FORTRAN calling a C dll which in turn calls another FORTRAN dll

Question

First a disclaimer that I am not an expert in interoperability between C and FORTRAN.

I have my main program in FORTRAN (GNU FORTRAN compiler). It needs to call a C dll for some calculations. However, the C dll needs to call another 3rd party dll which is written in FORTRAN. So basically the line of calls is:

Main FORTRAN Program --> C dll --> 3rd party FORTRAN dll.

I am not able to get this to work at all. I am not able to get any more debug information. The only error I see is "Program received signal SIGSEGV, Segmentation fault."

The Main FORTRAN --> C dll works fine. I tested by commenting the call to the FORTRAN dll.

I further did the following:

Test Program C++ --> C dll --> 3rd party FORTRAN dll.

The above case works perfectly fine. So it forces me to conclude that the error is due to the calling sequence from FORTRAN --> C --> FORTRAN

My question is, is there any special consideration for such a calling sequence?

Thanks for the help.

Regards, snkp

Edit: Problem Code

Fortran part

!Interface declaration

INTERFACE

  SUBROUTINE SetupProgram(Num,NumComponents,ComponentConc,ConcPhase,ErrNum,Name,hr,herr,hfm)BIND(C,NAME='SetupProgram')

      USE ISO_C_BINDING

      INTEGER(kind=C_LONG), VALUE   :: Num
      INTEGER(kind=C_LONG)          :: NumComponents
      REAL(kind=C_DOUBLE),DIMENSION(20)  :: ComponentConc
      INTEGER(kind=C_LONG)          :: ConcPhase
      INTEGER(kind=C_LONG)          :: ErrNum
      CHARACTER(kind=C_CHAR),DIMENSION(20) :: Name
      CHARACTER(kind=C_CHAR) :: hr
      CHARACTER(kind=C_CHAR) :: herr
      CHARACTER(kind=C_CHAR) :: hfm
   END SUBROUTINE

END INTERFACE

!Main Fortran

PROGRAM Simulator

  USE iso_c_binding, ONLY : c_ptr,c_double,c_f_pointer,C_INT,C_LOC,C_CHAR,C_NULL_CHAR

      INTEGER(kind=C_INT) ID !ID
      INTEGER(kind=C_LONG)  :: NumComponents
      REAL, DIMENSION(20)  :: ComponentConc
      INTEGER(kind=C_LONG)          :: CompositionPhase
      INTEGER(kind=C_LONG)          :: ErrNum
      CHARACTER(kind=C_CHAR,LEN=3) :: hr1 = ''
      CHARACTER(kind=C_CHAR,LEN=255) :: herr1 = ''
      CHARACTER(kind=C_CHAR,LEN=255),DIMENSION(20) :: Name1 = ''
      CHARACTER(kind=C_CHAR,LEN=255) :: hfm1 = ''

      CALL SetupProgram(ID,NumComponents,ComponentConc,CompositionPhase,ErrNum,Name1,hr1,herr1,hfm1)

END PROGRAM

C Part

    //Header File
#ifdef BUILD_DLL
    #define DLL_EXPORT __declspec(dllexport)
#else
    #define DLL_IMPORT __declspec(dllimport)
#endif

//#ifdef __cplusplus
extern "C"
{
//#endif

void DLL_EXPORT __cdecl SetupProgram(int Num,long& NumComponents,double ComponentConc[],long& ConcPhase,long& ErrNum,
                                     char* Name,char hr[],char herr[],char hfm[]);
}
typedef void (__stdcall *fp_SETUPdllTYPE)(long &,char*,char*,char*,long &,char*,long ,long ,long ,long );  //char
extern fp_SETUPdllTYPE SETUPdll;

const long propcharlength=255;
const long lengthofreference=3;
const long errormessagelength=255;
const long nmax=20;

//cpp file
fp_SETUPdllTYPE SETUPdll;

void DLL_EXPORT __cdecl SetupProgram(int Num,long& NumComponents,double ComponentConc[],long& ConcPhase,long& ErrNum,
                                     char* Name,char hr[],char herr[],char hfm[]);
{
 strcpy(hfm,"123.abc");
 strcpy(hr,"DEF");
 strcpy(herr,"OK");

 switch (Num){

  case 1:
    NumComponents = 1;
    strcpy(Name,"123.abc");
    ComponentConc[0]=1.0;
    ConcPhase = 1;
    break;
  case 2:
    NumComponents = 1;
    strcpy(Name,"321.cba");
    ComponentConc[0]=1.0;
    ConcPhase = 1;
    break;
  case R410A:
    NumComponents = 3;
    strcpy(Name,"12.abc");
    strcat(Name,"|34.abc");
    strcat(Name,"|56.dca");
    ComponentConc[0] = 0.6;
    ComponentConc[1] = 0.4;
    ComponentConc[2] = 0.0;
    ConcPhase = 1;
    break;
  default:
    NumComponents = 1;
    strcpy(Name,"321.cba;
    ComponentConc[0]=1.0;
    ConcPhase = 1;
    break;
}

    SETUPdll(NumComponents, Name,
         hfm, hr, ErrNum, herr,
         propcharlength*nmax, propcharlength,
         lengthofreference, errormessagelength);

}

When I comment out the SETUPdll call from the cpp file then FORTRAN calls the c++ dll correctly and gets all the character and long variables. As soon as I uncomment the SETUPdll call the program is not successful anymore.

I hope this helps.

Regards snkp