linux-kernel - Re: [PATCH] tools lib: Reinstate strlcpy() header guard with __UCLIBC_

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Date:	Thu, 18 Aug 2016 11:07:22 -0300
From:	Arnaldo Carvalho de Melo <acme@...hat.com>
To:	Vineet Gupta <Vineet.Gupta1@...opsys.com>
Cc:	linux-kernel@...r.kernel.org, linux-snps-arc@...ts.infradead.org,
	osh Poimboeuf <jpoimboe@...hat.com>,
	Adrian Hunter <adrian.hunter@...el.com>,
	Alexey Brodkin <Alexey.Brodkin@...opsys.com>,
	David Ahern <dsahern@...il.com>, Jiri Olsa <jolsa@...nel.org>,
	Namhyung Kim <namhyung@...nel.org>,
	Wang Nan <wangnan0@...wei.com>,
	Petri Gynther <pgynther@...gle.com>,
	Peter Zijlstra <peterz@...radead.org>, acme@...nel.org
Subject: Re: [PATCH] tools lib: Reinstate strlcpy() header guard with
 __UCLIBC__

Em Wed, Aug 17, 2016 at 01:00:50PM -0700, Vineet Gupta escreveu:
> perf tools build in recent kernels spews splat when cross compiling with uClibc
> 
> |   CC       util/alias.o
> | In file included from tools/perf/util/../ui/../util/cache.h:8:0,
> |                 from tools/perf/util/../ui/helpline.h:7,
> |                 from tools/perf/util/debug.h:8,
> |                 from arch/../util/cpumap.h:9,
> |                 from arch/../util/env.h:5,
> |                 from arch/common.h:4,
> |                 from arch/common.c:3:
> | tools/include/linux/string.h:12:15: warning: redundant redeclaration of ‘strlcpy’ [-Wredundant-decls]
> |  extern size_t strlcpy(char *dest, const char *src, size_t size);
>                ^
> This is after commit 61a6445e463a31 ("tools lib: Guard the strlcpy() header with
> __GLIBC__"). While the commit was right in theory, issue is uClibc also
> defines __GLIBC__ for application headers.
> 
> Instead of reverting the commit, manually revert with some addeed commentary to
> same effect.

Well, you can't revert it, as this will make it break elsewhere. So
please check if

#if defined(__GLIBC__) && !defined(__UCLIBC__)

suits uclibc.

Are you aware of any readily available tarball or docker image that has
a uclibc based devel env that I could grab? I'd add it to my build setup
to make sure I (and my downstreamers) don't break uclibc environments in
the future.

- Arnaldo
 
> Cc: Adrian Hunter <adrian.hunter@...el.com>
> Cc: Alexey Brodkin <Alexey.Brodkin@...opsys.com>
> Cc: David Ahern <dsahern@...il.com>
> Cc: Jiri Olsa <jolsa@...nel.org>
> Cc: Namhyung Kim <namhyung@...nel.org>
> Cc: Wang Nan <wangnan0@...wei.com>
> Cc: Petri Gynther <pgynther@...gle.com>
> Cc: Peter Zijlstra (Intel) <peterz@...radead.org>
> Signed-off-by: Vineet Gupta <vgupta@...opsys.com>
> ---
>  tools/include/linux/string.h | 7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/tools/include/linux/string.h b/tools/include/linux/string.h
> index b96879477311..5a9e30334ffa 100644
> --- a/tools/include/linux/string.h
> +++ b/tools/include/linux/string.h
> @@ -8,7 +8,12 @@ void *memdup(const void *src, size_t len);
>  
>  int strtobool(const char *s, bool *res);
>  
> -#ifdef __GLIBC__
> +/*
> + * Ideally instead of blacklisting libs which define this already (uclibc,
> + * musl..), we could whitelist libs which reuire it (glibc). However uClibc
> + * also defines __GLIBC__ for user application headers
> + */
> +#ifndef __UCLIBC__
>  extern size_t strlcpy(char *dest, const char *src, size_t size);
>  #endif
>  
> -- 
> 2.7.4