Horton

Re: encode/decode support for base64url

Florents Tselai <florents.tselai@gmail.com>

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From: Florents Tselai <florents.tselai@gmail.com>
To: "Chao (Evan) Li" <li.evan.chao@gmail.com>
Cc: Daniel Gustafsson <daniel@yesql.se>, Masahiko Sawada <sawada.mshk@gmail.com>, "David E. Wheeler" <david@justatheory.com>, Aleksander Alekseev <aleksander@tigerdata.com>, PostgreSQL Hackers <pgsql-hackers@postgresql.org>, Cary Huang <cary.huang@highgo.ca>, Przemysław Sztoch <przemyslaw@sztoch.pl>
Date: 2025-09-19T06:45:21Z
Lists: pgsql-hackers 

> On 19 Sep 2025, at 6:50 AM, Chao Li <li.evan.chao@gmail.com> wrote:

Great to see you around Evan!

> 
> I reviewed and tested this patch. Overall looks good to me. Actually, I think this patched fixed a bug of current implementation of base64 encoding by moving the logic of handling newline into “if (pos<0)”.

IIUC what you mean, I can’t confirm that.

Both existing and new implementation handle new lines the same 

SELECT decode(E'QUFB\nQUFB', 'base64url');
     decode     
----------------
 \x414141414141
(1 row)


> 
> Just a few small comments:
> 
>> On Sep 19, 2025, at 03:19, Daniel Gustafsson <daniel@yesql.se> wrote:
>> 
>> <v9-0001-Add-support-for-base64url-encoding-and-decoding.patch>
> 
> 
> 1.
> ```
> + * Helper for decoding base64 or base64url.  When url is passed as true the
> + * input will be encoded using base64url.  len bytes in src is encoded into
> + * dst.
> + */
> ```
> 
> It’s not common to use two white-spaces after “.”, usually we need only one.

I agree with this

> 
> 2.
> ```
> +	/* handle remainder */
>  	if (pos != 2)
> ```
> 
> The comment is understandable, but slightly vague: remainder of what?
> 
> Maybe rephrase to “handle remaining bytes in buf”.

Agree too.

> 
> 3.
> ```
>  					ereport(ERROR,
>  							(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
> -							 errmsg("unexpected \"=\" while decoding base64 sequence")));
> +							 errmsg("unexpected \"=\" while decoding %s sequence", url ? "base64url" : "base64")));
> ```
> 
> This is a normal usage that injects sub-strings based on condition. However, PG doesn’t like that, see here: https://www.postgresql.org/docs/devel/nls-programmer.html#NLS-GUIDELINES 

Well, that’s a very interesting catch. 
I’ll let a comitter confirm & advise.