fcntl(F_DUPFD) sets wrong errno

[dmik]

If you pass an invalid file descriptor to the fcntl(F_DUPFD) call, it will return -1 and set errno to EPERM. This is wrong as according to the specs it should set it to EBADF in such a case (and it does so on *nix).

Here is the test case proving that:

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

int main()
{
    int fd = 100; // must be an invalid fd
    int flags = fcntl(fd, F_GETFL);
    printf ("fcntl(%d,F_GETFL)=%d errno=%d\n", fd, flags, errno);

    int fd2 = fcntl(fd, F_DUPFD, 200);
    printf ("dupfd(%d,200,F_DUPFD)=%d errno=%d\n", fd, fd2, errno);

    return 0;
}

[dmik]

There is at least one known failing case that I had to work around like this: ​http://trac.netlabs.org/ports/changeset/1125.