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Path fetcher: Simplify fingerprint computation

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This commit is contained in:
Eelco Dolstra 2025-09-22 23:02:02 +02:00 • committed by John Ericson
parent 3450a72ba0
commit ec6d5c7de3
1 changed files with 15 additions and 27 deletions
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42
src/libfetchers/path.cc
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@ -123,8 +123,6 @@ struct PathInputScheme : InputScheme
auto absPath = getAbsPath(input);
Activity act(*logger, lvlTalkative, actUnknown, fmt("copying %s to the store", absPath));
// FIXME: check whether access to 'path' is allowed.
auto storePath = store->maybeParseStorePath(absPath.string());
@ -133,43 +131,33 @@ struct PathInputScheme : InputScheme
time_t mtime = 0;
if (!storePath || storePath->name() != "source" || !store->isValidPath(*storePath)) {
Activity act(*logger, lvlTalkative, actUnknown, fmt("copying %s to the store", absPath));
// FIXME: try to substitute storePath.
auto src = sinkToSource(
[&](Sink & sink) { mtime = dumpPathAndGetMtime(absPath.string(), sink, defaultPathFilter); });
storePath = store->addToStoreFromDump(*src, "source");
}
// To avoid copying the path again to the /nix/store, we need to add a cache entry.
ContentAddressMethod method = ContentAddressMethod::Raw::NixArchive;
auto fp = getFingerprint(store, input);
if (fp) {
auto cacheKey = makeFetchToStoreCacheKey(input.getName(), *fp, method, "/");
input.settings->getCache()->upsert(cacheKey, *store, {}, *storePath);
}
auto accessor = ref{store->getFSAccessor(*storePath)};
// To prevent `fetchToStore()` copying the path again to Nix
// store, pre-create an entry in the fetcher cache.
auto info = store->queryPathInfo(*storePath);
accessor->fingerprint =
fmt("path:%s", store->queryPathInfo(*storePath)->narHash.to_string(HashFormat::SRI, true));
input.settings->getCache()->upsert(
makeFetchToStoreCacheKey(
input.getName(), *accessor->fingerprint, ContentAddressMethod::Raw::NixArchive, "/"),
*store,
{},
*storePath);
/* Trust the lastModified value supplied by the user, if
any. It's not a "secure" attribute so we don't care. */
if (!input.getLastModified())
input.attrs.insert_or_assign("lastModified", uint64_t(mtime));
return {ref{store->getFSAccessor(*storePath)}, std::move(input)};
}
std::optional<std::string> getFingerprint(ref<Store> store, const Input & input) const override
{
if (isRelative(input))
return std::nullopt;
/* If this path is in the Nix store, use the hash of the
store object and the subpath. */
auto path = getAbsPath(input);
try {
auto [storePath, subPath] = store->toStorePath(path.string());
auto info = store->queryPathInfo(storePath);
return fmt("path:%s:%s", info->narHash.to_string(HashFormat::Base16, false), subPath);
} catch (Error &) {
return std::nullopt;
}
return {accessor, std::move(input)};
}
std::optional<ExperimentalFeature> experimentalFeature() const override