daemon: Fix 'HashSink::currentHash()'.

Before that, calls to 'HashSink::currentHash()' would eventually lead to
a segfault because the underlying gcrypt handle has been closed.  (Note
that this method is only used via 'importPaths' and 'exportPath', though.)

* nix/libutil/gcrypt-hash.hh (struct guix_hash_context): Add a
  constructor and a copy constructor; move out of 'extern "C"'.
* nix/libutil/gcrypt-hash.cc (guix_hash_final): Clear 'md_handle' upon
  exit.
* nix/sync-with-upstream (top_srcdir): Change hash.{cc,hh} to read
  'struct Ctx' instead of 'union Ctx'.

1 files changed, 1 insertions, 0 deletions

diff --git a/nix/libutil/gcrypt-hash.cc b/nix/libutil/gcrypt-hash.cc
index 553f633b93..c4ae7bfcc2 100644
--- a/nix/libutil/gcrypt-hash.cc
+++ b/nix/libutil/gcrypt-hash.cc
@@ -45,6 +45,7 @@ guix_hash_final (void *resbuf, struct guix_hash_context *ctx,
   memcpy (resbuf, gcry_md_read (ctx->md_handle, algo),
 	  gcry_md_get_algo_dlen (algo));
   gcry_md_close (ctx->md_handle);
+  ctx->md_handle = NULL;
 }
 
 }