diff options
Diffstat (limited to 'krebs/4lib')
| -rw-r--r-- | krebs/4lib/default.nix | 3 | ||||
| -rw-r--r-- | krebs/4lib/genid.nix | 37 |
2 files changed, 40 insertions, 0 deletions
diff --git a/krebs/4lib/default.nix b/krebs/4lib/default.nix index 1cabeae27..dfc51bbe4 100644 --- a/krebs/4lib/default.nix +++ b/krebs/4lib/default.nix @@ -7,6 +7,8 @@ let out = rec { eq = x: y: x == y; + mod = x: y: x - y * (x / y); + addName = name: set: set // { inherit name; }; @@ -17,6 +19,7 @@ let out = rec { dir.has-default-nix = path: pathExists (path + "/default.nix"); dns = import ./dns.nix { inherit lib; }; + genid = import ./genid.nix { lib = lib // out; }; git = import ./git.nix { lib = lib // out; }; listset = import ./listset.nix { inherit lib; }; shell = import ./shell.nix { inherit lib; }; diff --git a/krebs/4lib/genid.nix b/krebs/4lib/genid.nix new file mode 100644 index 000000000..0aed1d351 --- /dev/null +++ b/krebs/4lib/genid.nix @@ -0,0 +1,37 @@ +{ lib, ... }: +with lib; +with builtins; +let out = genid; + + # id = genid s = (hash s + min) % max + # min <= genid s < max + # + # min = 2^24 = 16777216 = 0x001000000 + # max = 2^32 = 4294967296 = 0x100000000 + # + # id is bigger than UID of nobody and GID of nogroup + # see <nixos/modules/misc/ids.nix> and some spare for stuff like lxd. + # + # :: str -> uint32 + genid = s: sum16 (addmod16_16777216 (hash s)); + + # :: str -> list8 uint4 + hash = s: + map hexint (stringToCharacters (substring 32 8 (hashString "sha1" s))); + + # :: list uint -> uint + sum16 = foldl (a: i: a * 16 + i) 0; + + # :: list8 uint4 -> list1 uint8 ++ list6 uint4 + addmod16_16777216 = x: let + a = 16 * head x + head (tail x); + d = tail (tail x); + in [(mod (a + 1) 256)] ++ d; + + # :: char -> uint4 + hexint = x: hexvals.${toLower x}; + + # :: attrset char uint4 + hexvals = listToAttrs (imap (i: c: { name = c; value = i - 1; }) + (stringToCharacters "0123456789abcdef")); +in out |