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Simplify "final" inputs

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We now just check that the fetcher doesn't change any attributes in
the input, and return all the original attributes (i.e. discarding any
new attributes and keeping any attributes that the fetcher didn't
keep).
This commit is contained in:
Eelco Dolstra 2024-11-01 16:33:51 +01:00
parent 5c49d0b5d2
commit f314e35b37
3 changed files with 51 additions and 38 deletions
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50
src/libfetchers/fetchers.cc
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@ -193,7 +193,7 @@ std::pair<StorePath, Input> Input::fetchToStore(ref<Store> store) const
assert(final.isFinal());
scheme->checkLocks(*this, final);
checkLocks(*this, final);
return {storePath, final};
} catch (Error & e) {
@ -205,8 +205,35 @@ std::pair<StorePath, Input> Input::fetchToStore(ref<Store> store) const
return {std::move(storePath), input};
}
void InputScheme::checkLocks(const Input & specified, const Input & final) const
void Input::checkLocks(Input specified, Input & final)
{
/* If the original input is final, then we just return the
original attributes, dropping any new fields returned by the
fetcher. However, any fields that are in both the original and
final input must be identical. */
if (specified.isFinal()) {
/* Backwards compatibility hack: we had some lock files in the
past that 'narHash' fields with incorrect base-64
formatting (lacking the trailing '=', e.g. 'sha256-ri...Mw'
instead of ''sha256-ri...Mw='). So fix that. */
if (auto prevNarHash = specified.getNarHash())
specified.attrs.insert_or_assign("narHash", prevNarHash->to_string(HashFormat::SRI, true));
for (auto & field : specified.attrs) {
auto field2 = final.attrs.find(field.first);
if (field2 != final.attrs.end() && field.second != field2->second)
throw Error("mismatch in field '%s' of final input '%s', got '%s'",
field.first,
attrsToJSON(specified.attrs),
attrsToJSON(final.attrs));
}
final.attrs = specified.attrs;
return;
}
if (auto prevNarHash = specified.getNarHash()) {
if (final.getNarHash() != prevNarHash) {
if (final.getNarHash())
@ -235,23 +262,6 @@ void InputScheme::checkLocks(const Input & specified, const Input & final) const
throw Error("'revCount' attribute mismatch in input '%s', expected %d",
final.to_string(), *prevRevCount);
}
/* If the original input is final, then the result must be the
same (i.e. cannot remove, add or change fields. */
if (specified.isFinal()) {
/* Backwards compatibility hack: we had some lock files in the
past that 'narHash' fields with incorrect base-64
formatting (lacking the trailing '=', e.g. 'sha256-ri...Mw'
instead of ''sha256-ri...Mw='). So fix */
auto specified2 = specified;
if (auto prevNarHash = specified2.getNarHash())
specified2.attrs.insert_or_assign("narHash", prevNarHash->to_string(HashFormat::SRI, true));
if (specified2.attrs != final.attrs)
throw Error("fetching final input '%s' resulted in different input '%s'",
attrsToJSON(specified2.attrs), attrsToJSON(final.attrs));
}
}
std::pair<ref<SourceAccessor>, Input> Input::getAccessor(ref<Store> store) const
@ -259,7 +269,7 @@ std::pair<ref<SourceAccessor>, Input> Input::getAccessor(ref<Store> store) const
try {
auto [accessor, final] = getAccessorUnchecked(store);
scheme->checkLocks(*this, final);
checkLocks(*this, final);
return {accessor, std::move(final)};
} catch (Error & e) {