nativelibc/unlink.c

/*	A part of the Native C Library for Windows NT
	Copyright 2007-2015 PC GO Ld.
	Copyright 2015-2026 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 <errno.h>
#include <fcntl.h>
#include <unistd.h>
#include <pathname.h>
#include <ntstatus.h>

// Can't use read-only pointer...
static int remove_directory(OBJECT_ATTRIBUTES *obj_attr) {
	long int status;
	void *handle;
#ifdef NATIVELIBC_DENY_REMOVE_DIRECTORY_BY_SYMBOLIC_LINK
	status = NtOpenSymbolicLinkObject(&handle, 0, obj_attr);
	if(status != STATUS_OBJECT_TYPE_MISMATCH) {
		// Refuse to operate on a symbolic link even the original path contents a '/' at end
		if(status >= 0 || status == STATUS_ACCESS_DENIED) {
			if(status >= 0) NtClose(handle);
			errno = ENOTDIR;
		} else __set_errno_from_ntstatus(status);
		return -1;
	}
#endif
	status = NtOpenDirectoryObject(&handle, DIRECTORY_QUERY | DELETE, obj_attr);
	//printf("nativelibc debug: rmdir: check is dir object: status = 0x%lx\n", status);
	if(status != STATUS_OBJECT_TYPE_MISMATCH) {
		if(status < 0) {
			__set_errno_from_ntstatus(status);
			return -1;
		}

		unsigned long int context = 0;
		status = NtQueryDirectoryObject(handle, NULL, 0, 0, 1, &context, NULL);
		//printf("nativelibc debug: rmdir: check dir object contents: status = 0x%lx\n", status);
		if(status != STATUS_NO_MORE_ENTRIES) {
			NtClose(handle);
			if(status < 0) __set_errno_from_ntstatus(status);
			else errno = ENOTEMPTY;
			return -1;
		}

		OBJECT_BASIC_INFORMATION obi;
		status = NtQueryObject(handle, ObjectBasicInformation, &obi, sizeof obi, NULL);
		//printf("nativelibc debug: rmdir: check other opens: NtQueryObject status = 0x%lx\n", status);
		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);
		//printf("nativelibc debug: rmdir: remove dir object: status = 0x%lx\n", status);
		NtClose(handle);
		return __set_errno_from_ntstatus(status) ? -1 : 0;
	}

	IO_STATUS_BLOCK io_status;
	unsigned long int file_share = FILE_SHARE_READ | FILE_SHARE_WRITE | FILE_SHARE_DELETE;
	unsigned long int options = FILE_DIRECTORY_FILE | FILE_SYNCHRONOUS_IO_NONALERT | FILE_OPEN_FOR_BACKUP_INTENT;
	status = NtOpenFile(&handle, FILE_LIST_DIRECTORY | DELETE | SYNCHRONIZE, obj_attr, &io_status, file_share, options);
	//printf("nativelibc debug: rmdir: check is dir file: status = 0x%lx\n", status);
	if(status != STATUS_OBJECT_TYPE_MISMATCH) {
		if(status < 0) {
			__set_errno_from_ntstatus(status);
			return -1;
		}

		size_t fni_size = sizeof(FILE_NAMES_INFORMATION) + 2 * sizeof(wchar_t);
		FILE_NAMES_INFORMATION *fni = malloc(fni_size);
		if(!fni) {
			NtClose(handle);
			errno = ENOMEM;
			return -1;
		}
		while(1) {
			status = NtQueryDirectoryFile(handle, NULL, NULL, NULL, &io_status, fni, fni_size, FileNamesInformation, 0, NULL, 0);
			//printf("nativelibc debug: rmdir: check dir file contents: status = 0x%lx\n", status);
			if(status == STATUS_NO_MORE_FILES) break;
			if(status == STATUS_BUFFER_OVERFLOW) goto notempty;
			if(status < 0) {
				free(fni);
				NtClose(handle);
				__set_errno_from_ntstatus(status);
				return -1;
			}
			if(fni->FileNameLength > 2 * sizeof(wchar_t) || fni->FileName[0] != L'.' ||
			   (fni->FileNameLength > sizeof(wchar_t) && fni->FileName[1] != L'.')) {
notempty:
				free(fni);
				NtClose(handle);
				errno = ENOTEMPTY;
				return -1;
			}
		}
		free(fni);

		FILE_DISPOSITION_INFORMATION fdi = { .DeleteFile = 1 };
		status = NtSetInformationFile(handle, &io_status, &fdi, sizeof fdi, FileDispositionInformation);
		//printf("nativelibc debug: rmdir: remove dir file: status = 0x%lx\n", status);
		if(__set_errno_from_ntstatus(NtClose(handle))) return -1;
		return __set_errno_from_ntstatus(status) ? -1 : 0;
	}

	// The pathname exists but is not a directory
	errno = ENOTDIR;
	return -1;
}

// 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 unlinkat(int dir_fd, const char *path, int flags) {
	if(dir_fd == -1) {
		errno = EBADF;
		return -1;
	}
	if(!path) {
		errno = EFAULT;
		return -1;
	}
	if(!*path) {
		errno = ENOENT;
		return -1;
	}
	if(flags & ~AT_REMOVEDIR) {
		errno = EINVAL;
		return -1;
	}

	if(strcmp(path, "/") == 0) {
		// Special case
		errno = EISDIR;
		return -1;
	}

	UNICODE_STRING nt_path;
	RtlCreateUnicodeStringFromAsciiz(&nt_path, path);
	int request_dir = 0;
	if(nt_path.Length > sizeof(wchar_t) && nt_path.Buffer[nt_path.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;
		nt_path.Buffer[nt_path.Length / sizeof(wchar_t) - 1] = 0;
		nt_path.Length -= sizeof(wchar_t);
		nt_path.MaximumLength -= sizeof(wchar_t);
	}
	PATHNAME_UNIX2NT_UTF16_STRUCT(nt_path);
	OBJECT_ATTRIBUTES obj_attr = {
		.Length = sizeof(OBJECT_ATTRIBUTES), .ObjectName = &nt_path
	};
	if(*path != '/') {
		if(dir_fd == AT_FDCWD) {
			RtlFreeUnicodeString(&nt_path);
			errno = EPERM;
			return -1;
		}
		obj_attr.RootDirectory = (void *)dir_fd;
	}

	void *handle;

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

	if(flags & AT_REMOVEDIR) {
		int r = remove_directory(&obj_attr);
		int e = errno;
		RtlFreeUnicodeString(&nt_path);
		errno = e;
		return r;
	}

	long int status = NtOpenDirectoryObject(&handle, 0, &obj_attr);
	//printf("nativelibc debug: unlink: status = 0x%lx\n", status);
	if(status != STATUS_OBJECT_TYPE_MISMATCH) {
		RtlFreeUnicodeString(&nt_path);
#ifdef NATIVELIBC_ALLOW_UNLINK_DIRECTORY
		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, &obj_attr, &io_status, file_share, options);
	RtlFreeUnicodeString(&nt_path);
	if(status < 0) {
		__set_errno_from_ntstatus(status);
		return -1;
	}
	if(request_dir) {
		NtClose(handle);
		errno = ENOTDIR;
		return -1;
	}
	//status = NtDeleteFile(&obj_attr);
	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;
}

int unlink(const char *path) {
	return unlinkat(AT_FDCWD, path, 0);
}