linux-kernel - [PATCH 2/3] tools lib: Reinstate strlcpy() header guard with __UCLIBC_

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Date:   Thu, 18 Aug 2016 17:40:53 -0300
From:   Arnaldo Carvalho de Melo <acme@...nel.org>
To:     Ingo Molnar <mingo@...nel.org>
Cc:     linux-kernel@...r.kernel.org,
        Vineet Gupta <Vineet.Gupta1@...opsys.com>,
        Vineet Gupta <vgupta@...opsys.com>,
        Adrian Hunter <adrian.hunter@...el.com>,
        Alexey Brodkin <Alexey.Brodkin@...opsys.com>,
        David Ahern <dsahern@...il.com>, Jiri Olsa <jolsa@...nel.org>,
        Josh Poimboeuf <jpoimboe@...hat.com>,
        Namhyung Kim <namhyung@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Petri Gynther <pgynther@...gle.com>,
        Wang Nan <wangnan0@...wei.com>,
        linux-snps-arc@...ts.infradead.org,
        Arnaldo Carvalho de Melo <acme@...hat.com>
Subject: [PATCH 2/3] tools lib: Reinstate strlcpy() header guard with __UCLIBC__

From: Vineet Gupta <Vineet.Gupta1@...opsys.com>

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__").

The problem is uClibc also defines __GLIBC__ for exported headers for
applications. So add that specific check to not trip for uClibc.

Signed-off-by: Vineet Gupta <vgupta@...opsys.com>
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: Josh Poimboeuf <jpoimboe@...hat.com>
Cc: Namhyung Kim <namhyung@...nel.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Petri Gynther <pgynther@...gle.com>
Cc: Wang Nan <wangnan0@...wei.com>
Cc: linux-snps-arc@...ts.infradead.org
Link: http://lkml.kernel.org/r/1471537703-16439-1-git-send-email-vgupta@synopsys.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@...hat.com>
---
 tools/include/linux/string.h | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/tools/include/linux/string.h b/tools/include/linux/string.h
index b96879477311..f436d2420a18 100644
--- a/tools/include/linux/string.h
+++ b/tools/include/linux/string.h
@@ -8,7 +8,11 @@ void *memdup(const void *src, size_t len);
 
 int strtobool(const char *s, bool *res);
 
-#ifdef __GLIBC__
+/*
+ * glibc based builds needs the extern while uClibc doesn't.
+ * However uClibc headers also define __GLIBC__ hence the hack below
+ */
+#if defined(__GLIBC__) && !defined(__UCLIBC__)
 extern size_t strlcpy(char *dest, const char *src, size_t size);
 #endif
 
-- 
2.7.4