ports/98590: [FIX] ports rxvt-devel on amd64 crashes inside rxvt_selection_send()

[Yoshiaki Kasahara]

On Fri, 04 Jan 2008 14:55:28 +0100,
	Pav Lucistnik <pav at FreeBSD.org> said:

> Can you verify this does the right thing on both i386 and amd64?

How can I verify that? (How can I satisfy the requirement?)  Actually
I'm not confident about my patch.

I tried to build rxvt-devel on an i386 platform with the patch.  It
seems that it didn't change the behavior of cut & paste.  And at least
I'm sure it doesn't change anything on i386 (because the values before
and after the patch are equivalent), and it prevents crash on amd64.

The 5th argument of XChangeProperty is 'int format', and it only
accepts 8, 16, and 32.

from the manpage of XChangeProperty(3):

       format    Specifies whether the data should be viewed as a list of
                 8-bit, 16-bit, or 32-bit quantities.  Possible values are 8,
                 16, and 32.  This information allows the X server to cor-
                 rectly perform byte-swap operations as necessary.  If the
                 format is 16-bit or 32-bit, you must explicitly cast your
                 data pointer to an (unsigned char *) in the call to XChange-
                 Property.

'Time' is defined in /usr/local/include/X11/X.h as

typedef unsigned long Time;

On i386, sizeof(Time) is 4, so 8*4=32 is a valid input for XChangeProperty.
On amd64, sizeof(Time) is 8, so 8*8=64 is an invalid input for that
(triggers XError).

To tell the truth, I don't know how to pass a 64bit parameter to
XChangeProperty (r->h->selection_time is 64bit on amd64).  So, using
'32' doesn't change the behaviour on i386, but I'm not really sure on
amd64.  Maybe only lower 4 bytes are used (guessed only from the
following description of the manpage)

       prop_return
                 Returns the data in the specified format.  If the returned
                 format is 8, the returned data is represented as a char
                 array. If the returned format is 16, the returned data is
                 represented as a array of short int type and should be cast
                 to that type to obtain the elements. If the returned format
                 is 32, the property data will be stored as an array of longs
                 (which in a 64-bit application will be 64-bit values that are
                 padded in the upper 4 bytes).

Regards,
-- 
Yoshiaki Kasahara
Research Institute for Information Technology, Kyushu University
kasahara at nc.kyushu-u.ac.jp