unused
   */
-   enum enum_type
+  enum enum_type
   {
     OBJECT, ARRAY, STRING, INT, UINT, DOUBLE,
     LITERAL_NULL, LITERAL_TRUE, LITERAL_FALSE,
@@ -4934,8 +4934,12 @@ class Field_mysql_json :public Field_blob
   };
   String *val_str(String *, String *);
   bool parse_mysql(String*, bool, const char *) const;
-  bool parse_array_or_object();
-  bool parse_scalar();
+  //size_t read_offset_or_size(const char *, bool);
+  //enum_type type() const {return m_type;}
+  //bool parse_array_or_object(bool, const char *,size_t ,bool);
+  //bool parse_scalar();
+  //private:
+  //  const enum_type m_type;
 
 };
 
-- 
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