SMART: add eMMC health via sysfs (#1736)

* SMART: add eMMC health via sysfs

Read eMMC wear/EOL indicators from /sys/class/block/mmcblk*/device and expose in SMART device list. Includes mocked sysfs tests and UI tweaks for unknown temps.

* small optimizations for emmc scan and parsing

* smart: keep smartctl optional only for Linux hosts with eMMC

* update smart alerts to handle warning state

* refactor: rename binPath to smartctlPath and replace hasSmartctl with smartctlPath checks

---------

Co-authored-by: henrygd <hank@henrygd.me>

agent/emmc_common.go

@@ -0,0 +1,95 @@
+package agent
+
+import (
+	"fmt"
+	"strconv"
+	"strings"
+)
+
+func isEmmcBlockName(name string) bool {
+	if !strings.HasPrefix(name, "mmcblk") {
+		return false
+	}
+	suffix := strings.TrimPrefix(name, "mmcblk")
+	if suffix == "" {
+		return false
+	}
+	for _, c := range suffix {
+		if c < '0' || c > '9' {
+			return false
+		}
+	}
+	return true
+}
+
+func parseHexOrDecByte(s string) (uint8, bool) {
+	s = strings.TrimSpace(s)
+	if s == "" {
+		return 0, false
+	}
+	base := 10
+	if strings.HasPrefix(s, "0x") || strings.HasPrefix(s, "0X") {
+		base = 16
+		s = s[2:]
+	}
+	parsed, err := strconv.ParseUint(s, base, 8)
+	if err != nil {
+		return 0, false
+	}
+	return uint8(parsed), true
+}
+
+func parseHexBytePair(s string) (uint8, uint8, bool) {
+	fields := strings.Fields(s)
+	if len(fields) < 2 {
+		return 0, 0, false
+	}
+	a, okA := parseHexOrDecByte(fields[0])
+	b, okB := parseHexOrDecByte(fields[1])
+	if !okA && !okB {
+		return 0, 0, false
+	}
+	return a, b, true
+}
+
+func emmcSmartStatus(preEOL uint8) string {
+	switch preEOL {
+	case 0x01:
+		return "PASSED"
+	case 0x02:
+		return "WARNING"
+	case 0x03:
+		return "FAILED"
+	default:
+		return "UNKNOWN"
+	}
+}
+
+func emmcPreEOLString(preEOL uint8) string {
+	switch preEOL {
+	case 0x01:
+		return "0x01 (normal)"
+	case 0x02:
+		return "0x02 (warning)"
+	case 0x03:
+		return "0x03 (urgent)"
+	default:
+		return fmt.Sprintf("0x%02x", preEOL)
+	}
+}
+
+func emmcLifeTimeString(v uint8) string {
+	// JEDEC eMMC: 0x01..0x0A => 0-100% used in 10% steps, 0x0B => exceeded.
+	switch {
+	case v == 0:
+		return "0x00 (not reported)"
+	case v >= 0x01 && v <= 0x0A:
+		low := int(v-1) * 10
+		high := int(v) * 10
+		return fmt.Sprintf("0x%02x (%d-%d%% used)", v, low, high)
+	case v == 0x0B:
+		return "0x0b (>100% used)"
+	default:
+		return fmt.Sprintf("0x%02x", v)
+	}
+}