From 169cffd1d05db8d7c385b48a503a8ea80f1dcfb6 Mon Sep 17 00:00:00 2001
From: Simon Cruanes <simon.cruanes.2007@m4x.org>
Date: Thu, 21 Mar 2024 17:39:05 -0400
Subject: [PATCH] add Util_zlib.decompress_slice

---
 imandrakit.opam          |  1 -
 imandrakit.opam.template |  1 -
 src/core/util_zlib.ml    | 10 +++++++---
 src/core/util_zlib.mli   |  1 +
 4 files changed, 8 insertions(+), 5 deletions(-)

diff --git a/imandrakit.opam b/imandrakit.opam
index 47938aa7..3f4cf343 100644
--- a/imandrakit.opam
+++ b/imandrakit.opam
@@ -47,7 +47,6 @@ build: [
   ]
 ]
 dev-repo: "git+https://github.com/imandra-ai/imandrakit.git"
-
 pin-depends: [
   ["moonpool.dev" "git+https://github.com/c-cube/moonpool#main"]
 ]
diff --git a/imandrakit.opam.template b/imandrakit.opam.template
index 62831850..b7a4caa4 100644
--- a/imandrakit.opam.template
+++ b/imandrakit.opam.template
@@ -1,4 +1,3 @@
-
 pin-depends: [
   ["moonpool.dev" "git+https://github.com/c-cube/moonpool#main"]
 ]
diff --git a/src/core/util_zlib.ml b/src/core/util_zlib.ml
index 9f5b4f6e..a10d9fc5 100644
--- a/src/core/util_zlib.ml
+++ b/src/core/util_zlib.ml
@@ -11,12 +11,14 @@ let compress ?(buf = Buffer.create 32) (s : bytes) : bytes =
 let compress_str ?buf s : string =
   compress ?buf (Bytes.unsafe_of_string s) |> Bytes.unsafe_to_string
 
-let decompress ?(buf = Buffer.create 32) (s : bytes) : bytes =
+let decompress_slice ?(buf = Buffer.create 32) (s : bytes) offset len : bytes =
+  if offset + len > Bytes.length s then invalid_arg "Util_zlib.decompress";
   Buffer.clear buf;
-  let i = ref 0 in
+  let i = ref offset in
+  let last = offset + len in
   Zlib.uncompress ~header:false
     (fun bytes ->
-      let len = min (Bytes.length s - !i) (Bytes.length bytes) in
+      let len = min (last - !i) (Bytes.length bytes) in
       if len > 0 then (
         Bytes.blit s !i bytes 0 len;
         i := !i + len
@@ -25,5 +27,7 @@ let decompress ?(buf = Buffer.create 32) (s : bytes) : bytes =
     (fun bytes len -> Buffer.add_subbytes buf bytes 0 len);
   Buffer.contents buf |> Bytes.unsafe_of_string
 
+let decompress ?buf s : bytes = decompress_slice ?buf s 0 (Bytes.length s)
+
 let decompress_str ?buf s : string =
   decompress ?buf (Bytes.unsafe_of_string s) |> Bytes.unsafe_to_string
diff --git a/src/core/util_zlib.mli b/src/core/util_zlib.mli
index 4e7376bf..99ecea87 100644
--- a/src/core/util_zlib.mli
+++ b/src/core/util_zlib.mli
@@ -8,4 +8,5 @@ val compress_str : ?buf:Buffer.t -> string -> string
 val decompress : ?buf:Buffer.t -> bytes -> bytes
 (** Decompress the bytes. *)
 
+val decompress_slice : ?buf:Buffer.t -> bytes -> int -> int -> bytes
 val decompress_str : ?buf:Buffer.t -> string -> string