[cmucl-ticket] [cmucl] #36: file-position broken for utf16 and utf32

[cmucl]

#36: file-position broken for utf16 and utf32
--------------------+-------------------------------------------------------
 Reporter:  rtoy    |       Owner:  somebody
     Type:  defect  |      Status:  new     
 Priority:  minor   |   Milestone:          
Component:  Core    |     Version:  19f     
 Keywords:          |  
--------------------+-------------------------------------------------------
 Consider this code:

 {{{
 (defun bug (&optional (format :utf16))
   (with-open-file (s "/tmp/bom.txt"
                      :direction :output
                      :if-exists :supersede
                      :external-format format)
     (format s "Hello~%"))
   (with-open-file (s "/tmp/bom.txt"
                      :direction :input
                      :external-format format)
     (print (read-char s))
     (print (file-position s)))
   (values))
 }}}

 Running {{{(bug :utf16)}}} produces
 {{{
 #\H
 2
 }}}

 {{{(bug :utf32)}}} produces
 {{{
 #\H
 4
 }}}

 In both cases, the actual position is wrong.  For utf16, the position
 should 4; utf32, 8.  The BOM has been ignored.

 This is caused by {{{STRING-ENCODE}}} outputting the BOM for these
 formats.  {{{STRING-ENCODE)}}} is used to figure out how many octets have
 not yet been processed but have been read from the file.  If the BOM was
 not output, the position would be correct.

 This bug (will) occur in the 2010-02 snapshot and later.

-- 
Ticket URL: <http://trac.common-lisp.net/cmucl/ticket/36>
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