mirror of
https://github.com/NixOS/nix
synced 2025-06-25 06:31:14 +02:00
c98026e982
This adds a setting 'lazy-trees' that causes flake inputs to be
"mounted" as virtual filesystems on top of /nix/store as random
"virtual" store paths. Only when the store path is actually used as a
dependency of a store derivation do we materialize ("devirtualize")
the input by copying it to its content-addressed location in the
store.
String contexts determine when devirtualization happens. One wrinkle
is that there are cases where we had store paths without proper
contexts, in particular when the user does `toString <path>` (where
<path> is a source tree in the Nix store) and passes the result to a
derivation. This usage was always broken, since it can result in
derivations that lack correct references. But to ensure that we don't
change evaluation results, we introduce a new type of context that
results in devirtualization but not in store references. We also now
print a warning about this.
128 lines
3.6 KiB
C++
128 lines
3.6 KiB
C++
#include "nix/expr/value-to-json.hh"
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#include "nix/expr/eval-inline.hh"
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#include "nix/store/store-api.hh"
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#include "nix/util/signals.hh"
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#include <cstdlib>
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#include <iomanip>
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#include <nlohmann/json.hpp>
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namespace nix {
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using json = nlohmann::json;
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// TODO: rename. It doesn't print.
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json printValueAsJSON(EvalState & state, bool strict,
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Value & v, const PosIdx pos, NixStringContext & context, bool copyToStore)
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{
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checkInterrupt();
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if (strict) state.forceValue(v, pos);
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json out;
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switch (v.type()) {
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case nInt:
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out = v.integer().value;
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break;
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case nBool:
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out = v.boolean();
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break;
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case nString:
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copyContext(v, context);
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out = v.c_str();
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break;
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case nPath:
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if (copyToStore)
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out = state.store->printStorePath(
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state.copyPathToStore(context, v.path()));
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else
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out = v.path().path.abs();
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break;
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case nNull:
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// already initialized as null
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break;
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case nAttrs: {
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auto maybeString = state.tryAttrsToString(pos, v, context, false, false);
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if (maybeString) {
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out = *maybeString;
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break;
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}
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if (auto i = v.attrs()->get(state.sOutPath))
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return printValueAsJSON(state, strict, *i->value, i->pos, context, copyToStore);
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else {
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out = json::object();
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for (auto & a : v.attrs()->lexicographicOrder(state.symbols)) {
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try {
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out.emplace(state.symbols[a->name], printValueAsJSON(state, strict, *a->value, a->pos, context, copyToStore));
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} catch (Error & e) {
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e.addTrace(state.positions[a->pos],
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HintFmt("while evaluating attribute '%1%'", state.symbols[a->name]));
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throw;
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}
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}
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}
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break;
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}
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case nList: {
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out = json::array();
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int i = 0;
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for (auto elem : v.listItems()) {
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try {
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out.push_back(printValueAsJSON(state, strict, *elem, pos, context, copyToStore));
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} catch (Error & e) {
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e.addTrace(state.positions[pos],
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HintFmt("while evaluating list element at index %1%", i));
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throw;
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}
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i++;
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}
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break;
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}
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case nExternal:
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return v.external()->printValueAsJSON(state, strict, context, copyToStore);
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break;
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case nFloat:
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out = v.fpoint();
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break;
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case nThunk:
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case nFunction:
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state.error<TypeError>(
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"cannot convert %1% to JSON",
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showType(v)
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)
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.atPos(v.determinePos(pos))
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.debugThrow();
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}
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return out;
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}
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void printValueAsJSON(EvalState & state, bool strict,
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Value & v, const PosIdx pos, std::ostream & str, NixStringContext & context, bool copyToStore)
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{
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try {
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str << printValueAsJSON(state, strict, v, pos, context, copyToStore);
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} catch (nlohmann::json::exception & e) {
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throw JSONSerializationError("JSON serialization error: %s", e.what());
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}
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}
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json ExternalValueBase::printValueAsJSON(EvalState & state, bool strict,
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NixStringContext & context, bool copyToStore) const
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{
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state.error<TypeError>("cannot convert %1% to JSON", showType())
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.debugThrow();
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}
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}
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