From 02f9c2f9c793ae438fde20b4d91a633e8fb26edb Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Reynir=20Bj=C3=B6rnsson?= <reynir@reynir.dk>
Date: Thu, 3 Oct 2024 18:10:21 +0200
Subject: [PATCH] Remove unnecessary complexity

Opam 2 only supports md5, sha256 and sha512. We don't need the extra
complexity of other hash algorithms. Opam 2 will fail to parse such an
opam file anyway.
---
 mirage/archive_checksum.ml | 71 +++-----------------------------------
 1 file changed, 4 insertions(+), 67 deletions(-)

diff --git a/mirage/archive_checksum.ml b/mirage/archive_checksum.ml
index 89d5514..86513f5 100644
--- a/mirage/archive_checksum.ml
+++ b/mirage/archive_checksum.ml
@@ -1,7 +1,7 @@
 
 
 module Hash = struct
-  type t = [ `MD5 | `SHA1 | `SHA224 | `SHA256 | `SHA384 | `SHA512 ]
+  type t = (* OpamHash.kind = *) [ `MD5 | `SHA256 | `SHA512 ]
 
   (* Make the compiler check that (t :> Digestif.hash') *)
   let _ = fun (h :t) -> (h :> Digestif.hash')
@@ -11,26 +11,14 @@ module Hash = struct
     | `SHA512, `SHA512 -> 0
     | `SHA512, _ -> 1
     | _, `SHA512 -> -1
-    | `SHA384, `SHA384 -> 0
-    | `SHA384, _ -> 1
-    | _, `SHA384 -> -1
     | `SHA256, `SHA256 -> 0
     | `SHA256, _ -> 1
     | _, `SHA256 -> -1
-    | `SHA224, `SHA224 -> 0
-    | `SHA224, _ -> 1
-    | _, `SHA224 -> -1
-    | `SHA1, `SHA1 -> 0
-    | `SHA1, `MD5 -> 1
     | `MD5, `MD5 -> 0
-    | `MD5, _ -> -1
 
   let to_string = function
     | `MD5 -> "md5"
-    | `SHA1 -> "sha1"
-    | `SHA224 -> "sha224"
     | `SHA256 -> "sha256"
-    | `SHA384 -> "sha384"
     | `SHA512 -> "sha512"
 
   let of_string = function
@@ -42,78 +30,29 @@ end
 
 module HM = Map.Make(Hash)
 
-module Running_hash = struct
-  type _ t =
-    | MD5 : Digestif.MD5.ctx -> [> `MD5 ] t
-    | SHA1 : Digestif.SHA1.ctx -> [> `SHA1 ] t
-    | SHA224 : Digestif.SHA224.ctx -> [> `SHA224 ] t
-    | SHA256 : Digestif.SHA256.ctx -> [> `SHA256 ] t
-    | SHA384 : Digestif.SHA384.ctx -> [> `SHA384 ] t
-    | SHA512 : Digestif.SHA512.ctx -> [> `SHA512 ] t
-
-  let empty : _ -> _ t = function
-    | `MD5 -> MD5 Digestif.MD5.empty
-    | `SHA1 -> SHA1 Digestif.SHA1.empty
-    | `SHA224 -> SHA224 Digestif.SHA224.empty
-    | `SHA256 -> SHA256 Digestif.SHA256.empty
-    | `SHA384 -> SHA384 Digestif.SHA384.empty
-    | `SHA512 -> SHA512 Digestif.SHA512.empty
-
-  let feed_string t data =
-    match t with
-    | MD5 t -> MD5 (Digestif.MD5.feed_string t data)
-    | SHA1 t -> SHA1 (Digestif.SHA1.feed_string t data)
-    | SHA224 t -> SHA224 (Digestif.SHA224.feed_string t data)
-    | SHA256 t -> SHA256 (Digestif.SHA256.feed_string t data)
-    | SHA384 t -> SHA384 (Digestif.SHA384.feed_string t data)
-    | SHA512 t -> SHA512 (Digestif.SHA512.feed_string t data)
-
-  let get t =
-    match t with
-    | MD5 t -> Digestif.MD5.(to_raw_string (get t))
-    | SHA1 t -> Digestif.SHA1.(to_raw_string (get t))
-    | SHA224 t -> Digestif.SHA224.(to_raw_string (get t))
-    | SHA256 t -> Digestif.SHA256.(to_raw_string (get t))
-    | SHA384 t -> Digestif.SHA384.(to_raw_string (get t))
-    | SHA512 t -> Digestif.SHA512.(to_raw_string (get t))
-
-  let hash_alg t =
-    match t with
-    | MD5 _ -> `MD5
-    | SHA1 _ -> `SHA1
-    | SHA224 _ -> `SHA224
-    | SHA256 _ -> `SHA256
-    | SHA384 _ -> `SHA384
-    | SHA512 _ -> `SHA512
-end
-
 type 'a digests = {
   md5 : Digestif.MD5.ctx;
   sha256 : Digestif.SHA256.ctx;
   sha512 : Digestif.SHA512.ctx;
-  csum : 'a Running_hash.t;
 }
 
-let empty_digests h =
-  let csum = Running_hash.empty h in
+let empty_digests =
   {
     md5 = Digestif.MD5.empty;
     sha256 = Digestif.SHA256.empty;
     sha512 = Digestif.SHA512.empty;
-    csum;
   }
 
-let update_digests { md5; sha256; sha512; csum } data =
+let update_digests { md5; sha256; sha512 } data =
   {
     md5 = Digestif.MD5.feed_string md5 data;
     sha256 = Digestif.SHA256.feed_string sha256 data;
     sha512 = Digestif.SHA512.feed_string sha512 data;
-    csum = Running_hash.feed_string csum data;
   }
 
 let init_write csums =
   let hash, csum = HM.max_binding csums in
-  (hash, csum), Ok (empty_digests hash, `Init)
+  (hash, csum), Ok (empty_digests, `Init)
 
 let digests_to_hm digests =
   HM.empty
@@ -123,5 +62,3 @@ let digests_to_hm digests =
     Digestif.SHA256.(to_raw_string (get digests.sha256))
   |> HM.add `SHA512
     Digestif.SHA512.(to_raw_string (get digests.sha512))
-  |> HM.add (Running_hash.hash_alg digests.csum)
-    (Running_hash.get digests.csum)