From e36e169d6ca5476920ebe49ad532e40ea85d039b Mon Sep 17 00:00:00 2001
From: Tero Marttila <terom@fixme.fi>
Date: Thu, 23 Jun 2016 00:51:19 +0300
Subject: [PATCH] digitalPin: do not export if the /sys/class/gpio/... file
 already exists

---
 host/generic/digitalpin.go | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/host/generic/digitalpin.go b/host/generic/digitalpin.go
index 80a81ea..b50c5db 100644
--- a/host/generic/digitalpin.go
+++ b/host/generic/digitalpin.go
@@ -62,7 +62,21 @@ func (p *digitalPin) init() error {
 	return nil
 }
 
+func (p *digitalPin) isExported() bool {
+	if _, err := os.Stat(p.basePath()); err == nil {
+		return true
+	} else if os.IsNotExist(err) {
+		return false
+	} else {
+		// unknown
+		return false
+	}
+}
+
 func (p *digitalPin) export() error {
+	if p.isExported() {
+		return nil
+	}
 	exporter, err := os.OpenFile("/sys/class/gpio/export", os.O_WRONLY, os.ModeExclusive)
 	if err != nil {
 		return err