154 lines
3.9 KiB
C++
154 lines
3.9 KiB
C++
#pragma once
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#include "types.hh"
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#include "serialise.hh"
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namespace nix {
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MakeError(BadHash, Error);
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enum HashType : char { htMD5 = 42, htSHA1, htSHA256, htSHA512 };
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const int md5HashSize = 16;
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const int sha1HashSize = 20;
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const int sha256HashSize = 32;
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const int sha512HashSize = 64;
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extern const string base32Chars;
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enum Base : int { Base64, Base32, Base16, SRI };
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struct Hash
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{
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constexpr static size_t maxHashSize = 64;
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size_t hashSize = 0;
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uint8_t hash[maxHashSize] = {};
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HashType type;
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/* Create a zero-filled hash object. */
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Hash(HashType type) : type(type) { init(); };
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/* Initialize the hash from a string representation, in the format
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"[<type>:]<base16|base32|base64>" or "<type>-<base64>" (a
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Subresource Integrity hash expression). If the 'type' argument
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is not present, then the hash type must be specified in the
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string. */
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Hash(std::string_view s, std::optional<HashType> type);
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// type must be provided
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Hash(std::string_view s, HashType type);
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// hash type must be part of string
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Hash(std::string_view s);
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void init();
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/* Check whether a hash is set. */
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operator bool () const { return (bool) type; }
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/* Check whether two hash are equal. */
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bool operator == (const Hash & h2) const;
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/* Check whether two hash are not equal. */
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bool operator != (const Hash & h2) const;
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/* For sorting. */
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bool operator < (const Hash & h) const;
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/* Returns the length of a base-16 representation of this hash. */
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size_t base16Len() const
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{
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return hashSize * 2;
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}
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/* Returns the length of a base-32 representation of this hash. */
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size_t base32Len() const
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{
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return (hashSize * 8 - 1) / 5 + 1;
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}
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/* Returns the length of a base-64 representation of this hash. */
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size_t base64Len() const
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{
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return ((4 * hashSize / 3) + 3) & ~3;
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}
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/* Return a string representation of the hash, in base-16, base-32
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or base-64. By default, this is prefixed by the hash type
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(e.g. "sha256:"). */
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std::string to_string(Base base, bool includeType) const;
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std::string gitRev() const
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{
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assert(type == htSHA1);
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return to_string(Base16, false);
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}
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std::string gitShortRev() const
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{
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assert(type == htSHA1);
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return std::string(to_string(Base16, false), 0, 7);
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}
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};
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/* Helper that defaults empty hashes to the 0 hash. */
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Hash newHashAllowEmpty(std::string hashStr, std::optional<HashType> ht);
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/* Print a hash in base-16 if it's MD5, or base-32 otherwise. */
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string printHash16or32(const Hash & hash);
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/* Compute the hash of the given string. */
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Hash hashString(HashType ht, std::string_view s);
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/* Compute the hash of the given file. */
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Hash hashFile(HashType ht, const Path & path);
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/* Compute the hash of the given path. The hash is defined as
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(essentially) hashString(ht, dumpPath(path)). */
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typedef std::pair<Hash, unsigned long long> HashResult;
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HashResult hashPath(HashType ht, const Path & path,
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PathFilter & filter = defaultPathFilter);
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/* Compress a hash to the specified number of bytes by cyclically
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XORing bytes together. */
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Hash compressHash(const Hash & hash, unsigned int newSize);
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/* Parse a string representing a hash type. */
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HashType parseHashType(std::string_view s);
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/* Will return nothing on parse error */
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std::optional<HashType> parseHashTypeOpt(std::string_view s);
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/* And the reverse. */
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string printHashType(HashType ht);
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union Ctx;
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struct AbstractHashSink : virtual Sink
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{
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virtual HashResult finish() = 0;
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};
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class HashSink : public BufferedSink, public AbstractHashSink
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{
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private:
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HashType ht;
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Ctx * ctx;
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unsigned long long bytes;
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public:
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HashSink(HashType ht);
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HashSink(const HashSink & h);
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~HashSink();
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void write(const unsigned char * data, size_t len) override;
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HashResult finish() override;
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HashResult currentHash();
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};
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}
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