From cc511fd65b7b6de9e87e72fb4bed16fc7efeb8b7 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <eelco.dolstra@logicblox.com>
Date: Tue, 18 Dec 2012 18:50:05 +0100
Subject: [PATCH] Check for potential infinite select() loops when building

---
 src/libstore/build.cc | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/libstore/build.cc b/src/libstore/build.cc
index ce87eaed2..035151bb2 100644
--- a/src/libstore/build.cc
+++ b/src/libstore/build.cc
@@ -3141,6 +3141,8 @@ void Worker::waitForInput()
         }
     }
 
+    assert(fdMax != 0);
+
     if (select(fdMax, &fds, 0, 0, useTimeout ? &timeout : 0) == -1) {
         if (errno == EINTR) return;
         throw SysError("waiting for input");