perf tools: Add build_id__is_defined function

Adding build_id__is_defined helper to check build id is defined and is
!= zero build id.
Signed-off-by: NJiri Olsa <jolsa@kernel.org>
Acked-by: NNamhyung Kim <namhyung@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Alexey Budankov <alexey.budankov@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Michael Petlan <mpetlan@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Song Liu <songliubraving@fb.com>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lore.kernel.org/lkml/20201126170026.2619053-8-jolsa@kernel.orgSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/build-id.c

@@ -37,6 +37,7 @@
 
 #include <linux/ctype.h>
 #include <linux/zalloc.h>
+#include <linux/string.h>
 #include <asm/bug.h>
 
 static bool no_buildid_cache;
@@ -912,3 +913,8 @@ void build_id__init(struct build_id *bid, const u8 *data, size_t size)
 	memcpy(bid->data, data, size);
 	bid->size = size;
 }
+
+bool build_id__is_defined(const struct build_id *bid)
+{
+	return bid && bid->size ? !!memchr_inv(bid->data, 0, bid->size) : false;
+}

tools/perf/util/build-id.h

@@ -21,6 +21,7 @@ struct feat_fd;
 
 void build_id__init(struct build_id *bid, const u8 *data, size_t size);
 int build_id__sprintf(const struct build_id *build_id, char *bf);
+bool build_id__is_defined(const struct build_id *bid);
 int sysfs__sprintf_build_id(const char *root_dir, char *sbuild_id);
 int filename__sprintf_build_id(const char *pathname, char *sbuild_id);
 char *build_id_cache__kallsyms_path(const char *sbuild_id, char *bf,