add md5:update and md5:sum methods

frontend/MD5.lua

@@ -208,14 +208,25 @@ local function bin2str(output, input, len)
     end
 end
 
-local function md5(luastr)
+local md5 = {}
+
+function md5:new()
+    self.ctx = ffi.new("MD5_CTX")
+    MD5Init(self.ctx)
+end
+
+function md5:update(luastr)
+    MD5Update(self.ctx, ffi.cast("const char*", luastr), #luastr)
+end
+
+function md5:sum(luastr)
     local buf = ffi.new("char[33]")
     local hash = ffi.new("uint8_t[16]")
-    local ctx = ffi.new("MD5_CTX")
-
-    MD5Init(ctx)
-    MD5Update(ctx, ffi.cast("const char*", luastr), #luastr)
-    MD5Final(hash, ctx)
+    if luastr then
+        md5:new()
+        md5:update(luastr)
+    end
+    MD5Final(hash, self.ctx)
 
     bin2str(buf, hash, ffi.sizeof(hash))
 

frontend/cache.lua

@@ -122,7 +122,7 @@ function Cache:check(key, ItemClass)
         end
         return self.cache[key]
     elseif ItemClass then
-        local cached = self.cached[md5(key)]
+        local cached = self.cached[md5:sum(key)]
         if cached then
             local item = ItemClass:new{}
             local ok, msg = pcall(item.load, item, cached)
@@ -159,7 +159,7 @@ function Cache:serialize()
         -- only dump cache item that requests serialization explicitly
         if cache_item.persistent and cache_item.dump then
             DEBUG("dump cache item", key)
-            cache_size = cache_item:dump(cache_path..md5(key)) or 0
+            cache_size = cache_item:dump(cache_path..md5:sum(key)) or 0
             if cache_size > 0 then break end
         end
     end

spec/unit/md5_spec.lua

@@ -4,9 +4,16 @@ local md5 = require("MD5")
 
 describe("MD5 module", function()
     it("should calculate correct MD5 hashes", function()
-        assert.is_equal(md5(""), "d41d8cd98f00b204e9800998ecf8427e")
-        assert.is_equal(md5("\0"), "93b885adfe0da089cdf634904fd59f71")
-        assert.is_equal(md5("0123456789abcdefX"), "1b05aba914a8b12315c7ee52b42f3d35")
+        assert.is_equal(md5:sum(""), "d41d8cd98f00b204e9800998ecf8427e")
+        assert.is_equal(md5:sum("\0"), "93b885adfe0da089cdf634904fd59f71")
+        assert.is_equal(md5:sum("0123456789abcdefX"), "1b05aba914a8b12315c7ee52b42f3d35")
+    end)
+    it("should calculate MD5 sum by updating", function()
+        md5:new()
+        md5:update("0123456789")
+        md5:update("abcdefghij")
+        local md5sum = md5:sum()
+        assert.is_equal(md5sum, md5:sum("0123456789abcdefghij"))
     end)
 end)