nativelibc/unlink.c

/*	A part of the Native C Library for Windows NT
	Copyright 2007-2015 PC GO Ld.
	Copyright 2015-2017 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 <errno.h>
#include <fcntl.h>
#include <unistd.h>
#include <pathname.h>
#include <ntstatus.h>

// Handle will be closed
static int unlink_object(void *handle) {
	OBJECT_BASIC_INFORMATION obi;
	long int status = NtQueryObject(handle, ObjectBasicInformation, &obi, sizeof obi, NULL);
	if(status < 0) {
		NtClose(handle);
		__set_errno_from_ntstatus(status);
		return -1;
	}
	if(obi.HandleCount > 1) {
		NtClose(handle);
		errno = EBUSY;
		return -1;
	}
	status = NtMakeTemporaryObject(handle);
	long int close_status = NtClose(handle);
	if(status < 0) {
		__set_errno_from_ntstatus(status);
		return -1;
	}
	if(close_status < 0) {
		__set_errno_from_ntstatus(close_status);
		return -1;
	}
	return 0;
}

int unlink(const char *name) {
	if(!name) {
		errno = EFAULT;
		return -1;
	}
	if(!*name) {
		errno = ENOENT;
		return -1;
	}

	if(*name != '/') {
		errno = ENOSYS;
		return -1;
	}

	if(!name[1]) {
#ifdef _ALLOW_UNLINK_DIRECTORIES
		errno = EBUSY;
#else
		errno = EPERM;
#endif
		return -1;
	}

	UNICODE_STRING name1;
	RtlCreateUnicodeStringFromAsciiz(&name1, name);
	int request_dir = 0;
	if(name1.Length > sizeof(wchar_t) && name1.Buffer[name1.Length / sizeof(wchar_t) - 1] == L'/') {
		// This function may not allow unlinking of a directory and will fail anyways; just continue for setting errno.
		request_dir = 1;
		name1.Buffer[name1.Length / sizeof(wchar_t) - 1] = 0;
		name1.Length -= sizeof(wchar_t);
		name1.MaximumLength -= sizeof(wchar_t);
	}
	PATHNAME_UNIX2NT_UTF16_STRUCT(name1);
	OBJECT_ATTRIBUTES o = { sizeof(OBJECT_ATTRIBUTES), NULL, &name1, 0, NULL, NULL };
	void *handle;

	if(!request_dir) {
		long int status = NtOpenSymbolicLinkObject(&handle, DELETE, &o);
		//printf("nativelibc debug: unlink: status = 0x%lx\n", status);
		if(status != STATUS_OBJECT_TYPE_MISMATCH) {
			RtlFreeUnicodeString(&name1);
			if(status < 0) {
				__set_errno_from_ntstatus(status);
				return -1;
			}
			return unlink_object(handle);
		}
	}

	long int status = NtOpenDirectoryObject(&handle, 0, &o);
	//printf("nativelibc debug: unlink: status = 0x%lx\n", status);
	if(status != STATUS_OBJECT_TYPE_MISMATCH) {
		RtlFreeUnicodeString(&name1);
#ifdef _ALLOW_UNLINK_DIRECTORIES
		if(status < 0) __set_errno_from_ntstatus(status);
		else return unlink_object(handle);
#else
		if(status >= 0 || status == STATUS_ACCESS_DENIED) {
			if(status >= 0) NtClose(handle);
			errno = EPERM;
		} else __set_errno_from_ntstatus(status);
#endif
		return -1;
	}

	IO_STATUS_BLOCK io_status;
	unsigned long int file_share = FILE_SHARE_READ | FILE_SHARE_WRITE | FILE_SHARE_DELETE;
	unsigned long int options = FILE_NON_DIRECTORY_FILE | FILE_SYNCHRONOUS_IO_NONALERT | FILE_OPEN_FOR_BACKUP_INTENT;
	status = NtOpenFile(&handle, DELETE | SYNCHRONIZE, &o, &io_status, file_share, options);
	RtlFreeUnicodeString(&name1);
	if(status < 0) {
		__set_errno_from_ntstatus(status);
		return -1;
	}
	if(request_dir) {
		NtClose(handle);
		errno = ENOTDIR;
		return -1;
	}
	//status = NtDeleteFile(&o);
	FILE_DISPOSITION_INFORMATION fdi;
	fdi.DeleteFile = 1;
	status = NtSetInformationFile(handle, &io_status, &fdi, sizeof fdi, FileDispositionInformation);
	if(__set_errno_from_ntstatus(NtClose(handle))) return -1;
	return __set_errno_from_ntstatus(status) ? -1 : 0;
}