fix(agent): read /proc/uptime on linux instead of sysinfo(2) (#2180)

gopsutil's host.Uptime() calls the sysinfo(2) syscall. Inside an LXC
container lxcfs virtualizes /proc/uptime but cannot intercept a
syscall, so every container reported the host's uptime.

Reads /proc/uptime on linux and falls back to host.Uptime() if the file
is missing or unparseable, so other platforms are unchanged.

agent/fans.go

@@ -72,14 +72,30 @@ func discoverHwmonFans(root string) ([]fanSensor, error) {
 	var sensors []fanSensor
 	for _, entry := range entries {
 		chipDir := filepath.Join(root, entry.Name())
-		chipName := utils.ReadStringFile(filepath.Join(chipDir, "name"))
+		sensorDir := chipDir
+		inputs, _ := filepath.Glob(filepath.Join(sensorDir, "fan*_input"))
+
+		// Some legacy hwmon drivers (notably applesmc) register a hwmon class
+		// device but create fan attributes on the parent platform device. In
+		// sysfs that parent is exposed through hwmonN/device.
+		if len(inputs) == 0 {
+			deviceDir := filepath.Join(chipDir, "device")
+			if deviceInputs, _ := filepath.Glob(filepath.Join(deviceDir, "fan*_input")); len(deviceInputs) > 0 {
+				sensorDir = deviceDir
+				inputs = deviceInputs
+			}
+		}
+
+		chipName := utils.ReadStringFile(filepath.Join(sensorDir, "name"))
+		if chipName == "" {
+			chipName = utils.ReadStringFile(filepath.Join(chipDir, "name"))
+		}
 		if chipName == "" {
 			chipName = entry.Name()
 		}
-		inputs, _ := filepath.Glob(filepath.Join(chipDir, "fan*_input"))
 		for _, inputPath := range inputs {
 			base := strings.TrimSuffix(filepath.Base(inputPath), "_input")
-			label := utils.ReadStringFile(filepath.Join(chipDir, base+"_label"))
+			label := utils.ReadStringFile(filepath.Join(sensorDir, base+"_label"))
 			key := chipName + "_" + base
 			if label != "" {
 				key = chipName + "_" + label

agent/fans_test.go

@@ -50,6 +50,24 @@ func TestReadHwmonFans(t *testing.T) {
 	}, fans)
 }
 
+// TestReadHwmonFansLegacyParent verifies legacy hwmon layouts such as applesmc,
+// where the hwmon class node exists but fan attributes live on hwmonN/device.
+func TestReadHwmonFansLegacyParent(t *testing.T) {
+	root := t.TempDir()
+	deviceDir := filepath.Join(root, "devices", "applesmc.768")
+	writeFile(t, filepath.Join(deviceDir, "name"), "applesmc\n")
+	writeFile(t, filepath.Join(deviceDir, "fan1_input"), "1202\n")
+	writeFile(t, filepath.Join(deviceDir, "fan1_label"), "Exhaust\n")
+
+	chipDir := filepath.Join(root, "hwmon1")
+	require.NoError(t, os.MkdirAll(chipDir, 0o755))
+	require.NoError(t, os.Symlink(deviceDir, filepath.Join(chipDir, "device")))
+
+	fans, err := readHwmonFans(root)
+	require.NoError(t, err)
+	assert.Equal(t, map[string]uint16{"applesmc_Exhaust": 1202}, fans)
+}
+
 // TestReadHwmonFansMissingRoot returns an error rather than panicking when the
 // hwmon root doesn't exist (e.g. running on a kernel without hwmon support).
 func TestReadHwmonFansMissingRoot(t *testing.T) {

agent/fingerprint.go

@@ -50,6 +50,9 @@ func generateFingerprint(hostname, cpuModel string) string {
 			if info, err := cpu.Info(); err == nil && len(info) > 0 {
 				cpuModel = info[0].ModelName
 			}
+			if cpuModel == "" {
+				cpuModel = getCpuModelFromCpuinfo()
+			}
 		}
 		fingerprint = hostname + cpuModel
 	}

agent/system.go

@@ -4,6 +4,7 @@ import (
 	"bufio"
 	"errors"
 	"fmt"
+	"io"
 	"log/slog"
 	"os"
 	"runtime"
@@ -78,6 +79,12 @@ func (a *Agent) refreshSystemDetails() {
 	if info, err := cpu.Info(); err == nil && len(info) > 0 {
 		a.systemDetails.CpuModel = info[0].ModelName
 	}
+	// gopsutil doesn't parse the "cpu model" field from /proc/cpuinfo, which
+	// is the only source of the CPU model name on MIPS. Fall back to reading
+	// it directly when ModelName is empty.
+	if a.systemDetails.CpuModel == "" {
+		a.systemDetails.CpuModel = getCpuModelFromCpuinfo()
+	}
 	// cores / threads
 	cores, _ := cpu.Counts(false)
 	threads := hostInfo.NCPU
@@ -258,13 +265,66 @@ func (a *Agent) getSystemStats(cacheTimeMs uint16) system.Stats {
 	a.systemInfo.MemPct = systemStats.MemPct
 	a.systemInfo.DiskPct = systemStats.DiskPct
 	a.systemInfo.Battery = systemStats.Battery
-	a.systemInfo.Uptime, _ = host.Uptime()
+	a.systemInfo.Uptime, _ = getUptime()
 	a.systemInfo.BandwidthBytes = systemStats.Bandwidth[0] + systemStats.Bandwidth[1]
 	a.systemInfo.Threads = a.systemDetails.Threads
 
 	return systemStats
 }
 
+// cpuModelFallbackKeys are the field names to look for in /proc/cpuinfo when
+// gopsutil fails to return a ModelName. The "cpu model" key is used on MIPS
+// (e.g. "MIPS 1004Kc V2.15"), while "system type" provides SoC information
+// on various embedded architectures.
+var cpuModelFallbackKeys = []string{"cpu model", "system type"}
+
+// getCpuModelFromCpuinfo reads /proc/cpuinfo and returns a CPU model string.
+// This is a fallback for architectures where gopsutil's cpu.Info() does not
+// populate ModelName, most notably MIPS.
+func getCpuModelFromCpuinfo() string {
+	file, err := os.Open("/proc/cpuinfo")
+	if err != nil {
+		return ""
+	}
+	defer file.Close()
+	return parseCpuModel(file)
+}
+
+// parseCpuModel scans r (expected to be /proc/cpuinfo content) and returns
+// a combined CPU model string. It collects values from all matching keys
+// and joins them with " / " when multiple are found.
+func parseCpuModel(r io.Reader) string {
+	lines := readLines(r)
+	var parts []string
+	for _, key := range cpuModelFallbackKeys {
+		for _, line := range lines {
+			after, found := strings.CutPrefix(line, key)
+			if !found {
+				continue
+			}
+			after = strings.TrimSpace(after)
+			if len(after) < 2 || after[0] != ':' {
+				continue
+			}
+			if value := strings.TrimSpace(after[1:]); value != "" {
+				parts = append(parts, value)
+				break
+			}
+		}
+	}
+	return strings.Join(parts, " / ")
+}
+
+// readLines reads all lines from r into a slice.
+func readLines(r io.Reader) []string {
+	scanner := bufio.NewScanner(r)
+	var lines []string
+	for scanner.Scan() {
+		lines = append(lines, scanner.Text())
+	}
+	return lines
+}
+
 // calculateHostMemoryUsage derives counters defensively because /proc/meminfo may
 // change while gopsutil reads it. Invalid unsigned subtractions saturate at zero.
 func calculateHostMemoryUsage(v *mem.VirtualMemoryStat, htop bool) (used, cacheBuff, swapUsed uint64) {

agent/system_test.go

@@ -1,6 +1,7 @@
 package agent
 
 import (
+	"strings"
 	"testing"
 
 	"github.com/henrygd/beszel/internal/common"
@@ -113,3 +114,81 @@ func TestUpdateSystemDetailsMarksDetailsDirty(t *testing.T) {
 	assert.False(t, agent.detailsDirty)
 	assert.Nil(t, original.Details)
 }
+
+func TestParseCpuModel(t *testing.T) {
+	tests := []struct {
+		name     string
+		input    string
+		expected string
+	}{
+		{
+			name: "MIPS with both cpu model and system type",
+			input: `system type             : MediaTek MT7621 ver:1 eco:3
+machine                 : ASUS RT-AX53U
+processor               : 0
+cpu model               : MIPS 1004Kc V2.15
+BogoMIPS                : 586.13
+wait instruction        : yes`,
+			expected: "MIPS 1004Kc V2.15 / MediaTek MT7621 ver:1 eco:3",
+		},
+		{
+			name: "MIPS with different SoC",
+			input: `system type             : Atheros AR7161 rev 2
+machine                 : NETGEAR WNDR3700
+processor               : 0
+cpu model               : MIPS 24Kc V7.4
+BogoMIPS                : 452.19`,
+			expected: "MIPS 24Kc V7.4 / Atheros AR7161 rev 2",
+		},
+		{
+			name: "only system type when cpu model missing",
+			input: `system type             : Broadcom BCM47xx
+processor               : 0
+BogoMIPS                : 296.11`,
+			expected: "Broadcom BCM47xx",
+		},
+		{
+			name: "only cpu model when system type missing",
+			input: `processor               : 0
+cpu model               : MIPS 34Kc V2.15
+BogoMIPS                : 300.00`,
+			expected: "MIPS 34Kc V2.15",
+		},
+		{
+			name: "x86 cpuinfo returns empty",
+			input: `processor	: 0
+vendor_id	: GenuineIntel
+cpu family	: 6
+model		: 142
+model name	: Intel(R) Core(TM) i5-8250U CPU @ 1.60GHz
+stepping	: 10`,
+			expected: "",
+		},
+		{
+			name:     "empty input",
+			input:    "",
+			expected: "",
+		},
+		{
+			name: "cpu model with extra whitespace",
+			input: `processor               : 0
+cpu model               :   MIPS 34Kc V2.15
+BogoMIPS                : 300.00`,
+			expected: "MIPS 34Kc V2.15",
+		},
+		{
+			name: "cpu model without value",
+			input: `processor               : 0
+cpu model               :
+BogoMIPS                : 300.00`,
+			expected: "",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			result := parseCpuModel(strings.NewReader(tt.input))
+			assert.Equal(t, tt.expected, result)
+		})
+	}
+}

agent/uptime_linux.go

@@ -0,0 +1,44 @@
+//go:build linux
+
+package agent
+
+import (
+	"math"
+	"os"
+	"strconv"
+	"strings"
+
+	"github.com/shirou/gopsutil/v4/host"
+)
+
+// uptimeFilePath is a variable so tests can point it at a fixture.
+var uptimeFilePath = "/proc/uptime"
+
+// getUptime returns the system uptime in seconds.
+//
+// This reads /proc/uptime instead of using host.Uptime(), which calls the
+// sysinfo(2) syscall. Inside an LXC container lxcfs virtualizes /proc/uptime
+// but cannot intercept a syscall, so sysinfo(2) reports the host's uptime
+// rather than the container's.
+//
+// Falls back to host.Uptime() if /proc/uptime is missing or unparseable, so
+// behavior is unchanged anywhere the file isn't available.
+func getUptime() (uint64, error) {
+	data, err := os.ReadFile(uptimeFilePath)
+	if err != nil {
+		return host.Uptime()
+	}
+	fields := strings.Fields(string(data))
+	if len(fields) == 0 {
+		return host.Uptime()
+	}
+	seconds, err := strconv.ParseFloat(fields[0], 64)
+	if err != nil ||
+		math.IsNaN(seconds) ||
+		math.IsInf(seconds, 0) ||
+		seconds < 0 ||
+		seconds >= 1<<64 {
+		return host.Uptime()
+	}
+	return uint64(seconds), nil
+}

agent/uptime_linux_test.go

@@ -0,0 +1,101 @@
+//go:build linux
+
+package agent
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+)
+
+func TestGetUptimeFromProc(t *testing.T) {
+	tests := []struct {
+		name     string
+		contents string
+		want     uint64
+	}{
+		{"typical", "12345.67 98765.43\n", 12345},
+		{"zero", "0.00 0.00\n", 0},
+		{"no trailing newline", "42.99 7.00", 42},
+		{"single field", "600.5", 600},
+		{"large value", "266030.12 1000000.00\n", 266030},
+	}
+
+	prev := uptimeFilePath
+	t.Cleanup(func() { uptimeFilePath = prev })
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			path := filepath.Join(t.TempDir(), "uptime")
+			if err := os.WriteFile(path, []byte(tt.contents), 0o644); err != nil {
+				t.Fatal(err)
+			}
+			uptimeFilePath = path
+
+			got, err := getUptime()
+			if err != nil {
+				t.Fatalf("getUptime() returned error: %v", err)
+			}
+			if got != tt.want {
+				t.Errorf("getUptime() = %d, want %d", got, tt.want)
+			}
+		})
+	}
+}
+
+func writeUptime(contents string) func(t *testing.T) string {
+	return func(t *testing.T) string {
+		path := filepath.Join(t.TempDir(), "uptime")
+		if err := os.WriteFile(path, []byte(contents), 0o644); err != nil {
+			t.Fatal(err)
+		}
+		return path
+	}
+}
+
+// Malformed, missing, or out-of-range input must fall back to host.Uptime()
+// rather than returning a bogus value, so the agent still reports something sane.
+func TestGetUptimeFallsBack(t *testing.T) {
+	prev := uptimeFilePath
+	t.Cleanup(func() { uptimeFilePath = prev })
+
+	for _, tt := range []struct {
+		name    string
+		prepare func(t *testing.T) string
+	}{
+		{"missing file", func(t *testing.T) string {
+			return filepath.Join(t.TempDir(), "does-not-exist")
+		}},
+		{"empty file", func(t *testing.T) string {
+			path := filepath.Join(t.TempDir(), "uptime")
+			if err := os.WriteFile(path, nil, 0o644); err != nil {
+				t.Fatal(err)
+			}
+			return path
+		}},
+		{"unparseable", func(t *testing.T) string {
+			path := filepath.Join(t.TempDir(), "uptime")
+			if err := os.WriteFile(path, []byte("not-a-number 1.0\n"), 0o644); err != nil {
+				t.Fatal(err)
+			}
+			return path
+		}},
+		{"NaN", writeUptime("NaN 1.0\n")},
+		{"positive infinity", writeUptime("+Inf 1.0\n")},
+		{"negative infinity", writeUptime("-Inf 1.0\n")},
+		{"negative", writeUptime("-42.5 1.0\n")},
+		{"exceeds uint64 range", writeUptime("1e20 1.0\n")},
+	} {
+		t.Run(tt.name, func(t *testing.T) {
+			uptimeFilePath = tt.prepare(t)
+
+			got, err := getUptime()
+			if err != nil {
+				t.Fatalf("getUptime() returned error: %v", err)
+			}
+			if got == 0 {
+				t.Error("getUptime() = 0, expected fallback to host.Uptime()")
+			}
+		})
+	}
+}

agent/uptime_stub.go

@@ -0,0 +1,10 @@
+//go:build !linux
+
+package agent
+
+import "github.com/shirou/gopsutil/v4/host"
+
+// getUptime returns the system uptime in seconds.
+func getUptime() (uint64, error) {
+	return host.Uptime()
+}