nativelibc/symlink.c

/*	A part of the Native C Library for Windows NT
	Copyright 2007-2015 PC GO Ld.
	Copyright 2026 Rivoreo

	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 <fcntl.h>
#include <errno.h>
#include <pathname.h>

int symlinkat(const char *oldpath, int dir_fd, const char *newpath) {
	if(dir_fd == -1) {
		errno = EBADF;
		return -1;
	}
	if(!oldpath || !newpath) {
		errno = EFAULT;
		return -1;
	}

	void *handle;
	UNICODE_STRING old_path;
	UNICODE_STRING new_path;
	RtlCreateUnicodeStringFromAsciiz(&old_path, oldpath);
	RtlCreateUnicodeStringFromAsciiz(&new_path, newpath);
	if(old_path.Length > sizeof(wchar_t) && old_path.Buffer[old_path.Length / sizeof(wchar_t) - 1] == L'/') {
		old_path.Buffer[old_path.Length / sizeof(wchar_t) - 1] = 0;
		old_path.Length -= sizeof(wchar_t);
		old_path.MaximumLength -= sizeof(wchar_t);
	}
	PATHNAME_UNIX2NT_UTF16_STRUCT(old_path);
	PATHNAME_UNIX2NT_UTF16_STRUCT(new_path);
	OBJECT_ATTRIBUTES new_object_attr = {
		.Length = sizeof(OBJECT_ATTRIBUTES), .ObjectName = &new_path, .Attributes = OBJ_PERMANENT
	};
	if(*newpath != '/') {
		if(dir_fd == AT_FDCWD) {
			RtlFreeUnicodeString(&new_path);
			errno = EPERM;
			return -1;
		}
		new_object_attr.RootDirectory = (void *)dir_fd;
	}
	long int status = NtCreateSymbolicLinkObject(&handle, SYMBOLIC_LINK_ALL_ACCESS, &new_object_attr, &old_path);
	RtlFreeUnicodeString(&old_path);
	RtlFreeUnicodeString(&new_path);
	if(__set_errno_from_ntstatus(status)) return -1;
	if(__set_errno_from_ntstatus(NtClose(handle))) return -1;
	return 0;
}

int symlink(const char *oldpath, const char *newpath) {
	return symlinkat(oldpath, AT_FDCWD, newpath);
}