bug#29992: [PATCH] services: postgresql: Use pg_ctl to start and stop postgres.

["Clément Lassieur" <clement@lassieur.org>]

Ludovic Courtès <ludo@gnu.org> writes:

> Clément Lassieur <clement@lassieur.org> skribis:
>
>> Fixes <https://bugs.gnu.org/29992>.
>>
>> * gnu/services/databases.scm (postgresql-shepherd-service): Replace
>> make-forkexec-constructor and make-kill-destructor with pg_ctl.
>
> [...]
>
>> +     (let* ((pg_ctl-wrapper
>> +             ;; Wrapper script that switches to the 'postgres' user before
>> +             ;; launching daemon.
>> +             (program-file
>> +              "pg_ctl-wrapper"
>> +              #~(begin
>> +                  (use-modules (ice-9 match)
>> +                               (ice-9 format))
>> +                  (match (command-line)
>> +                    ((_ mode)
>> +                     (let ((user (getpwnam "postgres"))
>> +                           (pg_ctl #$(file-append postgresql "/bin/pg_ctl")))
>> +                       (setgid (passwd:gid user))
>> +                       (setuid (passwd:uid user))
>> +                       (system
>> +                        (format #f "~a -D ~a -o '--config-file=~a -p ~d' ~a"
>> +                                pg_ctl #$data-directory #$config-file #$port
>> +                                mode))))))))
>
> I think we should use ‘execl’ here instead of ‘system’ so that (1) the
> exit code is correct, and (2) we don’t go through /bin/sh.

Hi Ludovic, thank you for the review.

How do you pass single quotes as an ‘execl’ argument?

https://www.postgresql.org/docs/9.3/static/app-pg-ctl.html says:
--8<---------------cut here---------------start------------->8---
-o options
    Specifies options to be passed directly to the postgres command.
    The options should usually be surrounded by single or double quotes
    to ensure that they are passed through as a group.
--8<---------------cut here---------------end--------------->8---

Also, I don't understand how the exit code matters since Guile scripts
seem to always return 0, no matter if the last return value is true or
false.

Clément