Merge pull request JohnSundell#23 from SteveBarnegren/dont_close_standard_file_handlers

Don't close standard file handlers

Author: JohnSundell

Sources/ShellOut.swift

@@ -394,8 +394,13 @@ private extension Process {
 
         waitUntilExit()
 
-        outputHandle?.closeFile()
-        errorHandle?.closeFile()
+        if let handle = outputHandle, !handle.isStandard {
+            handle.closeFile()
+        }
+
+        if let handle = errorHandle, !handle.isStandard {
+            handle.closeFile()
+        }
 
         #if !os(Linux)
         outputPipe.fileHandleForReading.readabilityHandler = nil
@@ -418,6 +423,14 @@ private extension Process {
     }
 }
 
+private extension FileHandle {
+    var isStandard: Bool {
+        return self === FileHandle.standardOutput ||
+            self === FileHandle.standardError ||
+            self === FileHandle.standardInput
+    }
+}
+
 private extension Data {
     func shellOutput() -> String {
         guard let output = String(data: self, encoding: .utf8) else {