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#pragma once
#include "types.hh"
#include "serialise.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 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
{
assert(type == htSHA1);
return to_string(Base16, false);
}
std::string gitShortRev() const
{
assert(type == htSHA1);
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 hashStr, std::optional<HashType> ht);
/* Print a hash in base-16 if it's MD5, or base-32 otherwise. */
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. */
string 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 write(const unsigned char * data, size_t len) override;
HashResult finish() override;
HashResult currentHash();
};
}
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