perf tools: Introduce usage_with_options_msg()

Now usage_with_options() setup a pager before printing message so normal
printf() or pr_err() will not be shown.  The usage_with_options_msg()
can be used to print some help message before usage strings.

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Acked-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.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/1445701767-12731-4-git-send-email-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 15 insertions, 7 deletions

diff --git a/tools/perf/util/strbuf.c b/tools/perf/util/strbuf.c
index 4abe23550c73..25671fa16618 100644
--- a/tools/perf/util/strbuf.c
+++ b/tools/perf/util/strbuf.c
@@ -82,23 +82,22 @@ void strbuf_add(struct strbuf *sb, const void *data, size_t len)
 	strbuf_setlen(sb, sb->len + len);
 }
 
-void strbuf_addf(struct strbuf *sb, const char *fmt, ...)
+void strbuf_addv(struct strbuf *sb, const char *fmt, va_list ap)
 {
 	int len;
-	va_list ap;
+	va_list ap_saved;
 
 	if (!strbuf_avail(sb))
 		strbuf_grow(sb, 64);
-	va_start(ap, fmt);
+
+	va_copy(ap_saved, ap);
 	len = vsnprintf(sb->buf + sb->len, sb->alloc - sb->len, fmt, ap);
-	va_end(ap);
 	if (len < 0)
 		die("your vsnprintf is broken");
 	if (len > strbuf_avail(sb)) {
 		strbuf_grow(sb, len);
-		va_start(ap, fmt);
-		len = vsnprintf(sb->buf + sb->len, sb->alloc - sb->len, fmt, ap);
-		va_end(ap);
+		len = vsnprintf(sb->buf + sb->len, sb->alloc - sb->len, fmt, ap_saved);
+		va_end(ap_saved);
 		if (len > strbuf_avail(sb)) {
 			die("this should not happen, your vsnprintf is broken");
 		}
@@ -106,6 +105,15 @@ void strbuf_addf(struct strbuf *sb, const char *fmt, ...)
 	strbuf_setlen(sb, sb->len + len);
 }
 
+void strbuf_addf(struct strbuf *sb, const char *fmt, ...)
+{
+	va_list ap;
+
+	va_start(ap, fmt);
+	strbuf_addv(sb, fmt, ap);
+	va_end(ap);
+}
+
 ssize_t strbuf_read(struct strbuf *sb, int fd, ssize_t hint)
 {
 	size_t oldlen = sb->len;