core/pkgs/top-level/impure.nix

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/* Impure default args for `pkgs/top-level/default.nix`. See that file
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for the meaning of each argument.
*/
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let
homeDir = builtins.getEnv "HOME";
# Return x if it evaluates, or def if it throws an exception.
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try = x: def:
let res = builtins.tryEval x;
in if res.success then res.value else def;
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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;
}
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# These are needed only because nix's `--arg` command-line logic doesn't work
# with unnamed parameters allowed by ...
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, system ? localSystem.system, crossSystem ? localSystem
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, # Fallback: The contents of the configuration file found at $NIXPKGS_CONFIG or
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# $HOME/.config/nixpkgs/config.nix.
config ? let
configFile = builtins.getEnv "NIXPKGS_CONFIG";
configFile2 = homeDir + "/.config/nixpkgs/config.nix";
configFile3 = homeDir + "/.nixpkgs/config.nix"; # obsolete
in if configFile != "" && builtins.pathExists configFile then
import configFile
else if homeDir != "" && builtins.pathExists configFile2 then
import configFile2
else if homeDir != "" && builtins.pathExists configFile3 then
import configFile3
else
{ }
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, # Overlays are used to extend Nixpkgs collection with additional
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# collections of packages. These collection of packages are part of the
# fix-point made by Nixpkgs.
overlays ? let
isDir = path: builtins.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 = builtins.readDir path;
in map (n: import (path + ("/" + n))) (builtins.filter (n:
(builtins.match ".*\\.nix" n != null &&
# ignore Emacs lock files (.#foo.nix)
builtins.match "\\.#.*" n == null)
|| builtins.pathExists (path + ("/" + n + "/default.nix")))
(builtins.attrNames content))
else
# it's a file, so the result is the contents of the file itself
import path;
in if pathOverlays != "" && builtins.pathExists pathOverlays then
overlays pathOverlays
else if builtins.pathExists homeOverlaysFile
&& builtins.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 builtins.pathExists homeOverlaysFile then
if isDir homeOverlaysFile then
throw (homeOverlaysFile + " should be a file")
else
overlays homeOverlaysFile
else if builtins.pathExists homeOverlaysDir then
if !(isDir homeOverlaysDir) then
throw (homeOverlaysDir + " should be a directory")
else
overlays homeOverlaysDir
else
[ ]
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, crossOverlays ? [ ]
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, ... }@args:
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# 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;
})