[Haskell-cafe] readFile and closing a file

Say I acquire a text by readFile, feed it to a lazy parser and the parser stops reading because of a parse error. After the parser error I won't fetch more characters from the text file, but readFile does not get to know that and cannot close the file. Actually, when encountering a parser error I could read the remaining characters from the file in order to let readFile close the file eventually, but this sounds rather inefficient. So, what is the right way to go, or do I have to stay away from readFile (and maybe unsafeInterleaveIO at all)?