Re: copying to clipboard silently discards lines

[Benjamin Riefenstahl <b.riefenstahl@turtle-trading.net>]

Hi Chong Yidong,


"Chong Yidong" writes:
> The bug is in the Lisp_Object QUNICODE, which specifies the
> "utf-16le-dos" coding system used by `selection-coding-system'.

QUINCODE is just a symbol, a unique string.  It is used for looking up
the actual coding-system.  setup_coding_system() in src/coding.c does
that lookup by filling in the struct coding_system.

> When a coding_system is extracted from QUNICODE, the parameter
> coding->spec.ccl.encoder.buf_magnification is 1. This causes a call to
> encoding_buffer_size (in convert_to_handle_as_coded, w32select.c:247) to
> return a buffer size that is too small for the encoded string.
>
> I'm guessing the magnification has to be set to 2, because `abc...'
> gets encoded to `a\0b\0c\0...' (encoding_buffer_size multiplies this
> again by 2, because of the CRLF issue.)

That would indicate that the coding-system "utf-16le-dos" itself has a
bug.  The source code description comment for encoding_buffer_size()
says

 Return maximum size (bytes) of a buffer enough for encoding SRC_BYTES
 of text to CODING.

which matches its usage in w32select.c, I think.

> Trouble is, I can't find where the `spec.ccl...', or indeed any of
> the other parameters of QUNICODE are initialized.

Grep is our friend ;-).  The coding-system (and its CCL programs) is
created in lisp/international/ccl.el using (define-ccl-program ...).
The parameter BUFFER_MAGNIFICATION for that function is set as 1 there
for the encoders (ccl-encode-mule-utf-16le, ccl-encode-mule-utf-16be,
ccl-encode-mule-utf-16le-with-signature,
ccl-encode-mule-utf-16be-with-signature), so that might well be the
problem.

Can you try and replace that 1 with 2 and see if your problem goes
away?


benny