perf tools: Change perf_mem__snp_scnprintf to return nb of displayed bytes

Moving strncat/strcpy calls into scnprintf to easily track number of
displayed bytes. It will be used in following patch.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/r/1456303616-26926-12-git-send-email-jolsa@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/mem-events.c

@@ -194,7 +194,7 @@ static const char * const snoop_access[] = {
 	"HitM",
 };
 
-void perf_mem__snp_scnprintf(char *out, size_t sz, struct mem_info *mem_info)
+int perf_mem__snp_scnprintf(char *out, size_t sz, struct mem_info *mem_info)
 {
 	size_t i, l = 0;
 	u64 m = PERF_MEM_SNOOP_NA;
@@ -212,12 +212,13 @@ void perf_mem__snp_scnprintf(char *out, size_t sz, struct mem_info *mem_info)
 			strcat(out, " or ");
 			l += 4;
 		}
-		strncat(out, snoop_access[i], sz - l);
-		l += strlen(snoop_access[i]);
+		l += scnprintf(out + l, sz - l, snoop_access[i]);
 	}
 
 	if (*out == '\0')
-		strcpy(out, "N/A");
+		l += scnprintf(out, sz - l, "N/A");
+
+	return l;
 }
 
 void perf_mem__lck_scnprintf(char *out, size_t sz __maybe_unused,

tools/perf/util/mem-events.h

@@ -27,7 +27,7 @@ char *perf_mem_events__name(int i);
 struct mem_info;
 int perf_mem__tlb_scnprintf(char *out, size_t sz, struct mem_info *mem_info);
 int perf_mem__lvl_scnprintf(char *out, size_t sz, struct mem_info *mem_info);
-void perf_mem__snp_scnprintf(char *out, size_t sz, struct mem_info *mem_info);
+int perf_mem__snp_scnprintf(char *out, size_t sz, struct mem_info *mem_info);
 void perf_mem__lck_scnprintf(char *out, size_t sz, struct mem_info *mem_info);
 
 #endif /* __PERF_MEM_EVENTS_H */