0abb3ad537
This adds a command 'nix make-content-addressable' that rewrites the specified store paths into content-addressable paths. The advantage of such paths is that 1) they can be imported without signatures; 2) they can enable deduplication in cases where derivation changes do not cause output changes (apart from store path hashes). For example, $ nix make-content-addressable -r nixpkgs.cowsay rewrote '/nix/store/g1g31ah55xdia1jdqabv1imf6mcw0nb1-glibc-2.25-49' to '/nix/store/48jfj7bg78a8n4f2nhg269rgw1936vj4-glibc-2.25-49' ... rewrote '/nix/store/qbi6rzpk0bxjw8lw6azn2mc7ynnn455q-cowsay-3.03+dfsg1-16' to '/nix/store/iq6g2x4q62xp7y7493bibx0qn5w7xz67-cowsay-3.03+dfsg1-16' We can then copy the resulting closure to another store without signatures: $ nix copy --trusted-public-keys '' ---to ~/my-nix /nix/store/iq6g2x4q62xp7y7493bibx0qn5w7xz67-cowsay-3.03+dfsg1-16 In order to support self-references in content-addressable paths, these paths are hashed "modulo" self-references, meaning that self-references are zeroed out during hashing. Somewhat annoyingly, this means that the NAR hash stored in the Nix database is no longer necessarily equal to the output of "nix hash-path"; for content-addressable paths, you need to pass the --modulo flag: $ nix path-info --json /nix/store/iq6g2x4q62xp7y7493bibx0qn5w7xz67-cowsay-3.03+dfsg1-16 | jq -r .[].narHash sha256:0ri611gdilz2c9rsibqhsipbfs9vwcqvs811a52i2bnkhv7w9mgw $ nix hash-path --type sha256 --base32 /nix/store/iq6g2x4q62xp7y7493bibx0qn5w7xz67-cowsay-3.03+dfsg1-16 1ggznh07khq0hz6id09pqws3a8q9pn03ya3c03nwck1kwq8rclzs $ nix hash-path --type sha256 --base32 /nix/store/iq6g2x4q62xp7y7493bibx0qn5w7xz67-cowsay-3.03+dfsg1-16 --modulo iq6g2x4q62xp7y7493bibx0qn5w7xz67 0ri611gdilz2c9rsibqhsipbfs9vwcqvs811a52i2bnkhv7w9mgw
83 lines
2.5 KiB
C++
83 lines
2.5 KiB
C++
#include "command.hh"
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#include "store-api.hh"
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#include "references.hh"
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using namespace nix;
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struct CmdMakeContentAddressable : StorePathsCommand
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{
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CmdMakeContentAddressable()
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{
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realiseMode = Build;
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}
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std::string name() override
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{
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return "make-content-addressable";
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}
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std::string description() override
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{
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return "test";
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}
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void run(ref<Store> store, Paths storePaths) override
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{
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auto paths = store->topoSortPaths(PathSet(storePaths.begin(), storePaths.end()));
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paths.reverse();
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std::map<Path, Path> remappings;
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for (auto & path : paths) {
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auto oldInfo = store->queryPathInfo(path);
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auto oldHashPart = storePathToHash(path);
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auto name = storePathToName(path);
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StringSink sink;
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store->narFromPath(path, sink);
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StringMap rewrites;
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ValidPathInfo info;
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for (auto & ref : oldInfo->references) {
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if (ref == path)
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info.references.insert("self");
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else {
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auto replacement = get(remappings, ref, ref);
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// FIXME: warn about unremapped paths?
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info.references.insert(replacement);
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if (replacement != ref)
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rewrites[storePathToHash(ref)] = storePathToHash(replacement);
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}
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}
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*sink.s = rewriteStrings(*sink.s, rewrites);
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HashModuloSink hashModuloSink(htSHA256, oldHashPart);
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hashModuloSink((unsigned char *) sink.s->data(), sink.s->size());
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info.narHash = hashModuloSink.finish().first;
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info.narSize = sink.s->size();
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replaceInSet(info.references, path, std::string("self"));
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info.path = store->makeFixedOutputPath(true, info.narHash, name, info.references);
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replaceInSet(info.references, std::string("self"), info.path);
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info.ca = makeFixedOutputCA(true, info.narHash);
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printError("rewrote '%s' to '%s'", path, info.path);
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auto source = sinkToSource([&](Sink & nextSink) {
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RewritingSink rsink2(oldHashPart, storePathToHash(info.path), nextSink);
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rsink2((unsigned char *) sink.s->data(), sink.s->size());
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rsink2.flush();
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});
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store->addToStore(info, *source);
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remappings[path] = info.path;
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}
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}
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};
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static RegisterCommand r1(make_ref<CmdMakeContentAddressable>());
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