nativelibc/posix-io/dup.c

/*	A part of the Native C Library for Windows NT
	Copyright 2007-2015 PC GO Ld.

	This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version.

	This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
*/

#include <windows.h>
#include <nt.h>
#include <errno.h>
#include <unistd.h>

int dup(int oldfd) {
	int real_fd;
	void *r;
	switch(oldfd) {
		case STDOUT_FILENO:
			real_fd = _get_stdout_fd();
			break;
		case STDERR_FILENO:
			real_fd = _get_stderr_fd();
			break;
		default:
			real_fd = oldfd;
			goto action;
	}
	switch(real_fd) {
		case TTY_FD_INVALID:
			errno = EBADF;
			return -1;
		case TTY_FD_DEFAULT:
			errno = EPERM;
			return -1;
	}
action:	;
	long int status = NtDuplicateObject((void *)-1, (void *)real_fd, (void *)-1, &r, 0, 0, DUPLICATE_SAME_ATTRIBUTES | DUPLICATE_SAME_ACCESS);
	return __set_errno_from_ntstatus(status) ? -1 : (int)r;
}