[plt-scheme] resources-fork size under MacOS classic

From: Matthew Flatt (mflatt at cs.utah.edu)
Date: Thu Oct 10 08:49:13 EDT 2002

At Thu, 10 Oct 2002 08:19:29 +0200, "Nicolas Chevallier" wrote:
> Is there anyway to get the logical the data-fork size or the resources-size
> under MacOS classic?
> (file-size path) returns the sum of them.

Here's some code that I use.

      ; file-path-string -> num
      (define (data-fork-size dest)
	(if (eq? (system-type) 'macos)
	    ;; Can't use `file-size', because that includes the resource fork.
            ;; Read all the data to EOF, then check the position of the file
            ;; pointer. (Maybe using file-position with a big number to
            ;; move the pointer would be better than reading?)
	    (let ([p (open-input-file dest)]
		  [s (make-string 4096)])
	      (let loop ()
		(if (eof-object? (read-string-avail! s p))
		     (file-position p)
		     (close-input-port p))
	    ;; File has only a "data fork":
	    (file-size dest)))


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