office: no more orphan processes (hopefully)

internal/pkg/printer/office.go

@@ -5,6 +5,8 @@ import (
 	"fmt"
 	"os"
 	"path/filepath"
+	"strings"
+	"syscall"
 
 	"github.com/phayes/freeport"
 	"github.com/thecodingmachine/gotenberg/internal/pkg/conf"
@@ -104,8 +106,7 @@ func unoconv(ctx context.Context, logger xlog.Logger, fpath, destination string,
 			args = append(args, "--printer", "PaperOrientation=landscape")
 		}
 		args = append(args, "--output", destination, fpath)
-		cmd, err := xexec.CommandContext(
+		cmd, err := xexec.Command(
-			ctx,
 			logger,
 			"unoconv",
 			args...,
@@ -114,7 +115,34 @@ func unoconv(ctx context.Context, logger xlog.Logger, fpath, destination string,
 			return err
 		}
 		xexec.LogBeforeExecute(logger, cmd)
-		return cmd.Run()
+		// see https://medium.com/@felixge/killing-a-child-process-and-all-of-its-children-in-go-54079af94773.
+		kill := func() {
+			err := syscall.Kill(-cmd.Process.Pid, syscall.SIGKILL)
+			if err == nil {
+				return
+			}
+			if !strings.Contains(err.Error(), "no such process") {
+				logger.ErrorOp(op, err)
+			}
+		}
+		cmd.SysProcAttr = &syscall.SysProcAttr{Setpgid: true}
+		if err := cmd.Start(); err != nil {
+			return err
+		}
+		result := make(chan error, 1)
+		go func() {
+			result <- cmd.Wait()
+		}()
+		select {
+		case err := <-result:
+			logger.DebugfOp(op, "command '%s' finished", strings.Join(cmd.Args, " "))
+			kill()
+			return err
+		case <-ctx.Done():
+			logger.DebugfOp(op, "command '%s' failed to finish before context.Context deadline", strings.Join(cmd.Args, " "))
+			kill()
+			return ctx.Err()
+		}
 	}
 	if err := resolver(); err != nil {
 		return xerror.New(op, err)