tun: replace ErrorBatch() with errors.Join()

Reviewed-by: Maisem Ali <maisem@tailscale.com>
Signed-off-by: Jordan Whited <jordan@tailscale.com>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>

tun/errors.go

@@ -2,7 +2,6 @@ package tun
 
 import (
 	"errors"
-	"fmt"
 )
 
 var (
@@ -11,50 +10,3 @@ var (
 	// reads to cease.
 	ErrTooManySegments = errors.New("too many segments")
 )
-
-type errorBatch []error
-
-// ErrorBatch takes a possibly nil or empty list of errors, and if the list is
-// non-nil returns an error type that wraps all of the errors. Expected usage is
-// to append to an []errors and coerce the set to an error using this method.
-func ErrorBatch(errs []error) error {
-	if len(errs) == 0 {
-		return nil
-	}
-	return errorBatch(errs)
-}
-
-func (e errorBatch) Error() string {
-	if len(e) == 0 {
-		return ""
-	}
-	if len(e) == 1 {
-		return e[0].Error()
-	}
-	return fmt.Sprintf("batch operation: %v (and %d more errors)", e[0], len(e)-1)
-}
-
-func (e errorBatch) Is(target error) bool {
-	for _, err := range e {
-		if errors.Is(err, target) {
-			return true
-		}
-	}
-	return false
-}
-
-func (e errorBatch) As(target interface{}) bool {
-	for _, err := range e {
-		if errors.As(err, target) {
-			return true
-		}
-	}
-	return false
-}
-
-func (e errorBatch) Unwrap() error {
-	if len(e) == 0 {
-		return nil
-	}
-	return e[0]
-}

tun/tun_linux.go

@@ -338,7 +338,7 @@ func (tun *NativeTun) Write(bufs [][]byte, offset int) (int, error) {
 		tun.writeOpMu.Unlock()
 	}()
 	var (
-		errs  []error
+		errs  error
 		total int
 	)
 	tun.toWrite = tun.toWrite[:0]
@@ -359,12 +359,12 @@ func (tun *NativeTun) Write(bufs [][]byte, offset int) (int, error) {
 			return total, os.ErrClosed
 		}
 		if err != nil {
-			errs = append(errs, err)
+			errs = errors.Join(errs, err)
 		} else {
 			total += n
 		}
 	}
-	return total, ErrorBatch(errs)
+	return total, errs
 }
 
 // handleVirtioRead splits in into bufs, leaving offset bytes at the front of