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authorEelco Dolstra <edolstra@gmail.com>2018-03-30 00:56:13 +0200
committerEelco Dolstra <edolstra@gmail.com>2019-10-21 17:47:24 +0200
commit0abb3ad53795aa3a4792d30e5721a337f0eddfb7 (patch)
treeda8324e1796eaf0e7d41c5425f15ad8e4cacfd94 /src
parentaabf5c86c9df1b4e1616a4cf06ee14a6edf2e5e1 (diff)
Allow content-addressable paths to have references
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
Diffstat (limited to 'src')
-rw-r--r--src/libstore/build.cc19
-rw-r--r--src/libstore/local-store.cc21
-rw-r--r--src/libstore/references.cc62
-rw-r--r--src/libstore/references.hh29
-rw-r--r--src/libstore/store-api.cc36
-rw-r--r--src/libstore/store-api.hh3
-rw-r--r--src/libutil/hash.cc20
-rw-r--r--src/libutil/hash.hh11
-rw-r--r--src/libutil/serialise.hh2
-rw-r--r--src/libutil/util.cc13
-rw-r--r--src/libutil/util.hh14
-rw-r--r--src/nix/command.cc2
-rw-r--r--src/nix/command.hh4
-rw-r--r--src/nix/hash.cc22
-rw-r--r--src/nix/make-content-addressable.cc82
-rw-r--r--src/nix/verify.cc12
16 files changed, 288 insertions, 64 deletions
diff --git a/src/libstore/build.cc b/src/libstore/build.cc
index 0e0f8a545..68c2f2ce3 100644
--- a/src/libstore/build.cc
+++ b/src/libstore/build.cc
@@ -727,23 +727,6 @@ HookInstance::~HookInstance()
//////////////////////////////////////////////////////////////////////
-typedef map<std::string, std::string> StringRewrites;
-
-
-std::string rewriteStrings(std::string s, const StringRewrites & rewrites)
-{
- for (auto & i : rewrites) {
- size_t j = 0;
- while ((j = s.find(i.first, j)) != string::npos)
- s.replace(j, i.first.size(), i.second);
- }
- return s;
-}
-
-
-//////////////////////////////////////////////////////////////////////
-
-
typedef enum {rpAccept, rpDecline, rpPostpone} HookReply;
class SubstitutionGoal;
@@ -865,7 +848,7 @@ private:
#endif
/* Hash rewriting. */
- StringRewrites inputRewrites, outputRewrites;
+ StringMap inputRewrites, outputRewrites;
typedef map<Path, Path> RedirectedOutputs;
RedirectedOutputs redirectedOutputs;
diff --git a/src/libstore/local-store.cc b/src/libstore/local-store.cc
index d86f7b1d2..1280ecab5 100644
--- a/src/libstore/local-store.cc
+++ b/src/libstore/local-store.cc
@@ -5,6 +5,7 @@
#include "worker-protocol.hh"
#include "derivations.hh"
#include "nar-info.hh"
+#include "references.hh"
#include <iostream>
#include <algorithm>
@@ -1009,17 +1010,21 @@ void LocalStore::addToStore(const ValidPathInfo & info, Source & source,
/* While restoring the path from the NAR, compute the hash
of the NAR. */
- HashSink hashSink(htSHA256);
+ std::unique_ptr<AbstractHashSink> hashSink;
+ if (info.ca == "")
+ hashSink = std::make_unique<HashSink>(htSHA256);
+ else
+ hashSink = std::make_unique<HashModuloSink>(htSHA256, storePathToHash(info.path));
LambdaSource wrapperSource([&](unsigned char * data, size_t len) -> size_t {
size_t n = source.read(data, len);
- hashSink(data, n);
+ (*hashSink)(data, n);
return n;
});
restorePath(realPath, wrapperSource);
- auto hashResult = hashSink.finish();
+ auto hashResult = hashSink->finish();
if (hashResult.first != info.narHash)
throw Error("hash mismatch importing path '%s';\n wanted: %s\n got: %s",
@@ -1241,7 +1246,15 @@ bool LocalStore::verifyStore(bool checkContents, RepairFlag repair)
/* Check the content hash (optionally - slow). */
printMsg(lvlTalkative, format("checking contents of '%1%'") % i);
- HashResult current = hashPath(info->narHash.type, toRealPath(i));
+
+ std::unique_ptr<AbstractHashSink> hashSink;
+ if (info->ca == "")
+ hashSink = std::make_unique<HashSink>(info->narHash.type);
+ else
+ hashSink = std::make_unique<HashModuloSink>(info->narHash.type, storePathToHash(info->path));
+
+ dumpPath(toRealPath(i), *hashSink);
+ auto current = hashSink->finish();
if (info->narHash != nullHash && info->narHash != current.first) {
printError(format("path '%1%' was modified! "
diff --git a/src/libstore/references.cc b/src/libstore/references.cc
index 0dcc264c3..605ca9815 100644
--- a/src/libstore/references.cc
+++ b/src/libstore/references.cc
@@ -118,4 +118,66 @@ PathSet scanForReferences(const string & path,
}
+RewritingSink::RewritingSink(const std::string & from, const std::string & to, Sink & nextSink)
+ : from(from), to(to), nextSink(nextSink)
+{
+ assert(from.size() == to.size());
+}
+
+void RewritingSink::operator () (const unsigned char * data, size_t len)
+{
+ std::string s(prev);
+ s.append((const char *) data, len);
+
+ size_t j = 0;
+ while ((j = s.find(from, j)) != string::npos) {
+ matches.push_back(pos + j);
+ s.replace(j, from.size(), to);
+ }
+
+ prev = s.size() < from.size() ? s : std::string(s, s.size() - from.size() + 1, from.size() - 1);
+
+ auto consumed = s.size() - prev.size();
+
+ pos += consumed;
+
+ if (consumed) nextSink((unsigned char *) s.data(), consumed);
+}
+
+void RewritingSink::flush()
+{
+ if (prev.empty()) return;
+ pos += prev.size();
+ nextSink((unsigned char *) prev.data(), prev.size());
+ prev.clear();
+}
+
+HashModuloSink::HashModuloSink(HashType ht, const std::string & modulus)
+ : hashSink(ht)
+ , rewritingSink(modulus, std::string(modulus.size(), 0), hashSink)
+{
+}
+
+void HashModuloSink::operator () (const unsigned char * data, size_t len)
+{
+ rewritingSink(data, len);
+}
+
+HashResult HashModuloSink::finish()
+{
+ rewritingSink.flush();
+
+ /* Hash the positions of the self-references. This ensures that a
+ NAR with self-references and a NAR with some of the
+ self-references already zeroed out do not produce a hash
+ collision. FIXME: proof. */
+ for (auto & pos : rewritingSink.matches) {
+ auto s = fmt("|%d", pos);
+ hashSink((unsigned char *) s.data(), s.size());
+ }
+
+ auto h = hashSink.finish();
+ return {h.first, rewritingSink.pos};
+}
+
}
diff --git a/src/libstore/references.hh b/src/libstore/references.hh
index 013809d12..c38bdd720 100644
--- a/src/libstore/references.hh
+++ b/src/libstore/references.hh
@@ -7,5 +7,32 @@ namespace nix {
PathSet scanForReferences(const Path & path, const PathSet & refs,
HashResult & hash);
-
+
+struct RewritingSink : Sink
+{
+ std::string from, to, prev;
+ Sink & nextSink;
+ uint64_t pos = 0;
+
+ std::vector<uint64_t> matches;
+
+ RewritingSink(const std::string & from, const std::string & to, Sink & nextSink);
+
+ void operator () (const unsigned char * data, size_t len) override;
+
+ void flush();
+};
+
+struct HashModuloSink : AbstractHashSink
+{
+ HashSink hashSink;
+ RewritingSink rewritingSink;
+
+ HashModuloSink(HashType ht, const std::string & modulus);
+
+ void operator () (const unsigned char * data, size_t len) override;
+
+ HashResult finish() override;
+};
+
}
diff --git a/src/libstore/store-api.cc b/src/libstore/store-api.cc
index be13fa49a..1a1b24e3b 100644
--- a/src/libstore/store-api.cc
+++ b/src/libstore/store-api.cc
@@ -205,15 +205,27 @@ Path Store::makeOutputPath(const string & id,
}
+static std::string makeType(string && type, const PathSet & references)
+{
+ for (auto & i : references) {
+ type += ":";
+ type += i;
+ }
+ return type;
+}
+
+
Path Store::makeFixedOutputPath(bool recursive,
- const Hash & hash, const string & name) const
+ const Hash & hash, const string & name, const PathSet & references) const
{
- return hash.type == htSHA256 && recursive
- ? makeStorePath("source", hash, name)
- : makeStorePath("output:out", hashString(htSHA256,
+ if (hash.type == htSHA256 && recursive) {
+ return makeStorePath(makeType("source", references), hash, name);
+ } else {
+ assert(references.empty());
+ return makeStorePath("output:out", hashString(htSHA256,
"fixed:out:" + (recursive ? (string) "r:" : "") +
- hash.to_string(Base16) + ":"),
- name);
+ hash.to_string(Base16) + ":"), name);
+ }
}
@@ -224,12 +236,7 @@ Path Store::makeTextPath(const string & name, const Hash & hash,
/* Stuff the references (if any) into the type. This is a bit
hacky, but we can't put them in `s' since that would be
ambiguous. */
- string type = "text";
- for (auto & i : references) {
- type += ":";
- type += i;
- }
- return makeStorePath(type, hash, name);
+ return makeStorePath(makeType("text", references), hash, name);
}
@@ -785,8 +792,9 @@ bool ValidPathInfo::isContentAddressed(const Store & store) const
else if (hasPrefix(ca, "fixed:")) {
bool recursive = ca.compare(6, 2, "r:") == 0;
Hash hash(std::string(ca, recursive ? 8 : 6));
- if (references.empty() &&
- store.makeFixedOutputPath(recursive, hash, storePathToName(path)) == path)
+ auto refs = references;
+ replaceInSet(refs, path, std::string("self"));
+ if (store.makeFixedOutputPath(recursive, hash, storePathToName(path), refs) == path)
return true;
else
warn();
diff --git a/src/libstore/store-api.hh b/src/libstore/store-api.hh
index ba8990755..250e1a4bc 100644
--- a/src/libstore/store-api.hh
+++ b/src/libstore/store-api.hh
@@ -303,7 +303,8 @@ public:
const Hash & hash, const string & name) const;
Path makeFixedOutputPath(bool recursive,
- const Hash & hash, const string & name) const;
+ const Hash & hash, const string & name,
+ const PathSet & references = {}) const;
Path makeTextPath(const string & name, const Hash & hash,
const PathSet & references) const;
diff --git a/src/libutil/hash.cc b/src/libutil/hash.cc
index 1c14ebb18..7caee1da7 100644
--- a/src/libutil/hash.cc
+++ b/src/libutil/hash.cc
@@ -256,23 +256,9 @@ Hash hashString(HashType ht, const string & s)
Hash hashFile(HashType ht, const Path & path)
{
- Ctx ctx;
- Hash hash(ht);
- start(ht, ctx);
-
- AutoCloseFD fd = open(path.c_str(), O_RDONLY | O_CLOEXEC);
- if (!fd) throw SysError(format("opening file '%1%'") % path);
-
- std::vector<unsigned char> buf(8192);
- ssize_t n;
- while ((n = read(fd.get(), buf.data(), buf.size()))) {
- checkInterrupt();
- if (n == -1) throw SysError(format("reading file '%1%'") % path);
- update(ht, ctx, buf.data(), n);
- }
-
- finish(ht, ctx, hash.hash);
- return hash;
+ HashSink sink(ht);
+ readFile(path, sink);
+ return sink.finish().first;
}
diff --git a/src/libutil/hash.hh b/src/libutil/hash.hh
index 2dbc3b630..ffa43ecf5 100644
--- a/src/libutil/hash.hh
+++ b/src/libutil/hash.hh
@@ -111,7 +111,12 @@ string printHashType(HashType ht);
union Ctx;
-class HashSink : public BufferedSink
+struct AbstractHashSink : virtual Sink
+{
+ virtual HashResult finish() = 0;
+};
+
+class HashSink : public BufferedSink, public AbstractHashSink
{
private:
HashType ht;
@@ -122,8 +127,8 @@ public:
HashSink(HashType ht);
HashSink(const HashSink & h);
~HashSink();
- void write(const unsigned char * data, size_t len);
- HashResult finish();
+ void write(const unsigned char * data, size_t len) override;
+ HashResult finish() override;
HashResult currentHash();
};
diff --git a/src/libutil/serialise.hh b/src/libutil/serialise.hh
index a344a5ac7..0120aeecb 100644
--- a/src/libutil/serialise.hh
+++ b/src/libutil/serialise.hh
@@ -24,7 +24,7 @@ struct Sink
/* A buffered abstract sink. */
-struct BufferedSink : Sink
+struct BufferedSink : virtual Sink
{
size_t bufSize, bufPos;
std::unique_ptr<unsigned char[]> buffer;
diff --git a/src/libutil/util.cc b/src/libutil/util.cc
index 6f3bf7ae8..2e416edef 100644
--- a/src/libutil/util.cc
+++ b/src/libutil/util.cc
@@ -1260,6 +1260,19 @@ string replaceStrings(const std::string & s,
}
+std::string rewriteStrings(const std::string & _s, const StringMap & rewrites)
+{
+ auto s = _s;
+ for (auto & i : rewrites) {
+ if (i.first == i.second) continue;
+ size_t j = 0;
+ while ((j = s.find(i.first, j)) != string::npos)
+ s.replace(j, i.first.size(), i.second);
+ }
+ return s;
+}
+
+
string statusToString(int status)
{
if (!WIFEXITED(status) || WEXITSTATUS(status) != 0) {
diff --git a/src/libutil/util.hh b/src/libutil/util.hh
index f057fdb2c..3493e80b5 100644
--- a/src/libutil/util.hh
+++ b/src/libutil/util.hh
@@ -362,6 +362,20 @@ string replaceStrings(const std::string & s,
const std::string & from, const std::string & to);
+std::string rewriteStrings(const std::string & s, const StringMap & rewrites);
+
+
+/* If a set contains 'from', remove it and insert 'to'. */
+template<typename T>
+void replaceInSet(std::set<T> & set, const T & from, const T & to)
+{
+ auto i = set.find(from);
+ if (i == set.end()) return;
+ set.erase(i);
+ set.insert(to);
+}
+
+
/* Convert the exit status of a child as returned by wait() into an
error string. */
string statusToString(int status);
diff --git a/src/nix/command.cc b/src/nix/command.cc
index 3d7d582d6..532f331a7 100644
--- a/src/nix/command.cc
+++ b/src/nix/command.cc
@@ -129,7 +129,7 @@ void StorePathsCommand::run(ref<Store> store)
}
else {
- for (auto & p : toStorePaths(store, NoBuild, installables))
+ for (auto & p : toStorePaths(store, realiseMode, installables))
storePaths.push_back(p);
if (recursive) {
diff --git a/src/nix/command.hh b/src/nix/command.hh
index 97a6fee7f..45ad1cd2a 100644
--- a/src/nix/command.hh
+++ b/src/nix/command.hh
@@ -139,6 +139,10 @@ private:
bool recursive = false;
bool all = false;
+protected:
+
+ RealiseMode realiseMode = NoBuild;
+
public:
StorePathsCommand(bool recursive = false);
diff --git a/src/nix/hash.cc b/src/nix/hash.cc
index af4105e28..9c06e6116 100644
--- a/src/nix/hash.cc
+++ b/src/nix/hash.cc
@@ -2,6 +2,8 @@
#include "hash.hh"
#include "legacy.hh"
#include "shared.hh"
+#include "references.hh"
+#include "archive.hh"
using namespace nix;
@@ -13,6 +15,7 @@ struct CmdHash : Command
bool truncate = false;
HashType ht = htSHA256;
std::vector<std::string> paths;
+ std::experimental::optional<std::string> modulus;
CmdHash(Mode mode) : mode(mode)
{
@@ -23,6 +26,11 @@ struct CmdHash : Command
mkFlag()
.longName("type")
.mkHashTypeFlag(&ht);
+ mkFlag()
+ .longName("modulo")
+ .description("compute hash modulo specified string")
+ .labels({"modulus"})
+ .dest(&modulus);
expectArgs("paths", &paths);
}
@@ -41,7 +49,19 @@ struct CmdHash : Command
void run() override
{
for (auto path : paths) {
- Hash h = mode == mFile ? hashFile(ht, path) : hashPath(ht, path).first;
+
+ std::unique_ptr<AbstractHashSink> hashSink;
+ if (modulus)
+ hashSink = std::make_unique<HashModuloSink>(ht, *modulus);
+ else
+ hashSink = std::make_unique<HashSink>(ht);
+
+ if (mode == mFile)
+ readFile(path, *hashSink);
+ else
+ dumpPath(path, *hashSink);
+
+ Hash h = hashSink->finish().first;
if (truncate && h.hashSize > 20) h = compressHash(h, 20);
std::cout << format("%1%\n") %
h.to_string(base, base == SRI);
diff --git a/src/nix/make-content-addressable.cc b/src/nix/make-content-addressable.cc
new file mode 100644
index 000000000..14ed06413
--- /dev/null
+++ b/src/nix/make-content-addressable.cc
@@ -0,0 +1,82 @@
+#include "command.hh"
+#include "store-api.hh"
+#include "references.hh"
+
+using namespace nix;
+
+struct CmdMakeContentAddressable : StorePathsCommand
+{
+ CmdMakeContentAddressable()
+ {
+ realiseMode = Build;
+ }
+
+ std::string name() override
+ {
+ return "make-content-addressable";
+ }
+
+ std::string description() override
+ {
+ return "test";
+ }
+
+ void run(ref<Store> store, Paths storePaths) override
+ {
+ auto paths = store->topoSortPaths(PathSet(storePaths.begin(), storePaths.end()));
+
+ paths.reverse();
+
+ std::map<Path, Path> remappings;
+
+ for (auto & path : paths) {
+ auto oldInfo = store->queryPathInfo(path);
+ auto oldHashPart = storePathToHash(path);
+ auto name = storePathToName(path);
+
+ StringSink sink;
+ store->narFromPath(path, sink);
+
+ StringMap rewrites;
+
+ ValidPathInfo info;
+ for (auto & ref : oldInfo->references) {
+ if (ref == path)
+ info.references.insert("self");
+ else {
+ auto replacement = get(remappings, ref, ref);
+ // FIXME: warn about unremapped paths?
+ info.references.insert(replacement);
+ if (replacement != ref)
+ rewrites[storePathToHash(ref)] = storePathToHash(replacement);
+ }
+ }
+
+ *sink.s = rewriteStrings(*sink.s, rewrites);
+
+ HashModuloSink hashModuloSink(htSHA256, oldHashPart);
+ hashModuloSink((unsigned char *) sink.s->data(), sink.s->size());
+
+ info.narHash = hashModuloSink.finish().first;
+ info.narSize = sink.s->size();
+ replaceInSet(info.references, path, std::string("self"));
+ info.path = store->makeFixedOutputPath(true, info.narHash, name, info.references);
+ replaceInSet(info.references, std::string("self"), info.path);
+ info.ca = makeFixedOutputCA(true, info.narHash);
+
+ printError("rewrote '%s' to '%s'", path, info.path);
+
+ auto source = sinkToSource([&](Sink & nextSink) {
+ RewritingSink rsink2(oldHashPart, storePathToHash(info.path), nextSink);
+ rsink2((unsigned char *) sink.s->data(), sink.s->size());
+ rsink2.flush();
+ });
+
+ store->addToStore(info, *source);
+
+ remappings[path] = info.path;
+ }
+ }
+};
+
+static RegisterCommand r1(make_ref<CmdMakeContentAddressable>());
diff --git a/src/nix/verify.cc b/src/nix/verify.cc
index 74d9673b6..4b0f80c62 100644
--- a/src/nix/verify.cc
+++ b/src/nix/verify.cc
@@ -3,6 +3,7 @@
#include "store-api.hh"
#include "sync.hh"
#include "thread-pool.hh"
+#include "references.hh"
#include <atomic>
@@ -88,10 +89,15 @@ struct CmdVerify : StorePathsCommand
if (!noContents) {
- HashSink sink(info->narHash.type);
- store->narFromPath(info->path, sink);
+ std::unique_ptr<AbstractHashSink> hashSink;
+ if (info->ca == "")
+ hashSink = std::make_unique<HashSink>(info->narHash.type);
+ else
+ hashSink = std::make_unique<HashModuloSink>(info->narHash.type, storePathToHash(info->path));
- auto hash = sink.finish();
+ store->narFromPath(info->path, *hashSink);
+
+ auto hash = hashSink->finish();
if (hash.first != info->narHash) {
corrupted++;