From 251a8e3c394f30c0975ce73e819134f4a64f8aac Mon Sep 17 00:00:00 2001
From: Nick Craig-Wood <nick@craig-wood.com>
Date: Thu, 23 Nov 2023 19:56:13 +0000
Subject: [PATCH] hash: allow runtime configuration of supported hashes for
 testing

---
 fs/hash/hash.go | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/fs/hash/hash.go b/fs/hash/hash.go
index 4540b40cf..23956cee6 100644
--- a/fs/hash/hash.go
+++ b/fs/hash/hash.go
@@ -55,6 +55,16 @@ func RegisterHash(name, alias string, width int, newFunc func() hash.Hash) Type
 	return hashType
 }
 
+// SupportOnly makes the hash package only support the types passed
+// in. Used for testing.
+//
+// It returns the previously supported types.
+func SupportOnly(new []Type) (old []Type) {
+	old = supported
+	supported = new
+	return old
+}
+
 // ErrUnsupported should be returned by filesystem,
 // if it is requested to deliver an unsupported hash type.
 var ErrUnsupported = errors.New("hash type not supported")