libluna: Return a new Digest structure instead of a Buffer from SHA256

apps/sha256sum.cpp

@@ -20,9 +20,9 @@ Result<int> luna_main(int argc, char** argv)
         SHA256 sha;
 
         TRY(sha.append(data.data(), data.size()));
-        auto hash = TRY(sha.digest());
+        auto digest = TRY(sha.digest());
+        auto string = TRY(digest.to_string());
 
-        auto string = TRY(sha.hash_to_string(hash));
         os::println("%s %s", string.chars(), path.chars());
     }
 

libluna/include/luna/SHA.h

@@ -9,6 +9,7 @@
 
 #pragma once
 #include <luna/Buffer.h>
+#include <luna/Slice.h>
 #include <luna/String.h>
 
 /**
@@ -26,14 +27,28 @@ class SHA256
      */
     Result<void> append(const u8* data, usize size);
 
+    class Digest
+    {
+      public:
+        const Slice<u8> bytes()
+        {
+            return { m_bytes, 32 };
+        }
+
+        Result<String> to_string();
+
+      private:
+        u8 m_bytes[32];
+
+        friend class SHA256;
+    };
+
     /**
      * @brief Calculate the final hash.
      *
-     * @return Buffer The calculated hash.
+     * @return Digest The calculated hash digest.
      */
-    Result<Buffer> digest();
-
-    static Result<String> hash_to_string(const Buffer& buffer);
+    Result<Digest> digest();
 
   private:
     Buffer m_message;

libluna/src/SHA.cpp

@@ -42,7 +42,7 @@ Result<void> SHA256::append(const u8* data, usize size)
 
 // Thank you to https://sha256algorithm.com/ for showing me how the SHA256 algorithm works, and effectively, how to
 // implement it!
-Result<Buffer> SHA256::digest()
+Result<SHA256::Digest> SHA256::digest()
 {
     usize message_block_length = m_message.size() + 1 + sizeof(u64);
     usize message_block_chunks = ceil_div(message_block_length, 64ul);
@@ -160,26 +160,26 @@ Result<Buffer> SHA256::digest()
     h6 = __builtin_bswap32(h6);
     h7 = __builtin_bswap32(h7);
 
-    Buffer result;
-    TRY(result.append_data((const u8*)&h0, sizeof(u32)));
-    TRY(result.append_data((const u8*)&h1, sizeof(u32)));
-    TRY(result.append_data((const u8*)&h2, sizeof(u32)));
-    TRY(result.append_data((const u8*)&h3, sizeof(u32)));
-    TRY(result.append_data((const u8*)&h4, sizeof(u32)));
-    TRY(result.append_data((const u8*)&h5, sizeof(u32)));
-    TRY(result.append_data((const u8*)&h6, sizeof(u32)));
-    TRY(result.append_data((const u8*)&h7, sizeof(u32)));
+    Digest result;
+    memcpy(&result.m_bytes[0], &h0, sizeof(u32));
+    memcpy(&result.m_bytes[4], &h1, sizeof(u32));
+    memcpy(&result.m_bytes[8], &h2, sizeof(u32));
+    memcpy(&result.m_bytes[12], &h3, sizeof(u32));
+    memcpy(&result.m_bytes[16], &h4, sizeof(u32));
+    memcpy(&result.m_bytes[20], &h5, sizeof(u32));
+    memcpy(&result.m_bytes[24], &h6, sizeof(u32));
+    memcpy(&result.m_bytes[28], &h7, sizeof(u32));
 
     m_message.try_resize(0); // Don't need this anymore.
 
     return result;
 }
 
-Result<String> SHA256::hash_to_string(const Buffer& buffer)
+Result<String> SHA256::Digest::to_string()
 {
     StringBuilder sb;
 
-    for (usize i = 0; i < buffer.size(); i++) { sb.format("%02x", buffer.data()[i]); }
+    for (usize i = 0; i < sizeof(m_bytes); i++) { sb.format("%02x", m_bytes[i]); }
 
     return sb.string();
 }