WIP: SMART statistics

block.go

@@ -26,6 +26,7 @@ type Device struct {
 // system implementations.
 type devicer interface {
 	Identify() ([512]byte, error)
+	ReadSMART() (*SMARTData, error)
 	Size() (uint64, error)
 
 	io.Closer

block_linux.go

@@ -92,6 +92,26 @@ func (d *device) Size() (uint64, error) {
 	return size, err
 }
 
+const (
+	_HDIO_DRIVE_CMD    = 0x031f
+	_WIN_SMART         = 0xb0
+	_SMART_READ_VALUES = 0xd0
+)
+
+func (d *device) ReadSMART() (*SMARTData, error) {
+	b := [516]byte{}
+	b[0] = _WIN_SMART
+	b[2] = _SMART_READ_VALUES
+	b[3] = 1
+
+	_, err := d.ioctl(d.fd, _HDIO_DRIVE_CMD, uintptr(unsafe.Pointer(&b[0])))
+	if err != nil {
+		return nil, err
+	}
+
+	return parseSMARTData(b), nil
+}
+
 // Read implements io.Reader for a block device.
 func (d *device) Read(b []byte) (int, error) {
 	return d.dev.Read(b)

smart.go

@@ -0,0 +1,94 @@
+package block
+
+import (
+	"encoding/binary"
+	"unsafe"
+)
+
+// nativeEndian is the native endian byte order for this machine, determined
+// on package init.
+var nativeEndian binary.ByteOrder
+
+// Courtesy of golang.org/x/net/ipv4
+func init() {
+	i := uint32(1)
+	b := (*[4]byte)(unsafe.Pointer(&i))
+	if b[0] == 1 {
+		nativeEndian = binary.LittleEndian
+	} else {
+		nativeEndian = binary.BigEndian
+	}
+}
+
+func parseSMARTData(raw [516]byte) *SMARTData {
+	sd := &SMARTData{}
+
+	// Skip 4 bytes ATA header
+	sd.Revision = nativeEndian.Uint16(raw[4:6])
+
+	i := 6
+	for c := 0; c < _NR_ATTRIBUTES; c++ {
+		sd.Values[c].ID = raw[i]
+		i++
+
+		sd.Values[c].Status = nativeEndian.Uint16(raw[i : i+2])
+		i += 2
+
+		sd.Values[c].Value = raw[i]
+		i++
+
+		copy(sd.Values[c].Vendor[:], raw[i:i+8])
+		i += 8
+	}
+
+	sd.OfflineStatus = raw[i]
+	i++
+
+	sd.Vendor1 = raw[i]
+	i++
+
+	sd.OfflineTimeout = nativeEndian.Uint16(raw[i : i+2])
+	i += 2
+
+	sd.Vendor2 = raw[i]
+	i++
+
+	sd.OfflineCapability = raw[i]
+	i++
+
+	sd.SMARTCapability = nativeEndian.Uint16(raw[i : i+2])
+	i += 2
+
+	copy(sd.Reserved[:], raw[i:i+16])
+	i += 16
+
+	copy(sd.Vendor[:], raw[i:i+125])
+	i += 125
+
+	sd.Checksum = raw[i]
+
+	return sd
+}
+
+type SMARTData struct {
+	Revision          uint16
+	Values            [_NR_ATTRIBUTES]Value
+	OfflineStatus     uint8
+	Vendor1           uint8
+	OfflineTimeout    uint16
+	Vendor2           uint8
+	OfflineCapability uint8
+	SMARTCapability   uint16
+	Reserved          [16]byte
+	Vendor            [125]byte
+	Checksum          uint8
+}
+
+const _NR_ATTRIBUTES = 30
+
+type Value struct {
+	ID     uint8
+	Status uint16
+	Value  uint8
+	Vendor [8]byte
+}