bug#63590: 29.0.90; can't load sqlite extension

[Eli Zaretskii <eliz@gnu.org>]

> Date: Fri, 19 May 2023 15:25:21 +0200
> From:  Lennart Vogelsang via "Bug reports for GNU Emacs,
>  the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>
> 
> To reproduce, I've created an empty folder, cd'ed into it, started
> emacs -Q, copied the sqlite's csv extension source code [0] into 
> csvtable.c,
> compiled it with
> 
>       gcc -O3 -Wall -Wno-unknown-pragmas -fPIC -shared -lm -o 
> csvtable.so csvtable.c
> 
> and executed the following elisp forms in the scratch buffer:
> 
>       (setq-local mydb (sqlite-open))
>       (sqlite-load-extension mydb "./csvtable.so")
> 
> I get a nil return value from the second expression, indicating
> that it did not load the extension (verified by using the `csv` module
> in a `sqlite-execute` call). If I try the same from the `sqlite3` cli
> interface, it works:
> 
>       .load ./csvtable.so

I think you made one more change to csv.c: you renamed the function
sqlite3_csv_init to the name sqlite3_csvtable_init.  Otherwise, the
loading would fail, because sqlite3's cli will not find the entry
function it expects.

More importantly: the csv.c source file to which you point, viz.:

  https://www.sqlite.org/src/artifact?ci=trunk&filename=ext/misc/csv.c

is NOT the source file of the libsqlite3_mod_csvtable.so extension
distributed by Debian, which we currently have on the "allow list", it
is a different extension.  The source of csvtable is here:

  https://packages.debian.org/sid/libsqlite3-mod-csvtable