From: Jiri Olsa <jolsa@xxxxxxxxxx> [ Upstream commit 279ab04dbea1370d2eac0f854270369ccaef8a44 ] We are getting false positive gcc warning when we compile with gcc9 (9.1.1): CC jvmti/libjvmti.o In file included from /usr/include/string.h:494, from jvmti/libjvmti.c:5: In function ‘strncpy’, inlined from ‘copy_class_filename.constprop’ at jvmti/libjvmti.c:166:3: /usr/include/bits/string_fortified.h:106:10: error: ‘__builtin_strncpy’ specified bound depends on the length of the source argument [-Werror=stringop-overflow=] 106 | return __builtin___strncpy_chk (__dest, __src, __len, __bos (__dest)); | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ jvmti/libjvmti.c: In function ‘copy_class_filename.constprop’: jvmti/libjvmti.c:165:26: note: length computed here 165 | size_t file_name_len = strlen(file_name); | ^~~~~~~~~~~~~~~~~ cc1: all warnings being treated as errors As per Arnaldo's suggestion use strlcpy(), which does the same thing and keeps gcc silent. Suggested-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx> Signed-off-by: Jiri Olsa <jolsa@xxxxxxxxxx> Cc: Alexander Shishkin <alexander.shishkin@xxxxxxxxxxxxxxx> Cc: Ben Gainey <ben.gainey@xxxxxxx> Cc: Namhyung Kim <namhyung@xxxxxxxxxx> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> Cc: Stephane Eranian <eranian@xxxxxxxxxx> Link: http://lkml.kernel.org/r/20190531131321.GB1281@krava Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> --- tools/perf/jvmti/libjvmti.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/tools/perf/jvmti/libjvmti.c b/tools/perf/jvmti/libjvmti.c index 6add3e982614..3361d98a4edd 100644 --- a/tools/perf/jvmti/libjvmti.c +++ b/tools/perf/jvmti/libjvmti.c @@ -1,5 +1,6 @@ // SPDX-License-Identifier: GPL-2.0 #include <linux/compiler.h> +#include <linux/string.h> #include <sys/types.h> #include <stdio.h> #include <string.h> @@ -150,8 +151,7 @@ copy_class_filename(const char * class_sign, const char * file_name, char * resu result[i] = '\0'; } else { /* fallback case */ - size_t file_name_len = strlen(file_name); - strncpy(result, file_name, file_name_len < max_length ? file_name_len : max_length); + strlcpy(result, file_name, max_length); } } -- 2.20.1