lix/src/libstore/derivations.hh

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#pragma once
#include "path.hh"
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#include "types.hh"
#include "hash.hh"
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#include "content-address.hh"
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#include <map>
#include <variant>
namespace nix {
/* Abstract syntax of derivations. */
* Removed the `id' attribute hack. * Formalise the notion of fixed-output derivations, i.e., derivations for which a cryptographic hash of the output is known in advance. Changes to such derivations should not propagate upwards through the dependency graph. Previously this was done by specifying the hash component of the output path through the `id' attribute, but this is insecure since you can lie about it (i.e., you can specify any hash and then produce a completely different output). Now the responsibility for checking the output is moved from the builder to Nix itself. A fixed-output derivation can be created by specifying the `outputHash' and `outputHashAlgo' attributes, the latter taking values `md5', `sha1', and `sha256', and the former specifying the actual hash in hexadecimal or in base-32 (auto-detected by looking at the length of the attribute value). MD5 is included for compatibility but should be considered deprecated. * Removed the `drvPath' pseudo-attribute in derivation results. It's no longer necessary. * Cleaned up the support for multiple output paths in derivation store expressions. Each output now has a unique identifier (e.g., `out', `devel', `docs'). Previously there was no way to tell output paths apart at the store expression level. * `nix-hash' now has a flag `--base32' to specify that the hash should be printed in base-32 notation. * `fetchurl' accepts parameters `sha256' and `sha1' in addition to `md5'. * `nix-prefetch-url' now prints out a SHA-1 hash in base-32. (TODO: a flag to specify the hash.)
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struct DerivationOutputInputAddressed
* Removed the `id' attribute hack. * Formalise the notion of fixed-output derivations, i.e., derivations for which a cryptographic hash of the output is known in advance. Changes to such derivations should not propagate upwards through the dependency graph. Previously this was done by specifying the hash component of the output path through the `id' attribute, but this is insecure since you can lie about it (i.e., you can specify any hash and then produce a completely different output). Now the responsibility for checking the output is moved from the builder to Nix itself. A fixed-output derivation can be created by specifying the `outputHash' and `outputHashAlgo' attributes, the latter taking values `md5', `sha1', and `sha256', and the former specifying the actual hash in hexadecimal or in base-32 (auto-detected by looking at the length of the attribute value). MD5 is included for compatibility but should be considered deprecated. * Removed the `drvPath' pseudo-attribute in derivation results. It's no longer necessary. * Cleaned up the support for multiple output paths in derivation store expressions. Each output now has a unique identifier (e.g., `out', `devel', `docs'). Previously there was no way to tell output paths apart at the store expression level. * `nix-hash' now has a flag `--base32' to specify that the hash should be printed in base-32 notation. * `fetchurl' accepts parameters `sha256' and `sha1' in addition to `md5'. * `nix-prefetch-url' now prints out a SHA-1 hash in base-32. (TODO: a flag to specify the hash.)
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{
/* Will need to become `std::optional<StorePath>` once input-addressed
derivations are allowed to depend on cont-addressed derivations */
StorePath path;
};
struct DerivationOutputFixed
{
FixedOutputHash hash; /* hash used for expected hash computation */
};
struct DerivationOutputFloating
{
/* information used for expected hash computation */
FileIngestionMethod method;
HashType hashType;
};
struct DerivationOutput
{
std::variant<
DerivationOutputInputAddressed,
DerivationOutputFixed,
DerivationOutputFloating
> 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 Error("floating content-addressed derivations are not yet implemented");
return *p;
}
* Removed the `id' attribute hack. * Formalise the notion of fixed-output derivations, i.e., derivations for which a cryptographic hash of the output is known in advance. Changes to such derivations should not propagate upwards through the dependency graph. Previously this was done by specifying the hash component of the output path through the `id' attribute, but this is insecure since you can lie about it (i.e., you can specify any hash and then produce a completely different output). Now the responsibility for checking the output is moved from the builder to Nix itself. A fixed-output derivation can be created by specifying the `outputHash' and `outputHashAlgo' attributes, the latter taking values `md5', `sha1', and `sha256', and the former specifying the actual hash in hexadecimal or in base-32 (auto-detected by looking at the length of the attribute value). MD5 is included for compatibility but should be considered deprecated. * Removed the `drvPath' pseudo-attribute in derivation results. It's no longer necessary. * Cleaned up the support for multiple output paths in derivation store expressions. Each output now has a unique identifier (e.g., `out', `devel', `docs'). Previously there was no way to tell output paths apart at the store expression level. * `nix-hash' now has a flag `--base32' to specify that the hash should be printed in base-32 notation. * `fetchurl' accepts parameters `sha256' and `sha1' in addition to `md5'. * `nix-prefetch-url' now prints out a SHA-1 hash in base-32. (TODO: a flag to specify the hash.)
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};
typedef std::map<string, DerivationOutput> DerivationOutputs;
/* For inputs that are sub-derivations, we specify exactly which
output IDs we are interested in. */
typedef std::map<StorePath, StringSet> DerivationInputs;
typedef std::map<string, string> StringPairs;
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struct BasicDerivation
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{
* Removed the `id' attribute hack. * Formalise the notion of fixed-output derivations, i.e., derivations for which a cryptographic hash of the output is known in advance. Changes to such derivations should not propagate upwards through the dependency graph. Previously this was done by specifying the hash component of the output path through the `id' attribute, but this is insecure since you can lie about it (i.e., you can specify any hash and then produce a completely different output). Now the responsibility for checking the output is moved from the builder to Nix itself. A fixed-output derivation can be created by specifying the `outputHash' and `outputHashAlgo' attributes, the latter taking values `md5', `sha1', and `sha256', and the former specifying the actual hash in hexadecimal or in base-32 (auto-detected by looking at the length of the attribute value). MD5 is included for compatibility but should be considered deprecated. * Removed the `drvPath' pseudo-attribute in derivation results. It's no longer necessary. * Cleaned up the support for multiple output paths in derivation store expressions. Each output now has a unique identifier (e.g., `out', `devel', `docs'). Previously there was no way to tell output paths apart at the store expression level. * `nix-hash' now has a flag `--base32' to specify that the hash should be printed in base-32 notation. * `fetchurl' accepts parameters `sha256' and `sha1' in addition to `md5'. * `nix-prefetch-url' now prints out a SHA-1 hash in base-32. (TODO: a flag to specify the hash.)
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DerivationOutputs outputs; /* keyed on symbolic IDs */
StorePathSet inputSrcs; /* inputs that are sources */
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string platform;
Path builder;
Strings args;
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StringPairs env;
std::string name;
BasicDerivation() { }
virtual ~BasicDerivation() { };
/* Return the path corresponding to the output identifier `id' in
the given derivation. */
const StorePath findOutput(const Store & store, const std::string & id) const;
bool isBuiltin() const;
/* Return true iff this is a fixed-output derivation. */
bool isFixedOutput() const;
/* Return the output paths of a derivation. */
StorePathSet outputPaths(const Store & store) const;
/* Return the output names of a derivation. */
StringSet outputNames() const;
static std::string_view nameFromPath(const StorePath & storePath);
};
struct Derivation : BasicDerivation
{
DerivationInputs inputDrvs; /* inputs that are sub-derivations */
/* Print a derivation. */
std::string unparse(const Store & store, bool maskOutputs,
std::map<std::string, StringSet> * actualInputs = nullptr) const;
Derivation() { }
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};
class Store;
enum RepairFlag : bool { NoRepair = false, Repair = true };
/* Write a derivation to the Nix store, and return its path. */
StorePath writeDerivation(ref<Store> store,
const Derivation & drv, std::string_view name, RepairFlag repair = NoRepair);
/* Read a derivation from a file. */
Derivation readDerivation(const Store & store, const Path & drvPath, std::string_view name);
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// FIXME: remove
bool isDerivation(const string & fileName);
// 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.
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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, DrvHashModulo> DrvHashes;
extern DrvHashes drvHashes; // FIXME: global, not thread-safe
bool wantOutput(const string & output, const std::set<string> & wanted);
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);
std::string hashPlaceholder(const std::string & outputName);
}