Q32217: Using B_OnExit Across a CHAIN Hangs System; Compiled BASIC

Article: Q32217
Product(s): See article
Version(s): 6.00 6.00b 7.00 | 6.00 6.00b 7.00
Operating System(s): MS-DOS | OS/2
Keyword(s): ENDUSER | buglist6.00 buglist6.00b buglist7.00 B_QuickBas | mspl13_basic
Last Modified: 17-JAN-1990

Chaining to and from programs that use B_OnExit causes the system to
hang.

Microsoft has confirmed this to be a problem in Microsoft QuickBASIC
Versions 4.00 and 4.00b (buglist4.00, buglist4.00b), in Microsoft
BASIC Compiler Version 6.00 and 6.00b for MS-DOS and MS OS/2, and in
Microsoft BASIC Professional Development System (PDS) Version 7.00 for
MS-DOS and MS OS/2. We are researching this problem and will post new
information here as it becomes available.

Please note that the B_OnExit routine is documented on Pages 319-321
of the "Microsoft QuickBASIC 4.0: Learning and Using" manual for
Microsoft QuickBASIC Versions 4.00 and 4.00b (this is the same manual
for Microsoft BASIC Compiler Versions 6.00 and 6.00b), and in the
"Microsoft BASIC 7.0: Programmer's Guide" on Pages 474-475.

The following steps reproduce the problem using source code provided
farther below:

1. Use the following software to reproduce the problem:

   a. Microsoft QuickBASIC Versions 4.00, 4.00b, Microsoft BASIC
      Compiler Version 6.00 or 6.00b, or Microsoft BASIC PDS Version
      7.00.

   b. Microsoft C Compiler Version 5.10

2. Type the following command lines:

      BC BUGTEST.BAS;
      BC BUGNEXT.BAS;
      CL /c /AM BUGC.C
      LINK /NOE BUGTEST+BUGC;
      LINK /NOE BUGNEXT+BUGC;

3. Run BUGTEST.EXE from the DOS prompt.

4. At the "CHAIN Y/N?" prompt, type Y.

The system locks up when BUGNEXT exits.

Please note the following:

1. You must link BUGC.OBJ with BUGNEXT.OBJ even though it is not
   called.

2. Both programs apparently run correctly until you exit BUGNEXT.

Code Example
------------

'BUGTEST.BAS

        DECLARE SUB IntProc CDECL
        DEFINT A-Z
        PRINT "[***** ENTRY TO MAIN  *****]"
        CALL InProc
        INPUT "CHAIN Y/N";T$
        IF T$="Y" OR T$="y" THEN
           CHAIN "BUGNEXT.EXE"
        END IF
        SYSTEM
        END

'BUGNEXT.BAS

        DEFINT A-Z
        PRINT "[***** CHAIN *****]"
        SYSTEM
        END

/* BUGC.C */

#include <malloc.h>
extern pascal far B_OnExit();  /* Declare the routine */

void IntProc()
{
  void TermProc();             /* Declare TermProc routine */
  printf ("\nIn the C IntProc routine\n");
  B_OnExit(TermProc);          /* Log termination routine with BASIC */
}

void TermProc()                         /* The TermProc function is */
{                                       /* called before any restarting */
  printf ("\nIn C TermProc routine\n"); /* or termination of the program. */
}

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