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Make the Store API more type-safe

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Most functions now take a StorePath argument rather than a Path (which
is just an alias for std::string). The StorePath constructor ensures
that the path is syntactically correct (i.e. it looks like
<store-dir>/<base32-hash>-<name>). Similarly, functions like
buildPaths() now take a StorePathWithOutputs, rather than abusing Path
by adding a '!<outputs>' suffix.

Note that the StorePath type is implemented in Rust. This involves
some hackery to allow Rust values to be used directly in C++, via a
helper type whose destructor calls the Rust type's drop()
function. The main issue is the dynamic nature of C++ move semantics:
after we have moved a Rust value, we should not call the drop function
on the original value. So when we move a value, we set the original
value to bitwise zero, and the destructor only calls drop() if the
value is not bitwise zero. This should be sufficient for most types.

Also lots of minor cleanups to the C++ API to make it more modern
(e.g. using std::optional and std::string_view in some places).
This commit is contained in:
Eelco Dolstra 2019-12-05 19:11:09 +01:00
parent ebd89999c2
commit bbe97dff8b
98 changed files with 2638 additions and 2880 deletions
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133
src/libexpr/primops.cc
View file

@ -44,29 +44,28 @@ std::pair<string, string> decodeContext(const string & s)
InvalidPathError::InvalidPathError(const Path & path) :
EvalError(format("path '%1%' is not valid") % path), path(path) {}
EvalError("path '%s' is not valid", path), path(path) {}
void EvalState::realiseContext(const PathSet & context)
{
PathSet drvs;
std::vector<StorePathWithOutputs> drvs;
for (auto & i : context) {
std::pair<string, string> decoded = decodeContext(i);
Path ctx = decoded.first;
assert(store->isStorePath(ctx));
auto ctx = store->parseStorePath(decoded.first);
if (!store->isValidPath(ctx))
throw InvalidPathError(ctx);
if (!decoded.second.empty() && nix::isDerivation(ctx)) {
drvs.insert(decoded.first + "!" + decoded.second);
throw InvalidPathError(store->printStorePath(ctx));
if (!decoded.second.empty() && ctx.isDerivation()) {
drvs.push_back(StorePathWithOutputs{ctx.clone(), {decoded.second}});
/* Add the output of this derivation to the allowed
paths. */
if (allowedPaths) {
auto drv = store->derivationFromPath(decoded.first);
auto drv = store->derivationFromPath(store->parseStorePath(decoded.first));
DerivationOutputs::iterator i = drv.outputs.find(decoded.second);
if (i == drv.outputs.end())
throw Error("derivation '%s' does not have an output named '%s'", decoded.first, decoded.second);
allowedPaths->insert(i->second.path);
allowedPaths->insert(store->printStorePath(i->second.path));
}
}
}
@ -74,10 +73,11 @@ void EvalState::realiseContext(const PathSet & context)
if (drvs.empty()) return;
if (!evalSettings.enableImportFromDerivation)
throw EvalError(format("attempted to realize '%1%' during evaluation but 'allow-import-from-derivation' is false") % *(drvs.begin()));
throw EvalError("attempted to realize '%1%' during evaluation but 'allow-import-from-derivation' is false",
store->printStorePath(drvs.begin()->path));
/* For performance, prefetch all substitute info. */
PathSet willBuild, willSubstitute, unknown;
StorePathSet willBuild, willSubstitute, unknown;
unsigned long long downloadSize, narSize;
store->queryMissing(drvs, willBuild, willSubstitute, unknown, downloadSize, narSize);
store->buildPaths(drvs);
@ -100,8 +100,9 @@ static void prim_scopedImport(EvalState & state, const Pos & pos, Value * * args
Path realPath = state.checkSourcePath(state.toRealPath(path, context));
if (state.store->isStorePath(path) && state.store->isValidPath(path) && isDerivation(path)) {
Derivation drv = readDerivation(realPath);
// FIXME
if (state.store->isStorePath(path) && state.store->isValidPath(state.store->parseStorePath(path)) && isDerivation(path)) {
Derivation drv = readDerivation(*state.store, realPath);
Value & w = *state.allocValue();
state.mkAttrs(w, 3 + drv.outputs.size());
Value * v2 = state.allocAttr(w, state.sDrvPath);
@ -115,7 +116,7 @@ static void prim_scopedImport(EvalState & state, const Pos & pos, Value * * args
for (const auto & o : drv.outputs) {
v2 = state.allocAttr(w, state.symbols.create(o.first));
mkString(*v2, o.second.path, {"!" + o.first + "!" + path});
mkString(*v2, state.store->printStorePath(o.second.path), {"!" + o.first + "!" + path});
outputsVal->listElems()[outputs_index] = state.allocValue();
mkString(*(outputsVal->listElems()[outputs_index++]), o.first);
}
@ -676,24 +677,24 @@ static void prim_derivationStrict(EvalState & state, const Pos & pos, Value * *
runs. */
if (path.at(0) == '=') {
/* !!! This doesn't work if readOnlyMode is set. */
PathSet refs;
state.store->computeFSClosure(string(path, 1), refs);
StorePathSet refs;
state.store->computeFSClosure(state.store->parseStorePath(std::string_view(path).substr(1)), refs);
for (auto & j : refs) {
drv.inputSrcs.insert(j);
if (isDerivation(j))
drv.inputDrvs[j] = state.store->queryDerivationOutputNames(j);
drv.inputSrcs.insert(j.clone());
if (j.isDerivation())
drv.inputDrvs[j.clone()] = state.store->queryDerivationOutputNames(j);
}
}
/* Handle derivation outputs of the form ‘!<name>!<path>’. */
else if (path.at(0) == '!') {
std::pair<string, string> ctx = decodeContext(path);
drv.inputDrvs[ctx.first].insert(ctx.second);
drv.inputDrvs[state.store->parseStorePath(ctx.first)].insert(ctx.second);
}
/* Otherwise it's a source file. */
else
drv.inputSrcs.insert(path);
drv.inputSrcs.insert(state.store->parseStorePath(path));
}
/* Do we have all required attributes? */
@ -703,10 +704,8 @@ static void prim_derivationStrict(EvalState & state, const Pos & pos, Value * *
throw EvalError(format("required attribute 'system' missing, at %1%") % posDrvName);
/* Check whether the derivation name is valid. */
checkStoreName(drvName);
if (isDerivation(drvName))
throw EvalError(format("derivation names are not allowed to end in '%1%', at %2%")
% drvExtension % posDrvName);
throw EvalError("derivation names are not allowed to end in '%s', at %s", drvExtension, posDrvName);
if (outputHash) {
/* Handle fixed-output derivations. */
@ -716,52 +715,51 @@ static void prim_derivationStrict(EvalState & state, const Pos & pos, Value * *
HashType ht = outputHashAlgo.empty() ? htUnknown : parseHashType(outputHashAlgo);
Hash h(*outputHash, ht);
Path outPath = state.store->makeFixedOutputPath(outputHashRecursive, h, drvName);
if (!jsonObject) drv.env["out"] = outPath;
drv.outputs["out"] = DerivationOutput(outPath,
(outputHashRecursive ? "r:" : "") + printHashType(h.type),
h.to_string(Base16, false));
auto outPath = state.store->makeFixedOutputPath(outputHashRecursive, h, drvName);
if (!jsonObject) drv.env["out"] = state.store->printStorePath(outPath);
drv.outputs.insert_or_assign("out", DerivationOutput(std::move(outPath),
(outputHashRecursive ? "r:" : "") + printHashType(h.type),
h.to_string(Base16, false)));
}
else {
/* Construct the "masked" store derivation, which is the final
one except that in the list of outputs, the output paths
are empty, and the corresponding environment variables have
an empty value. This ensures that changes in the set of
output names do get reflected in the hash. */
/* Compute a hash over the "masked" store derivation, which is
the final one except that in the list of outputs, the
output paths are empty strings, and the corresponding
environment variables have an empty value. This ensures
that changes in the set of output names do get reflected in
the hash. */
for (auto & i : outputs) {
if (!jsonObject) drv.env[i] = "";
drv.outputs[i] = DerivationOutput("", "", "");
}
/* Use the masked derivation expression to compute the output
path. */
Hash h = hashDerivationModulo(*state.store, drv);
Hash h = hashDerivationModulo(*state.store, Derivation(drv), true);
for (auto & i : drv.outputs)
if (i.second.path == "") {
Path outPath = state.store->makeOutputPath(i.first, h, drvName);
if (!jsonObject) drv.env[i.first] = outPath;
i.second.path = outPath;
}
for (auto & i : outputs) {
auto outPath = state.store->makeOutputPath(i, h, drvName);
if (!jsonObject) drv.env[i] = state.store->printStorePath(outPath);
drv.outputs.insert_or_assign(i,
DerivationOutput(std::move(outPath), "", ""));
}
}
/* Write the resulting term into the Nix store directory. */
Path drvPath = writeDerivation(state.store, drv, drvName, state.repair);
auto drvPath = writeDerivation(state.store, drv, drvName, state.repair);
auto drvPathS = state.store->printStorePath(drvPath);
printMsg(lvlChatty, format("instantiated '%1%' -> '%2%'")
% drvName % drvPath);
printMsg(lvlChatty, "instantiated '%1%' -> '%2%'", drvName, drvPathS);
/* Optimisation, but required in read-only mode! because in that
case we don't actually write store derivations, so we can't
read them later. */
drvHashes[drvPath] = hashDerivationModulo(*state.store, drv);
drvHashes.insert_or_assign(drvPath.clone(),
hashDerivationModulo(*state.store, Derivation(drv), false));
state.mkAttrs(v, 1 + drv.outputs.size());
mkString(*state.allocAttr(v, state.sDrvPath), drvPath, {"=" + drvPath});
mkString(*state.allocAttr(v, state.sDrvPath), drvPathS, {"=" + drvPathS});
for (auto & i : drv.outputs) {
mkString(*state.allocAttr(v, state.symbols.create(i.first)),
i.second.path, {"!" + i.first + "!" + drvPath});
state.store->printStorePath(i.second.path), {"!" + i.first + "!" + drvPathS});
}
v.attrs->sort();
}
@ -814,7 +812,7 @@ static void prim_storePath(EvalState & state, const Pos & pos, Value * * args, V
throw EvalError(format("path '%1%' is not in the Nix store, at %2%") % path % pos);
Path path2 = state.store->toStorePath(path);
if (!settings.readOnlyMode)
state.store->ensurePath(path2);
state.store->ensurePath(state.store->parseStorePath(path2));
context.insert(path2);
mkString(v, path, context);
}
@ -1010,17 +1008,17 @@ static void prim_toFile(EvalState & state, const Pos & pos, Value * * args, Valu
string name = state.forceStringNoCtx(*args[0], pos);
string contents = state.forceString(*args[1], context, pos);
PathSet refs;
StorePathSet refs;
for (auto path : context) {
if (path.at(0) != '/')
throw EvalError(format("in 'toFile': the file '%1%' cannot refer to derivation outputs, at %2%") % name % pos);
refs.insert(path);
refs.insert(state.store->parseStorePath(path));
}
Path storePath = settings.readOnlyMode
auto storePath = state.store->printStorePath(settings.readOnlyMode
? state.store->computeStorePathForText(name, contents, refs)
: state.store->addTextToStore(name, contents, refs, state.repair);
: state.store->addTextToStore(name, contents, refs, state.repair));
/* Note: we don't need to add `context' to the context of the
result, since `storePath' itself has references to the paths
@ -1060,21 +1058,18 @@ static void addPath(EvalState & state, const Pos & pos, const string & name, con
return state.forceBool(res, pos);
}) : defaultPathFilter;
Path expectedStorePath;
if (expectedHash) {
expectedStorePath =
state.store->makeFixedOutputPath(recursive, expectedHash, name);
}
std::optional<StorePath> expectedStorePath;
if (expectedHash)
expectedStorePath = state.store->makeFixedOutputPath(recursive, expectedHash, name);
Path dstPath;
if (!expectedHash || !state.store->isValidPath(expectedStorePath)) {
dstPath = settings.readOnlyMode
if (!expectedHash || !state.store->isValidPath(*expectedStorePath)) {
dstPath = state.store->printStorePath(settings.readOnlyMode
? state.store->computeStorePathForPath(name, path, recursive, htSHA256, filter).first
: state.store->addToStore(name, path, recursive, htSHA256, filter, state.repair);
if (expectedHash && expectedStorePath != dstPath) {
throw Error(format("store path mismatch in (possibly filtered) path added from '%1%'") % path);
}
: state.store->addToStore(name, path, recursive, htSHA256, filter, state.repair));
if (expectedHash && expectedStorePath != state.store->parseStorePath(dstPath))
throw Error("store path mismatch in (possibly filtered) path added from '%s'", path);
} else
dstPath = expectedStorePath;
dstPath = state.store->printStorePath(*expectedStorePath);
mkString(v, dstPath, {dstPath});
}
@ -1091,7 +1086,7 @@ static void prim_filterSource(EvalState & state, const Pos & pos, Value * * args
if (args[0]->type != tLambda)
throw TypeError(format("first argument in call to 'filterSource' is not a function but %1%, at %2%") % showType(*args[0]) % pos);
addPath(state, pos, baseNameOf(path), path, args[0], true, Hash(), v);
addPath(state, pos, std::string(baseNameOf(path)), path, args[0], true, Hash(), v);
}
static void prim_path(EvalState & state, const Pos & pos, Value * * args, Value & v)
@ -2151,7 +2146,7 @@ void EvalState::createBaseEnv()
}
if (!evalSettings.pureEval) {
mkString(v, settings.thisSystem);
mkString(v, settings.thisSystem.get());
addConstant("__currentSystem", v);
}