[tip:perf/core] perf tools: Setup pager when printing usage and help

[tip-bot for Namhyung Kim <tipbot@zytor.com>]

Commit-ID:  01b19455c08cc37d1c3ef174524278e84c92fec1
Gitweb:     http://git.kernel.org/tip/01b19455c08cc37d1c3ef174524278e84c92fec1
Author:     Namhyung Kim <namhyung@kernel.org>
AuthorDate: Sun, 25 Oct 2015 00:49:26 +0900
Committer:  Arnaldo Carvalho de Melo <acme@redhat.com>
CommitDate: Mon, 26 Oct 2015 14:08:48 -0300

perf tools: Setup pager when printing usage and help

It's annoying to see error or help message when command has many options
like in perf record, report or top.  So setup pager when print parser
error or help message - it should be OK since no UI is enabled at the
parsing time.  The usage_with_options() already disables it by calling
exit_browser() anyway.

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Acked-by: Ingo Molnar <mingo@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1445701767-12731-3-git-send-email-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
 tools/perf/util/parse-options.c | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/tools/perf/util/parse-options.c b/tools/perf/util/parse-options.c
index b8d9822..eeeed98 100644
--- a/tools/perf/util/parse-options.c
+++ b/tools/perf/util/parse-options.c
@@ -7,6 +7,8 @@
 #define OPT_SHORT 1
 #define OPT_UNSET 2
 
+static struct strbuf error_buf = STRBUF_INIT;
+
 static int opterror(const struct option *opt, const char *reason, int flags)
 {
 	if (flags & OPT_SHORT)
@@ -540,9 +542,11 @@ int parse_options_subcommand(int argc, const char **argv, const struct option *o
 		exit(130);
 	default: /* PARSE_OPT_UNKNOWN */
 		if (ctx.argv[0][1] == '-') {
-			error("unknown option `%s'", ctx.argv[0] + 2);
+			strbuf_addf(&error_buf, "unknown option `%s'",
+				    ctx.argv[0] + 2);
 		} else {
-			error("unknown switch `%c'", *ctx.opt);
+			strbuf_addf(&error_buf, "unknown switch `%c'",
+				    *ctx.opt);
 		}
 		usage_with_options(usagestr, options);
 	}
@@ -711,6 +715,13 @@ int usage_with_options_internal(const char * const *usagestr,
 	if (!usagestr)
 		return PARSE_OPT_HELP;
 
+	setup_pager();
+
+	if (strbuf_avail(&error_buf)) {
+		fprintf(stderr, "  Error: %s\n", error_buf.buf);
+		strbuf_release(&error_buf);
+	}
+
 	fprintf(stderr, "\n Usage: %s\n", *usagestr++);
 	while (*usagestr && **usagestr)
 		fprintf(stderr, "    or: %s\n", *usagestr++);