tvl-depot/users/Profpatsch/netstring/default.nix
Profpatsch e219c13328 feat(Profpatsch): add netstring helper function & python lib
Simple helper function to generate a netstring that is a list of
key-value pairs, to serialize a nix dict. Also adds a python lib to
read the serialized form into a dict again.

Change-Id: I306c0cfd51640c0658d32c8d3a4f3d332ba448f0
Reviewed-on: https://cl.tvl.fyi/c/depot/+/2315
Tested-by: BuildkiteCI
Reviewed-by: Profpatsch <mail@profpatsch.de>
2021-01-03 16:12:33 +00:00

58 lines
1.3 KiB
Nix

{ lib, pkgs, depot, ... }:
let
toNetstring = s:
"${toString (builtins.stringLength s)}:${s},";
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
'';
tests = import ./tests.nix {
inherit
depot
pkgs
lib
python-netstring
toNetstring
toNetstringKeyVal
;
};
in {
inherit
toNetstring
toNetstringKeyVal
python-netstring
tests
;
}