perf header: Add is_perf_magic() func

With this function, other modules can basically check whether a file is
a legal perf data file by checking its first 8 bytes against all
possible perf magic numbers.

Change the function name from check_perf_magic to more meaningful
is_perf_magic as suggested by acme.

Signed-off-by: Feng Tang <feng.tang@intel.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1351569369-26732-7-git-send-email-feng.tang@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

2 files changed, 11 insertions, 0 deletions

diff --git a/tools/perf/util/header.c b/tools/perf/util/header.c
index 514ed1bd41a2..195a47a8f052 100644
--- a/tools/perf/util/header.c
+++ b/tools/perf/util/header.c
@@ -2341,6 +2341,16 @@ static int try_all_pipe_abis(uint64_t hdr_sz, struct perf_header *ph)
         return -1;
 }
 
+bool is_perf_magic(u64 magic)
+{
+        if (!memcmp(&magic, __perf_magic1, sizeof(magic))
+                || magic == __perf_magic2
+                || magic == __perf_magic2_sw)
+                return true;
+
+        return false;
+}
+
 static int check_magic_endian(u64 magic, uint64_t hdr_sz,
                               bool is_pipe, struct perf_header *ph)
 {
diff --git a/tools/perf/util/header.h b/tools/perf/util/header.h
index 879d215cdac9..5f1cd6884f37 100644
--- a/tools/perf/util/header.h
+++ b/tools/perf/util/header.h
@@ -154,6 +154,7 @@ int perf_event__synthesize_build_id(struct perf_tool *tool,
 int perf_event__process_build_id(struct perf_tool *tool,
                                  union perf_event *event,
                                  struct perf_session *session);
+bool is_perf_magic(u64 magic);
 
 /*
  * arch specific callback