From 80d7994f52ccefca2f2fbe4ee64741a6f49884ff Mon Sep 17 00:00:00 2001 From: John Ericson Date: Wed, 6 Sep 2023 22:57:37 -0400 Subject: Special-case error message to add extra information The Derivation parser and old ATerm unfortunately leaves few ways to get nice errors when an old version of Nix encounters a new version of the format. The most likely scenario for this to occur is with a new client making a derivation that the old daemon it is communicating with cannot understand. The extensions we just created for dynamic derivation deps will add a version field, solving the problem going forward, but there is still the issue of what to do about old versions of Nix up to now. The solution here is to carefully catch the bad error from the daemon that is likely to indicate this problem, and add some extra context to it. There is another "Ugly backwards compatibility hack" in `remote-store.cc` that also works by transforming an error. Co-authored-by: Robert Hensing --- src/libstore/remote-store.cc | 19 ++++++++++++++++++- 1 file changed, 18 insertions(+), 1 deletion(-) (limited to 'src/libstore/remote-store.cc') diff --git a/src/libstore/remote-store.cc b/src/libstore/remote-store.cc index 58f72beb9..a639346d1 100644 --- a/src/libstore/remote-store.cc +++ b/src/libstore/remote-store.cc @@ -172,7 +172,24 @@ void RemoteStore::ConnectionHandle::processStderr(Sink * sink, Source * source, auto ex = handle->processStderr(sink, source, flush); if (ex) { daemonException = true; - std::rethrow_exception(ex); + try { + std::rethrow_exception(ex); + } catch (const Error & e) { + // Nix versions before #4628 did not have an adequate behavior for reporting that the derivation format was upgraded. + // To avoid having to add compatibility logic in many places, we expect to catch almost all occurrences of the + // old incomprehensible error here, so that we can explain to users what's going on when their daemon is + // older than #4628 (2023). + if (experimentalFeatureSettings.isEnabled(Xp::DynamicDerivations) && + GET_PROTOCOL_MINOR(handle->daemonVersion) <= 35) + { + auto m = e.msg(); + if (m.find("parsing derivation") != std::string::npos && + m.find("expected string") != std::string::npos && + m.find("Derive([") != std::string::npos) + throw Error("%s, this might be because the daemon is too old to understand dependencies on dynamic derivations. Check to see if the raw dervation is in the form '%s'", std::move(m), "DrvWithVersion(..)"); + } + throw; + } } } -- cgit v1.2.3