[PATCH iproute2-next 6/7] genl: put help to stdout and usage to stderr

[Stephen Hemminger <stephen@networkplumber.org>]

Similar change to other iproute2 commands.
Syntax error should print to stderr and exit with non-zero.
Help command should print to stdout and exit with zero status.

Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
---
 genl/genl.c | 14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/genl/genl.c b/genl/genl.c
index b497a3ad..27b679df 100644
--- a/genl/genl.c
+++ b/genl/genl.c
@@ -7,6 +7,8 @@
 
 #include <stdio.h>
 #include <stdlib.h>
+#include <stdbool.h>
+#include <stddef.h>
 #include <unistd.h>
 #include <fcntl.h>
 #include <dlfcn.h>
@@ -90,16 +92,16 @@ noexist:
 	return f;
 }
 
-static void usage(void) __attribute__((noreturn));
+static void usage(bool help) __attribute__((noreturn));
 
-static void usage(void)
+static void usage(bool help)
 {
-	fprintf(stderr,
+	fprintf(help ? stdout : stderr,
 		"Usage: genl [ OPTIONS ] OBJECT [help] }\n"
 		"where  OBJECT := { ctrl etc }\n"
 		"       OPTIONS := { -V[ersion] | -s[tatistics] | -d[etails] | -r[aw] |\n"
 		"                    -j[son] | -p[retty] }\n");
-	exit(-1);
+	exit(help ? EXIT_SUCCESS : EXIT_FAILURE);
 }
 
 int main(int argc, char **argv)
@@ -122,7 +124,7 @@ int main(int argc, char **argv)
 		} else if (matches(argv[1], "-pretty") == 0) {
 			++pretty;
 		} else if (matches(argv[1], "-help") == 0) {
-			usage();
+			usage(true);
 		} else {
 			fprintf(stderr,
 				"Option \"%s\" is unknown, try \"genl -help\".\n",
@@ -146,5 +148,5 @@ int main(int argc, char **argv)
 		return ret;
 	}
 
-	usage();
+	usage(true);
 }
-- 
2.53.0