perf tools: Use scnprintf where applicable

Several places were expecting that the value returned was the number of
characters printed, not what would be printed if there was space.

Fix it by using the scnprintf and vscnprintf variants we inherited from
the kernel sources.

Some corner cases where the number of printed characters were not
accounted were fixed too.

Reported-by: Anton Blanchard <anton@samba.org>
Cc: Anton Blanchard <anton@samba.org>
Cc: Eric B Munson <emunson@mgebm.net>
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Yanmin Zhang <yanmin_zhang@linux.intel.com>
Cc: stable@kernel.org
Link: http://lkml.kernel.org/n/tip-kwxo2eh29cxmd8ilixi2005x@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 1 insertions, 1 deletions

diff --git a/tools/perf/util/ui/helpline.c b/tools/perf/util/ui/helpline.c
index 4f48f5901b30..2f950c2641c8 100644
--- a/tools/perf/util/ui/helpline.c
+++ b/tools/perf/util/ui/helpline.c
@@ -64,7 +64,7 @@ int ui_helpline__show_help(const char *format, va_list ap)
         static int backlog;
 
         pthread_mutex_lock(&ui__lock);
-        ret = vsnprintf(ui_helpline__last_msg + backlog,
+        ret = vscnprintf(ui_helpline__last_msg + backlog,
                         sizeof(ui_helpline__last_msg) - backlog, format, ap);
         backlog += ret;