libutil: make AutoCloseFD a better resource

add a reset() method to close the wrapped fd instead of assigning magic
constants. also make the from-fd constructor explicit so you can't
accidentally assign the *wrong* magic constant, or even an unrelated
integer that also just happens to be an fd by pure chance.

Change-Id: I51311b0f6e040240886b5103d39d1794a6acc325

1 files changed, 1 insertions, 1 deletions

diff --git a/src/nix-channel/nix-channel.cc b/src/nix-channel/nix-channel.cc
index a12fa8e64..26003f021 100644
--- a/src/nix-channel/nix-channel.cc
+++ b/src/nix-channel/nix-channel.cc
@@ -83,7 +83,7 @@ static void update(const StringSet & channelNames)
     writeFull(fd.get(),
         #include "unpack-channel.nix.gen.hh"
         );
-    fd = -1;
+    fd.reset();
     AutoDelete del(unpackChannelPath, false);
 
     // Download each channel.