Platform: Consolidate regular file resolution

Reuse ResolveRegularFile for Lua loading/signing, local config, and assets.
Only evaluate file symlinks when needed, tolerating junction-related
resolution failures on a best-effort basis.

main/commands/all/lua/sign.go

@@ -5,6 +5,7 @@ import (
 	"path/filepath"
 
 	xlua "github.com/xtls/xray-core/common/lua"
+	"github.com/xtls/xray-core/common/platform"
 	"github.com/xtls/xray-core/main/commands/base"
 )
 
@@ -32,15 +33,15 @@ func executeSign(cmd *base.Command, args []string) {
 		cmd.Usage()
 	}
 
-	info, err := os.Stat(args[0])
+	input, info, err := platform.ResolveRegularFile(args[0])
 	if err != nil {
 		base.Fatalf("failed to inspect Lua file: %s", err)
 	}
-	if !info.Mode().IsRegular() {
-		base.Fatalf("Lua input is not a regular file: %s", args[0])
+	if filepath.Ext(input) != ".lua" {
+		base.Fatalf("Lua file extension must be .lua")
 	}
 
-	code, err := os.ReadFile(args[0])
+	code, err := os.ReadFile(input)
 	if err != nil {
 		base.Fatalf("failed to read Lua file: %s", err)
 	}
@@ -58,7 +59,7 @@ func executeSign(cmd *base.Command, args []string) {
 	}
 	output := *signOutput
 	if output == "" {
-		output = args[0]
+		output = input
 	}
 	if err := writeSignedFile(output, signed, info.Mode().Perm()); err != nil {
 		base.Fatalf("failed to write signed Lua file: %s", err)
@@ -66,15 +67,9 @@ func executeSign(cmd *base.Command, args []string) {
 }
 
 func writeSignedFile(path string, code []byte, mode os.FileMode) error {
-	if info, err := os.Stat(path); err == nil {
-		if !info.Mode().IsRegular() {
-			return &os.PathError{Op: "write", Path: path, Err: os.ErrInvalid}
-		}
+	if resolved, info, err := platform.ResolveRegularFile(path); err == nil {
+		path = resolved
 		mode = info.Mode().Perm()
-		path, err = filepath.EvalSymlinks(path)
-		if err != nil {
-			return err
-		}
 	} else if !os.IsNotExist(err) {
 		return err
 	}