CODEWITHSUNDEEP
fortranintel-fortran
user7698505
user7698505

Reputation:

Error when running Fortran program (forrtl: severe (157): Program Exception - access violation)

I have a C program that has a function named get_name. This function returns a string (i.e. char *) and changes the argument size (passed to it) with the size of the string:

char *get_name(int &size)
{
     *size = strlen(name);   // name is a C global variable declared as a char *
     return name;
}

I have created the following Fortran module to be able to call the C function get_name:

MODULE X

    USE, INTRINSIC :: iso_c_binding, ONLY: c_intptr_t

    IMPLICIT NONE

    INTERFACE

        TYPE(c_ptr) FUNCTION get_name_(size) BIND(C, name = "get_name")
            USE, INTRINSIC :: iso_c_binding, ONLY: c_int, c_ptr
            INTEGER(c_int), INTENT(OUT) :: size
        END FUNCTION

    END INTERFACE

    CONTAINS

        FUNCTION get_name()
            USE, INTRINSIC :: iso_c_binding, ONLY: c_int, c_char, c_f_pointer, c_ptr, c_associated
            !DEC$ ATTRIBUTES DLLEXPORT :: get_name
            CHARACTER(LEN = :), ALLOCATABLE :: get_name
            INTEGER(c_int) :: size
            TYPE(c_ptr) :: c_string

            c_string = get_name_(size)

            IF (c_associated(c_string)) THEN
                BLOCK
                    CHARACTER(KIND = c_char, LEN = size), POINTER :: f_string
                    CALL c_f_pointer(c_string, f_string)
                    get_name = f_string
                END BLOCK
            ELSE
                get_name = ""
            END IF

        END FUNCTION

END MODULE

I can successfully compile this Fortran module using IFORT 2016 in Windows, IFORT 2016 in Linux, and gfortran in Linux.

To test things, I have created a short Fortran program:

PROGRAM Test

    USE X

    WRITE(*, *) "Name: ", get_name()

END PROGRAM

I can successfully compile this Fortran program using IFORT 2016 in Windows, IFORT 2016 in Linux, and gfortran in Linux.

Now, when running the program it works well in IFORT 2016 for Linux, gfortran in Linux, but not in IFORT 2016 for Windows. It actually gives the following error:

 forrtl: severe (157): Program Exception - access violation

Any idea how this error can be solved?

Upvotes: 0

Views: 1361

Answers (1)

bbu
bbu

Reputation: 782

I assume your C function is char *get_name(int *size) instead of using a C++ reference.

Then this code works here on Windows and Linux with Ifort 16 and gcc-6.3.1 or Visual Studio 2015.

Please add your used C compiler and command lines to compile the code. I used:

cl -c testc.c && ifort -c testf.f /extend-source:132 && ifort testm.f testf.obj testc.obj /extend-source:132 && testm.exe

Btw: If you are using this function in parallel code I would suggest to avoid the block construct - I had bad experience using this in parallel (OpenMP) code with Ifort 16.

Upvotes: 2

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