From 689bfc793987950590a6066b91c6f8ca166a5fca Mon Sep 17 00:00:00 2001
From: Ian Gulliver <flamingcow@gmail.com>
Date: Wed, 9 Mar 2016 18:28:00 -0800
Subject: [PATCH] Open stdin and stdout to something if they don't arrive open,
 or bad things happen.

---
 adsbus/adsbus.c   |  2 ++
 adsbus/stdinout.c | 15 ++++++++++++++-
 adsbus/stdinout.h |  1 +
 3 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/adsbus/adsbus.c b/adsbus/adsbus.c
index 7c68fc2..1d9b218 100644
--- a/adsbus/adsbus.c
+++ b/adsbus/adsbus.c
@@ -33,6 +33,8 @@ static void adsbus_opts_add() {
 }
 
 int main(int argc, char *argv[]) {
+	stdinout_preinit();
+
 	adsbus_opts_add();
 
 	opts_init(argc, argv);
diff --git a/adsbus/stdinout.c b/adsbus/stdinout.c
index 3a9e88e..97af4fe 100644
--- a/adsbus/stdinout.c
+++ b/adsbus/stdinout.c
@@ -13,10 +13,14 @@
 
 static opts_group stdinout_opts;
 
+static void stdinout_open(int fd, char *path, int flags) {
+	assert(open(path, flags | O_CLOEXEC | O_NOCTTY) == fd);
+}
+
 static void stdinout_reopen(int fd, char *path, int flags) {
 	// Presumes that all fds < fd are open
 	assert(!close(fd));
-	assert(open(path, flags | O_CLOEXEC | O_NOCTTY) == fd);
+	stdinout_open(fd, path, flags);
 }
 
 static bool stdinout_stdin(const char __attribute__((unused)) *arg) {
@@ -35,6 +39,15 @@ static bool stdinout_stdout(const char *arg) {
 	return flow_new_send_hello(fd, send_flow, serializer, NULL);
 }
 
+void stdinout_preinit() {
+	if (fcntl(STDIN_FILENO, F_GETFD) == -1) {
+		stdinout_open(STDIN_FILENO, "/dev/null", O_RDONLY);
+	}
+	if (fcntl(STDOUT_FILENO, F_GETFD) == -1) {
+		stdinout_open(STDOUT_FILENO, "/dev/full", O_WRONLY);
+	}
+}
+
 void stdinout_opts_add() {
 	opts_add("stdin", NULL, stdinout_stdin, stdinout_opts);
 	opts_add("stdout", "FORMAT", stdinout_stdout, stdinout_opts);
diff --git a/adsbus/stdinout.h b/adsbus/stdinout.h
index b741cac..a13f598 100644
--- a/adsbus/stdinout.h
+++ b/adsbus/stdinout.h
@@ -1,5 +1,6 @@
 #pragma once
 
+void stdinout_preinit(void);
 void stdinout_opts_add(void);
 void stdinout_init(void);
 void stdinout_cleanup(void);