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Merge branch 'misc-ca' of https://github.com/obsidiansystems/nix

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This commit is contained in:
Eelco Dolstra 2020-08-05 16:50:05 +02:00
parent 25f7912156 e561a13a58
commit e48f944e9d
13 changed files with 392 additions and 134 deletions
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6
src/libexpr/primops.cc
View file

@ -774,7 +774,7 @@ static void prim_derivationStrict(EvalState & state, const Pos & pos, Value * *
auto outPath = state.store->makeFixedOutputPath(ingestionMethod, h, drvName);
if (!jsonObject) drv.env["out"] = state.store->printStorePath(outPath);
drv.outputs.insert_or_assign("out", DerivationOutput {
.output = DerivationOutputFixed {
.output = DerivationOutputCAFixed {
.hash = FixedOutputHash {
.method = ingestionMethod,
.hash = std::move(h),
@ -800,7 +800,9 @@ static void prim_derivationStrict(EvalState & state, const Pos & pos, Value * *
});
}
Hash h = hashDerivationModulo(*state.store, Derivation(drv), true);
// Regular, non-CA derivation should always return a single hash and not
// hash per output.
Hash h = std::get<0>(hashDerivationModulo(*state.store, Derivation(drv), true));
for (auto & i : outputs) {
auto outPath = state.store->makeOutputPath(i, h, drvName);

2
src/libfetchers/git.cc
View file

@ -121,7 +121,7 @@ struct GitInputScheme : InputScheme
args.push_back(*ref);
}
if (input.getRev()) throw Error("cloning a specific revision is not implemented");
if (input.getRev()) throw UnimplementedError("cloning a specific revision is not implemented");
args.push_back(destDir);

66
src/libstore/build.cc
View file

@ -806,8 +806,8 @@ private:
/* RAII object to delete the chroot directory. */
std::shared_ptr<AutoDelete> autoDelChroot;
/* Whether this is a fixed-output derivation. */
bool fixedOutput;
/* The sort of derivation we are building. */
DerivationType derivationType;
/* Whether to run the build in a private network namespace. */
bool privateNetwork = false;
@ -1197,7 +1197,7 @@ void DerivationGoal::haveDerivation()
if (parsedDrv->contentAddressed()) {
settings.requireExperimentalFeature("ca-derivations");
throw Error("ca-derivations isn't implemented yet");
throw UnimplementedError("ca-derivations isn't implemented yet");
}
@ -1392,12 +1392,12 @@ void DerivationGoal::inputsRealised()
debug("added input paths %s", worker.store.showPaths(inputPaths));
/* Is this a fixed-output derivation? */
fixedOutput = drv->isFixedOutput();
/* What type of derivation are we building? */
derivationType = drv->type();
/* Don't repeat fixed-output derivations since they're already
verified by their output hash.*/
nrRounds = fixedOutput ? 1 : settings.buildRepeat + 1;
nrRounds = derivationIsFixed(derivationType) ? 1 : settings.buildRepeat + 1;
/* Okay, try to build. Note that here we don't wait for a build
slot to become available, since we don't need one if there is a
@ -1783,7 +1783,7 @@ void DerivationGoal::buildDone()
st =
dynamic_cast<NotDeterministic*>(&e) ? BuildResult::NotDeterministic :
statusOk(status) ? BuildResult::OutputRejected :
fixedOutput || diskFull ? BuildResult::TransientFailure :
derivationIsImpure(derivationType) || diskFull ? BuildResult::TransientFailure :
BuildResult::PermanentFailure;
}
@ -1996,7 +1996,7 @@ void DerivationGoal::startBuilder()
else if (settings.sandboxMode == smDisabled)
useChroot = false;
else if (settings.sandboxMode == smRelaxed)
useChroot = !fixedOutput && !noChroot;
useChroot = !(derivationIsImpure(derivationType)) && !noChroot;
}
if (worker.store.storeDir != worker.store.realStoreDir) {
@ -2165,7 +2165,7 @@ void DerivationGoal::startBuilder()
"nogroup:x:65534:\n") % sandboxGid).str());
/* Create /etc/hosts with localhost entry. */
if (!fixedOutput)
if (!(derivationIsImpure(derivationType)))
writeFile(chrootRootDir + "/etc/hosts", "127.0.0.1 localhost\n::1 localhost\n");
/* Make the closure of the inputs available in the chroot,
@ -2373,7 +2373,7 @@ void DerivationGoal::startBuilder()
us.
*/
if (!fixedOutput)
if (!(derivationIsImpure(derivationType)))
privateNetwork = true;
userNamespaceSync.create();
@ -2574,7 +2574,7 @@ void DerivationGoal::initEnv()
derivation, tell the builder, so that for instance `fetchurl'
can skip checking the output. On older Nixes, this environment
variable won't be set, so `fetchurl' will do the check. */
if (fixedOutput) env["NIX_OUTPUT_CHECKED"] = "1";
if (derivationIsFixed(derivationType)) env["NIX_OUTPUT_CHECKED"] = "1";
/* *Only* if this is a fixed-output derivation, propagate the
values of the environment variables specified in the
@ -2585,7 +2585,7 @@ void DerivationGoal::initEnv()
to the builder is generally impure, but the output of
fixed-output derivations is by definition pure (since we
already know the cryptographic hash of the output). */
if (fixedOutput) {
if (derivationIsImpure(derivationType)) {
for (auto & i : parsedDrv->getStringsAttr("impureEnvVars").value_or(Strings()))
env[i] = getEnv(i).value_or("");
}
@ -3195,7 +3195,7 @@ void DerivationGoal::runChild()
/* Fixed-output derivations typically need to access the
network, so give them access to /etc/resolv.conf and so
on. */
if (fixedOutput) {
if (derivationIsImpure(derivationType)) {
ss.push_back("/etc/resolv.conf");
// Only use nss functions to resolve hosts and
@ -3436,7 +3436,7 @@ void DerivationGoal::runChild()
sandboxProfile += "(import \"sandbox-defaults.sb\")\n";
if (fixedOutput)
if (derivationIsImpure(derivationType))
sandboxProfile += "(import \"sandbox-network.sb\")\n";
/* Our rwx outputs */
@ -3721,9 +3721,22 @@ void DerivationGoal::registerOutputs()
hash). */
std::optional<ContentAddress> ca;
if (fixedOutput) {
FixedOutputHash outputHash = std::get<DerivationOutputFixed>(i.second.output).hash;
if (! std::holds_alternative<DerivationOutputInputAddressed>(i.second.output)) {
DerivationOutputCAFloating outputHash;
std::visit(overloaded {
[&](DerivationOutputInputAddressed doi) {
assert(false); // Enclosing `if` handles this case in other branch
},
[&](DerivationOutputCAFixed dof) {
outputHash = DerivationOutputCAFloating {
.method = dof.hash.method,
.hashType = dof.hash.hash.type,
};
},
[&](DerivationOutputCAFloating dof) {
outputHash = dof;
},
}, i.second.output);
if (outputHash.method == FileIngestionMethod::Flat) {
/* The output path should be a regular file without execute permission. */
@ -3737,12 +3750,17 @@ void DerivationGoal::registerOutputs()
/* Check the hash. In hash mode, move the path produced by
the derivation to its content-addressed location. */
Hash h2 = outputHash.method == FileIngestionMethod::Recursive
? hashPath(outputHash.hash.type, actualPath).first
: hashFile(outputHash.hash.type, actualPath);
? hashPath(outputHash.hashType, actualPath).first
: hashFile(outputHash.hashType, actualPath);
auto dest = worker.store.makeFixedOutputPath(outputHash.method, h2, i.second.path(worker.store, drv->name).name());
if (outputHash.hash != h2) {
// true if either floating CA, or incorrect fixed hash.
bool needsMove = true;
if (auto p = std::get_if<DerivationOutputCAFixed>(& i.second.output)) {
Hash & h = p->hash.hash;
if (h != h2) {
/* Throw an error after registering the path as
valid. */
@ -3750,9 +3768,15 @@ void DerivationGoal::registerOutputs()
delayedException = std::make_exception_ptr(
BuildError("hash mismatch in fixed-output derivation '%s':\n wanted: %s\n got: %s",
worker.store.printStorePath(dest),
outputHash.hash.to_string(SRI, true),
h.to_string(SRI, true),
h2.to_string(SRI, true)));
} else {
// matched the fixed hash, so no move needed.
needsMove = false;
}
}
if (needsMove) {
Path actualDest = worker.store.Store::toRealPath(dest);
if (worker.store.isValidPath(dest))

4
src/libstore/content-address.cc
View file

@ -26,10 +26,6 @@ std::string makeFixedOutputCA(FileIngestionMethod method, const Hash & hash)
+ hash.to_string(Base32, true);
}
// FIXME Put this somewhere?
template<class... Ts> struct overloaded : Ts... { using Ts::operator()...; };
template<class... Ts> overloaded(Ts...) -> overloaded<Ts...>;
std::string renderContentAddress(ContentAddress ca) {
return std::visit(overloaded {
[](TextHash th) {

287
src/libstore/derivations.cc
View file

@ -7,23 +7,54 @@
namespace nix {
// FIXME Put this somewhere?
template<class... Ts> struct overloaded : Ts... { using Ts::operator()...; };
template<class... Ts> overloaded(Ts...) -> overloaded<Ts...>;
StorePath DerivationOutput::path(const Store & store, std::string_view drvName) const
std::optional<StorePath> DerivationOutput::pathOpt(const Store & store, std::string_view drvName) const
{
return std::visit(overloaded {
[](DerivationOutputInputAddressed doi) {
return doi.path;
[](DerivationOutputInputAddressed doi) -> std::optional<StorePath> {
return { doi.path };
},
[&](DerivationOutputCAFixed dof) -> std::optional<StorePath> {
return {
store.makeFixedOutputPath(dof.hash.method, dof.hash.hash, drvName)
};
},
[](DerivationOutputCAFloating dof) -> std::optional<StorePath> {
return std::nullopt;
},
[&](DerivationOutputFixed dof) {
return store.makeFixedOutputPath(dof.hash.method, dof.hash.hash, drvName);
}
}, output);
}
bool derivationIsCA(DerivationType dt) {
switch (dt) {
case DerivationType::InputAddressed: return false;
case DerivationType::CAFixed: return true;
case DerivationType::CAFloating: return true;
};
// Since enums can have non-variant values, but making a `default:` would
// disable exhaustiveness warnings.
assert(false);
}
bool derivationIsFixed(DerivationType dt) {
switch (dt) {
case DerivationType::InputAddressed: return false;
case DerivationType::CAFixed: return true;
case DerivationType::CAFloating: return false;
};
assert(false);
}
bool derivationIsImpure(DerivationType dt) {
switch (dt) {
case DerivationType::InputAddressed: return false;
case DerivationType::CAFixed: return true;
case DerivationType::CAFloating: return false;
};
assert(false);
}
bool BasicDerivation::isBuiltin() const
{
return string(builder, 0, 8) == "builtin:";
@ -123,14 +154,21 @@ static DerivationOutput parseDerivationOutput(const Store & store, std::istrings
}
const HashType hashType = parseHashType(hashAlgo);
return DerivationOutput {
.output = DerivationOutputFixed {
.hash = FixedOutputHash {
.method = std::move(method),
.hash = Hash::parseNonSRIUnprefixed(hash, hashType),
},
}
};
return hash != ""
? DerivationOutput {
.output = DerivationOutputCAFixed {
.hash = FixedOutputHash {
.method = std::move(method),
.hash = Hash::parseNonSRIUnprefixed(hash, hashType),
},
}
}
: DerivationOutput {
.output = DerivationOutputCAFloating {
.method = std::move(method),
.hashType = std::move(hashType),
},
};
} else
return DerivationOutput {
.output = DerivationOutputInputAddressed {
@ -278,13 +316,20 @@ string Derivation::unparse(const Store & store, bool maskOutputs,
if (first) first = false; else s += ',';
s += '('; printUnquotedString(s, i.first);
s += ','; printUnquotedString(s, maskOutputs ? "" : store.printStorePath(i.second.path(store, name)));
if (auto hash = std::get_if<DerivationOutputFixed>(&i.second.output)) {
s += ','; printUnquotedString(s, hash->hash.printMethodAlgo());
s += ','; printUnquotedString(s, hash->hash.hash.to_string(Base16, false));
} else {
s += ','; printUnquotedString(s, "");
s += ','; printUnquotedString(s, "");
}
std::visit(overloaded {
[&](DerivationOutputInputAddressed doi) {
s += ','; printUnquotedString(s, "");
s += ','; printUnquotedString(s, "");
},
[&](DerivationOutputCAFixed dof) {
s += ','; printUnquotedString(s, dof.hash.printMethodAlgo());
s += ','; printUnquotedString(s, dof.hash.hash.to_string(Base16, false));
},
[&](DerivationOutputCAFloating dof) {
s += ','; printUnquotedString(s, makeFileIngestionPrefix(dof.method) + printHashType(dof.hashType));
s += ','; printUnquotedString(s, "");
},
}, i.second.output);
s += ')';
}
@ -336,60 +381,134 @@ bool isDerivation(const string & fileName)
}
bool BasicDerivation::isFixedOutput() const
DerivationType BasicDerivation::type() const
{
return outputs.size() == 1 &&
outputs.begin()->first == "out" &&
std::holds_alternative<DerivationOutputFixed>(outputs.begin()->second.output);
std::set<std::string_view> inputAddressedOutputs, fixedCAOutputs, floatingCAOutputs;
std::optional<HashType> floatingHashType;
for (auto & i : outputs) {
std::visit(overloaded {
[&](DerivationOutputInputAddressed _) {
inputAddressedOutputs.insert(i.first);
},
[&](DerivationOutputCAFixed _) {
fixedCAOutputs.insert(i.first);
},
[&](DerivationOutputCAFloating dof) {
floatingCAOutputs.insert(i.first);
if (!floatingHashType) {
floatingHashType = dof.hashType;
} else {
if (*floatingHashType != dof.hashType)
throw Error("All floating outputs must use the same hash type");
}
},
}, i.second.output);
}
if (inputAddressedOutputs.empty() && fixedCAOutputs.empty() && floatingCAOutputs.empty()) {
throw Error("Must have at least one output");
} else if (! inputAddressedOutputs.empty() && fixedCAOutputs.empty() && floatingCAOutputs.empty()) {
return DerivationType::InputAddressed;
} else if (inputAddressedOutputs.empty() && ! fixedCAOutputs.empty() && floatingCAOutputs.empty()) {
if (fixedCAOutputs.size() > 1)
// FIXME: Experimental feature?
throw Error("Only one fixed output is allowed for now");
if (*fixedCAOutputs.begin() != "out")
throw Error("Single fixed output must be named \"out\"");
return DerivationType::CAFixed;
} else if (inputAddressedOutputs.empty() && fixedCAOutputs.empty() && ! floatingCAOutputs.empty()) {
return DerivationType::CAFloating;
} else {
throw Error("Can't mix derivation output types");
}
}
DrvHashes drvHashes;
/* pathDerivationModulo and hashDerivationModulo are mutually recursive
*/
/* Returns the hash of a derivation modulo fixed-output
subderivations. A fixed-output derivation is a derivation with one
output (`out') for which an expected hash and hash algorithm are
specified (using the `outputHash' and `outputHashAlgo'
attributes). We don't want changes to such derivations to
propagate upwards through the dependency graph, changing output
paths everywhere.
/* Look up the derivation by value and memoize the
`hashDerivationModulo` call.
*/
static const DrvHashModulo & pathDerivationModulo(Store & store, const StorePath & drvPath)
{
auto h = drvHashes.find(drvPath);
if (h == drvHashes.end()) {
assert(store.isValidPath(drvPath));
// Cache it
h = drvHashes.insert_or_assign(
drvPath,
hashDerivationModulo(
store,
store.readDerivation(drvPath),
false)).first;
}
return h->second;
}
For instance, if we change the url in a call to the `fetchurl'
function, we do not want to rebuild everything depending on it
(after all, (the hash of) the file being downloaded is unchanged).
So the *output paths* should not change. On the other hand, the
*derivation paths* should change to reflect the new dependency
graph.
/* See the header for interface details. These are the implementation details.
That's what this function does: it returns a hash which is just the
hash of the derivation ATerm, except that any input derivation
paths have been replaced by the result of a recursive call to this
function, and that for fixed-output derivations we return a hash of
its output path. */
Hash hashDerivationModulo(Store & store, const Derivation & drv, bool maskOutputs)
For fixed-output derivations, each hash in the map is not the
corresponding output's content hash, but a hash of that hash along
with other constant data. The key point is that the value is a pure
function of the output's contents, and there are no preimage attacks
either spoofing an output's contents for a derivation, or
spoofing a derivation for an output's contents.
For regular derivations, it looks up each subderivation from its hash
and recurs. If the subderivation is also regular, it simply
substitutes the derivation path with its hash. If the subderivation
is fixed-output, however, it takes each output hash and pretends it
is a derivation hash producing a single "out" output. This is so we
don't leak the provenance of fixed outputs, reducing pointless cache
misses as the build itself won't know this.
*/
DrvHashModulo hashDerivationModulo(Store & store, const Derivation & drv, bool maskOutputs)
{
/* Return a fixed hash for fixed-output derivations. */
if (drv.isFixedOutput()) {
DerivationOutputs::const_iterator i = drv.outputs.begin();
auto hash = std::get<DerivationOutputFixed>(i->second.output);
return hashString(htSHA256, "fixed:out:"
+ hash.hash.printMethodAlgo() + ":"
+ hash.hash.hash.to_string(Base16, false) + ":"
+ store.printStorePath(i->second.path(store, drv.name)));
switch (drv.type()) {
case DerivationType::CAFloating:
throw Error("Regular input-addressed derivations are not yet allowed to depend on CA derivations");
case DerivationType::CAFixed: {
std::map<std::string, Hash> outputHashes;
for (const auto & i : drv.outputs) {
auto & dof = std::get<DerivationOutputCAFixed>(i.second.output);
auto hash = hashString(htSHA256, "fixed:out:"
+ dof.hash.printMethodAlgo() + ":"
+ dof.hash.hash.to_string(Base16, false) + ":"
+ store.printStorePath(i.second.path(store, drv.name)));
outputHashes.insert_or_assign(i.first, std::move(hash));
}
return outputHashes;
}
case DerivationType::InputAddressed:
break;
}
/* For other derivations, replace the inputs paths with recursive
calls to this function.*/
calls to this function. */
std::map<std::string, StringSet> inputs2;
for (auto & i : drv.inputDrvs) {
auto h = drvHashes.find(i.first);
if (h == drvHashes.end()) {
assert(store.isValidPath(i.first));
h = drvHashes.insert_or_assign(i.first, hashDerivationModulo(store,
store.readDerivation(i.first), false)).first;
}
inputs2.insert_or_assign(h->second.to_string(Base16, false), i.second);
const auto & res = pathDerivationModulo(store, i.first);
std::visit(overloaded {
// Regular non-CA derivation, replace derivation
[&](Hash drvHash) {
inputs2.insert_or_assign(drvHash.to_string(Base16, false), i.second);
},
// CA derivation's output hashes
[&](CaOutputHashes outputHashes) {
std::set<std::string> justOut = { "out" };
for (auto & output : i.second) {
/* Put each one in with a single "out" output.. */
const auto h = outputHashes.at(output);
inputs2.insert_or_assign(
h.to_string(Base16, false),
justOut);
}
},
}, res);
}
return hashString(htSHA256, drv.unparse(store, maskOutputs, &inputs2));
@ -431,14 +550,21 @@ static DerivationOutput readDerivationOutput(Source & in, const Store & store)
hashAlgo = string(hashAlgo, 2);
}
auto hashType = parseHashType(hashAlgo);
return DerivationOutput {
.output = DerivationOutputFixed {
.hash = FixedOutputHash {
.method = std::move(method),
.hash = Hash::parseNonSRIUnprefixed(hash, hashType),
},
}
};
return hash != ""
? DerivationOutput {
.output = DerivationOutputCAFixed {
.hash = FixedOutputHash {
.method = std::move(method),
.hash = Hash::parseNonSRIUnprefixed(hash, hashType),
},
}
}
: DerivationOutput {
.output = DerivationOutputCAFloating {
.method = std::move(method),
.hashType = std::move(hashType),
},
};
} else
return DerivationOutput {
.output = DerivationOutputInputAddressed {
@ -498,12 +624,19 @@ void writeDerivation(Sink & out, const Store & store, const BasicDerivation & dr
for (auto & i : drv.outputs) {
out << i.first
<< store.printStorePath(i.second.path(store, drv.name));
if (auto hash = std::get_if<DerivationOutputFixed>(&i.second.output)) {
out << hash->hash.printMethodAlgo()
<< hash->hash.hash.to_string(Base16, false);
} else {
out << "" << "";
}
std::visit(overloaded {
[&](DerivationOutputInputAddressed doi) {
out << "" << "";
},
[&](DerivationOutputCAFixed dof) {
out << dof.hash.printMethodAlgo()
<< dof.hash.hash.to_string(Base16, false);
},
[&](DerivationOutputCAFloating dof) {
out << (makeFileIngestionPrefix(dof.method) + printHashType(dof.hashType))
<< "";
},
}, i.second.output);
}
writeStorePaths(store, out, drv.inputSrcs);
out << drv.platform << drv.builder << drv.args;

90
src/libstore/derivations.hh
View file

@ -6,6 +6,7 @@
#include "content-address.hh"
#include <map>
#include <variant>
namespace nix {
@ -13,20 +14,46 @@ namespace nix {
/* Abstract syntax of derivations. */
/* The traditional non-fixed-output derivation type. */
struct DerivationOutputInputAddressed
{
/* Will need to become `std::optional<StorePath>` once input-addressed
derivations are allowed to depend on cont-addressed derivations */
StorePath path;
};
struct DerivationOutputFixed
/* Fixed-output derivations, whose output paths are content addressed
according to that fixed output. */
struct DerivationOutputCAFixed
{
FixedOutputHash hash; /* hash used for expected hash computation */
};
/* Floating-output derivations, whose output paths are content addressed, but
not fixed, and so are dynamically calculated from whatever the output ends
up being. */
struct DerivationOutputCAFloating
{
/* information used for expected hash computation */
FileIngestionMethod method;
HashType hashType;
};
struct DerivationOutput
{
std::variant<DerivationOutputInputAddressed, DerivationOutputFixed> output;
StorePath path(const Store & store, std::string_view drvName) const;
std::variant<
DerivationOutputInputAddressed,
DerivationOutputCAFixed,
DerivationOutputCAFloating
> output;
std::optional<HashType> hashAlgoOpt(const Store & store) const;
std::optional<StorePath> pathOpt(const Store & store, std::string_view drvName) const;
/* DEPRECATED: Remove after CA drvs are fully implemented */
StorePath path(const Store & store, std::string_view drvName) const {
auto p = pathOpt(store, drvName);
if (!p) throw UnimplementedError("floating content-addressed derivations are not yet implemented");
return *p;
}
};
typedef std::map<string, DerivationOutput> DerivationOutputs;
@ -37,6 +64,25 @@ typedef std::map<StorePath, StringSet> DerivationInputs;
typedef std::map<string, string> StringPairs;
enum struct DerivationType : uint8_t {
InputAddressed,
CAFixed,
CAFloating,
};
/* Do the outputs of the derivation have paths calculated from their content,
or from the derivation itself? */
bool derivationIsCA(DerivationType);
/* Is the content of the outputs fixed a-priori via a hash? Never true for
non-CA derivations. */
bool derivationIsFixed(DerivationType);
/* Is the derivation impure and needs to access non-deterministic resources, or
pure and can be sandboxed? Note that whether or not we actually sandbox the
derivation is controlled separately. Never true for non-CA derivations. */
bool derivationIsImpure(DerivationType);
struct BasicDerivation
{
DerivationOutputs outputs; /* keyed on symbolic IDs */
@ -53,7 +99,7 @@ struct BasicDerivation
bool isBuiltin() const;
/* Return true iff this is a fixed-output derivation. */
bool isFixedOutput() const;
DerivationType type() const;
/* Return the output paths of a derivation. */
StorePathSet outputPaths(const Store & store) const;
@ -90,10 +136,42 @@ Derivation readDerivation(const Store & store, const Path & drvPath, std::string
// FIXME: remove
bool isDerivation(const string & fileName);
Hash hashDerivationModulo(Store & store, const Derivation & drv, bool maskOutputs);
// known CA drv's output hashes, current just for fixed-output derivations
// whose output hashes are always known since they are fixed up-front.
typedef std::map<std::string, Hash> CaOutputHashes;
typedef std::variant<
Hash, // regular DRV normalized hash
CaOutputHashes
> DrvHashModulo;
/* Returns hashes with the details of fixed-output subderivations
expunged.
A fixed-output derivation is a derivation whose outputs have a
specified content hash and hash algorithm. (Currently they must have
exactly one output (`out'), which is specified using the `outputHash'
and `outputHashAlgo' attributes, but the algorithm doesn't assume
this.) We don't want changes to such derivations to propagate upwards
through the dependency graph, changing output paths everywhere.
For instance, if we change the url in a call to the `fetchurl'
function, we do not want to rebuild everything depending on it---after
all, (the hash of) the file being downloaded is unchanged. So the
*output paths* should not change. On the other hand, the *derivation
paths* should change to reflect the new dependency graph.
For fixed-output derivations, this returns a map from the name of
each output to its hash, unique up to the output's contents.
For regular derivations, it returns a single hash of the derivation
ATerm, after subderivations have been likewise expunged from that
derivation.
*/
DrvHashModulo hashDerivationModulo(Store & store, const Derivation & drv, bool maskOutputs);
/* Memoisation of hashDerivationModulo(). */
typedef std::map<StorePath, Hash> DrvHashes;
typedef std::map<StorePath, DrvHashModulo> DrvHashes;
extern DrvHashes drvHashes; // FIXME: global, not thread-safe

41
src/libstore/local-store.cc
View file

@ -544,11 +544,8 @@ void LocalStore::checkDerivationOutputs(const StorePath & drvPath, const Derivat
std::string drvName(drvPath.name());
drvName = string(drvName, 0, drvName.size() - drvExtension.size());
auto check = [&](const StorePath & expected, const StorePath & actual, const std::string & varName)
auto envHasRightPath = [&](const StorePath & actual, const std::string & varName)
{
if (actual != expected)
throw Error("derivation '%s' has incorrect output '%s', should be '%s'",
printStorePath(drvPath), printStorePath(actual), printStorePath(expected));
auto j = drv.env.find(varName);
if (j == drv.env.end() || parseStorePath(j->second) != actual)
throw Error("derivation '%s' has incorrect environment variable '%s', should be '%s'",
@ -556,16 +553,34 @@ void LocalStore::checkDerivationOutputs(const StorePath & drvPath, const Derivat
};
if (drv.isFixedOutput()) {
DerivationOutputs::const_iterator out = drv.outputs.find("out");
if (out == drv.outputs.end())
throw Error("derivation '%s' does not have an output named 'out'", printStorePath(drvPath));
}
// Don't need the answer, but do this anyways to assert is proper
// combination. The code below is more general and naturally allows
// combinations that are currently prohibited.
drv.type();
else {
Hash h = hashDerivationModulo(*this, drv, true);
for (auto & i : drv.outputs)
check(makeOutputPath(i.first, h, drvName), i.second.path(*this, drv.name), i.first);
std::optional<Hash> h;
for (auto & i : drv.outputs) {
std::visit(overloaded {
[&](DerivationOutputInputAddressed doia) {
if (!h) {
// somewhat expensive so we do lazily
auto temp = hashDerivationModulo(*this, drv, true);
h = std::get<Hash>(temp);
}
StorePath recomputed = makeOutputPath(i.first, *h, drvName);
if (doia.path != recomputed)
throw Error("derivation '%s' has incorrect output '%s', should be '%s'",
printStorePath(drvPath), printStorePath(doia.path), printStorePath(recomputed));
envHasRightPath(doia.path, i.first);
},
[&](DerivationOutputCAFixed dof) {
StorePath path = makeFixedOutputPath(dof.hash.method, dof.hash.hash, drvName);
envHasRightPath(path, i.first);
},
[&](DerivationOutputCAFloating _) {
throw UnimplementedError("Floating CA output derivations are not yet implemented");
},
}, i.second.output);
}
}

2
src/libstore/misc.cc
View file

@ -113,7 +113,7 @@ std::optional<ContentAddress> getDerivationCA(const BasicDerivation & drv)
{
auto out = drv.outputs.find("out");
if (out != drv.outputs.end()) {
if (auto v = std::get_if<DerivationOutputFixed>(&out->second.output))
if (auto v = std::get_if<DerivationOutputCAFixed>(&out->second.output))
return v->hash;
}
return std::nullopt;

4
src/libstore/store-api.cc
View file

@ -193,10 +193,6 @@ StorePath Store::makeFixedOutputPath(
}
}
// FIXME Put this somewhere?
template<class... Ts> struct overloaded : Ts... { using Ts::operator()...; };
template<class... Ts> overloaded(Ts...) -> overloaded<Ts...>;
StorePath Store::makeFixedOutputPathFromCA(std::string_view name, ContentAddress ca,
const StorePathSet & references, bool hasSelfReference) const
{

1
src/libutil/error.hh
View file

@ -192,6 +192,7 @@ public:
MakeError(Error, BaseError);
MakeError(UsageError, Error);
MakeError(UnimplementedError, Error);
class SysError : public Error
{

5
src/libutil/util.hh
View file

@ -601,4 +601,9 @@ constexpr auto enumerate(T && iterable)
}
// C++17 std::visit boilerplate
template<class... Ts> struct overloaded : Ts... { using Ts::operator()...; };
template<class... Ts> overloaded(Ts...) -> overloaded<Ts...>;
}

2
src/nix/develop.cc
View file

@ -135,7 +135,7 @@ StorePath getDerivationEnvironment(ref<Store> store, const StorePath & drvPath)
drv.env["_outputs_saved"] = drv.env["outputs"];
drv.env["outputs"] = "out";
drv.inputSrcs.insert(std::move(getEnvShPath));
Hash h = hashDerivationModulo(*store, drv, true);
Hash h = std::get<0>(hashDerivationModulo(*store, drv, true));
auto shellOutPath = store->makeOutputPath("out", h, drvName);
drv.outputs.insert_or_assign("out", DerivationOutput { .output = DerivationOutputInputAddressed {
.path = shellOutPath

16
src/nix/show-derivation.cc
View file

@ -70,10 +70,18 @@ struct CmdShowDerivation : InstallablesCommand
for (auto & output : drv.outputs) {
auto outputObj(outputsObj.object(output.first));
outputObj.attr("path", store->printStorePath(output.second.path(*store, drv.name)));
if (auto hash = std::get_if<DerivationOutputFixed>(&output.second.output)) {
outputObj.attr("hashAlgo", hash->hash.printMethodAlgo());
outputObj.attr("hash", hash->hash.hash.to_string(Base16, false));
}
std::visit(overloaded {
[&](DerivationOutputInputAddressed doi) {
},
[&](DerivationOutputCAFixed dof) {
outputObj.attr("hashAlgo", dof.hash.printMethodAlgo());
outputObj.attr("hash", dof.hash.hash.to_string(Base16, false));
},
[&](DerivationOutputCAFloating dof) {
outputObj.attr("hashAlgo", makeFileIngestionPrefix(dof.method) + printHashType(dof.hashType));
},
}, output.second.output);
}
}