chore: add common method to list available disks using /sys/block

Returns the list of disks with device name, size and model info.
To be used in Sidero and Talos.

Signed-off-by: Artem Chernyshev <[email protected]>

blockdevice/util/disks.go

@@ -0,0 +1,94 @@
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this
+// file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+package util
+
+import (
+	"fmt"
+	"io/ioutil"
+	"os"
+	"path/filepath"
+	"strconv"
+	"strings"
+)
+
+// Disk reresents disk information obtained by reading /sys/block.
+type Disk struct {
+	// Size disk size in bytes.
+	Size uint64
+	// Model from /sys/block/*/device/model.
+	Model string
+	// DeviceName device name (e.g. /dev/sda).
+	DeviceName string
+}
+
+// GetDisks returns list of disks by reading /sys/block.
+func GetDisks() ([]*Disk, error) {
+	disks := []*Disk{}
+
+	sysblock := "/sys/block"
+
+	devices, err := ioutil.ReadDir(sysblock)
+	if err != nil {
+		return nil, fmt.Errorf("failed to read /sys/block directory %w", err)
+	}
+
+	readFile := func(path string) (string, error) {
+		f, e := os.Open(filepath.Join(sysblock, path))
+
+		if e != nil {
+			return "", fmt.Errorf("failed to open file %w", err)
+		}
+
+		data, e := ioutil.ReadAll(f)
+
+		if e != nil {
+			return "", fmt.Errorf("failed to read file %w", err)
+		}
+
+		return string(data), nil
+	}
+
+	for _, dev := range devices {
+		skip := false
+		deviceName := filepath.Base(dev.Name())
+
+		for _, prefix := range []string{"sg", "sr", "loop", "md", "dm-"} {
+			if strings.HasPrefix(deviceName, prefix) {
+				skip = true
+
+				break
+			}
+		}
+
+		if skip {
+			continue
+		}
+
+		var size uint64
+
+		s, err := readFile(filepath.Join(dev.Name(), "size"))
+		if err != nil {
+			continue
+		}
+
+		size, err = strconv.ParseUint(strings.TrimSpace(s), 10, 64)
+		if err != nil {
+			continue
+		}
+
+		model, err := readFile(filepath.Join(dev.Name(), "device/model"))
+		if err != nil {
+			model = ""
+		}
+
+		disks = append(disks, &Disk{
+			DeviceName: fmt.Sprintf("/dev/%s", deviceName),
+			Size:       size,
+			Model:      model,
+		})
+	}
+
+	return disks, nil
+}