Feat: crash log (#7)

Merged #6
- crash log (db0e1be9a02f70927124f9f3563df5e9dee3a764)
- perf(watchdog): limit buffer size and optimize crash substring search (https://github.com/versenilvis/IRIS/pull/7/commits/7725434fedf8b32929dc0d71e1256fda13cfdfca)
- refactor(crash): use dynamic buffer for stack trace capture (https://github.com/versenilvis/IRIS/pull/7/commits/07809a4330a1236471e8dae0e83afd4323a4c83a)

root/crash.go

@@ -0,0 +1,150 @@
+package root
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+	"runtime"
+	"strings"
+	"sync"
+	"syscall"
+	"time"
+
+	"github.com/spf13/cobra"
+)
+
+// startRescueShell starts a fallback shell if the application crashes to keep the terminal open
+func startRescueShell() {
+	shell := os.Getenv("SHELL")
+	if shell == "" {
+		shell = "/bin/sh"
+	}
+	_ = syscall.Exec(shell, []string{shell}, os.Environ())
+}
+
+var (
+	lastCrashFile string
+	lastCrashMu   sync.Mutex
+)
+
+// writeCrashLog writes the crash info and stack trace to a new log file
+func WriteCrashLog(err any) {
+	home, errDir := os.UserHomeDir()
+	if errDir != nil {
+		return
+	}
+	dir := filepath.Join(home, ".iris", "crashes")
+	_ = os.MkdirAll(dir, 0755)
+	logFile := filepath.Join(dir, fmt.Sprintf("crash_%s.log", time.Now().Format("20060102_150405")))
+
+	lastCrashMu.Lock()
+	lastCrashFile = logFile
+	lastCrashMu.Unlock()
+
+	f, errOpen := os.OpenFile(logFile, os.O_CREATE|os.O_APPEND|os.O_WRONLY, 0600)
+	if errOpen != nil {
+		return
+	}
+	defer f.Close()
+
+	_, _ = fmt.Fprintf(f, "=== IRIS CRASH %s ===\n", time.Now().Format(time.RFC3339))
+	_, _ = fmt.Fprintf(f, "version: %s\nos: %s/%s\n\n", Version, runtime.GOOS, runtime.GOARCH)
+	_, _ = fmt.Fprintf(f, "panic: %v\n\n", err)
+
+	var n int
+	buf := make([]byte, 1024)
+	for {
+		n = runtime.Stack(buf, true)
+		if n < len(buf) {
+			break
+		}
+		buf = make([]byte, 2*len(buf))
+	}
+	_, _ = f.Write(buf[:n])
+	_, _ = fmt.Fprintln(f)
+}
+
+// getLatestCrashLog returns the path to the newest crash log file
+func getLatestCrashLog() string {
+	home, err := os.UserHomeDir()
+	if err != nil {
+		return ""
+	}
+	dir := filepath.Join(home, ".iris", "crashes")
+	files, err := os.ReadDir(dir)
+	if err != nil || len(files) == 0 {
+		oldLog := filepath.Join(home, ".iris", "crash.log")
+		if _, err := os.Stat(oldLog); err == nil {
+			return oldLog
+		}
+		return ""
+	}
+
+	var latest string
+	for _, f := range files {
+		if f.IsDir() {
+			continue
+		}
+		name := f.Name()
+		if strings.HasPrefix(name, "crash_") && strings.HasSuffix(name, ".log") {
+			if name > latest {
+				latest = name
+			}
+		}
+	}
+	if latest == "" {
+		oldLog := filepath.Join(home, ".iris", "crash.log")
+		if _, err := os.Stat(oldLog); err == nil {
+			return oldLog
+		}
+		return ""
+	}
+	return filepath.Join(dir, latest)
+}
+
+// printCrashNotice prints the crash notice with absolute path to the log file
+func printCrashNotice() {
+	lastCrashMu.Lock()
+	logFile := lastCrashFile
+	lastCrashMu.Unlock()
+	if logFile == "" {
+		logFile = getLatestCrashLog()
+	}
+	_, _ = fmt.Fprintf(os.Stderr, "\n\033[31m[IRIS] crashed, report saved to %s\033[0m\n", logFile)
+}
+
+var (
+	// crashCmd is the cobra command to manage crash logs
+	CrashCmd = &cobra.Command{
+		Use:   "crash-log",
+		Short: "manage iris crash logs",
+		Run: func(cmd *cobra.Command, args []string) {
+			home, err := os.UserHomeDir()
+			if err != nil {
+				cmd.Printf("failed to get home directory: %v\n", err)
+				return
+			}
+
+			if ClearLog {
+				_ = os.RemoveAll(filepath.Join(home, ".iris", "crashes"))
+				_ = os.Remove(filepath.Join(home, ".iris", "crash.log"))
+				cmd.Println("crash log cleared")
+				return
+			}
+
+			logFile := getLatestCrashLog()
+			if logFile == "" {
+				cmd.Println("no crash log found")
+				return
+			}
+			cmd.Println(logFile)
+		},
+	}
+	// clearLog is the flag to clear the crash log
+	ClearLog bool
+)
+
+func init() {
+	CrashCmd.Flags().BoolVar(&ClearLog, "clear", false, "clear the crash log")
+	rootCmd.AddCommand(CrashCmd)
+}