From a09603f851045b031e990d2d663958ccb49db525 Mon Sep 17 00:00:00 2001 From: Jiri Olsa Date: Mon, 2 Jul 2018 15:42:01 +0200 Subject: [PATCH] perf tools: Fix compilation errors on gcc8 MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit We are getting following warnings on gcc8 that break compilation: $ make CC jvmti/jvmti_agent.o jvmti/jvmti_agent.c: In function ‘jvmti_open’: jvmti/jvmti_agent.c:252:35: error: ‘/jit-’ directive output may be truncated \ writing 5 bytes into a region of size between 1 and 4096 [-Werror=format-truncation=] snprintf(dump_path, PATH_MAX, "%s/jit-%i.dump", jit_path, getpid()); There's no point in checking the result of snprintf call in jvmti_open, the following open call will fail in case the name is mangled or too long. Using tools/lib/ function scnprintf that touches the return value from the snprintf() calls and thus get rid of those warnings. $ make DEBUG=1 CC arch/x86/util/perf_regs.o arch/x86/util/perf_regs.c: In function ‘arch_sdt_arg_parse_op’: arch/x86/util/perf_regs.c:229:4: error: ‘strncpy’ output truncated before terminating nul copying 2 bytes from a string of the same length [-Werror=stringop-truncation] strncpy(prefix, "+0", 2); ^~~~~~~~~~~~~~~~~~~~~~~~ Using scnprintf instead of the strncpy (which we know is safe in here) to get rid of that warning. Signed-off-by: Jiri Olsa Cc: Alexander Shishkin Cc: David Ahern Cc: Namhyung Kim Cc: Peter Zijlstra Link: http://lkml.kernel.org/r/20180702134202.17745-1-jolsa@kernel.org Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/arch/x86/util/perf_regs.c | 2 +- tools/perf/jvmti/jvmti_agent.c | 3 ++- 2 files changed, 3 insertions(+), 2 deletions(-) diff --git a/tools/perf/arch/x86/util/perf_regs.c b/tools/perf/arch/x86/util/perf_regs.c index 4b2caf6..fead6b3 100644 --- a/tools/perf/arch/x86/util/perf_regs.c +++ b/tools/perf/arch/x86/util/perf_regs.c @@ -226,7 +226,7 @@ int arch_sdt_arg_parse_op(char *old_op, char **new_op) else if (rm[2].rm_so != rm[2].rm_eo) prefix[0] = '+'; else - strncpy(prefix, "+0", 2); + scnprintf(prefix, sizeof(prefix), "+0"); } /* Rename register */ diff --git a/tools/perf/jvmti/jvmti_agent.c b/tools/perf/jvmti/jvmti_agent.c index 0c6d100..ac1bcdc 100644 --- a/tools/perf/jvmti/jvmti_agent.c +++ b/tools/perf/jvmti/jvmti_agent.c @@ -35,6 +35,7 @@ #include #include /* for gettid() */ #include +#include #include "jvmti_agent.h" #include "../util/jitdump.h" @@ -249,7 +250,7 @@ void *jvmti_open(void) /* * jitdump file name */ - snprintf(dump_path, PATH_MAX, "%s/jit-%i.dump", jit_path, getpid()); + scnprintf(dump_path, PATH_MAX, "%s/jit-%i.dump", jit_path, getpid()); fd = open(dump_path, O_CREAT|O_TRUNC|O_RDWR, 0666); if (fd == -1) -- 2.7.4