File Size Error under VPIX and PCNFS

[Tillmann A. Basien]

During my work as an autherized SCO reseller I get many problems. On of
my last was, that open access can^t create indexfiles with the correct
size. Some month a go I posted a question to this subject and I got no
answer.
So I analysed the problem with some hand made tools to get the int21 call
list of a dos-application (one day work).
With that tools I found a explanation of the problem.

Is there anybody who can confirm my results ?

Here is the test programm for MSC 5.1:
===============================================================================

#include <stdio.h>
#include <fcntl.h>
#include <io.h>
#include <sys\types.h>
#include <sys\stat.h>
#include <dos.h>
/*****************************************************************************
	TEST PROGRAMM TO DEMONSTRATE A VPIX ANDA PC_NFS ERROR
	
	During my work with VP/ix I got on MS WORD and Open Access two
	identical problems. WORD can't open a spezified file and Open Access
	creates an indexfile with the size of 0 insteed of 512. So I wrote a
	programm to analyse the INT21 calls of the applications. And I found
	the following explanation.
		
	On virtuell drives the DOS-seek(0x42) and DOS-write(0x40) systemcalls
	does not work correctly.
	
	This programms creates a file calles TEST.XX. In this file, which
	actually has the size 0, the programm will go to position 512. 
	Then  0 bytes will be written and the file will be closed.
	On a pure DOS-Drive (C: or D:) the new file has the size of 512 bytes.
	On a network viruell drive or a VP/ix drive the size will be 0.
	
	TB PEM GmbH, 2.April 1991
*/

main()
{
 int fp;
 int rtn;
 long pos;
 union REGS in,out;
 
 /* creat file								*/
 _dos_creat("test.xx",_A_NORMAL,&fp); printf("open: %d\n",fp);

 /* Seek to position 512 behind the actuell EOF position		*/
 in.h.ah=0x42; in.h.al=0x00; in.x.bx=fp; in.x.cx=0; in.x.dx=512;
 intdos(&in,&out);   printf("lseek: %04x:%04x\n",out.x.dx,out.x.ax);

 /* Write 0 Bytes, to fill the 512 bytes infront of EOF			*/
 rtn=_dos_write(fp,&fp,0,0);       printf("write: %d\n",rtn);
 
 /* close the file							*/
 _dos_close(fp);

}
-- 
					             basien at PEM-Stuttgart.de
Dipl.-Ing. Tillmann A. Basien           PEM Programmentwicklungsgesellschaft
Vaihinger Str.49, PostBox 810165                      fuer Microcomputer mbH
FRG 7000 Stuttgart 80             voice: +49-711-713045  fax: +49-711-713047