// +build linux,s390x

// Copyright (c) 2015-2021 MinIO, Inc.
//
// This file is part of MinIO Object Storage stack
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as published by
// the Free Software Foundation, either version 3 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 Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.

package disk

import (
	"fmt"
	"strconv"
	"syscall"
)

// fsType2StringMap - list of filesystems supported on linux
var fsType2StringMap = map[string]string{
	"1021994":  "TMPFS",
	"137d":     "EXT",
	"4244":     "HFS",
	"4d44":     "MSDOS",
	"52654973": "REISERFS",
	"5346544e": "NTFS",
	"58465342": "XFS",
	"61756673": "AUFS",
	"6969":     "NFS",
	"ef51":     "EXT2OLD",
	"ef53":     "EXT4",
	"f15f":     "ecryptfs",
	"794c7630": "overlayfs",
	"2fc12fc1": "zfs",
	"ff534d42": "cifs",
	"53464846": "wslfs",
}

// getFSType returns the filesystem type of the underlying mounted filesystem
func getFSType(ftype uint32) string {
	fsTypeHex := strconv.FormatUint(uint64(ftype), 16)
	fsTypeString, ok := fsType2StringMap[fsTypeHex]
	if !ok {
		return "UNKNOWN"
	}
	return fsTypeString
}

// GetInfo returns total and free bytes available in a directory, e.g. `/`.
func GetInfo(path string) (info Info, err error) {
	s := syscall.Statfs_t{}
	err = syscall.Statfs(path, &s)
	if err != nil {
		return Info{}, err
	}
	reservedBlocks := s.Bfree - s.Bavail
	info = Info{
		Total:  uint64(s.Frsize) * (s.Blocks - reservedBlocks),
		Free:   uint64(s.Frsize) * s.Bavail,
		Files:  s.Files,
		Ffree:  s.Ffree,
		FSType: getFSType(s.Type),
	}
	// Check for overflows.
	// https://github.com/minio/minio/issues/8035
	// XFS can show wrong values at times error out
	// in such scenarios.
	if info.Free > info.Total {
		return info, fmt.Errorf("detected free space (%d) > total disk space (%d), fs corruption at (%s). please run 'fsck'", info.Free, info.Total, path)
	}
	info.Used = info.Total - info.Free
	return info, nil
}