1 files changed, 133 insertions, 0 deletions
diff --git a/src/libutil/hash.hh b/src/libutil/hash.hh
new file mode 100644
index 000000000000..02e213fc7b35
--- /dev/null
+++ b/src/libutil/hash.hh
@@ -0,0 +1,133 @@
+#pragma once
+
+#include "types.hh"
+#include "serialise.hh"
+
+
+namespace nix {
+
+
+MakeError(BadHash, Error);
+
+
+enum HashType : char { htUnknown, htMD5, htSHA1, htSHA256, htSHA512 };
+
+
+const int md5HashSize = 16;
+const int sha1HashSize = 20;
+const int sha256HashSize = 32;
+const int sha512HashSize = 64;
+
+extern const string base32Chars;
+
+
+struct Hash
+{
+    static const unsigned int maxHashSize = 64;
+    unsigned int hashSize;
+    unsigned char hash[maxHashSize];
+
+    HashType type;
+
+    /* Create an unset hash object. */
+    Hash();
+
+    /* Create a zero-filled hash object. */
+    Hash(HashType type);
+
+    /* Check whether a hash is set. */
+    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;
+    }
+
+    std::string to_string(bool base32 = true) const;
+};
+
+
+/* Convert a hash to a hexadecimal representation. */
+string printHash(const Hash & hash);
+
+Hash parseHash(const string & s);
+
+/* Parse a hexadecimal representation of a hash code. */
+Hash parseHash(HashType ht, const string & s);
+
+/* Convert a hash to a base-32 representation. */
+string printHash32(const Hash & hash);
+
+/* Print a hash in base-16 if it's MD5, or base-32 otherwise. */
+string printHash16or32(const Hash & hash);
+
+/* Parse a base-32 representation of a hash code. */
+Hash parseHash32(HashType ht, const string & s);
+
+/* Parse a base-16 or base-32 representation of a hash code. */
+Hash parseHash16or32(HashType ht, const string & s);
+
+/* Verify that the given string is a valid hash code. */
+bool isHash(const string & s);
+
+/* Compute the hash of the given string. */
+Hash hashString(HashType ht, const string & 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)). */
+struct PathFilter;
+extern PathFilter defaultPathFilter;
+typedef std::pair<Hash, unsigned long long> 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(const string & s);
+
+/* And the reverse. */
+string printHashType(HashType ht);
+
+
+union Ctx;
+
+class HashSink : public BufferedSink
+{
+private:
+    HashType ht;
+    Ctx * ctx;
+    unsigned long long bytes;
+
+public:
+    HashSink(HashType ht);
+    HashSink(const HashSink & h);
+    ~HashSink();
+    void write(const unsigned char * data, size_t len);
+    HashResult finish();
+    HashResult currentHash();
+};
+
+
+}