84 lines
3.2 KiB
Nix
84 lines
3.2 KiB
Nix
{ runCommand, nix, lib }:
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# Replace a single dependency in the requisites tree of drv, propagating
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# the change all the way up the tree, without a full rebuild. This can be
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# useful, for example, to patch a security hole in libc and still use your
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# system safely without rebuilding the world. This should be a short term
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# solution, as soon as a rebuild can be done the properly rebuild derivation
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# should be used. The old dependency and new dependency MUST have the same-length
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# name, and ideally should have close-to-identical directory layout.
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#
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# Example: safeFirefox = replaceDependency {
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# drv = firefox;
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# oldDependency = glibc;
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# newDependency = overrideDerivation glibc (attrs: {
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# patches = attrs.patches ++ [ ./fix-glibc-hole.patch ];
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# });
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# };
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# This will rebuild glibc with your security patch, then copy over firefox
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# (and all of its dependencies) without rebuilding further.
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{ drv, oldDependency, newDependency, verbose ? true }:
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with lib;
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let
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warn = if verbose then builtins.trace else (x: y: y);
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references = import (runCommand "references.nix" { exportReferencesGraph = [ "graph" drv ]; } ''
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(echo {
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while read path
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do
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echo " \"$path\" = ["
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read count
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read count
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while [ "0" != "$count" ]
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do
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read ref_path
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if [ "$ref_path" != "$path" ]
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then
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echo " (builtins.storePath $ref_path)"
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fi
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count=$(($count - 1))
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done
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echo " ];"
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done < graph
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echo }) > $out
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'').outPath;
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discard = builtins.unsafeDiscardStringContext;
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oldStorepath = builtins.storePath (discard (toString oldDependency));
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referencesOf = drv: references.${discard (toString drv)};
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dependsOnOldMemo = listToAttrs (map
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(drv: { name = discard (toString drv);
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value = elem oldStorepath (referencesOf drv) ||
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any dependsOnOld (referencesOf drv);
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}) (builtins.attrNames references));
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dependsOnOld = drv: dependsOnOldMemo.${discard (toString drv)};
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drvName = drv:
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discard (substring 33 (stringLength (builtins.baseNameOf drv)) (builtins.baseNameOf drv));
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rewriteHashes = drv: hashes: runCommand (drvName drv) { nixStore = "${nix.out}/bin/nix-store"; } ''
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$nixStore --dump ${drv} | sed 's|${baseNameOf drv}|'$(basename $out)'|g' | sed -e ${
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concatStringsSep " -e " (mapAttrsToList (name: value:
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"'s|${baseNameOf name}|${baseNameOf value}|g'"
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) hashes)
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} | $nixStore --restore $out
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'';
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rewrittenDeps = listToAttrs [ {name = discard (toString oldDependency); value = newDependency;} ];
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rewriteMemo = listToAttrs (map
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(drv: { name = discard (toString drv);
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value = rewriteHashes (builtins.storePath drv)
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(filterAttrs (n: v: builtins.elem (builtins.storePath (discard (toString n))) (referencesOf drv)) rewriteMemo);
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})
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(filter dependsOnOld (builtins.attrNames references))) // rewrittenDeps;
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drvHash = discard (toString drv);
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in assert (stringLength (drvName (toString oldDependency)) == stringLength (drvName (toString newDependency)));
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rewriteMemo.${drvHash} or (warn "replace-dependency.nix: Derivation ${drvHash} does not depend on ${discard (toString oldDependency)}" drv)
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