1 files changed, 69 insertions, 0 deletions
diff --git a/users/Profpatsch/netstring/default.nix b/users/Profpatsch/netstring/default.nix
new file mode 100644
index 000000000000..e85cf24dd8e6
--- /dev/null
+++ b/users/Profpatsch/netstring/default.nix
@@ -0,0 +1,69 @@
+{ lib, pkgs, depot, ... }:
+let
+  toNetstring = s:
+    "${toString (builtins.stringLength s)}:${s},";
+
+  toNetstringList = xs:
+    lib.concatStrings (map toNetstring xs);
+
+  toNetstringKeyVal = attrs:
+    lib.concatStrings
+      (lib.mapAttrsToList
+        (k: v: toNetstring (toNetstring k + toNetstring v))
+        attrs);
+
+  python-netstring = depot.users.Profpatsch.writers.python3Lib
+    {
+      name = "netstring";
+    } ''
+    def read_netstring(bytes):
+        (int_length, rest) = bytes.split(sep=b':', maxsplit=1)
+        val = rest[:int(int_length)]
+        # has to end on a ,
+        assert(rest[len(val)] == ord(','))
+        return (val, rest[len(val) + 1:])
+
+    def read_netstring_key_val(bytes):
+        (keyvalnet, rest) = read_netstring(bytes)
+        (key, valnet) = read_netstring(keyvalnet)
+        (val, nothing) = read_netstring(valnet)
+        assert(nothing == b"")
+        return (key, val, rest)
+
+    def read_netstring_key_val_list(bytes):
+        rest = bytes
+        res = {}
+        while rest != b"":
+            (key, val, r) = read_netstring_key_val(rest)
+            rest = r
+            res[key] = val
+        return res
+  '';
+
+  rust-netstring = depot.nix.writers.rustSimpleLib
+    {
+      name = "netstring";
+    } ''
+    pub fn to_netstring(s: &[u8]) -> Vec<u8> {
+        let len = s.len();
+        // length of the integer as ascii
+        let i_len = ((len as f64).log10() as usize) + 1;
+        let ns_len = i_len + 1 + len + 1;
+        let mut res = Vec::with_capacity(ns_len);
+        res.extend_from_slice(format!("{}:", len).as_bytes());
+        res.extend_from_slice(s);
+        res.push(b',');
+        res
+    }
+  '';
+
+in
+depot.nix.readTree.drvTargets {
+  inherit
+    toNetstring
+    toNetstringList
+    toNetstringKeyVal
+    python-netstring
+    rust-netstring
+    ;
+}