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Q63782: "Permission Denied" If SHELL to 7.00 .EXE Using ISAM from TSR

Article: Q63782
Product(s): See article
Version(s): 7.00 7.10
Operating System(s): MS-DOS
Keyword(s): ENDUSER | SR# S900702-42 buglist7.00 buglist7.10 | mspl13_basic
Last Modified: 2-NOV-1990

If you SHELL from one program that uses ISAM to another ISAM program
that uses the PROISAM.EXE or PROISAMD.EXE terminate-and-stay-resident
(TSR) program, a "Permission Denied" error occurs when the OPEN
statement is executed in the child (SHELLed) process (see Example 2
below). This problem does not occur when ISAM support is linked into
the .EXE programs instead of using the TSR program.

Microsoft has confirmed this to be a problem in Microsoft BASIC
Professional Development System (PDS) versions 7.00 and 7.10. We are
researching this problem and will post new information here as it
becomes available.

To work around this problem, use a CHAIN statement instead of SHELL,
or LINK ISAM support to your .EXE instead of using the ISAM TSR
program.

In addition, SHELLing to the ISAM utilities (ISAMIO.EXE, ISAMCVT.EXE,
ISAMREPR.EXE, or ISAMPACK.EXE) may generate unusual error messages,
because they are not designed to be SHELLed; this is not a software
problem but is a design limitation. For example, ISAMPACK.EXE fails
with the message "Unknown error number." A workaround is shown below
in Example 1.

Note that the SETUP.EXE program for BASIC PDS 7.00 and 7.10 lets you
choose one of the following four ISAM support options for compiled
.EXE programs:

1. ISAM Routines in TSR
2. ISAM Routines in LIB, Support Database Creation and Access
3. ISAM Routines in LIB, Support Database Access Only
4. No ISAM support

Only Option 1 creates PROISAM.EXE and PROISAMD.EXE TSR programs that
can be used with BASIC compiled .EXE programs. The TSR program created
in Option 1 can also be used in QBX.EXE. Options 2 and 3 create
PROISAM.EXE and PROISAMD.EXE TSR programs that CANNOT be used in
compiled .EXE programs, and that can only be used by QBX.EXE and the
ISAM utilities (ISAMIO.EXE, ISAMCVT.EXE, ISAMREPR.EXE, and
ISAMPACK.EXE). Options 2 and 3 create .LIB libraries for linking ISAM
support into your .EXE programs. The fourth SETUP option does not copy
any ISAM-related files onto your computer.

A problem occurs whenever a SHELLed (child) process attempts to access
the PROISAM or PROISAMD TSR program. Specifically, the problem occurs
when you SHELL to an ISAM utility (which requires the TSR program --
see Example 1), or SHELL to a BASIC .EXE program that requires the
ISAM TSR (see Example 2).

Example 1
---------

Because the ISAM utilities (ISAMIO.EXE, ISAMCVT.EXE, ISAMREPR.EXE, or
ISAMPACK.EXE) require the ISAM TSR program, the best way to work
around the SHELLing problem is to link the BASIC .EXE (the parent
process that executes the SHELL) to the ISAM .LIB, and then SHELL to
an MS-DOS batch (.BAT) file that loads the TSR program, executes the
ISAM utility, and then unloads the TSR program. The following is an
example of this type of batch file:

   REM  Start PACK.BAT
      PROISAMD
      ISAMPACK isamfile.dat
      PROISAMD /D
   REM  End PACK.BAT

Example 2
---------

The following program (when SHELLed to itself or any other program
that OPENs any ISAM file) will cause a "Permission Denied" error in
the SHELLed copy:

   ' ISAMTEST.BAS
   TYPE test
     x AS INTEGER
   END TYPE
   OPEN "test" FOR ISAM test "test" as #1
   CLOSE #1
   INPUT "Do you want to shell?", a$
   IF a$="Y" THEN SHELL "ISAMTEST"    ' Put the name of this .EXE here.
   END

Compile and link this program as follows:

   BC ISAMTEST.BAS;   (BC compile options don't affect the problem)
   LINK ISAMTEST;

To duplicate the problem, run the PROISAM.EXE or PROISAMD.EXE TSR
program, then run the above program. To work around the problem, link
ISAM support to the program instead of using the ISAM TSR program, or
use CHAIN instead of SHELL.

Note that if you chose the "ISAM routines in TSR" option during
SETUP.EXE and also retained component files during SETUP.EXE, there is
a special way to LINK ISAM support into your stand-alone .EXE program,
as described in a separate article, which can be found by using the
following query in this Knowledge Base:

   LINK and ISAM and component and even and SETUP and TSR

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