[tip:perf/core] perf header: Add is_perf_magic() func

[tip-bot for Feng Tang]

Commit-ID:  e84ba4e26833991d1c1c15a592b1474ee2b6dfdb
Gitweb:     http://git.kernel.org/tip/e84ba4e26833991d1c1c15a592b1474ee2b6dfdb
Author:     Feng Tang <feng.tang@xxxxxxxxx>
AuthorDate: Tue, 30 Oct 2012 11:56:07 +0800
Committer:  Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
CommitDate: Mon, 29 Oct 2012 11:56:59 -0200

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@xxxxxxxxx>
Cc: Andi Kleen <andi@xxxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxx>
Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Link: http://lkml.kernel.org/r/1351569369-26732-7-git-send-email-feng.tang@xxxxxxxxx
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
---
 tools/perf/util/header.c |   10 ++++++++++
 tools/perf/util/header.h |    1 +
 2 files changed, 11 insertions(+), 0 deletions(-)

diff --git a/tools/perf/util/header.c b/tools/perf/util/header.c
index 514ed1b..195a47a 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 879d215..5f1cd68 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
--
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