1 files changed, 28 insertions, 22 deletions

diff --git a/src/libutil/hash.hh b/src/libutil/hash.hh
index ad6093fca..6d6eb70ca 100644
--- a/src/libutil/hash.hh
+++ b/src/libutil/hash.hh
@@ -27,34 +27,38 @@ enum Base : int { Base64, Base32, Base16, SRI };
 
 struct Hash
 {
-    static const unsigned int maxHashSize = 64;
-    unsigned int hashSize = 0;
-    unsigned char hash[maxHashSize] = {};
+    constexpr static size_t maxHashSize = 64;
+    size_t hashSize = 0;
+    uint8_t hash[maxHashSize] = {};
 
-    std::optional<HashType> type = {};
-
-    /* Create an unset hash object. */
-    Hash() { };
+    HashType type;
 
     /* Create a zero-filled hash object. */
-    Hash(HashType type) : type(type) { init(); };
+    Hash(HashType type);
 
-    /* Initialize the hash from a string representation, in the format
+    /* 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. */
-    Hash(std::string_view s, std::optional<HashType> type);
-    // type must be provided
-    Hash(std::string_view s, HashType type);
-    // hash type must be part of string
-    Hash(std::string_view s);
+    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);
 
-    void init();
+    static Hash parseSRI(std::string_view original);
 
-    /* Check whether a hash is set. */
-    operator bool () const { return (bool) type; }
+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;
 
@@ -98,6 +102,8 @@ struct Hash
         assert(type == htSHA1);
         return std::string(to_string(Base16, false), 0, 7);
     }
+
+    static Hash dummy;
 };
 
 /* Helper that defaults empty hashes to the 0 hash. */
@@ -107,14 +113,14 @@ Hash newHashAllowEmpty(std::string hashStr, std::optional<HashType> ht);
 string printHash16or32(const Hash & hash);
 
 /* Compute the hash of the given string. */
-Hash hashString(HashType ht, const string & s);
+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, unsigned long long> HashResult;
+typedef std::pair<Hash, uint64_t> HashResult;
 HashResult hashPath(HashType ht, const Path & path,
     PathFilter & filter = defaultPathFilter);
 
@@ -123,10 +129,10 @@ HashResult hashPath(HashType ht, const Path & path,
 Hash compressHash(const Hash & hash, unsigned int newSize);
 
 /* Parse a string representing a hash type. */
-HashType parseHashType(const string & s);
+HashType parseHashType(std::string_view s);
 
 /* Will return nothing on parse error */
-std::optional<HashType> parseHashTypeOpt(const string & s);
+std::optional<HashType> parseHashTypeOpt(std::string_view s);
 
 /* And the reverse. */
 string printHashType(HashType ht);
@@ -144,7 +150,7 @@ class HashSink : public BufferedSink, public AbstractHashSink
 private:
     HashType ht;
     Ctx * ctx;
-    unsigned long long bytes;
+    uint64_t bytes;
 
 public:
     HashSink(HashType ht);