Fix #5299

No matter what, we need to resize the buffer to not have any scratch
space after we do the `read`. In the end of file case, `got` will be 0
from it's initial value.

Before, we forgot to resize in the EOF case with the break. Yes, we know
we didn't recieve any data in that case, but we still have the scatch
space to undo.

Co-Authored-By: Will Fancher <Will.Fancher@Obsidian.Systems>

1 files changed, 4 insertions, 1 deletions

diff --git a/src/libstore/local-store.cc b/src/libstore/local-store.cc
index 64019314f..3a1688272 100644
--- a/src/libstore/local-store.cc
+++ b/src/libstore/local-store.cc
@@ -8,6 +8,7 @@
 #include "references.hh"
 #include "callback.hh"
 #include "topo-sort.hh"
+#include "finally.hh"
 
 #include <iostream>
 #include <algorithm>
@@ -1333,13 +1334,15 @@ StorePath LocalStore::addToStoreFromDump(Source & source0, const string & name,
         auto want = std::min(chunkSize, settings.narBufferSize - oldSize);
         dump.resize(oldSize + want);
         auto got = 0;
+        Finally cleanup([&]() {
+            dump.resize(oldSize + got);
+        });
         try {
             got = source.read(dump.data() + oldSize, want);
         } catch (EndOfFile &) {
             inMemory = true;
             break;
         }
-        dump.resize(oldSize + got);
     }
 
     std::unique_ptr<AutoDelete> delTempDir;