Add `LOCAL INFILE` support

[mirromutth]

Motivation:

Add LOCAL INFILE support.

See also #206 .

Modification:

• [x] Improve envelope codec for SubsequenceClientMessage
• [x] Add LocalInfileRequest/LocalInfileResponse for text protocol
• [x] Add an option to enable/disable LOCAL INFILE support, and it should be a string to specify "safety path"
• [x] Add an option to specify file buffer size
• [x] Write docs

Result:

Query LOCAL INFILE support.

[mirromutth]

Hi, @jchrys @JohnNiang

In JDBC-MySQL, allowLoadLocalInfileInPath will work only if allowLoadLocalInfile=false. The allowLoadLocalInfile option means "allow LOAD DATA LOCAL INFILE and allow it to load file data from any path". It seems to be for historical reasons.

For example:

• allowLoadLocalInfile=true for allowed and unrestricted LOCAL INFILE
• allowLoadLocalInfileInPath=/opt for allowed and restricted LOCAL INFILE
• allowLoadLocalInfile=true&allowLoadLocalInfileInPath=/opt for allowed and UNRESTRICTED LOCAL INFILE, allowLoadLocalInfileInPath will be ignored

In my opinion, r2dbc-mysql should make allowLoadLocalInfile just mean "allow LOAD DATA LOCAL INFILE", and that can be restricted by loadLocalInfileInPath. Which means, loadLocalInfileInPath will work only if allowLoadLocalInfile=true, and all LOCAL INFILE can only read files in the path.

For example:

• allowLoadLocalInfile=true for allowed and unrestricted LOCAL INFILE
• allowLoadLocalInfile=true&loadLocalInfileInPath=/opt for allowed and restricted LOCAL INFILE
• loadLocalInfileInPath=/opt, LOCAL INFILE will not be allowed

This prevents users from accidentally setting up unrestricted file access.

Or we can make it the same as JDBC.

Any ideas?

[jchrys]

I agree with your idea but would like to suggest a slightly different approach.

What if we consider not supporting the allowLoadLocalInfile property? (or keep (jdbc version of)allowLoadLocalInfile = false)

I think that the property allowLoadLocalInfileInPath={path} could effectively convey the user's intentions(allowLoadLocalInfileInPath=/ for unrestricted case as well).

What are your thoughts on this?