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nix/src/libstore/export-import.cc
Sergei Zimmerman 143bd60136
libutil: Make HashResult a proper struct
This resolves an existing TODO and makes the
code slightly more readable.
2025-08-08 02:06:14 +03:00

97 lines
3 KiB
C++

#include "nix/util/serialise.hh"
#include "nix/store/store-api.hh"
#include "nix/util/archive.hh"
#include "nix/store/common-protocol.hh"
#include "nix/store/common-protocol-impl.hh"
#include <algorithm>
namespace nix {
void Store::exportPaths(const StorePathSet & paths, Sink & sink)
{
auto sorted = topoSortPaths(paths);
std::reverse(sorted.begin(), sorted.end());
for (auto & path : sorted) {
sink << 1;
exportPath(path, sink);
}
sink << 0;
}
void Store::exportPath(const StorePath & path, Sink & sink)
{
auto info = queryPathInfo(path);
HashSink hashSink(HashAlgorithm::SHA256);
TeeSink teeSink(sink, hashSink);
narFromPath(path, teeSink);
/* Refuse to export paths that have changed. This prevents
filesystem corruption from spreading to other machines.
Don't complain if the stored hash is zero (unknown). */
Hash hash = hashSink.currentHash().hash;
if (hash != info->narHash && info->narHash != Hash(info->narHash.algo))
throw Error(
"hash of path '%s' has changed from '%s' to '%s'!",
printStorePath(path),
info->narHash.to_string(HashFormat::Nix32, true),
hash.to_string(HashFormat::Nix32, true));
teeSink << exportMagic << printStorePath(path);
CommonProto::write(*this, CommonProto::WriteConn{.to = teeSink}, info->references);
teeSink << (info->deriver ? printStorePath(*info->deriver) : "") << 0;
}
StorePaths Store::importPaths(Source & source, CheckSigsFlag checkSigs)
{
StorePaths res;
while (true) {
auto n = readNum<uint64_t>(source);
if (n == 0)
break;
if (n != 1)
throw Error("input doesn't look like something created by 'nix-store --export'");
/* Extract the NAR from the source. */
StringSink saved;
TeeSource tee{source, saved};
NullFileSystemObjectSink ether;
parseDump(ether, tee);
uint32_t magic = readInt(source);
if (magic != exportMagic)
throw Error("Nix archive cannot be imported; wrong format");
auto path = parseStorePath(readString(source));
// Activity act(*logger, lvlInfo, "importing path '%s'", info.path);
auto references = CommonProto::Serialise<StorePathSet>::read(*this, CommonProto::ReadConn{.from = source});
auto deriver = readString(source);
auto narHash = hashString(HashAlgorithm::SHA256, saved.s);
ValidPathInfo info{path, narHash};
if (deriver != "")
info.deriver = parseStorePath(deriver);
info.references = references;
info.narSize = saved.s.size();
// Ignore optional legacy signature.
if (readInt(source) == 1)
readString(source);
// Can't use underlying source, which would have been exhausted
auto source = StringSource(saved.s);
addToStore(info, source, NoRepair, checkSigs);
res.push_back(info.path);
}
return res;
}
} // namespace nix