feat: add 'mobilecli device logs' support for streaming logs from mobile devices

cli/logs.go

@@ -0,0 +1,39 @@
+package cli
+
+import (
+	"fmt"
+
+	"github.com/mobile-next/mobilecli/commands"
+	"github.com/spf13/cobra"
+)
+
+var logsLimit int
+var logsProcess string
+var logsPID int
+
+var deviceLogsCmd = &cobra.Command{
+	Use:   "logs",
+	Short: "Stream device logs",
+	Long:  `Streams real-time logs from a device. Press Ctrl+C to stop.`,
+	RunE: func(cmd *cobra.Command, args []string) error {
+		response := commands.LogsCommand(commands.LogsRequest{
+			DeviceID: deviceId,
+			Limit:    logsLimit,
+			Process:  logsProcess,
+			PID:      logsPID,
+		})
+		if response.Status == "error" {
+			printJson(response)
+			return fmt.Errorf("%s", response.Error)
+		}
+		return nil
+	},
+}
+
+func init() {
+	deviceCmd.AddCommand(deviceLogsCmd)
+	deviceLogsCmd.Flags().StringVar(&deviceId, "device", "", "ID of the device to stream logs from")
+	deviceLogsCmd.Flags().IntVar(&logsLimit, "limit", 0, "Stop after N log entries (0 = unlimited)")
+	deviceLogsCmd.Flags().StringVar(&logsProcess, "process", "", "Filter by process name (substring match)")
+	deviceLogsCmd.Flags().IntVar(&logsPID, "pid", -1, "Filter by process ID")
+}

commands/logs.go

@@ -0,0 +1,49 @@
+package commands
+
+import (
+	"encoding/json"
+	"fmt"
+	"os"
+	"strings"
+
+	"github.com/mobile-next/mobilecli/devices"
+)
+
+type LogsRequest struct {
+	DeviceID string
+	Limit    int
+	Process  string
+	PID      int
+}
+
+func LogsCommand(req LogsRequest) *CommandResponse {
+	device, err := FindDeviceOrAutoSelect(req.DeviceID)
+	if err != nil {
+		return NewErrorResponse(fmt.Errorf("error finding device: %w", err))
+	}
+
+	encoder := json.NewEncoder(os.Stdout)
+	count := 0
+	err = device.StreamLogs(func(entry devices.LogEntry) bool {
+		if req.Process != "" && !strings.Contains(entry.Process, req.Process) {
+			return true
+		}
+		if req.PID >= 0 && entry.PID != req.PID {
+			return true
+		}
+
+		if err := encoder.Encode(entry); err != nil {
+			return false
+		}
+		count++
+		if req.Limit > 0 && count >= req.Limit {
+			return false
+		}
+		return true
+	})
+	if err != nil {
+		return NewErrorResponse(fmt.Errorf("error streaming logs: %w", err))
+	}
+
+	return NewSuccessResponse("done")
+}

devices/android.go

@@ -1344,3 +1344,7 @@ func (d *AndroidDevice) GetCrashReport(id string) ([]byte, error) {
 	}
 	return []byte(content), nil
 }
+
+func (d *AndroidDevice) StreamLogs(onLog func(LogEntry) bool) error {
+	return fmt.Errorf("device logs not yet supported for Android devices")
+}

devices/common.go

@@ -12,6 +12,18 @@ import (
 	"github.com/mobile-next/mobilecli/utils"
 )
 
+// LogEntry represents a single parsed log entry from a device
+type LogEntry struct {
+	Timestamp string `json:"timestamp"`
+	Message   string `json:"message"`
+	Level     string `json:"level"`
+	Subsystem string `json:"subsystem,omitempty"`
+	Category  string `json:"category,omitempty"`
+	PID       int    `json:"pid"`
+	Process   string `json:"process"`
+	EventType string `json:"eventType"`
+}
+
 type CrashReport struct {
 	ProcessName string `json:"processName"`
 	Timestamp   string `json:"timestamp"`
@@ -114,6 +126,7 @@ type ControllableDevice interface {
 	SetOrientation(orientation string) error
 	ListCrashReports() ([]CrashReport, error)
 	GetCrashReport(id string) ([]byte, error)
+	StreamLogs(onLog func(LogEntry) bool) error
 }
 
 // GetAllControllableDevices aggregates all known devices with options

devices/ios.go

@@ -18,6 +18,7 @@ import (
 	goios "github.com/danielpaulus/go-ios/ios"
 	"github.com/danielpaulus/go-ios/ios/crashreport"
 	"github.com/danielpaulus/go-ios/ios/diagnostics"
+	"github.com/danielpaulus/go-ios/ios/syslog"
 	"github.com/danielpaulus/go-ios/ios/installationproxy"
 	"github.com/danielpaulus/go-ios/ios/instruments"
 	"github.com/danielpaulus/go-ios/ios/testmanagerd"
@@ -1662,3 +1663,60 @@ func (d *IOSDevice) GetCrashReport(id string) ([]byte, error) {
 
 	return content, nil
 }
+
+func (d *IOSDevice) StreamLogs(onLog func(LogEntry) bool) error {
+	device, err := d.getEnhancedDevice()
+	if err != nil {
+		return fmt.Errorf("failed to get device: %w", err)
+	}
+
+	conn, err := syslog.New(device)
+	if err != nil {
+		return fmt.Errorf("failed to connect to syslog: %w", err)
+	}
+	defer conn.Close()
+
+	parse := syslog.Parser()
+
+	for {
+		msg, err := conn.ReadLogMessage()
+		if err != nil {
+			if errors.Is(err, io.EOF) {
+				return nil
+			}
+			return fmt.Errorf("syslog read error: %w", err)
+		}
+
+		msg = strings.TrimSuffix(msg, "\x00")
+		msg = strings.TrimSuffix(msg, "\x0A")
+		if msg == "" {
+			continue
+		}
+
+		entry, err := parse(msg)
+		if err != nil {
+			// unparseable line — emit raw message
+			if !onLog(LogEntry{
+				Message: msg,
+			}) {
+				return nil
+			}
+			continue
+		}
+
+		if !onLog(LogEntry{
+			Timestamp: entry.Timestamp,
+			Message:   entry.Message,
+			Level:     entry.Level,
+			Process:   entry.Process,
+			PID:       atoiOrZero(entry.PID),
+		}) {
+			return nil
+		}
+	}
+}
+
+func atoiOrZero(s string) int {
+	n, _ := strconv.Atoi(s)
+	return n
+}

devices/remote.go

@@ -500,3 +500,7 @@ func (r *RemoteDevice) GetCrashReport(id string) ([]byte, error) {
 	}
 	return []byte(result.Content), nil
 }
+
+func (r *RemoteDevice) StreamLogs(onLog func(LogEntry) bool) error {
+	return fmt.Errorf("device logs not yet supported for remote devices")
+}

devices/simulator.go

@@ -1,6 +1,7 @@
 package devices
 
 import (
+	"encoding/json"
 	"fmt"
 	"os"
 	"os/exec"
@@ -1045,3 +1046,76 @@ func (s SimulatorDevice) GetCrashReport(id string) ([]byte, error) {
 
 	return os.ReadFile(filepath.Join(diagnosticReportsDir, id))
 }
+
+// simctlLogEntry is the raw structure from xcrun simctl log stream --style json
+type simctlLogEntry struct {
+	Timestamp        string `json:"timestamp"`
+	EventMessage     string `json:"eventMessage"`
+	MessageType      string `json:"messageType"`
+	Subsystem        string `json:"subsystem"`
+	Category         string `json:"category"`
+	ProcessImagePath string `json:"processImagePath"`
+	ProcessID        int    `json:"processID"`
+	EventType        string `json:"eventType"`
+}
+
+func (s *SimulatorDevice) StreamLogs(onLog func(LogEntry) bool) error {
+	args := []string{"simctl", "spawn", s.UDID, "log", "stream", "--level", "info", "--style", "json"}
+	utils.Verbose("Running: xcrun %s", strings.Join(args, " "))
+
+	cmd := exec.Command("xcrun", args...)
+	stdout, err := cmd.StdoutPipe()
+	if err != nil {
+		return fmt.Errorf("failed to create stdout pipe: %w", err)
+	}
+
+	if err := cmd.Start(); err != nil {
+		return fmt.Errorf("failed to start log stream: %w", err)
+	}
+
+	decoder := json.NewDecoder(stdout)
+
+	// read opening '[' of the JSON array
+	token, err := decoder.Token()
+	if err != nil {
+		_ = cmd.Process.Kill()
+		return fmt.Errorf("failed to read opening token: %w", err)
+	}
+	if delim, ok := token.(json.Delim); !ok || delim != '[' {
+		_ = cmd.Process.Kill()
+		return fmt.Errorf("expected '[', got %v", token)
+	}
+
+	// decode entries one at a time until the stream ends
+	for decoder.More() {
+		var raw simctlLogEntry
+		if err := decoder.Decode(&raw); err != nil {
+			// stream ended (process killed) — not an error
+			break
+		}
+
+		// extract process name from full path
+		processName := raw.ProcessImagePath
+		if idx := strings.LastIndex(processName, "/"); idx != -1 {
+			processName = processName[idx+1:]
+		}
+
+		if !onLog(LogEntry{
+			Timestamp: raw.Timestamp,
+			Message:   raw.EventMessage,
+			Level:     raw.MessageType,
+			Subsystem: raw.Subsystem,
+			Category:  raw.Category,
+			PID:       raw.ProcessID,
+			Process:   processName,
+			EventType: raw.EventType,
+		}) {
+			_ = cmd.Process.Kill()
+			break
+		}
+	}
+
+	// we killed it ourselves, or stream ended naturally
+	_ = cmd.Wait()
+	return nil
+}