flexfax: pagesend -- Bug in StackBuffer

[Philippe Vanhaesendonck <philippe.vanhaesendonck@topgame.be>]

- Pardon me if this my exlanations are not always clear, but this is the
first time I looked at C++ code...

- My environment:
    - Hylafax  4.0 pl2
    - gcc: egcs-2.90.29 980515 (egcs-1.0.3 release)
    - Linix 2.0.34
    - Modem Xircom PCMCIA (class 1)

- Problem:
    SIGSEV in pagesend after (successfully) sending ucp page

- Dignostic:
    the problem can be easily reproduced with the following piece of
code:
int
main(int argc, char** argv)
{
    fxStackBuffer tmp;
    fxStackBuffer buf;

    buf.put("azertyuiopazertyuiopazertyuiop");
    tmp.put("azertyuiopazertyuiopazertyuiop");

    buf = tmp;
}

    What's happening? actually, after the 'buf = tmp', we have
        buf.buf contains the same value than tmp.buf
        buf.base == tmp.base  == tmp.buf
    so the destructor for fxStackBuffer tries free() something which
cannot be freed (tmp.buf) --look at  StackBuffer.c++ /
fxStackBuffer::~fxStackBuffer()

Solution: the following pagesend hack fixes the problem (note that this
piece of code only impacts UCP pagers):

-- Phil.

*** pageSendApp.c++.ori Sat Feb 14 11:49:44 1998
--- pageSendApp.c++     Sat Jul 25 23:10:16 1998
***************
*** 1069,1075 ****
      addUcpChecksum(tmp);      // append packet checksum
      tmp.put("\x03");

!     buf = tmp;

      /*
       * Send the packet to paging central.
--- 1069,1078 ----
      addUcpChecksum(tmp);      // append packet checksum
      tmp.put("\x03");

!     // buf = tmp;
!     // this gives problem with the destroy :-) VHD
!     buf.reset();              // VHD
!     buf.put(tmp);             // VHD

      /*
       * Send the packet to paging central.