[PATCH iproute2] ip: return correct status from help command

[Rose Wright <rosesophiewright@gmail.com>]

Currently, "ip help" or "ip -help" always returns an error code because usage() is used as a fall through on "ip" and defaults to stderr with -1.

This is a minor bug that breaks "ip help | grep" and other scripts that rely on standard exit codes. The fix is to pass the status code as a parameter into usage() and change stderr to stdout when needed.

Signed-off-by: Rose Wright <rosesophiewright@gmail.com>
---
 ip/ip.c | 15 ++++++++-------
 1 file changed, 8 insertions(+), 7 deletions(-)

diff --git a/ip/ip.c b/ip/ip.c
index e4b71bde..ee4595e8 100644
--- a/ip/ip.c
+++ b/ip/ip.c
@@ -52,11 +52,12 @@ const char *get_ip_lib_dir(void)
 	return lib_dir;
 }
 
-static void usage(void) __attribute__((noreturn));
+static void usage(int status) __attribute__((noreturn));
 
-static void usage(void)
+static void usage(int status)
 {
-	fprintf(stderr,
+	FILE *out = status == 0 ? stdout : stderr;
+	fprintf(out,
 		"Usage: ip [ OPTIONS ] OBJECT { COMMAND | help }\n"
 		"       ip [ -force ] -batch filename\n"
 		"where  OBJECT := { address | addrlabel | fou | help | ila | ioam | l2tp | link |\n"
@@ -72,12 +73,12 @@ static void usage(void)
 		"                    -o[neline] | -t[imestamp] | -ts[hort] | -b[atch] [filename] |\n"
 		"                    -rc[vbuf] [size] | -n[etns] name | -N[umeric] | -a[ll] |\n"
 		"                    -c[olor]}\n");
-	exit(-1);
+	exit(status);
 }
 
 static int do_help(int argc, char **argv)
 {
-	usage();
+	usage(0);
 	return 0;
 }
 
@@ -279,7 +280,7 @@ int main(int argc, char **argv)
 			rcvbuf = size;
 		} else if (matches_color(opt, &color)) {
 		} else if (matches(opt, "-help") == 0) {
-			usage();
+			usage(0);
 		} else if (matches(opt, "-netns") == 0) {
 			NEXT_ARG();
 			if (netns_switch(argv[1]))
@@ -321,5 +322,5 @@ int main(int argc, char **argv)
 		return do_cmd(argv[1], argc-1, argv+1, true);
 
 	rtnl_close(&rth);
-	usage();
+	usage(-1);
 }
-- 
2.54.0