helper/bwrap: merge Args and FDArgs

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

helper/bwrap/arg.go

@@ -23,42 +23,22 @@ type FDBuilder interface {
 }
 
 // Args returns a slice of bwrap args corresponding to c.
-func (c *Config) Args() (args []string) {
+func (c *Config) Args(syncFd *os.File, extraFiles *proc.ExtraFilesPre, files *[]proc.File) (args []string) {
 	builders := []Builder{
 		c.boolArgs(),
 		c.intArgs(),
 		c.stringArgs(),
 		c.pairArgs(),
-	}
-
-	// copy FSBuilder slice to builder slice
-	fb := make([]Builder, len(c.Filesystem)+1)
-	for i, f := range c.Filesystem {
-		fb[i] = f
-	}
-	fb[len(fb)-1] = c.Chmod
-	builders = append(builders, fb...)
-
-	// accumulate arg count
-	argc := 0
-	for _, b := range builders {
-		argc += b.Len()
-	}
-
-	args = make([]string, 0, argc)
-	for _, b := range builders {
-		b.Append(&args)
-	}
-
-	return
-}
-
-func (c *Config) FDArgs(syncFd *os.File, args *[]string, extraFiles *proc.ExtraFilesPre, files *[]proc.File) {
-	builders := []FDBuilder{
 		c.seccompArgs(),
 		newFile(positionalArgs[SyncFd], syncFd),
 	}
 
+	builders = slices.Grow(builders, len(c.Filesystem)+1)
+	for _, f := range c.Filesystem {
+		builders = append(builders, f)
+	}
+	builders = append(builders, c.Chmod)
+
 	argc := 0
 	fc := 0
 	for _, b := range builders {
@@ -67,22 +47,26 @@ func (c *Config) FDArgs(syncFd *os.File, args *[]string, extraFiles *proc.ExtraF
 			continue
 		}
 		argc += l
-		fc++
 
-		proc.InitFile(b, extraFiles)
+		if f, ok := b.(FDBuilder); ok {
+			fc++
+			proc.InitFile(f, extraFiles)
+		}
 	}
-
 	fc++ // allocate extra slot for stat fd
-	*args = slices.Grow(*args, argc)
-	*files = slices.Grow(*files, fc)
 
+	args = make([]string, 0, argc)
+	*files = slices.Grow(*files, fc)
 	for _, b := range builders {
 		if b.Len() < 1 {
 			continue
 		}
+		b.Append(&args)
 
-		b.Append(args)
-		*files = append(*files, b)
+		if f, ok := b.(FDBuilder); ok {
+			*files = append(*files, f)
+		}
 	}
+
 	return
 }