tvl-depot/users/Profpatsch/netstring/default.nix
Profpatsch d41caf2dd6 feat(users/Profpatsch/netstring): add nix toNetstring* functions
We can easily construct netstrings from nix strings, which is super
helpful to inject proper structured data into execline scripts.

Change-Id: Ie8bffed285896223db83652eaea868ece43592b9
Reviewed-on: https://cl.tvl.fyi/c/depot/+/3265
Tested-by: BuildkiteCI
Reviewed-by: Profpatsch <mail@profpatsch.de>
2021-11-13 00:57:28 +00:00

63 lines
1.7 KiB
Nix

{ 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.utils.drvTargets {
inherit
python-netstring
rust-netstring
;
}