Bug #76601 MySQL JSON UDFs: json_valid is reporting a valid JSON string as invalid

Description:
json_valid is returning 0 for a valid JSON string.  I am working with reddit comment data and this is the JSON block that is should report as valid.

{"gilded":0,"author_flair_css_class":null,"id":"n5","link_id":"t3_7k62w","subreddit":"WTF","downs":0,"ups":1,"edited":false,"score":1,"author":"[deleted]","subreddit_id":"t5_2qh61","body":"Maybe it's because involuntary imprisonment isn't natural. And [punishment](http://en.wikipedia.org/wiki/Punishment_(psychology\\)#Types_of_punishment) is the least effective behavior modifier.\n\nJust sayin'","retrieved_on":1428217161,"author_flair_text":null,"parent_id":"t1_c06vqpp","score_hidden":false,"controversiality":0,"name":"t1_n5","distinguished":null,"archived":true,"created_utc":"1229583186"}

You can use http://json.parser.online.fr/ and copy and paste that string to confirm that it is indeed valid.

How to repeat:
(I've escaped single quotes within this JSON in the following example)

SELECT json_valid('{"gilded":0,"author_flair_css_class":null,"id":"n5","link_id":"t3_7k62w","subreddit":"WTF","downs":0,"ups":1,"edited":false,"score":1,"author":"[deleted]","subreddit_id":"t5_2qh61","body":"Maybe it\'s because involuntary imprisonment isn\'t natural. And [punishment](http://en.wikipedia.org/wiki/Punishment_(psychology\\)#Types_of_punishment) is the least effective behavior modifier.\n\nJust sayin\'","retrieved_on":1428217161,"author_flair_text":null,"parent_id":"t1_c06vqpp","score_hidden":false,"controversiality":0,"name":"t1_n5","distinguished":null,"archived":true,"created_utc":"1229583186"}');
+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| json_valid('{"gilded":0,"author_flair_css_class":null,"id":"n5","link_id":"t3_7k62w","subreddit":"WTF","downs":0,"ups":1,"edited":false,"score":1,"author":"[deleted]","subreddit_id":"t5_2qh61","body":"Maybe it\'s because involuntary imprisonment isn\'t nat |
+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
|                                                                                                                                                                                                                                                                0 |
+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+

Suggested fix:
I haven't narrowed down what part of this JSON is giving the JSON UDF an issue, but hopefully the developer can narrow it down.

I've narrowed it down -- it is the two backslashes in the original JSON that is giving the UDF an issue.  It's still a valid bug.

The root cause of this issue may be related to bug #76598 in how the function is unescaping internally -- perhaps there is a mis-sequence of events internally between the MySQL unescaping and JSON spec unescaping.  

Just some ideas for Sveta if he is the one that will be looking at these bugs.

Thanks!

Hello Jason Baumgartner,

Thank you for the report.

Thanks,
Umesh