[YQTemplate] attempt to fix the parsing №1

utils.lua

@@ -67,20 +67,33 @@ end
 --- @return string name the name of the form field.
 --- @return string? content_type the content type of the attached file, or nil if entry is not a file.
 --- @return string data the value of the entry.
+--- We are doing some severe assumptions here.
+--- - Firstly we assume that if the first line of a header doesn't start with
+--- `Content-Disposition`, it is invalid and we can ignore it.
+--- - Secondly we assume that in the headers, any `CR` is always gonna be
+--- followed by a `LF` thus we only check for CR and advance by 2 when found
+--- - Thirdly we assume that the only headers that can matter are
+--- `Content-Disposition` (for the field name) and `Content-Type` (if this is a
+--- file upload for the type of the uploaded file.
+--- - Fourthly we assume a field name can't contain a double quote
 _m.parse_form_entry = function(entry)
-   local name, content_type, data
-   local _, end_of_header = entry:find("\r\n\r\n")
-   for dataline in entry:gmatch("(.-)\r\n") do
-      if dataline:sub(1, 19) == "Content-Disposition" then
-	 name = dataline:match("name=\"(.*)\"")
+   local cursor = 3
+   local name, ctype
+   while true do
+      if entry:sub(cursor, cursor) == "\r" then
+	 cursor = cursor + 2
+	 break
+      elseif entry:sub(cursor, cursor+18) == 'Content-Disposition' then
+	 cursor = cursor + 38
+	 name = string.match(entry, "(.*)\"", cursor)
+	 cursor = cursor + #name + 1 --[[ the closing quote ]] + 2 --[[ CRLF ]]
+      elseif entry:sub(cursor, cursor+11) == 'Content-Type' then
+	 cursor = cursor + 14
+	 ctype = string.match(entry, "(.*)\r", cursor)
+	 cursor = cursor + #ctype + 2 --[[ CRLF ]]
       end
-      if dataline:sub(1, 12) == "Content-Type" then
-	 content_type = dataline:match("Content-Type: (.*)\r\n")
-      end
-      if dataline == "" then break end
    end
-   data = entry:sub(end_of_header + 1)
-   return name, content_type, data
+   return name, ctype, entry:sub(cursor, -1)
 end
 
 return _m