feat(blockdevice): added sysblockdevicesize method and test

blockdevice/stats.go

@@ -209,6 +209,7 @@ const (
 	sysBlockQueue       = "queue"
 	sysBlockDM          = "dm"
 	sysUnderlyingDev    = "slaves"
+	sysBlockSize        = "size"
 )
 
 // FS represents the pseudo-filesystems proc and sys, which provides an
@@ -474,3 +475,13 @@ func (fs FS) SysBlockDeviceUnderlyingDevices(device string) (UnderlyingDeviceInf
 	return UnderlyingDeviceInfo{DeviceNames: underlying}, nil
 
 }
+
+// SysBlockDeviceSizeBytes returns the size of the block device from /sys/block/<device>/size
+// in bytes by multiplying the value by the Linux sector length of 512.
+func (fs FS) SysBlockDeviceSizeBytes(device string) (uint64, error) {
+	size, err := util.ReadUintFromFile(fs.sys.Path(sysBlockPath, device, sysBlockSize))
+	if err != nil {
+		return 0, err
+	}
+	return 512 * size, nil
+}

blockdevice/stats_test.go

@@ -219,3 +219,22 @@ func TestSysBlockDeviceUnderlyingDevices(t *testing.T) {
 		t.Errorf("Incorrect BlockQueueStat, expected: \n%+v, got: \n%+v", underlying0Expected, underlying0)
 	}
 }
+
+func TestSysBlockDeviceSize(t *testing.T) {
+	blockdevice, err := NewFS("testdata/fixtures/proc", "testdata/fixtures/sys")
+	if err != nil {
+		t.Fatalf("failed to access blockdevice fs: %v", err)
+	}
+	devices, err := blockdevice.SysBlockDevices()
+	if err != nil {
+		t.Fatal(err)
+	}
+	sizeBytes7, err := blockdevice.SysBlockDeviceSizeBytes(devices[7])
+	if err != nil {
+		t.Fatal(err)
+	}
+	sizeBytes7Expected := uint64(3750748848)
+	if sizeBytes7 != sizeBytes7Expected {
+		t.Errorf("Incorrect BlockDeviceSize, expected: \n%+v, got: \n%+v", sizeBytes7Expected, sizeBytes7)
+	}
+}

testdata/fixtures/sys/block/sda/size

@@ -0,0 +1 @@
+3750748848