perf script: Add --header/--header-only options

Currently the perf.data header is always displayed for stdio output,
which is no always useful.

Disabling header information by default and adding following options to
control header output:

  --header      - display header information
  --header-only - display header information only w/o further
                  processing
Signed-off-by: Jiri Olsa <jolsa@redhat.com>
Link: http://lkml.kernel.org/n/tip-0ehaawv5xc83w6ag03c5hi10@git.kernel.org
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/r/1386583370-1699-3-git-send-email-jolsa@redhat.comSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/Documentation/perf-script.txt

@@ -209,6 +209,12 @@ OPTIONS
 --show-mmap-events
 	Display mmap related events (e.g. MMAP, MMAP2).
 
+--header
+	Show perf.data header.
+
+--header-only
+	Show only perf.data header.
+
 SEE ALSO
 --------
 linkperf:perf-record[1], linkperf:perf-script-perl[1],

tools/perf/builtin-script.c

@@ -1494,6 +1494,8 @@ static int have_cmd(int argc, const char **argv)
 int cmd_script(int argc, const char **argv, const char *prefix __maybe_unused)
 {
 	bool show_full_info = false;
+	bool header = false;
+	bool header_only = false;
 	char *rec_script_path = NULL;
 	char *rep_script_path = NULL;
 	struct perf_session *session;
@@ -1532,6 +1534,8 @@ int cmd_script(int argc, const char **argv, const char *prefix __maybe_unused)
 	OPT_STRING('i', "input", &input_name, "file", "input file name"),
 	OPT_BOOLEAN('d', "debug-mode", &debug_mode,
 		   "do various checks like samples ordering and lost events"),
+	OPT_BOOLEAN(0, "header", &header, "Show data header."),
+	OPT_BOOLEAN(0, "header-only", &header_only, "Show only data header."),
 	OPT_STRING('k', "vmlinux", &symbol_conf.vmlinux_name,
 		   "file", "vmlinux pathname"),
 	OPT_STRING(0, "kallsyms", &symbol_conf.kallsyms_name,
@@ -1748,6 +1752,12 @@ int cmd_script(int argc, const char **argv, const char *prefix __maybe_unused)
 	if (session == NULL)
 		return -ENOMEM;
 
+	if (header || header_only) {
+		perf_session__fprintf_info(session, stdout, show_full_info);
+		if (header_only)
+			return 0;
+	}
+
 	script.session = session;
 
 	if (cpu_list) {
@@ -1755,9 +1765,6 @@ int cmd_script(int argc, const char **argv, const char *prefix __maybe_unused)
 			return -1;
 	}
 
-	if (!script_name && !generate_script_lang)
-		perf_session__fprintf_info(session, stdout, show_full_info);
-
 	if (!no_callchain)
 		symbol_conf.use_callchain = true;
 	else