lix/src/libstore/derivations.hh
John Ericson 7103c6da70 Remove references from fixed output derivation ab syntax
In other words, use a plain `ContentAddress` not
`ContentAddressWithReferences` for `DerivationOutput::CAFixed`.

Supporting fixed output derivations with (fixed) references would be a
cool feature, but it is out of scope at this moment.
2023-04-19 15:00:04 -04:00

512 lines
14 KiB
C++

#pragma once
///@file
#include "path.hh"
#include "types.hh"
#include "hash.hh"
#include "content-address.hh"
#include "repair-flag.hh"
#include "sync.hh"
#include "comparator.hh"
#include <map>
#include <variant>
namespace nix {
class Store;
/* Abstract syntax of derivations. */
/**
* The traditional non-fixed-output derivation type.
*/
struct DerivationOutputInputAddressed
{
StorePath path;
GENERATE_CMP(DerivationOutputInputAddressed, me->path);
};
/**
* Fixed-output derivations, whose output paths are content
* addressed according to that fixed output.
*/
struct DerivationOutputCAFixed
{
/**
* Method and hash used for expected hash computation.
*
* References are not allowed by fiat.
*/
ContentAddress ca;
/**
* Return the \ref StorePath "store path" corresponding to this output
*
* @param drvName The name of the derivation this is an output of, without the `.drv`.
* @param outputName The name of this output.
*/
StorePath path(const Store & store, std::string_view drvName, std::string_view outputName) const;
GENERATE_CMP(DerivationOutputCAFixed, me->ca);
};
/**
* 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
{
/**
* How the file system objects will be serialized for hashing
*/
ContentAddressMethod method;
/**
* How the serialization will be hashed
*/
HashType hashType;
GENERATE_CMP(DerivationOutputCAFloating, me->method, me->hashType);
};
/**
* Input-addressed output which depends on a (CA) derivation whose hash
* isn't known yet.
*/
struct DerivationOutputDeferred {
GENERATE_CMP(DerivationOutputDeferred);
};
/**
* Impure output which is moved to a content-addressed location (like
* CAFloating) but isn't registered as a realization.
*/
struct DerivationOutputImpure
{
/**
* How the file system objects will be serialized for hashing
*/
ContentAddressMethod method;
/**
* How the serialization will be hashed
*/
HashType hashType;
GENERATE_CMP(DerivationOutputImpure, me->method, me->hashType);
};
typedef std::variant<
DerivationOutputInputAddressed,
DerivationOutputCAFixed,
DerivationOutputCAFloating,
DerivationOutputDeferred,
DerivationOutputImpure
> _DerivationOutputRaw;
/**
* A single output of a BasicDerivation (and Derivation).
*/
struct DerivationOutput : _DerivationOutputRaw
{
using Raw = _DerivationOutputRaw;
using Raw::Raw;
using InputAddressed = DerivationOutputInputAddressed;
using CAFixed = DerivationOutputCAFixed;
using CAFloating = DerivationOutputCAFloating;
using Deferred = DerivationOutputDeferred;
using Impure = DerivationOutputImpure;
/**
* \note when you use this function you should make sure that you're
* passing the right derivation name. When in doubt, you should use
* the safer interface provided by
* BasicDerivation::outputsAndOptPaths
*/
std::optional<StorePath> path(const Store & store, std::string_view drvName, std::string_view outputName) const;
inline const Raw & raw() const {
return static_cast<const Raw &>(*this);
}
nlohmann::json toJSON(
const Store & store,
std::string_view drvName,
std::string_view outputName) const;
/**
* @param xpSettings Stop-gap to avoid globals during unit tests.
*/
static DerivationOutput fromJSON(
const Store & store,
std::string_view drvName,
std::string_view outputName,
const nlohmann::json & json,
const ExperimentalFeatureSettings & xpSettings = experimentalFeatureSettings);
};
typedef std::map<std::string, DerivationOutput> DerivationOutputs;
/**
* These are analogues to the previous DerivationOutputs data type,
* but they also contains, for each output, the (optional) store
* path in which it would be written. To calculate values of these
* types, see the corresponding functions in BasicDerivation.
*/
typedef std::map<std::string, std::pair<DerivationOutput, std::optional<StorePath>>>
DerivationOutputsAndOptPaths;
/**
* For inputs that are sub-derivations, we specify exactly which
* output IDs we are interested in.
*/
typedef std::map<StorePath, StringSet> DerivationInputs;
/**
* Input-addressed derivation types
*/
struct DerivationType_InputAddressed {
/**
* True iff the derivation type can't be determined statically,
* for instance because it (transitively) depends on a content-addressed
* derivation.
*/
bool deferred;
};
/**
* Content-addressed derivation types
*/
struct DerivationType_ContentAddressed {
/**
* Whether the derivation should be built safely inside a sandbox.
*/
bool sandboxed;
/**
* Whether the derivation's outputs' content-addresses are "fixed"
* or "floating.
*
* - Fixed: content-addresses are written down as part of the
* derivation itself. If the outputs don't end up matching the
* build fails.
*
* - Floating: content-addresses are not written down, we do not
* know them until we perform the build.
*/
bool fixed;
};
/**
* Impure derivation type
*
* This is similar at buil-time to the content addressed, not standboxed, not fixed
* type, but has some restrictions on its usage.
*/
struct DerivationType_Impure {
};
typedef std::variant<
DerivationType_InputAddressed,
DerivationType_ContentAddressed,
DerivationType_Impure
> _DerivationTypeRaw;
struct DerivationType : _DerivationTypeRaw {
using Raw = _DerivationTypeRaw;
using Raw::Raw;
using InputAddressed = DerivationType_InputAddressed;
using ContentAddressed = DerivationType_ContentAddressed;
using Impure = DerivationType_Impure;
/**
* Do the outputs of the derivation have paths calculated from their
* content, or from the derivation itself?
*/
bool isCA() const;
/**
* Is the content of the outputs fixed <em>a priori</em> via a hash?
* Never true for non-CA derivations.
*/
bool isFixed() const;
/**
* Whether the derivation is fully sandboxed. If false, the sandbox
* is opened up, e.g. the derivation has access to the network. Note
* that whether or not we actually sandbox the derivation is
* controlled separately. Always true for non-CA derivations.
*/
bool isSandboxed() const;
/**
* Whether the derivation is expected to produce the same result
* every time, and therefore it only needs to be built once. This is
* only false for derivations that have the attribute '__impure =
* true'.
*/
bool isPure() const;
/**
* Does the derivation knows its own output paths?
* Only true when there's no floating-ca derivation involved in the
* closure, or if fixed output.
*/
bool hasKnownOutputPaths() const;
inline const Raw & raw() const {
return static_cast<const Raw &>(*this);
}
};
struct BasicDerivation
{
/**
* keyed on symbolic IDs
*/
DerivationOutputs outputs;
/**
* inputs that are sources
*/
StorePathSet inputSrcs;
std::string platform;
Path builder;
Strings args;
StringPairs env;
std::string name;
BasicDerivation() = default;
virtual ~BasicDerivation() { };
bool isBuiltin() const;
/**
* Return true iff this is a fixed-output derivation.
*/
DerivationType type() const;
/**
* Return the output names of a derivation.
*/
StringSet outputNames() const;
/**
* Calculates the maps that contains all the DerivationOutputs, but
* augmented with knowledge of the Store paths they would be written
* into.
*/
DerivationOutputsAndOptPaths outputsAndOptPaths(const Store & store) const;
static std::string_view nameFromPath(const StorePath & storePath);
GENERATE_CMP(BasicDerivation,
me->outputs,
me->inputSrcs,
me->platform,
me->builder,
me->args,
me->env,
me->name);
};
struct Derivation : BasicDerivation
{
/**
* inputs that are sub-derivations
*/
DerivationInputs inputDrvs;
/**
* Print a derivation.
*/
std::string unparse(const Store & store, bool maskOutputs,
std::map<std::string, StringSet> * actualInputs = nullptr) const;
/**
* Return the underlying basic derivation but with these changes:
*
* 1. Input drvs are emptied, but the outputs of them that were used
* are added directly to input sources.
*
* 2. Input placeholders are replaced with realized input store
* paths.
*/
std::optional<BasicDerivation> tryResolve(Store & store) const;
/**
* Like the above, but instead of querying the Nix database for
* realisations, uses a given mapping from input derivation paths +
* output names to actual output store paths.
*/
std::optional<BasicDerivation> tryResolve(
Store & store,
const std::map<std::pair<StorePath, std::string>, StorePath> & inputDrvOutputs) const;
/**
* Check that the derivation is valid and does not present any
* illegal states.
*
* This is mainly a matter of checking the outputs, where our C++
* representation supports all sorts of combinations we do not yet
* allow.
*/
void checkInvariants(Store & store, const StorePath & drvPath) const;
Derivation() = default;
Derivation(const BasicDerivation & bd) : BasicDerivation(bd) { }
Derivation(BasicDerivation && bd) : BasicDerivation(std::move(bd)) { }
nlohmann::json toJSON(const Store & store) const;
static Derivation fromJSON(
const Store & store,
const nlohmann::json & json);
GENERATE_CMP(Derivation,
static_cast<const BasicDerivation &>(*me),
me->inputDrvs);
};
class Store;
/**
* Write a derivation to the Nix store, and return its path.
*/
StorePath writeDerivation(Store & store,
const Derivation & drv,
RepairFlag repair = NoRepair,
bool readOnly = false);
/**
* Read a derivation from a file.
*/
Derivation parseDerivation(const Store & store, std::string && s, std::string_view name);
/**
* \todo Remove.
*
* Use Path::isDerivation instead.
*/
bool isDerivation(std::string_view fileName);
/**
* Calculate the name that will be used for the store path for this
* output.
*
* This is usually <drv-name>-<output-name>, but is just <drv-name> when
* the output name is "out".
*/
std::string outputPathName(std::string_view drvName, std::string_view outputName);
/**
* The hashes modulo of a derivation.
*
* Each output is given a hash, although in practice only the content-addressed
* derivations (fixed-output or not) will have a different hash for each
* output.
*/
struct DrvHash {
/**
* Map from output names to hashes
*/
std::map<std::string, Hash> hashes;
enum struct Kind : bool {
/**
* Statically determined derivations.
* This hash will be directly used to compute the output paths
*/
Regular,
/**
* Floating-output derivations (and their reverse dependencies).
*/
Deferred,
};
/**
* The kind of derivation this is, simplified for just "derivation hash
* modulo" purposes.
*/
Kind kind;
};
void operator |= (DrvHash::Kind & self, const DrvHash::Kind & other) noexcept;
/**
* 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.
*/
DrvHash hashDerivationModulo(Store & store, const Derivation & drv, bool maskOutputs);
/**
* Return a map associating each output to a hash that uniquely identifies its
* derivation (modulo the self-references).
*
* \todo What is the Hash in this map?
*/
std::map<std::string, Hash> staticOutputHashes(Store & store, const Derivation & drv);
/**
* Memoisation of hashDerivationModulo().
*/
typedef std::map<StorePath, DrvHash> DrvHashes;
// FIXME: global, though at least thread-safe.
extern Sync<DrvHashes> drvHashes;
struct Source;
struct Sink;
Source & readDerivation(Source & in, const Store & store, BasicDerivation & drv, std::string_view name);
void writeDerivation(Sink & out, const Store & store, const BasicDerivation & drv);
/**
* This creates an opaque and almost certainly unique string
* deterministically from the output name.
*
* It is used as a placeholder to allow derivations to refer to their
* own outputs without needing to use the hash of a derivation in
* itself, making the hash near-impossible to calculate.
*/
std::string hashPlaceholder(const std::string_view outputName);
/**
* This creates an opaque and almost certainly unique string
* deterministically from a derivation path and output name.
*
* It is used as a placeholder to allow derivations to refer to
* content-addressed paths whose content --- and thus the path
* themselves --- isn't yet known. This occurs when a derivation has a
* dependency which is a CA derivation.
*/
std::string downstreamPlaceholder(const Store & store, const StorePath & drvPath, std::string_view outputName);
extern const Hash impureOutputHash;
}