Updating the mysql2_mysql_enc_to_rb conversion table to 8.0 List (#976)

Also add a check to make sure we do not go out of bounds.

Author: QuantamHD

.travis.yml

@@ -13,6 +13,7 @@ addons:
   hosts:
     - mysql2gem.example.com
   apt:
+    update: true
     packages:
     - mysql-server-5.6
     - mysql-client-core-5.6

ext/mysql2/mysql_enc_to_ruby.h

@@ -245,5 +245,15 @@ static const char *mysql2_mysql_enc_to_rb[] = {
   "UTF-8",
   "UTF-8",
   "UTF-8",
+  "UTF-8",
+  NULL,
+  NULL,
+  NULL,
+  NULL,
+  NULL,
+  NULL,
+  NULL,
   "UTF-8"
 };
+
+#define CHARSETNR_SIZE (sizeof(mysql2_mysql_enc_to_rb)/sizeof(mysql2_mysql_enc_to_rb[0]))

ext/mysql2/result.c

@@ -179,7 +179,8 @@ static VALUE mysql2_set_field_string_encoding(VALUE val, MYSQL_FIELD field, rb_e
     const char *enc_name;
     int enc_index;
 
-    enc_name = mysql2_mysql_enc_to_rb[field.charsetnr-1];
+    enc_name = (field.charsetnr-1 < CHARSETNR_SIZE) ? mysql2_mysql_enc_to_rb[field.charsetnr-1] : NULL;
+    
     if (enc_name != NULL) {
       /* use the field encoding we were able to match */
       enc_index = rb_enc_find_index(enc_name);