Question

I have a fortran program which calls a C function and opens a file using open()

main.f90:

PROGRAM TEST

    integer                        :: oflag, mode

    !Set oflag to O_CREAT|O_RDWR
    oflag = 66   
    mode = 600 

    call test2("test.txt", oflag, mode)

END PROGRAM

test.c:

#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <sys/types.h>

#pragma weak test2_     = test2
#pragma weak test2__    = test2
#pragma weak TEST2      = test2

void test2(char* filename, int* flag, int* mode)
{
    int fd; 
    if(-1 == (fd = open(filename, *flag, *mode)))
        puts("Returned -1");
}

I compile as:

gcc -c test.c
gfortran main.f90 test.o

When I run the program, it creates the file test.txt, but with incorrect permissions:

---x--x--T 1 xyz users    0 2011-09-24 16:40 test.txt

when it should have been

-rw------- 1 xyz users    0 2011-09-24 16:45 test.txt

If I call this function from another C program, it works fine. Can someone point out what is going wrong?

Specs:
64 bit linux
GNU Fortran (SUSE Linux) 4.5.0, GCC (SUSE Linux) 4.5.0

Thanks,
Kshitij

Answer 1

Your constants are wrong because permissions are typically specified in octal. Try this program:

#include <stdio.h>
#include <fcntl.h>

int main(void)
{
 printf("oflag=%d mode=%d\n", O_CREAT|O_RDWR, S_IRUSR|S_IWUSR);
}

I get:

oflag=66 mode=384

600 octal eqals 384 decimal.