On Wed, Jun 1, 2022 at 6:11 AM Rony G. Flatscher <[email protected]>
wrote:
> While debugging orexxole.cpp I am using the existing function
> pszDbgVarType(vt) which returns a pointer to a zero terminated string which
> gets defined for the entire program as CHAR szDbg[255]. The same buffer is
> used by pszDbgInvKind(), pszDbgTypekind(), pszDbgParmFlags() and
> pszDbVariant(). With the exception of pszDbgVarType() these debug functions
> are there but not used AFAICT.
>
> It allows to get a human readable string of the type 'vt' represents, e.g.
> "VT_ARRAY VT_VARIANT", "VT_R8" and the like.
>
> The strange observation is using pszDbgVarType() multiple times in a
> single debug statement like:
>
> if (*pDestVt & VT_ARRAY) // an array in hand
> {
> VARTYPE tmpVt = *pDestVt & VT_TYPEMASK;
> *fprintf(stderr, "orexxole.cpp # %d %s: --- b) VT_ARRAY: type=[%s]
> *pDestVt=[%s][d=%d][x%08x] %s tmpVt=[%s][d=%d][x%08x] |
> VT_ARRAY=[%s][d=%d][x%08x], VT_R8=[%s][d=%d][x%08x] \n\n",** __LINE__,
> __FUNCTION__,** "VT_ARRAY",** pszDbgVarType( *pDestVt ),
> *pDestVt , *pDestVt,** " /\\ ",** pszDbgVarType( tmpVt ),
> tmpVt , tmpVt,** pszDbgVarType(VT_ARRAY), VT_ARRAY, VT_ARRAY,**
> pszDbgVarType(VT_R8), VT_R8, VT_R8** );* }
>
> So there are four invocations of pszDbgVarType() with four different
> variables. The ouput is surprisingly:
>
> ... cut ...
> oorexxole.cpp # 419 pszDbgVarType, vt: d=[5] [x00000005] -> szDbg=[VT_R8]
> (return value)
> oorexxole.cpp # 419 pszDbgVarType, vt: d=[0] [x00000000] -> szDbg=[VT_ARRAY
> VT_EMPTY] (return value)
> oorexxole.cpp # 419 pszDbgVarType, vt: d=[5] [x00000005] -> szDbg=[VT_R8]
> (return value)
> oorexxole.cpp # 419 pszDbgVarType, vt: d=[5] [x00000005] -> szDbg=[VT_ARRAY
> VT_R8] (return value)
> (added linebreaks for better legibility):*orexxole.cpp # 4359
> checkForOverride: --- b) VT_ARRAY: type=[VT_ARRAY]
> *pDestVt=[VT_ARRAY VT_R8][d=8197][x00002005] /\
> tmpVt=[VT_ARRAY* *VT_R8][d=5][x00000005] |
> VT_ARRAY=[VT_ARRAY VT_R8][d=8192][x00002000],
> VT_R8=[VT_ARRAY VT_R8][d=5][x00000005]*
>
> Line # 419 above is a debug statement in pszDbgVarType() displaying the
> value it returns. It uses strcat() with the szDbg buffer which upon entry
> in this function sets element 0 to 0.
>
> VT_ARRAY has the decimal value 8192 (x2000), VT_R8 the decimal value 5
> (x0005), hence the following should be shown:
>
> pszDbgVarType(*pDestVt): "VT_ARRAY VT_R8"
> pszDbgVarType(tmpVt) : "VT_R8" (VT_TYPEMASK is defined as xFFF)
> pszDbgVarType(VT_ARRAY): "VT_ARRAY"
> pszDbgVarType(VT_R8) : "VT_R8"
>
> It is as if for some of those invocations of pszDbvVarType the wrong
> buffer gets returned, hence displaying wrong information.
>
Well, if the buffer gets reused, then each invocation is going to overlay
the information from the previous call, so fprintf() will be using the
information from the last call when it formats.
Of course, having spent an enormeous amount of time debugging I might have
> arrived at a point where I overlook the obvious, hence this posting
> requesting comments.
>
> ---rony
>
> P.S.: Contemplating to change the pszDbg...() functions to force a buffer
> to be supplied rather than using a single global buffer, noticing that at
> least pszDbgVarType() gets also used by orexxole.cpp. This way no wrong
> optimizations should be applicable and also multithreaded usage of
> oorexxole.cpp would be improved.
>
Just make sure the allocated buffer gets released afterwards. This change
is likely to be an incredible pain to accomplish.
Rick
>
> _______________________________________________
> Oorexx-devel mailing list
> [email protected]
> https://lists.sourceforge.net/lists/listinfo/oorexx-devel
>
_______________________________________________
Oorexx-devel mailing list
[email protected]
https://lists.sourceforge.net/lists/listinfo/oorexx-devel
