forked from lix-project/lix
325 lines
11 KiB
C++
325 lines
11 KiB
C++
#pragma once
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#include "path.hh"
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#include "types.hh"
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#include "hash.hh"
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#include "content-address.hh"
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#include "repair-flag.hh"
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#include "sync.hh"
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#include <map>
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#include <variant>
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namespace nix {
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/* Abstract syntax of derivations. */
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/* The traditional non-fixed-output derivation type. */
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struct DerivationOutputInputAddressed
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{
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StorePath path;
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};
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/* Fixed-output derivations, whose output paths are content addressed
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according to that fixed output. */
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struct DerivationOutputCAFixed
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{
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FixedOutputHash hash; /* hash used for expected hash computation */
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StorePath path(const Store & store, std::string_view drvName, std::string_view outputName) const;
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};
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/* Floating-output derivations, whose output paths are content addressed, but
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not fixed, and so are dynamically calculated from whatever the output ends
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up being. */
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struct DerivationOutputCAFloating
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{
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/* information used for expected hash computation */
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FileIngestionMethod method;
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HashType hashType;
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};
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/* Input-addressed output which depends on a (CA) derivation whose hash isn't
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* known yet.
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*/
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struct DerivationOutputDeferred {};
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/* Impure output which is moved to a content-addressed location (like
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CAFloating) but isn't registered as a realization.
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*/
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struct DerivationOutputImpure
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{
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/* information used for expected hash computation */
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FileIngestionMethod method;
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HashType hashType;
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};
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typedef std::variant<
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DerivationOutputInputAddressed,
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DerivationOutputCAFixed,
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DerivationOutputCAFloating,
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DerivationOutputDeferred,
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DerivationOutputImpure
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> _DerivationOutputRaw;
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struct DerivationOutput : _DerivationOutputRaw
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{
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using Raw = _DerivationOutputRaw;
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using Raw::Raw;
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using InputAddressed = DerivationOutputInputAddressed;
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using CAFixed = DerivationOutputCAFixed;
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using CAFloating = DerivationOutputCAFloating;
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using Deferred = DerivationOutputDeferred;
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using Impure = DerivationOutputImpure;
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/* Note, when you use this function you should make sure that you're passing
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the right derivation name. When in doubt, you should use the safer
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interface provided by BasicDerivation::outputsAndOptPaths */
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std::optional<StorePath> path(const Store & store, std::string_view drvName, std::string_view outputName) const;
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inline const Raw & raw() const {
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return static_cast<const Raw &>(*this);
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}
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};
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typedef std::map<std::string, DerivationOutput> DerivationOutputs;
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/* These are analogues to the previous DerivationOutputs data type, but they
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also contains, for each output, the (optional) store path in which it would
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be written. To calculate values of these types, see the corresponding
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functions in BasicDerivation */
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typedef std::map<std::string, std::pair<DerivationOutput, std::optional<StorePath>>>
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DerivationOutputsAndOptPaths;
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/* For inputs that are sub-derivations, we specify exactly which
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output IDs we are interested in. */
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typedef std::map<StorePath, StringSet> DerivationInputs;
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struct DerivationType_InputAddressed {
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bool deferred;
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};
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struct DerivationType_ContentAddressed {
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bool pure;
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bool fixed;
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};
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struct DerivationType_Impure {
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};
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typedef std::variant<
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DerivationType_InputAddressed,
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DerivationType_ContentAddressed,
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DerivationType_Impure
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> _DerivationTypeRaw;
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struct DerivationType : _DerivationTypeRaw {
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using Raw = _DerivationTypeRaw;
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using Raw::Raw;
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using InputAddressed = DerivationType_InputAddressed;
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using ContentAddressed = DerivationType_ContentAddressed;
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using Impure = DerivationType_Impure;
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/* Do the outputs of the derivation have paths calculated from their content,
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or from the derivation itself? */
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bool isCA() const;
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/* Is the content of the outputs fixed a-priori via a hash? Never true for
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non-CA derivations. */
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bool isFixed() const;
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/* Whether the derivation is fully sandboxed. If false, the
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sandbox is opened up, e.g. the derivation has access to the
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network. Note that whether or not we actually sandbox the
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derivation is controlled separately. Always true for non-CA
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derivations. */
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bool isSandboxed() const;
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/* Whether the derivation is expected to produce the same result
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every time, and therefore it only needs to be built once. This
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is only false for derivations that have the attribute '__impure
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= true'. */
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bool isPure() const;
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/* Does the derivation knows its own output paths?
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Only true when there's no floating-ca derivation involved in the
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closure, or if fixed output.
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*/
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bool hasKnownOutputPaths() const;
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inline const Raw & raw() const {
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return static_cast<const Raw &>(*this);
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}
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};
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struct BasicDerivation
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{
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DerivationOutputs outputs; /* keyed on symbolic IDs */
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StorePathSet inputSrcs; /* inputs that are sources */
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std::string platform;
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Path builder;
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Strings args;
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StringPairs env;
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std::string name;
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BasicDerivation() = default;
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virtual ~BasicDerivation() { };
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bool isBuiltin() const;
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/* Return true iff this is a fixed-output derivation. */
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DerivationType type() const;
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/* Return the output names of a derivation. */
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StringSet outputNames() const;
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/* Calculates the maps that contains all the DerivationOutputs, but
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augmented with knowledge of the Store paths they would be written
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into. */
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DerivationOutputsAndOptPaths outputsAndOptPaths(const Store & store) const;
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static std::string_view nameFromPath(const StorePath & storePath);
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};
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struct Derivation : BasicDerivation
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{
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DerivationInputs inputDrvs; /* inputs that are sub-derivations */
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/* Print a derivation. */
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std::string unparse(const Store & store, bool maskOutputs,
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std::map<std::string, StringSet> * actualInputs = nullptr) const;
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/* Return the underlying basic derivation but with these changes:
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1. Input drvs are emptied, but the outputs of them that were used are
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added directly to input sources.
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2. Input placeholders are replaced with realized input store paths. */
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std::optional<BasicDerivation> tryResolve(Store & store) const;
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/* Like the above, but instead of querying the Nix database for
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realisations, uses a given mapping from input derivation paths
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+ output names to actual output store paths. */
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std::optional<BasicDerivation> tryResolve(
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Store & store,
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const std::map<std::pair<StorePath, std::string>, StorePath> & inputDrvOutputs) const;
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Derivation() = default;
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Derivation(const BasicDerivation & bd) : BasicDerivation(bd) { }
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Derivation(BasicDerivation && bd) : BasicDerivation(std::move(bd)) { }
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};
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class Store;
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/* Write a derivation to the Nix store, and return its path. */
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StorePath writeDerivation(Store & store,
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const Derivation & drv,
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RepairFlag repair = NoRepair,
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bool readOnly = false);
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/* Read a derivation from a file. */
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Derivation parseDerivation(const Store & store, std::string && s, std::string_view name);
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// FIXME: remove
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bool isDerivation(const std::string & fileName);
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/* Calculate the name that will be used for the store path for this
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output.
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This is usually <drv-name>-<output-name>, but is just <drv-name> when
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the output name is "out". */
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std::string outputPathName(std::string_view drvName, std::string_view outputName);
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// The hashes modulo of a derivation.
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//
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// Each output is given a hash, although in practice only the content-addressed
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// derivations (fixed-output or not) will have a different hash for each
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// output.
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struct DrvHash {
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std::map<std::string, Hash> hashes;
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enum struct Kind : bool {
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// Statically determined derivations.
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// This hash will be directly used to compute the output paths
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Regular,
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// Floating-output derivations (and their reverse dependencies).
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Deferred,
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};
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Kind kind;
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};
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void operator |= (DrvHash::Kind & self, const DrvHash::Kind & other) noexcept;
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/* Returns hashes with the details of fixed-output subderivations
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expunged.
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A fixed-output derivation is a derivation whose outputs have a
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specified content hash and hash algorithm. (Currently they must have
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exactly one output (`out'), which is specified using the `outputHash'
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and `outputHashAlgo' attributes, but the algorithm doesn't assume
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this.) We don't want changes to such derivations to propagate upwards
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through the dependency graph, changing output paths everywhere.
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For instance, if we change the url in a call to the `fetchurl'
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function, we do not want to rebuild everything depending on it---after
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all, (the hash of) the file being downloaded is unchanged. So the
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*output paths* should not change. On the other hand, the *derivation
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paths* should change to reflect the new dependency graph.
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For fixed-output derivations, this returns a map from the name of
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each output to its hash, unique up to the output's contents.
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For regular derivations, it returns a single hash of the derivation
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ATerm, after subderivations have been likewise expunged from that
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derivation.
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*/
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DrvHash hashDerivationModulo(Store & store, const Derivation & drv, bool maskOutputs);
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/*
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Return a map associating each output to a hash that uniquely identifies its
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derivation (modulo the self-references).
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FIXME: what is the Hash in this map?
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*/
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std::map<std::string, Hash> staticOutputHashes(Store & store, const Derivation & drv);
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/* Memoisation of hashDerivationModulo(). */
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typedef std::map<StorePath, DrvHash> DrvHashes;
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// FIXME: global, though at least thread-safe.
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extern Sync<DrvHashes> drvHashes;
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bool wantOutput(const std::string & output, const std::set<std::string> & wanted);
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struct Source;
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struct Sink;
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Source & readDerivation(Source & in, const Store & store, BasicDerivation & drv, std::string_view name);
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void writeDerivation(Sink & out, const Store & store, const BasicDerivation & drv);
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/* This creates an opaque and almost certainly unique string
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deterministically from the output name.
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It is used as a placeholder to allow derivations to refer to their
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own outputs without needing to use the hash of a derivation in
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itself, making the hash near-impossible to calculate. */
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std::string hashPlaceholder(const std::string_view outputName);
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/* This creates an opaque and almost certainly unique string
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deterministically from a derivation path and output name.
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It is used as a placeholder to allow derivations to refer to
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content-addressed paths whose content --- and thus the path
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themselves --- isn't yet known. This occurs when a derivation has a
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dependency which is a CA derivation. */
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std::string downstreamPlaceholder(const Store & store, const StorePath & drvPath, std::string_view outputName);
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extern const Hash impureOutputHash;
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}
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