From 3dcca18c30cbc09652f5ac644a9f8750f9ced0c9 Mon Sep 17 00:00:00 2001
From: John Ericson <John.Ericson@Obsidian.Systems>
Date: Thu, 16 Jul 2020 13:39:03 +0000
Subject: [PATCH] Fix bug in TeeSource

We use this to simplify `LocalStore::addToStoreFromDump`.

Also, hope I fixed build error with old clang (used in Darwin CI).
---
 src/libstore/local-store.cc | 14 ++++----------
 src/libutil/serialise.hh    |  2 +-
 2 files changed, 5 insertions(+), 11 deletions(-)

diff --git a/src/libstore/local-store.cc b/src/libstore/local-store.cc
index b2b5afadd..96d10d9ba 100644
--- a/src/libstore/local-store.cc
+++ b/src/libstore/local-store.cc
@@ -1047,11 +1047,12 @@ StorePath LocalStore::addToStore(const string & name, const Path & _srcPath,
 }
 
 
-StorePath LocalStore::addToStoreFromDump(Source & source, const string & name,
+StorePath LocalStore::addToStoreFromDump(Source & source0, const string & name,
     FileIngestionMethod method, HashType hashAlgo, RepairFlag repair)
 {
     /* For computing the store path. */
     auto hashSink = std::make_unique<HashSink>(hashAlgo);
+    TeeSource source { source0, *hashSink };
 
     /* Read the source path into memory, but only if it's up to
        narBufferSize bytes. If it's larger, write it to a temporary
@@ -1078,8 +1079,6 @@ StorePath LocalStore::addToStoreFromDump(Source & source, const string & name,
             inMemory = true;
             break;
         }
-        /* Start hashing as we get data */
-        (*hashSink)((const uint8_t *) dump.data() + oldSize, got);
         dump.resize(oldSize + got);
     }
 
@@ -1087,14 +1086,9 @@ StorePath LocalStore::addToStoreFromDump(Source & source, const string & name,
     Path tempPath;
 
     if (!inMemory) {
+        /* Drain what we pulled so far, and then keep on pulling */
         StringSource dumpSource { dump };
-        TeeSource rest { source, *hashSink };
-        ChainSource bothSource {
-            .source1 = dumpSource,
-            /* Continue hashing what's left, but don't rehash what we
-               already did. */
-            .source2 = rest,
-        };
+        ChainSource bothSource { dumpSource, source };
 
         auto tempDir = createTempDir(realStoreDir, "add");
         delTempDir = std::make_unique<AutoDelete>(tempDir);
diff --git a/src/libutil/serialise.hh b/src/libutil/serialise.hh
index aa6b42597..5d9acf887 100644
--- a/src/libutil/serialise.hh
+++ b/src/libutil/serialise.hh
@@ -189,7 +189,7 @@ struct TeeSource : Source
     size_t read(unsigned char * data, size_t len)
     {
         size_t n = orig.read(data, len);
-        sink(data, len);
+        sink(data, n);
         return n;
     }
 };