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Date: Fri, 8 Mar 2024 01:52:28 +0100
From: Alejandro Colomar <alx@...nel.org>
To: Guillem Jover <guillem@...rons.org>, libc-alpha@...rceware.org,
musl@...ts.openwall.com
Cc: libbsd@...ts.freedesktop.org, "Serge E. Hallyn" <serge@...lyn.com>,
"Skyler Ferrante (RIT Student)" <sjf5462@....edu>,
Iker Pedrosa <ipedrosa@...hat.com>,
Christian Brauner <christian@...uner.io>,
shadow <~hallyn/shadow@...ts.sr.ht>
Subject: Re: Tweaking the program name for <err.h> functions
[TO += musl]
Hi!
On Fri, Mar 08, 2024 at 01:30:51AM +0100, Guillem Jover wrote:
> That is not portable because the BSDs do not support that variable.
> But all BSDs for which I've got a checkout (FreeBSD, NetBSD, OpenBSD,
> DragonflyBSD) support changing it via setprogname(), but that's not
> available in glibc (libbsd provides it though).
>
> libbsd and cosmopolitan libc support setting it via setprogname() or
> program_invocation_short_name.
>
> musl libc supports setting it via program_invocation_short_name.
>
> uclibc might support __progname and/or program_invocation_short_name
> depending on how it has been configured, but it does not support
> setting the err(3) program name via those.
Hmmm.
$ cat err.c
#define _GNU_SOURCE
#include <bsd/stdlib.h>
#include <err.h>
#include <errno.h>
#include <error.h>
int
main(void)
{
program_invocation_name = "foo";
program_invocation_short_name = "bar";
setprogname("baz");
error(0, errno, "fmt string");
err(1, "fmt2");
}
$ cc -Wall -Wextra err.c -lbsd
$ ./a.out
foo: fmt string
baz: fmt2: Success
This would already be portable enough for what I want, except that
libbsd isn't very welcome in some OSes as a core library. I guess I'll
need libc support.
>
> > Maybe it would be interesting to get the BSDs to support these pointers?
>
> They already have a way to control the program name though. (And
> it seems to me that using functions instead of global variables is
> superior. :)
Indeed. I didn't know about such function. I'll reformulate my
original suggestion to this other one:
How about adding setprogname(3) (and getprogname(3)) to GNU and musl
libc?
>
> Thanks,
> Guillem
Have a lovely night!
Alex
--
<https://www.alejandro-colomar.es/>
Looking for a remote C programming job at the moment.
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