Re: [PATCH] lib: vsprintf: add printf format conversion %M for errno strings

From	"Enrico Weigelt, metux IT consult" <enrico.weigelt@gr13.net>
Newsgroups	linux.kernel
Subject	Re: [PATCH] lib: vsprintf: add printf format conversion %M for errno strings
Date	2017-06-25 22:00 +0200
Message-ID	<tWlRo-NX-5@gated-at.bofh.it> (permalink)
References	<tWjmy-7RM-17@gated-at.bofh.it> <tWjwd-7UO-1@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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On 25.06.2017 19:27, Joe Perches wrote:

> Every use of %M is going to cause gcc when using __printf to emit
> a warning like:
> 
> unknown conversion type character ‘M’ in format [-Wformat=]

Yeah, that's still an open problem. Actually, I still haven't found out,
how it's done w/ all the other kernel-internal conversions. I was under
the impression, there was some magic to tell the compiler which letters
correspond to which types - unfortunately, didn't find anything like
that. Is that really hardcoded in gcc ?

> Beyond that, why is this useful?

Use that instead of %d where errno values are printed/logged.

> There can't possibly be any fast-path use.

I'm using it eg. for driver development - always having to look up the
numbers is quite ugly and time consuming.

> Why not just create a function that does errno/string conversions?

Already was about to do so. Shall I call it strerror() ?

--mtx

--
Enrico, Sohn von Wilfried, a.d.F. Weigelt,
metux IT consulting
+49-151-27565287

Thread

[PATCH] lib: vsprintf: add printf format conversion %M for errno strings "Enrico Weigelt, metux IT consult" <enrico.weigelt@gr13.net> - 2017-06-25 19:20 +0200
  Re: [PATCH] lib: vsprintf: add printf format conversion %M for  errno strings Joe Perches <joe@perches.com> - 2017-06-25 19:30 +0200
    Re: [PATCH] lib: vsprintf: add printf format conversion %M for errno  strings "Enrico Weigelt, metux IT consult" <enrico.weigelt@gr13.net> - 2017-06-25 22:00 +0200
      Re: [PATCH] lib: vsprintf: add printf format conversion %M for  errno strings Joe Perches <joe@perches.com> - 2017-06-25 22:20 +0200
        Re: [PATCH] lib: vsprintf: add printf format conversion %M for errno  strings "Enrico Weigelt, metux IT consult" <enrico.weigelt@gr13.net> - 2017-06-25 23:20 +0200
          Re: [PATCH] lib: vsprintf: add printf format conversion %M for errno  strings Randy Dunlap <rdunlap@infradead.org> - 2017-06-26 00:50 +0200
            Re: [PATCH] lib: vsprintf: add printf format conversion %M for errno  strings "Enrico Weigelt, metux IT consult" <enrico.weigelt@gr13.net> - 2017-06-26 02:50 +0200
            Re: [PATCH] lib: vsprintf: add printf format conversion %M for  errno strings Bernd Petrovitsch <bernd@petrovitsch.priv.at> - 2017-06-27 13:10 +0200
  Re: [PATCH] lib: vsprintf: add printf format conversion %M for errno  strings Randy Dunlap <rdunlap@infradead.org> - 2017-06-25 19:30 +0200

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