# Re: EOF detection

From: mh (crapsite@gmx.net)
Date: Thu May 10 2001 - 03:11:42 PDT

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  Marian Eichholz, Don, 10 Mai 2001 :
  > Nick Lamb wrote:
  ...
  > The point is, that the Xsane frontend allocates a buffer, depending on
  > the sane_param(? I don't have the specs here?) call returning the
  > dimensions of the scan window.
  >
  > Despite this, the frontend always requests blocks of 8KB (gray) and 64KB
  > (RGB), even if the end of the allocated
  > picture buffer lies within this chunk size and cannot swallow this whole
  > chunk.
  >
  > Thus, any backend that is keen to deliver actually more data than XSane
  > expects, will overflow XSane's scan buffer.
  >
  > You I right, I have to deliver some body of evidence :-)))

  I had this problem last year, with the plustek backend and an OpticPro 600P.
  IIRC the reason for this was, that XSane relies on the values it gets from
  a call to sane_get_parameters() *before* sane_start() is called. However, the
  plustek backend didn't return valid parameters at this stage, which resulted in
  the problem you described.
  I've just tested an old version of the plustek backend with XSane0.76, and the
  problem still seems to persists.
  I don't know whether one should call it a bug in XSane; at least it could be
  easily solved by calling sane_get_parameters() after sane_start() has been
  called. (Oliver?)

  Michael

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