/********************************************************/
/*  ntapi: Native API core library                      */
/*  Copyright (C) 2013--2021  SysDeer Technologies, LLC */
/*  Released under GPLv2 and GPLv3; see COPYING.NTAPI.  */
/********************************************************/

#include <ntapi/ntapi.h>
#include <ntapi/nt_fsctl.h>
#include <ntapi/nt_mount.h>
#include <ntapi/nt_statfs.h>
#include "ntapi_impl.h"

int32_t __stdcall __ntapi_tt_statfs(
	__in	void *			hfile,
	__out	nt_statfs *		statfs,
	__in	uint32_t		infolen,
	__out	uintptr_t *		buffer,
	__in	uint32_t		buffer_size,
	__in	uint32_t		flags)
{
	int32_t			status;
	nt_iosb			iosb;
	nt_unicode_string *	sdev;
	wchar16_t *		wch;
	wchar16_t *		wch_mark;
	wchar16_t *		wch_cap;
	uint32_t		offset;
	uint32_t		hash;
	void *			mnt_points_buffer;
	nt_mount_points *	mnt_points;
	nt_fsai *		fsai;
	nt_fsfsi *		fsfsi;
	uint32_t *		fsid;
	uint64_t *		pguid;
	uint32_t		written;

	/* validation */
	if (infolen < sizeof(*statfs))
		return NT_STATUS_INFO_LENGTH_MISMATCH;

	/* init */
	__ntapi->tt_aligned_block_memset(
		statfs,0,sizeof(*statfs));

	statfs->hfile           = hfile;
	statfs->dev_name_maxlen = (uint16_t)infolen - sizeof(*statfs);

	/* sigh */
	if (buffer_size >= 65536)
		buffer_size = 65535;

	/* maximum component length, file system type */
	if ((status = __ntapi->zw_query_volume_information_file(
			hfile,
			&iosb,
			buffer,
			buffer_size,
			NT_FILE_FS_ATTRIBUTE_INFORMATION)))
		return status;

	fsai = (nt_fsai *)buffer;
	statfs->f_type    = 0;
	statfs->f_namelen = fsai->maximum_component_name_length;

	statfs->nt_fstype_hash = __ntapi->tt_buffer_crc32(
		0,&fsai->file_system_name,
		fsai->file_system_name_length);

	/* max files per volume */
	switch (statfs->nt_fstype_hash) {
		case NT_FS_TYPE_HPFS_NAME_HASH:
		case NT_FS_TYPE_NTFS_NAME_HASH:
		case NT_FS_TYPE_SMB_NAME_HASH:
		case NT_FS_TYPE_UDF_NAME_HASH:
			statfs->f_files = 0xFFFFFFFF;
			break;

		case NT_FS_TYPE_FAT16_NAME_HASH:
			statfs->f_files = 0x10000;
			break;

		case NT_FS_TYPE_FAT32_NAME_HASH:
			statfs->f_files = 0x400000;
			break;

		default:
			/* pretend there is no limitation */
			statfs->f_files = (uint64_t)(-1);
			break;
	}

	/* number of free file records on volume */
	/* (skip, yet indicate that the volume is not empty) */
	statfs->f_ffree = (size_t)statfs->f_files >> 4 << 3;

	/* file system size information */
	if ((status = __ntapi->zw_query_volume_information_file(
			hfile,
			&iosb,
			buffer,
			buffer_size,
			NT_FILE_FS_FULL_SIZE_INFORMATION)))
		return status;

	fsfsi            = (nt_fsfsi *)buffer;
	statfs->f_blocks = fsfsi->total_allocation_units.quad;
	statfs->f_bfree  = fsfsi->actual_available_allocation_units.quad;
	statfs->f_bavail = fsfsi->caller_available_allocation_units.quad;
	statfs->f_bsize  = fsfsi->sectors_per_allocation_unit * fsfsi->bytes_per_sector;
	statfs->f_frsize = fsfsi->bytes_per_sector;

	/* system-unique device name */
	if ((status = __ntapi->zw_query_object(
			hfile,
			NT_OBJECT_NAME_INFORMATION,
			buffer,
			buffer_size,
			&written)))
		return status;

	sdev = (nt_unicode_string *)buffer;
	wch  = sdev->buffer;

	if (sdev->strlen < __DEVICE_PATH_PREFIX_LEN)
		return NT_STATUS_NOT_SUPPORTED;

	if ((wch[0] != '\\')
			|| (wch[1] != 'D')
			|| (wch[2] != 'e')
			|| (wch[3] != 'v')
			|| (wch[4] != 'i')
			|| (wch[5] != 'c')
			|| (wch[6] != 'e')
			|| (wch[7] != '\\'))
		return NT_STATUS_NOT_SUPPORTED;

	if (sdev->strlen < __DEVICE_MUP_PREFIX_LEN)
		return NT_STATUS_INVALID_HANDLE;

	if ((wch[8]=='M')
			&& (wch[9]=='u')
			&& (wch[10]=='p')
			&& (wch[11]=='\\')) {
		statfs->nt_drive_letter = 0;
		hash = __DEVICE_MUP_PREFIX_HASH;
		flags &= ~NT_STATFS_VOLUME_GUID;
		statfs->flags |= NT_STATFS_MUP_DEVICE;

		wch_mark = &wch[12];
		wch      = wch_mark;

		for (; *wch!='\\'; )
			wch++;
		wch++;
	} else {
		wch_mark = &wch[8];
		wch      = wch_mark;
		hash = __DEVICE_PATH_PREFIX_HASH;
	}

	wch_cap = sdev->buffer + (sdev->strlen / sizeof(wchar16_t));

	for (; wch<wch_cap && *wch!='\\'; )
		wch++;

	statfs->obj_name_strlen = sdev->strlen;
	statfs->obj_name_maxlen = statfs->dev_name_maxlen;
	statfs->dev_name_strlen = sizeof(uint16_t) * (uint16_t)(wch - sdev->buffer);
	statfs->dev_name_hash   = __ntapi->tt_buffer_crc32(
					hash,wch_mark,
					sizeof(wchar16_t) * (wch - wch_mark));

	/* device name */
	if (!(flags & NT_STATFS_DEV_NAME_COPY))
		(void)0;
	else if (statfs->dev_name_maxlen < sdev->strlen)
		return NT_STATUS_BUFFER_TOO_SMALL;
	else
		__ntapi->tt_memcpy_utf16(
			statfs->dev_name,
			sdev->buffer,
			sdev->strlen);

	/* f_fsid: hash of the system-unique device name */
	/* (never use the volume serial number) */
	fsid = (uint32_t *)&(statfs->f_fsid);
	fsid[0] = statfs->dev_name_hash;
	fsid[1] = 0;

	/* f_flags, nt_attr */
	statfs->f_flags = 0;
	statfs->nt_attr = 0;
	statfs->nt_padding = 0;

	if (!(flags & NT_STATFS_VOLUME_GUID)) {
		statfs->nt_drive_letter = 0;
		pguid    = (uint64_t *)&(statfs->nt_volume_guid);
		pguid[0] = 0;
		pguid[1] = 0;
		return NT_STATUS_SUCCESS;
	}

	/* dos device letter and volume guid */
	wch = (wchar16_t *)sdev->buffer;
	mnt_points_buffer = (void *)((uintptr_t)wch + statfs->dev_name_strlen);

	*(--wch) = statfs->dev_name_strlen;
	offset   = sizeof(nt_unicode_string) + statfs->dev_name_strlen;

	if ((status = __ntapi->tt_get_dos_drive_mount_points(
			0,0,
			(nt_mount_dev_name *)wch,
			mnt_points_buffer,
			buffer_size - offset)))
		return status;

	offset     = ((nt_mount_point_param *)mnt_points_buffer)->mount_points_offset;
	mnt_points = (nt_mount_points *)((uintptr_t)mnt_points_buffer + offset);

	status = __ntapi->tt_dev_mount_points_to_statfs(
		mnt_points,statfs);

	return status;
}