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cleanup and slightly refactor DrvInfo::queryOutputs

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Change-Id: I00d9ff707fe61995737b86af6d2eaa1e4d8116ff
This commit is contained in:
Qyriad 2024-07-07 13:56:28 -06:00
parent c347d3df8f
commit eb18dcb0ea
2 changed files with 118 additions and 48 deletions
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136
src/libexpr/get-drvs.cc
View file

@ -101,51 +101,120 @@ StorePath DrvInfo::queryOutPath()
return *outPath;
}
void DrvInfo::fillOutputs(bool withPaths)
{
auto fillDefault = [&]() {
std::optional<StorePath> outPath = std::nullopt;
if (withPaths) {
outPath.emplace(this->queryOutPath());
}
this->outputs.emplace("out", outPath);
};
// lol. lmao even.
if (this->attrs == nullptr) {
fillDefault();
return;
}
Attr * outputs = this->attrs->get(this->state->sOutputs);
if (outputs == nullptr) {
fillDefault();
return;
}
// NOTE(Qyriad): I don't think there is any codepath that can cause this to error.
this->state->forceList(
*outputs->value,
outputs->pos,
"while evaluating the 'outputs' attribute of a derivation"
);
for (auto [idx, elem] : enumerate(outputs->value->listItems())) {
// NOTE(Qyriad): This error should be *extremely* rare in practice.
// It is impossible to construct with `stdenv.mkDerivation`,
// `builtins.derivation`, or even `derivationStrict`. As far as we can tell,
// it is only possible by overriding a derivation attrset already created by
// one of those with `//` to introduce the failing `outputs` entry.
auto errMsg = fmt("while evaluating output %d of a derivation", idx);
std::string_view outputName = state->forceStringNoCtx(
*elem,
outputs->pos,
errMsg
);
if (withPaths) {
// Find the attr with this output's name...
Attr * out = this->attrs->get(this->state->symbols.create(outputName));
if (out == nullptr) {
// FIXME: throw error?
continue;
}
// Meanwhile we couldn't figure out any circumstances
// that cause this to error.
state->forceAttrs(*out->value, outputs->pos, errMsg);
// ...and evaluate its `outPath` attribute.
Attr * outPath = out->value->attrs->get(this->state->sOutPath);
if (outPath == nullptr) {
continue;
// FIXME: throw error?
}
NixStringContext context;
// And idk what could possibly cause this one to error
// that wouldn't error before here.
auto storePath = state->coerceToStorePath(
outPath->pos,
*outPath->value,
context,
errMsg
);
this->outputs.emplace(outputName, storePath);
} else {
this->outputs.emplace(outputName, std::nullopt);
}
}
}
DrvInfo::Outputs DrvInfo::queryOutputs(bool withPaths, bool onlyOutputsToInstall)
{
// If we haven't already cached the outputs set, then do so now.
if (outputs.empty()) {
/* Get the ‘outputs’ list. */
Bindings::iterator i;
if (attrs && (i = attrs->find(state->sOutputs)) != attrs->end()) {
state->forceList(*i->value, i->pos, "while evaluating the 'outputs' attribute of a derivation");
/* For each output... */
for (auto elem : i->value->listItems()) {
std::string output(state->forceStringNoCtx(*elem, i->pos, "while evaluating the name of an output of a derivation"));
if (withPaths) {
/* Evaluate the corresponding set. */
Bindings::iterator out = attrs->find(state->symbols.create(output));
if (out == attrs->end()) continue; // FIXME: throw error?
state->forceAttrs(*out->value, i->pos, "while evaluating an output of a derivation");
/* And evaluate its ‘outPath’ attribute. */
Bindings::iterator outPath = out->value->attrs->find(state->sOutPath);
if (outPath == out->value->attrs->end()) continue; // FIXME: throw error?
NixStringContext context;
outputs.emplace(output, state->coerceToStorePath(outPath->pos, *outPath->value, context, "while evaluating an output path of a derivation"));
} else
outputs.emplace(output, std::nullopt);
}
} else
outputs.emplace("out", withPaths ? std::optional{queryOutPath()} : std::nullopt);
// FIXME: this behavior seems kind of busted, since whether or not this
// DrvInfo will have paths is forever determined by the *first* call to
// this function??
fillOutputs(withPaths);
}
// Things that operate on derivations like packages, like `nix-env` and `nix build`,
// allow derivations to specify which outputs should be used in those user-facing
// cases if the user didn't specify an output explicitly.
// If the caller just wanted all the outputs for this derivation, though,
// then we're done here.
if (!onlyOutputsToInstall || !attrs)
return outputs;
Bindings::iterator i;
if (attrs && (i = attrs->find(state->sOutputSpecified)) != attrs->end() && state->forceBool(*i->value, i->pos, "while evaluating the 'outputSpecified' attribute of a derivation")) {
Outputs result;
auto out = outputs.find(queryOutputName());
if (out == outputs.end())
// Regardless of `meta.outputsToInstall`, though, you can select into a derivation
// output by its attribute, e.g. `pkgs.lix.dev`, which (lol?) sets the magic
// attribute `outputSpecified = true`, and changes the `outputName` attr to the
// explicitly selected-into output.
if (Attr * outSpecAttr = attrs->get(state->sOutputSpecified)) {
bool outputSpecified = this->state->forceBool(
*outSpecAttr->value,
outSpecAttr->pos,
"while evaluating the 'outputSpecified' attribute of a derivation"
);
if (outputSpecified) {
auto maybeOut = outputs.find(queryOutputName());
if (maybeOut == outputs.end()) {
throw Error("derivation does not have output '%s'", queryOutputName());
result.insert(*out);
return result;
}
return Outputs{*maybeOut};
}
}
else {
/* Check for `meta.outputsToInstall` and return `outputs` reduced to that. */
const Value * outTI = queryMeta("outputsToInstall");
if (!outTI) return outputs;
@ -160,7 +229,6 @@ DrvInfo::Outputs DrvInfo::queryOutputs(bool withPaths, bool onlyOutputsToInstall
result.insert(*out);
}
return result;
}
}

2
src/libexpr/get-drvs.hh
View file

@ -37,6 +37,8 @@ private:
bool checkMeta(Value & v);
void fillOutputs(bool withPaths = true);
public:
/**
* path towards the derivation