Fix Windows chown error (#28748)

* noop for windows chown

* changelog

changelog/28748.txt

@@ -0,0 +1,6 @@
+```release-note:bug
+agent: Fix chown error running agent on Windows with an auto-auth file sinks. 
+```
+```release-note:bug
+proxy: Fix chown error running proxy on Windows with an auto-auth file sink.
+```

command/agentproxyshared/sink/file/file_sink.go

@@ -13,6 +13,7 @@ import (
 	hclog "github.com/hashicorp/go-hclog"
 	uuid "github.com/hashicorp/go-uuid"
 	"github.com/hashicorp/vault/command/agentproxyshared/sink"
+	"github.com/hashicorp/vault/helper/osutil"
 )
 
 // fileSink is a Sink implementation that writes a token to a file
@@ -117,7 +118,7 @@ func (f *fileSink) WriteToken(token string) error {
 		return fmt.Errorf("error opening temp file in dir %s for writing: %w", targetDir, err)
 	}
 
-	if err := tmpFile.Chown(f.owner, f.group); err != nil {
+	if err := osutil.Chown(tmpFile, f.owner, f.group); err != nil {
 		return fmt.Errorf("error changing ownership of %s: %w", tmpFile.Name(), err)
 	}
 

helper/osutil/fileinfo_unix.go

@@ -8,6 +8,7 @@ package osutil
 import (
 	"fmt"
 	"io/fs"
+	"os"
 	"os/user"
 	"strconv"
 	"syscall"
@@ -59,3 +60,7 @@ func FileUidMatch(info fs.FileInfo, path string, uid int) (err error) {
 func Umask(newmask int) int {
 	return syscall.Umask(newmask)
 }
+
+func Chown(f *os.File, owner, group int) error {
+	return f.Chown(owner, group)
+}

helper/osutil/fileinfo_windows.go

@@ -7,6 +7,7 @@ package osutil
 
 import (
 	"io/fs"
+	"os"
 )
 
 func FileUidMatch(info fs.FileInfo, path string, uid int) error {
@@ -17,3 +18,7 @@ func FileUidMatch(info fs.FileInfo, path string, uid int) error {
 func Umask(newmask int) int {
 	return 0
 }
+
+func Chown(f *os.File, owner, group int) error {
+	return nil
+}