nix-super/src/libstore/content-address.hh

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#pragma once
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#include <variant>
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#include "hash.hh"
namespace nix {
enum struct FileIngestionMethod : uint8_t {
Flat = false,
Recursive = true
};
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struct TextHash {
Hash hash;
};
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/// Pair of a hash, and how the file system was ingested
struct FixedOutputHash {
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FileIngestionMethod method;
Hash hash;
std::string printMethodAlgo() const;
};
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/*
We've accumulated several types of content-addressed paths over the years;
fixed-output derivations support multiple hash algorithms and serialisation
methods (flat file vs NAR). Thus, ca has one of the following forms:
* text:sha256:<sha256 hash of file contents>: For paths
computed by makeTextPath() / addTextToStore().
* fixed:<r?>:<ht>:<h>: For paths computed by
makeFixedOutputPath() / addToStore().
*/
typedef std::variant<
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TextHash, // for paths computed by makeTextPath() / addTextToStore
FixedOutputHash // for path computed by makeFixedOutputPath
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> ContentAddress;
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/* Compute the prefix to the hash algorithm which indicates how the files were
ingested. */
std::string makeFileIngestionPrefix(const FileIngestionMethod m);
/* Compute the content-addressability assertion (ValidPathInfo::ca)
for paths created by makeFixedOutputPath() / addToStore(). */
std::string makeFixedOutputCA(FileIngestionMethod method, const Hash & hash);
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std::string renderContentAddress(ContentAddress ca);
std::string renderContentAddress(std::optional<ContentAddress> ca);
ContentAddress parseContentAddress(std::string_view rawCa);
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std::optional<ContentAddress> parseContentAddressOpt(std::string_view rawCaOpt);
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Hash getContentAddressHash(const ContentAddress & ca);
/*
We only have one way to hash text with references, so this is single-value
type is only useful in std::variant.
*/
struct TextHashMethod { };
struct FixedOutputHashMethod {
FileIngestionMethod fileIngestionMethod;
HashType hashType;
};
typedef std::variant<
TextHashMethod,
FixedOutputHashMethod
> ContentAddressMethod;
ContentAddressMethod parseContentAddressMethod(std::string_view rawCaMethod);
std::string renderContentAddressMethod(ContentAddressMethod caMethod);
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}