/dev/clipboard corrupted

Corinna Vinschen corinna-cygwin@cygwin.com
Thu Jul 19 09:42:00 GMT 2012

On Jul  9 01:15, Thomas Wolff wrote:
> Am 04.07.2012 10:15, schrieb Corinna Vinschen:
> >On Jul  3 18:29, Thomas Wolff wrote:
> >>...
> >>* The current (CVS) code will not work if even the first character
> >>to be converted
> >>    needs more bytes than the buffer provides, e.g. if the
> >>application calls read() with length 1 only.
> >>    Some extra buffering would be needed to make it work then.
> >Yes, indeed.  I'll have a look.
> ...
> >No, not yet.  This isn't exactly a regression from former behaviour.
> >Please provide a patch or remind me in a few weeks again.
> About the buffering I may send a patch when I find time.
> >
> >>* I assume the current code will also fail in non-UTF-8 locales;
> >>    if the wcs block being converted contains a non-convertible character,
> >>    it would abort since wcstombs returns -1
> >>    (assuming here that sys_wcstombs behaves alike in this respect)
> >It doesn't.  In fact, sys_cp_wcstombs was designed to never fail
> >to convert a string.  See the source code in strfunc.cc, line 447ff.
> Tested meanwhile. My assumption was too speculative, sorry.
> >>* I had previously observed that with a read size of n only n-1
> >>bytes would be delivered
> >>    and thought this was on purpose because wcstombs appends a final
> >>nul to its result.
> >>    Now n bytes are returned (if available) and in fact the byte
> >>behind the read() buffer is
> >>    overwritten (see modified test program).
> >It's not Cygwin overwriting the byte, your testcase is...
> Both were, actually...
> >>...
> >>		n = read (fd, filebuf, filebuflen);
> >>		if (out_tty) {
> >>			filebuf [n] = 0;
> >Hmm, what if n == filebuflen?
> I admit my test case was bogus in this respect *BLUSH*.
> However, yet the error is there, as a fixed test case reveals.
> Also your own testcase does print out "OVERWRITTEN".

I don't see this.  I use the same "Scoloplos" testcase and my
code does not print "OVERWRITTEN".


Corinna Vinschen                  Please, send mails regarding Cygwin to
Cygwin Project Co-Leader          cygwin AT cygwin DOT com
Red Hat

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