Local variables broken when debugging .obj files?

[terran 0]

I am debugging a Delphi application, which uses C Object files (.obj).

When enters a function, it shows correct Local variables, but when a step-in, it doesn't show correct Local variables.

Is it a bug?

 

Before entering function:

 

After entering function:

 

Previous function in stack:

 

Actually, ReadProc is assigned to SeekProc, WriteProc to CloseProc, and SeekProc to SizeProc.

 

Function in delphi:

type

  PTIFF = Pointer;
  TIFFReadWriteProc = function(Fd: THandle; Buffer: Pointer; Size: tmsize_t): Integer; cdecl;
  TIFFCloseProc = function(Fd: THandle): Integer; cdecl;
  TIFFSeekProc = function(Fd: THandle; Off: toff_t; Whence: Integer): toff_t; cdecl;
  TIFFSizeProc = function(Fd: THandle): toff_t; cdecl;
  TIFFMapFileProc = function(Fd: THandle; PBase: PPointer; PSize: poff_t): Integer; cdecl;
  TIFFUnmapFileProc = procedure(Fd: THandle; Base: Pointer; Size: toff_t); cdecl;


function _TIFFClientOpenExt(name: PAnsiChar;  mode: PAnsiChar;
                        clientdata: THandle; readproc: TIFFReadWriteProc;
                        writeproc: TIFFReadWriteProc; seekproc: TIFFSeekProc;
                        closeproc: TIFFCloseProc; sizeproc: TIFFSizeProc;
                        mapproc: TIFFMapFileProc; unmapproc:TIFFUnmapFileProc;
                        opts: Pointer): PTIFF; cdecl; external;

 

 

Function in C :

    typedef tmsize_t (*TIFFReadWriteProc)(thandle_t, void *, tmsize_t);
    typedef toff_t (*TIFFSeekProc)(thandle_t, toff_t, int);
    typedef int (*TIFFCloseProc)(thandle_t);
    typedef toff_t (*TIFFSizeProc)(thandle_t);
    typedef int (*TIFFMapFileProc)(thandle_t, void **base, toff_t *size);
    typedef void (*TIFFUnmapFileProc)(thandle_t, void *base, toff_t size);
////////////


TIFF *TIFFClientOpen(const char *name, const char *mode, thandle_t clientdata,
                     TIFFReadWriteProc readproc, TIFFReadWriteProc writeproc,
                     TIFFSeekProc seekproc, TIFFCloseProc closeproc,
                     TIFFSizeProc sizeproc, TIFFMapFileProc mapproc,
                     TIFFUnmapFileProc unmapproc)
{
    return TIFFClientOpenExt(name, mode, clientdata, readproc, writeproc,
                             seekproc, closeproc, sizeproc, mapproc, unmapproc,
                             NULL);
}

TIFF *TIFFClientOpenExt(const char *name, const char *mode,
                        thandle_t clientdata, TIFFReadWriteProc readproc,
                        TIFFReadWriteProc writeproc, TIFFSeekProc seekproc,
                        TIFFCloseProc closeproc, TIFFSizeProc sizeproc,
                        TIFFMapFileProc mapproc, TIFFUnmapFileProc unmapproc,
                        TIFFOpenOptions *opts)

 

Edited May 16, 2023 by terran

[Fr0sT.Brutal 897]

Is the function working well? I'd bet on incorrect parameters porting. 1st guess is differing calling convention but it seems valid

[PeterBelow 225]

10 hours ago, terran said:

When enters a function, it shows correct Local variables, but when a step-in, it doesn't show correct Local variables.

Is it a bug?

The obj files do not contain debug information so the IDE debugger is unable to work fully while the execution is inside code from the obj file.

[David Heffernan 2307]

I didn't even know that Delphi debugger would step into obj files. How did you compile the .obj file? Where is Delphi getting the debug info from?

[terran 0]

I compiled it with bcc32c -tM -tR -Od -v (CMake did it for me).

The object files compiled with the -v switch are twice as big, and of course contain some "debugging information". But it's not exact. 😄

 

No, the code doesn't work.

It is an old LibTiff library. It worked with a (20 years) old .OBJ files with no sources (and no debugging).

I compiled the new object files from .C sources, and with them it doesn't work.

The delphi unit to that library is not so much outdated. But it's not exact. 😄

[Fr0sT.Brutal 897]

What if you try to print arguments from that C function and test at runtime? I too didn't know that Delphi is able to step into OBJ. Probably this feature is buggy

Edited May 17, 2023 by Fr0sT.Brutal

[David Heffernan 2307]

If I were you I'd compile the code into a DLL and link to that. My experience is that works more reliably. I used to do the .obj dance back in the day but moved away from it. Very happy to have done so.