Question

When I attempt to overwrite an existing file, I get a “permission denied” error.
I noticed that the file which is created has the “Read-only” attribute set. When I manually unset this I can then overwrite the file. Is there some flag I can pass to open() which will automatically unset this when I create a file?

Below is a bare bones example which illustrates the problem. The first run works, but the second produces the “permission denied” error.

Thanks,
Zach (New to MingW/Windows 7)

#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <fcntl.h>
#include <errno.h>

int main(int argc, char ** argv) {
    int fid;
    double data = 12.0;

    if ( (fid = open("junk.data", O_WRONLY | O_CREAT | O_BINARY)) == -1 ) {
        printf("ERROR opening.\n\terror is:%s\n", strerror(errno));
        return 1;
    }

    write(fid, &data, sizeof(double));

    close(fid);

    return 0;
}

Answer 1

I tried both 0644 and S_IRUSR | S_IWUSR (with sys/stat.h included) and either works.

Make sure that you actually add it as third argument of open, instead as new term into the surrounding parentheses (as happened for me first, and compiles just fine)