1 files changed, 147 insertions, 0 deletions
diff --git a/third_party/nix/src/libutil/hash.hh b/third_party/nix/src/libutil/hash.hh
new file mode 100644
index 0000000000..8b52ac657e
--- /dev/null
+++ b/third_party/nix/src/libutil/hash.hh
@@ -0,0 +1,147 @@
+#pragma once
+
+#include <absl/status/statusor.h>
+
+#include "libproto/worker.grpc.pb.h"
+#include "libutil/serialise.hh"
+#include "libutil/types.hh"
+
+namespace nix {
+
+// Size of the hashes rendered in store paths, in bytes
+constexpr unsigned int kStorePathHashSize = 20;
+
+MakeError(BadHash, Error);
+
+// TODO(grfn): Replace this with the hash type enum from the daemon proto so we
+// don't have to juggle two different types
+enum HashType : char { htUnknown, htMD5, htSHA1, htSHA256, htSHA512 };
+
+std::optional<HashType> hash_type_from(nix::proto::HashType hash_type);
+
+nix::proto::HashType HashTypeToProto(HashType hash_type);
+
+const int md5HashSize = 16;
+const int sha1HashSize = 20;
+const int sha256HashSize = 32;
+const int sha512HashSize = 64;
+
+// omitted: E O U T
+constexpr char base32Chars[] = "0123456789abcdfghijklmnpqrsvwxyz";
+
+enum Base : int { Base64, Base32, Base16, SRI };
+
+struct Hash {
+  static const unsigned int maxHashSize = 64;
+  unsigned int hashSize = 0;
+  unsigned char hash[maxHashSize] = {};
+
+  HashType type = htUnknown;
+
+  /* Create an unset hash object. */
+  Hash(){};
+
+  /* Create a zero-filled hash object. */
+  explicit Hash(HashType type) : type(type) { init(); };
+
+  /* Initialize 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 htUnknown, then the hash type must be specified in the
+     string. */
+  explicit Hash(std::string_view s, HashType type = htUnknown);
+
+  /* Status-returning version of above constructor */
+  static absl::StatusOr<Hash> deserialize(std::string_view s,
+                                          HashType type = htUnknown);
+
+  // Legacy unwrapper for StatusOr. Throws BadHash.
+  static Hash unwrap_throw(absl::StatusOr<Hash> hash) noexcept(false);
+
+  void init();
+
+  /* Check whether a hash is set. */
+  explicit operator bool() const { return type != htUnknown; }
+
+  /* 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 = Base32, bool includeType = true) const;
+
+  /* Returns whether the passed string contains entirely valid base16
+     characters. */
+  static bool IsValidBase16(absl::string_view s);
+
+  /* Returns whether the passed string contains entirely valid base32
+     characters. */
+  static bool IsValidBase32(absl::string_view s);
+
+  // Convert this Hash to the format expected in store paths
+  [[nodiscard]] std::string ToStorePathHash() const;
+};
+
+/* 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, const std::string& s);
+
+/* Compute the hash of the given file. */
+Hash hashFile(HashType ht, const Path& path);
+
+/* A pair of the Hash, and the number of bytes consumed. */
+typedef std::pair<Hash, unsigned long long> HashResult;
+
+/* Compute the hash of the given path.  The hash is defined as
+   (essentially) hashString(ht, dumpPath(path)). */
+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(const std::string& s);
+
+/* And the reverse. */
+std::string printHashType(HashType ht);
+
+namespace hash {
+union Ctx;
+}
+
+class HashSink : public BufferedSink {
+ private:
+  HashType ht;
+  std::unique_ptr<hash::Ctx> ctx;
+  unsigned long long bytes;
+
+ public:
+  explicit HashSink(HashType ht);
+  HashSink(const HashSink& h);
+  ~HashSink();
+  void write(const unsigned char* data, size_t len);
+  HashResult finish();
+  HashResult currentHash();
+};
+
+}  // namespace nix