fix(3p/nix/hash): initialize HashSink.ctx r/1514

Fixup for CL 1492 (addcba11b05500ba28ade309de6bd53f8153a6c4)

Additionally, add a test to verify functionality of HashSink.

Change-Id: I2a74b925a1b93ed4d3add29021d759c93e813424
Reviewed-on: https://cl.tvl.fyi/c/depot/+/1507
Tested-by: BuildkiteCI
Reviewed-by: glittershark <grfn@gws.fyi>

1 files changed, 4 insertions, 1 deletions

diff --git a/third_party/nix/src/libutil/hash.cc b/third_party/nix/src/libutil/hash.cc
index e9901d0ccb94..4c6eef0e6d9b 100644
--- a/third_party/nix/src/libutil/hash.cc
+++ b/third_party/nix/src/libutil/hash.cc
@@ -361,7 +361,10 @@ Hash hashFile(HashType ht, const Path& path) {
   return hash;
 }
 
-HashSink::HashSink(HashType ht) : ht(ht), ctx(), bytes(0) { start(ht, *ctx); }
+HashSink::HashSink(HashType ht)
+    : ht(ht), ctx(std::make_unique<hash::Ctx>()), bytes(0) {
+  start(ht, *ctx);
+}
 
 HashSink::~HashSink() { bufPos = 0; }