nixpkgs/pkgs/top-level/impure.nix
John Ericson 2dde58903e top-level: Simplify impure and pure fallback
This is now possible, since the `platform` attribute has been removed in
PR #107214. I've been waiting to do a cleanup like this for a long time!
2021-01-23 10:01:38 -05:00

86 lines
3.3 KiB
Nix
Raw Permalink Blame History

This file contains ambiguous Unicode characters

This file contains Unicode characters that might be confused with other characters. If you think that this is intentional, you can safely ignore this warning. Use the Escape button to reveal them.

/* Impure default args for `pkgs/top-level/default.nix`. See that file
for the meaning of each argument. */
with builtins;
let
homeDir = builtins.getEnv "HOME";
# Return x if it evaluates, or def if it throws an exception.
try = x: def: let res = tryEval x; in if res.success then res.value else def;
in
{ # We put legacy `system` into `localSystem`, if `localSystem` was not passed.
# If neither is passed, assume we are building packages on the current
# (build, in GNU Autotools parlance) platform.
localSystem ? { system = args.system or builtins.currentSystem; }
# These are needed only because nix's `--arg` command-line logic doesn't work
# with unnamed parameters allowed by ...
, system ? localSystem.system
, crossSystem ? localSystem
, # Fallback: The contents of the configuration file found at $NIXPKGS_CONFIG or
# $HOME/.config/nixpkgs/config.nix.
config ? let
configFile = getEnv "NIXPKGS_CONFIG";
configFile2 = homeDir + "/.config/nixpkgs/config.nix";
configFile3 = homeDir + "/.nixpkgs/config.nix"; # obsolete
in
if configFile != "" && pathExists configFile then import configFile
else if homeDir != "" && pathExists configFile2 then import configFile2
else if homeDir != "" && pathExists configFile3 then import configFile3
else {}
, # Overlays are used to extend Nixpkgs collection with additional
# collections of packages. These collection of packages are part of the
# fix-point made by Nixpkgs.
overlays ? let
isDir = path: pathExists (path + "/.");
pathOverlays = try (toString <nixpkgs-overlays>) "";
homeOverlaysFile = homeDir + "/.config/nixpkgs/overlays.nix";
homeOverlaysDir = homeDir + "/.config/nixpkgs/overlays";
overlays = path:
# check if the path is a directory or a file
if isDir path then
# it's a directory, so the set of overlays from the directory, ordered lexicographically
let content = readDir path; in
map (n: import (path + ("/" + n)))
(builtins.filter (n: builtins.match ".*\\.nix" n != null || pathExists (path + ("/" + n + "/default.nix")))
(attrNames content))
else
# it's a file, so the result is the contents of the file itself
import path;
in
if pathOverlays != "" && pathExists pathOverlays then overlays pathOverlays
else if pathExists homeOverlaysFile && pathExists homeOverlaysDir then
throw ''
Nixpkgs overlays can be specified with ${homeOverlaysFile} or ${homeOverlaysDir}, but not both.
Please remove one of them and try again.
''
else if pathExists homeOverlaysFile then
if isDir homeOverlaysFile then
throw (homeOverlaysFile + " should be a file")
else overlays homeOverlaysFile
else if pathExists homeOverlaysDir then
if !(isDir homeOverlaysDir) then
throw (homeOverlaysDir + " should be a directory")
else overlays homeOverlaysDir
else []
, crossOverlays ? []
, ...
} @ args:
# If `localSystem` was explicitly passed, legacy `system` should
# not be passed, and vice-versa.
assert args ? localSystem -> !(args ? system);
assert args ? system -> !(args ? localSystem);
import ./. (builtins.removeAttrs args [ "system" ] // {
inherit config overlays localSystem;
})