Q61872: DosDevIOCtl() Category 5 Subfunction 66H Fails with C 6.00 API

Article: Q61872
Product(s): See article
Version(s): 6.00 6.00a | 6.00 6.00a
Operating System(s): MS-DOS | OS/2
Keyword(s): ENDUSER | buglist6.00 buglist6.00a | mspl13_c
Last Modified: 19-JAN-1991

The DOS version of DosDevIOCtl() Category 5 Subfunction 66H, found in
the API.LIB shipped with Microsoft C version 6.00, fails in native
DOS. The failure consists of returning an invalid printer status byte,
regardless of the printer's current status.

The DosDevIOCtl() function is used to determine printer status.
Although the function seems to work correctly when used from either
OS/2 or the DOS compatibility box of OS/2, it fails when run from
native DOS. When called, this function sets the value pointed to by
its first parameter to a status byte whose bits have the following
significance.

   Bit(s)  Significance (if set)
   ------  ---------------------

   0       Timed Out
   1-2     Reserved
   3       I/O error
   4       Printer selected
   5       Out of paper
   6       Acknowledge
   7       Printer not busy

The failure of this function results in a status byte value of 2 being
returned from the function regardless of the printer's status. This is
particularly bad because 2 is not even a valid return value for this
function. If the Microsoft C version 5.10 API.LIB is used, the
function works correctly, returning a status of 144 if the printer is
ready and 24 if the printer is off line. The only known workaround is
to use the earlier version of the library for this function call.

To reproduce the problem, create a bound version of the following
program using the C 6.00 API.LIB and run it on a computer physically
connected to a printer under native DOS:

Sample Code
-----------

#define INCL_DOSDEVICES
#define INCL_DOSFILEMGR
#include<os2.h>
#include<stdio.h>

void main(void)
{
 int handle;
 unsigned char pfstat,x=0;
 unsigned short actiontaken;
 unsigned short p;

 p=DosOpen("lpt1",&handle,&actiontaken,0l,0,0x0001,0x0041,0l);
 p=DosDevIOCtl(&pfstat,&x,0x0066,0x0005,handle);

 printf("pfstat=%d \n",(int)pfstat);

}

Microsoft has confirmed this to be a problem with C versions 6.00 and
6.00a. We are researching the problem and will post new information
here as it becomes available.

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