nixpkgs/lib/customisation.nix
2015-05-22 13:26:55 -07:00

185 lines
6.5 KiB
Nix

let
lib = import ./default.nix;
inherit (builtins) attrNames isFunction;
in
rec {
/* `overrideDerivation drv f' takes a derivation (i.e., the result
of a call to the builtin function `derivation') and returns a new
derivation in which the attributes of the original are overriden
according to the function `f'. The function `f' is called with
the original derivation attributes.
`overrideDerivation' allows certain "ad-hoc" customisation
scenarios (e.g. in ~/.nixpkgs/config.nix). For instance, if you
want to "patch" the derivation returned by a package function in
Nixpkgs to build another version than what the function itself
provides, you can do something like this:
mySed = overrideDerivation pkgs.gnused (oldAttrs: {
name = "sed-4.2.2-pre";
src = fetchurl {
url = ftp://alpha.gnu.org/gnu/sed/sed-4.2.2-pre.tar.bz2;
sha256 = "11nq06d131y4wmf3drm0yk502d2xc6n5qy82cg88rb9nqd2lj41k";
};
patches = [];
});
For another application, see build-support/vm, where this
function is used to build arbitrary derivations inside a QEMU
virtual machine.
*/
overrideDerivation = drv: f:
let
newDrv = derivation (drv.drvAttrs // (f drv));
in addPassthru newDrv (
{ meta = drv.meta or {};
passthru = if drv ? passthru then drv.passthru else {};
}
//
(drv.passthru or {})
//
(if (drv ? crossDrv && drv ? nativeDrv)
then {
crossDrv = overrideDerivation drv.crossDrv f;
nativeDrv = overrideDerivation drv.nativeDrv f;
}
else { }));
# usage: (you can use override multiple times)
# let d = makeOverridable stdenv.mkDerivation { name = ..; buildInputs; }
# noBuildInputs = d.override { buildInputs = []; }
# additionalBuildInputs = d.override ( args : args // { buildInputs = args.buildInputs ++ [ additional ]; } )
makeOverridable = f: origArgs:
let
ff = f origArgs;
overrideWith = newArgs: origArgs // (if builtins.isFunction newArgs then newArgs origArgs else newArgs);
in
if builtins.isAttrs ff then (ff //
{ override = newArgs: makeOverridable f (overrideWith newArgs);
deepOverride = newArgs:
makeOverridable f (lib.overrideExisting (lib.mapAttrs (deepOverrider newArgs) origArgs) newArgs);
overrideDerivation = fdrv:
makeOverridable (args: overrideDerivation (f args) fdrv) origArgs;
})
else if builtins.isFunction ff then
{ override = newArgs: makeOverridable f (overrideWith newArgs);
__functor = self: ff;
deepOverride = throw "deepOverride not yet supported for functors";
overrideDerivation = throw "overrideDerivation not yet supported for functors";
}
else ff;
deepOverrider = newArgs: name: x: if builtins.isAttrs x then (
if x ? deepOverride then (x.deepOverride newArgs) else
if x ? override then (x.override newArgs) else
x) else x;
/* Call the package function in the file `fn' with the required
arguments automatically. The function is called with the
arguments `args', but any missing arguments are obtained from
`autoArgs'. This function is intended to be partially
parameterised, e.g.,
callPackage = callPackageWith pkgs;
pkgs = {
libfoo = callPackage ./foo.nix { };
libbar = callPackage ./bar.nix { };
};
If the `libbar' function expects an argument named `libfoo', it is
automatically passed as an argument. Overrides or missing
arguments can be supplied in `args', e.g.
libbar = callPackage ./bar.nix {
libfoo = null;
enableX11 = true;
};
*/
callPackageWith = autoArgs: fn: args:
let
f = if builtins.isFunction fn then fn else import fn;
auto = builtins.intersectAttrs (builtins.functionArgs f) autoArgs;
in makeOverridable f (auto // args);
/* Add attributes to each output of a derivation without changing the derivation itself */
addPassthru = drv: passthru:
let
outputs = drv.outputs or [ "out" ];
commonAttrs = drv // (builtins.listToAttrs outputsList) //
({ all = map (x: x.value) outputsList; }) // passthru;
outputToAttrListElement = outputName:
{ name = outputName;
value = commonAttrs // {
inherit (drv.${outputName}) outPath drvPath type outputName;
};
};
outputsList = map outputToAttrListElement outputs;
in commonAttrs.${drv.outputName};
/* Strip a derivation of all non-essential attributes, returning
only those needed by hydra-eval-jobs. Also strictly evaluate the
result to ensure that there are no thunks kept alive to prevent
garbage collection. */
hydraJob = drv:
let
outputs = drv.outputs or ["out"];
commonAttrs =
{ inherit (drv) name system meta; inherit outputs; }
// lib.optionalAttrs (drv._hydraAggregate or false) {
_hydraAggregate = true;
constituents = map hydraJob (lib.flatten drv.constituents);
}
// (lib.listToAttrs outputsList);
makeOutput = outputName:
let output = drv.${outputName}; in
{ name = outputName;
value = commonAttrs // {
outPath = output.outPath;
drvPath = output.drvPath;
type = "derivation";
inherit outputName;
};
};
outputsList = map makeOutput outputs;
drv' = (lib.head outputsList).value;
in lib.deepSeq drv' drv';
/* Tests whether a derivation can be used by the current platform
Returns the derivation if true, otherwise null. */
shouldUsePkgSystem = system: pkg_: let pkg = (builtins.tryEval pkg_).value;
in if lib.any (x: x == system) (pkg.meta.platforms or [])
then pkg
else null;
/* Returns a configure flag string in an autotools format
trueStr: Prepended when cond is true
falseStr: Prepended when cond is false
cond: The condition for the prepended string type and value
name: The flag name
val: The value of the flag only set when cond is true */
mkFlag = trueStr: falseStr: cond: name: val:
if cond == null then null else
"--${if cond != false then trueStr else falseStr}${name}"
+ "${if val != null && cond != false then "=${val}" else ""}";
/* Flag setting helpers for autotools like packages */
mkEnable = mkFlag "enable-" "disable-";
mkWith = mkFlag "with-" "without-";
mkOther = mkFlag "" "" true;
}