Re: thread-safety: gmtime_r(), localtime_r()

On Thu, Jun 27, 2024 at 1:42 AM Peter Eisentraut <peter(at)eisentraut(dot)org>
wrote:

> Here is a patch for using gmtime_r() and localtime_r() instead of
> gmtime() and localtime(), for thread-safety.
>
> There are a few affected calls in libpq and ecpg's libpgtypes, which are
> probably effectively bugs, because those libraries already claim to be
> thread-safe.
>
> There is one affected call in the backend. Most of the backend
> otherwise uses the custom functions pg_gmtime() and pg_localtime(),
> which are implemented differently.
>
> Some portability fun: gmtime_r() and localtime_r() are in POSIX but are
> not available on Windows. Windows has functions gmtime_s() and
> localtime_s() that can fulfill the same purpose, so we can add some
> small wrappers around them. (Note that these *_s() functions are also
> different from the *_s() functions in the bounds-checking extension of
> C11. We are not using those here.)
>
> MinGW exposes neither *_r() nor *_s() by default. You can get at the
> POSIX-style *_r() functions by defining _POSIX_C_SOURCE appropriately
> before including <time.h>. (There is apparently probably also a way to
> get at the Windows-style *_s() functions by supplying some additional
> options or defines. But we might as well just use the POSIX ones.)
>
>
Hi! Looks good to me.
But why you don`t change localtime function at all places?
For example:
src/bin/pg_controldata/pg_controldata.c
src/bin/pg_dump/pg_backup_archiver.c
src/bin/initdb/findtimezone.c
Best regards, Stepan Neretin.