helper: use generic extra files interface

This replaces the pipes object and integrates context into helper process lifecycle.

Signed-off-by: Ophestra <cat@gensokyo.uk>

ldd/exec.go

@@ -1,20 +1,19 @@
 package ldd
 
 import (
-	"fmt"
+	"context"
 	"os"
-	"os/exec"
 	"strings"
+	"time"
 
 	"git.gensokyo.uk/security/fortify/helper"
 	"git.gensokyo.uk/security/fortify/helper/bwrap"
 )
 
-func Exec(p string) ([]*Entry, error) {
-	var (
-		h   helper.Helper
-		cmd *exec.Cmd
-	)
+const lddTimeout = 2 * time.Second
+
+func Exec(ctx context.Context, p string) ([]*Entry, error) {
+	var h helper.Helper
 
 	if b, err := helper.NewBwrap(
 		(&bwrap.Config{
@@ -29,17 +28,20 @@ func Exec(p string) ([]*Entry, error) {
 	); err != nil {
 		return nil, err
 	} else {
-		cmd = b.Unwrap()
 		h = b
 	}
 
-	cmd.Stdout, cmd.Stderr = new(strings.Builder), os.Stderr
-	if err := h.Start(); err != nil {
+	stdout := new(strings.Builder)
+	h.Stdout(stdout).Stderr(os.Stderr)
+
+	c, cancel := context.WithTimeout(ctx, lddTimeout)
+	defer cancel()
+	if err := h.Start(c, false); err != nil {
 		return nil, err
 	}
 	if err := h.Wait(); err != nil {
 		return nil, err
 	}
 
-	return Parse(cmd.Stdout.(fmt.Stringer))
+	return Parse(stdout)
 }