Add proper logfile support

shared/isWritable.go

@@ -0,0 +1,11 @@
+//go:build !windows
+// +build !windows
+
+package shared
+
+import "golang.org/x/sys/unix"
+
+// Copied from https://stackoverflow.com/a/20026945 and https://stackoverflow.com/a/49148866
+func IsWritable(path string) bool {
+	return unix.Access(path, unix.W_OK) == nil
+}