feat(update): add update deployment via web UI

- Deploy exe to alternate port 5033
- Current instance keeps running
- Add parallel mode and addr flag
- Add update panel to web UI
- Update OpenAPI spec and CLI

lib/update/update.go

@@ -0,0 +1,79 @@
+package update
+
+import (
+	"fmt"
+	"io"
+	"net"
+	"os"
+	"path/filepath"
+	"time"
+
+	"tea.chunkbyte.com/kato/go-worm/lib/config"
+)
+
+// Deploy saves exe and launches it on the alternate listen port (5032 <-> 5033).
+func Deploy(currentAddr string, body io.Reader) (savedPath, nextAddr string, err error) {
+	nextAddr, err = config.AlternateListenAddr(currentAddr)
+	if err != nil {
+		return "", "", err
+	}
+	if err := listenAvailable(nextAddr); err != nil {
+		return "", "", err
+	}
+
+	dir, err := config.UpdatesDir()
+	if err != nil {
+		return "", "", err
+	}
+	if err := os.MkdirAll(dir, 0o700); err != nil {
+		return "", "", err
+	}
+
+	name := fmt.Sprintf("update-%s.exe", time.Now().Format("20060102-150405"))
+	savedPath = filepath.Join(dir, name)
+	out, err := os.OpenFile(savedPath, os.O_CREATE|os.O_WRONLY|os.O_TRUNC, 0o700)
+	if err != nil {
+		return "", "", err
+	}
+
+	var head [2]byte
+	if _, err := io.ReadFull(body, head[:]); err != nil {
+		_ = out.Close()
+		_ = os.Remove(savedPath)
+		return "", "", fmt.Errorf("invalid executable")
+	}
+	if head[0] != 'M' || head[1] != 'Z' {
+		_ = out.Close()
+		_ = os.Remove(savedPath)
+		return "", "", fmt.Errorf("file is not a Windows executable")
+	}
+	if _, err := out.Write(head[:]); err != nil {
+		_ = out.Close()
+		_ = os.Remove(savedPath)
+		return "", "", err
+	}
+	if _, err := io.Copy(out, body); err != nil {
+		_ = out.Close()
+		_ = os.Remove(savedPath)
+		return "", "", err
+	}
+	if err := out.Close(); err != nil {
+		_ = os.Remove(savedPath)
+		return "", "", err
+	}
+
+	if err := deployLaunch(savedPath, nextAddr); err != nil {
+		_ = os.Remove(savedPath)
+		return "", "", err
+	}
+	return savedPath, nextAddr, nil
+}
+
+func listenAvailable(addr string) error {
+	ln, err := net.Listen("tcp", addr)
+	if err != nil {
+		return fmt.Errorf("port %s is not available: %w", addr, err)
+	}
+	_ = ln.Close()
+	return nil
+}