From b608ddda22ac33195ba57311d42ac83facbd8695 Mon Sep 17 00:00:00 2001
From: Michal Schmidt <mschmidt@redhat.com>
Date: Thu, 16 Feb 2012 00:04:00 +0100
Subject: [PATCH 2/2] better error message

Only suggest CONFIG_LATENCYTOP on ENOENT.
Print the message after curses is cleaned up to make it visible.
---
 src/latencytop.c |   18 +++++++++++++++---
 1 files changed, 15 insertions(+), 3 deletions(-)

diff --git a/src/latencytop.c b/src/latencytop.c
index 0ffb7f3..3b62c5d 100644
--- a/src/latencytop.c
+++ b/src/latencytop.c
@@ -24,6 +24,7 @@
 
 #define _GNU_SOURCE
 
+#include <errno.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <unistd.h>
@@ -113,6 +114,17 @@ static void fixup_reason(struct latency_line *line, char *c)
 		strncpy(line->reason, c2, 1024);
 }
 
+static int die_errno;
+
+static void print_error_msg(void) {
+	if (!die_errno)
+		return;
+
+	fprintf(stderr, "Failed to open /proc/latency_stats: %s\n", strerror(die_errno));
+	if (die_errno == ENOENT)
+		fprintf(stderr, "Please enable the CONFIG_LATENCYTOP configuration in your kernel.\n");
+}
+
 void parse_global_list(void)
 {
 	FILE *file;
@@ -120,8 +132,7 @@ void parse_global_list(void)
 	size_t dummy;
 	file = fopen("/proc/latency_stats","r+");
 	if (!file) {
-		fprintf(stderr, "Please enable the CONFIG_LATENCYTOP configuration in your kernel.\n");
-		fprintf(stderr, "Exiting...\n");
+		die_errno = errno;
 		exit(EXIT_FAILURE);
 	}
 	/* wipe first line */
@@ -540,7 +551,8 @@ int main(int argc, char **argv)
 
 	enable_sysctl();
 	atexit(cleanup_sysctl);
-
+	/* needs to run after curses is gone */
+	atexit(print_error_msg);
 #ifdef HAS_GTK_GUI
 	if (preinitialize_gtk_ui(&argc, &argv))
 		use_gtk = 1;
-- 
1.7.7.6