From 7c12435aae39c2bdb5a139390f2dd5b491d35241 Mon Sep 17 00:00:00 2001
From: Bjorn Andersson <bjorn.andersson@linaro.org>
Date: Wed, 9 May 2018 14:19:25 -0700
Subject: [PATCH] cdba: Gracefully handle stdin not being a tty

In the event that cdba is launched from e.g. a cron job stdin won't be a
tty and as such we can't modify the termios settings.

Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
---
 cdba.c | 26 +++++++++++++++++---------
 1 file changed, 17 insertions(+), 9 deletions(-)

diff --git a/cdba.c b/cdba.c
index cf7288b..cdcb463 100644
--- a/cdba.c
+++ b/cdba.c
@@ -47,19 +47,23 @@
 #include "circ_buf.h"
 #include "list.h"
 
-static struct termios orig_tios;
 static bool quit;
 
 static const char *fastboot_file;
 
-static int tty_unbuffer(void)
+static struct termios *tty_unbuffer(void)
 {
+	static struct termios orig_tios;
 	struct termios tios;
 	int ret;
 
 	ret = tcgetattr(STDIN_FILENO, &orig_tios);
-	if (ret < 0)
+	if (ret < 0) {
+		/* stdin is not a tty */
+		if (errno == ENOTTY)
+			return NULL;
 		err(1, "unable to retrieve tty tios");
+	}
 
 	memcpy(&tios, &orig_tios, sizeof(struct termios));
 	tios.c_lflag &= ~(ICANON | ECHO | ISIG);
@@ -70,17 +74,20 @@ static int tty_unbuffer(void)
 	if (ret)
 		err(1, "unable to update tty tios");
 
-	return 0;
+	return &orig_tios;
 }
 
-static void tty_reset(void)
+static void tty_reset(struct termios *orig_tios)
 {
 	int ret;
 
+	if (!orig_tios)
+		return;
+
 	tcflush(STDIN_FILENO, TCIFLUSH);
-	ret = tcsetattr(STDIN_FILENO, TCSANOW, &orig_tios);
+	ret = tcsetattr(STDIN_FILENO, TCSANOW, orig_tios);
 	if (ret < 0)
-		err(1, "unable to reset tty tios");
+		warn("unable to reset tty tios");
 }
 
 static int fork_ssh(const char *host, const char *cmd, int *pipes)
@@ -457,6 +464,7 @@ static void usage(void)
 
 int main(int argc, char **argv)
 {
+	struct termios *orig_tios;
 	struct work *next;
 	struct work *work;
 	struct circ_buf recv_buf = { 0 };
@@ -514,7 +522,7 @@ int main(int argc, char **argv)
 	tv.tv_sec = timeout;
 	tv.tv_usec = 0;
 
-	tty_unbuffer();
+	orig_tios = tty_unbuffer();
 
 	while (!quit) {
 		if (received_power_off) {
@@ -610,7 +618,7 @@ int main(int argc, char **argv)
 
 	wait(NULL);
 
-	tty_reset();
+	tty_reset(orig_tios);
 
 	return 0;
 }