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#pragma once
///@file
#include "types.hh"
#include "serialise.hh"
#include "file-system.hh"
namespace nix {
MakeError(BadHash, Error);
enum HashType : char { htMD5 = 42, htSHA1, htSHA256, htSHA512 };
const int md5HashSize = 16;
const int sha1HashSize = 20;
const int sha256HashSize = 32;
const int sha512HashSize = 64;
extern std::set<std::string> hashTypes;
extern const std::string base32Chars;
enum Base : int { Base64, Base32, Base16, SRI };
struct Hash
{
constexpr static size_t maxHashSize = 64;
size_t hashSize = 0;
uint8_t hash[maxHashSize] = {};
HashType type;
/**
* Create a zero-filled hash object.
*/
Hash(HashType type);
/**
* Parse the hash from a string representation in the format
* "[<type>:]<base16|base32|base64>" or "<type>-<base64>" (a
* Subresource Integrity hash expression). If the 'type' argument
* is not present, then the hash type must be specified in the
* string.
*/
static Hash parseAny(std::string_view s, std::optional<HashType> type);
/**
* Parse a hash from a string representation like the above, except the
* type prefix is mandatory is there is no separate arguement.
*/
static Hash parseAnyPrefixed(std::string_view s);
/**
* Parse a plain hash that musst not have any prefix indicating the type.
* The type is passed in to disambiguate.
*/
static Hash parseNonSRIUnprefixed(std::string_view s, HashType type);
static Hash parseSRI(std::string_view original);
private:
/**
* The type must be provided, the string view must not include <type>
* prefix. `isSRI` helps disambigate the various base-* encodings.
*/
Hash(std::string_view s, HashType type, bool isSRI);
public:
/**
* Check whether two hash are equal.
*/
bool operator == (const Hash & h2) const;
/**
* Check whether two hash are not equal.
*/
bool operator != (const Hash & h2) const;
/**
* For sorting.
*/
bool operator < (const Hash & h) const;
/**
* Returns the length of a base-16 representation of this hash.
*/
size_t base16Len() const
{
return hashSize * 2;
}
/**
* Returns the length of a base-32 representation of this hash.
*/
size_t base32Len() const
{
return (hashSize * 8 - 1) / 5 + 1;
}
/**
* Returns the length of a base-64 representation of this hash.
*/
size_t base64Len() const
{
return ((4 * hashSize / 3) + 3) & ~3;
}
/**
* Return a string representation of the hash, in base-16, base-32
* or base-64. By default, this is prefixed by the hash type
* (e.g. "sha256:").
*/
std::string to_string(Base base, bool includeType) const;
std::string gitRev() const
{
return to_string(Base16, false);
}
std::string gitShortRev() const
{
return std::string(to_string(Base16, false), 0, 7);
}
static Hash dummy;
};
/**
* Helper that defaults empty hashes to the 0 hash.
*/
Hash newHashAllowEmpty(std::string_view hashStr, std::optional<HashType> ht);
/**
* Print a hash in base-16 if it's MD5, or base-32 otherwise.
*/
std::string printHash16or32(const Hash & hash);
/**
* Compute the hash of the given string.
*/
Hash hashString(HashType ht, std::string_view s);
/**
* Compute the hash of the given file.
*/
Hash hashFile(HashType ht, const Path & path);
/**
* Compute the hash of the given path. The hash is defined as
* (essentially) hashString(ht, dumpPath(path)).
*/
typedef std::pair<Hash, uint64_t> HashResult;
HashResult hashPath(HashType ht, const Path & path,
PathFilter & filter = defaultPathFilter);
/**
* Compress a hash to the specified number of bytes by cyclically
* XORing bytes together.
*/
Hash compressHash(const Hash & hash, unsigned int newSize);
/**
* Parse a string representing a hash type.
*/
HashType parseHashType(std::string_view s);
/**
* Will return nothing on parse error
*/
std::optional<HashType> parseHashTypeOpt(std::string_view s);
/**
* And the reverse.
*/
std::string_view printHashType(HashType ht);
union Ctx;
struct AbstractHashSink : virtual Sink
{
virtual HashResult finish() = 0;
};
class HashSink : public BufferedSink, public AbstractHashSink
{
private:
HashType ht;
Ctx * ctx;
uint64_t bytes;
public:
HashSink(HashType ht);
HashSink(const HashSink & h);
~HashSink();
void writeUnbuffered(std::string_view data) override;
HashResult finish() override;
HashResult currentHash();
};
inline HashResult hashSource(HashType ht, Source & source)
{
HashSink h(ht);
source.drainInto(h);
return h.finish();
}
}
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