libutil: return a source from readFile

don't consume a sink, return a source instead. the only reason to not do
this is a very slight reduction in dynamic allocations, but since we are
going to *at least* do disk io that will not be a lot of overhead anyway

Change-Id: Iae2f879ec64c3c3ac1d5310eeb6a85e696d4614a

1 files changed, 1 insertions, 1 deletions

diff --git a/src/libstore/store-api.cc b/src/libstore/store-api.cc
index 55083e834..e954acff3 100644
--- a/src/libstore/store-api.cc
+++ b/src/libstore/store-api.cc
@@ -279,7 +279,7 @@ StorePath Store::addToStore(
         if (method == FileIngestionMethod::Recursive)
             dumpPath(srcPath, sink, filter);
         else
-            readFile(srcPath, sink);
+            readFileSource(srcPath)->drainInto(sink);
     });
     return addToStoreFromDump(*source, name, method, hashAlgo, repair, references);
 }