FIX: C0000005 Fatal Error With SET('RELATION') Function (221737)

SYMPTOMS

When repeatedly calling the SET() function and passing the "RELATION" argument, you might see an error similar to the the following:

Fatal error: Exception code=C0000005
Called from - <procedure name and line number> {<path and filename>}

The error may also appear as follows under Windows NT:

An application error has occurred and an application error log is being generated.
VFP6.exe
Exception: access violation (0xc0000005),Address 0x77f6489f

It is possible that use of the SET() function with certain other arguments could also cause this behavior. These are SET('FIELDS'), SET('ORDER'), SET('INDEX'), SET('NOCPTRANS'), and SET('SKIP').

STATUS

Microsoft has confirmed that this is a bug in the Microsoft products that are listed at the beginning of this article.

This bug was corrected in Visual Studio 6.0 Service Pack 3. For more information about Visual Studio service packs, please see the following articles in the Microsoft Knowledge Base:

194022 INFO: Visual Studio 6.0 Service Packs, What, Where, Why

194295 HOWTO: Tell That Visual Studio 6.0 Service Packs Are Installed

MORE INFORMATION

Steps to Reproduce Behavior

Run the following code from a program (.PRG) file:

FOR i = 1 TO 100
   @ 1,1 SAY i PICTURE '999'
   DO Proc1
ENDFOR

RETURN

PROCEDURE Proc1

   DELETE FILE a01.DBF
   DELETE FILE a01.CDX
   DELETE FILE a02.DBF
   DELETE FILE a02.CDX

   CREATE TABLE a01 (f1 c(10),f2 c(10),f3 c(10),f4 c(10))
   INDEX ON f1+f2+f3+f4 TAG f1234

   CREATE TABLE a02 (f1 c(10),f2 c(10),f3 c(10),f4 c(10))
   INDEX ON f1+f2+f3+f4 TAG f1234

   SELECT a02
   SET RELATION TO ;
      SUBS(f1,1,1)+SUBS(f2,2,2)+SUBS(f3,3,3)+SUBS(f4,4,4)+;
      SUBS(f1,5,5)+SUBS(f2,6,6)+SUBS(f3,7,7)+SUBS(f4,8,8) ;
      INTO a01

   * With the following line uncommented no error occurs
   * m.setrel = SPACE(1024)

   m.setrel = SET('RELATION')

   CLOSE DATA

   RETURN
ENDPROC

The error occurs. Allocating a buffer for the variable to which the value is stored will prevent the exception from occurring. You can remove the asterisk from the beginning of the line m.setrel = SPACE(1024) to demonstrate this.