[lxc-devel] [lxd/master] Fix Defer

[gsquire on Github]

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From 601d274f2d6fc935ac73d1e741c1ce2a570ab207 Mon Sep 17 00:00:00 2001
From: Garrett Squire <github at garrettsquire.com>
Date: Mon, 12 Oct 2020 22:21:36 -0700
Subject: [PATCH] Fix defer in for loop

This patch fixes a call to defer inside of a loop and instead uses an
anonymous function to ensure proper behavior.
---
 lxd-agent/templates.go | 70 ++++++++++++++++++++++--------------------
 1 file changed, 36 insertions(+), 34 deletions(-)

diff --git a/lxd-agent/templates.go b/lxd-agent/templates.go
index 8a2833d892..2ce6a6a252 100644
--- a/lxd-agent/templates.go
+++ b/lxd-agent/templates.go
@@ -35,51 +35,53 @@ func templatesApply(path string) ([]string, error) {
 	// Go through the files and copy them into place.
 	files := []string{}
 	for tplPath, tpl := range metadata.Templates {
-		filePath := filepath.Join(path, fmt.Sprintf("%s.out", tpl.Template))
+		func() {
+			filePath := filepath.Join(path, fmt.Sprintf("%s.out", tpl.Template))
 
-		if !shared.PathExists(filePath) {
-			continue
-		}
-
-		var w *os.File
-		if shared.PathExists(tplPath) {
-			if tpl.CreateOnly {
+			if !shared.PathExists(filePath) {
 				continue
 			}
 
-			// Open the existing file.
-			w, err = os.Create(tplPath)
-			if err != nil {
-				return nil, errors.Wrap(err, "Failed to create template file")
+			var w *os.File
+			if shared.PathExists(tplPath) {
+				if tpl.CreateOnly {
+					continue
+				}
+
+				// Open the existing file.
+				w, err = os.Create(tplPath)
+				if err != nil {
+					return nil, errors.Wrap(err, "Failed to create template file")
+				}
+			} else {
+				// Create the directories leading to the file.
+				os.MkdirAll(filepath.Dir(tplPath), 0755)
+
+				// Create the file itself.
+				w, err = os.Create(tplPath)
+				if err != nil {
+					return nil, err
+				}
+
+				// Fix mode.
+				w.Chmod(0644)
 			}
-		} else {
-			// Create the directories leading to the file.
-			os.MkdirAll(filepath.Dir(tplPath), 0755)
+			defer w.Close()
 
-			// Create the file itself.
-			w, err = os.Create(tplPath)
+			// Do the copy.
+			src, err := os.Open(filePath)
 			if err != nil {
 				return nil, err
 			}
+			defer src.Close()
 
-			// Fix mode.
-			w.Chmod(0644)
-		}
-		defer w.Close()
-
-		// Do the copy.
-		src, err := os.Open(filePath)
-		if err != nil {
-			return nil, err
-		}
-		defer src.Close()
-
-		_, err = io.Copy(w, src)
-		if err != nil {
-			return nil, err
-		}
+			_, err = io.Copy(w, src)
+			if err != nil {
+				return nil, err
+			}
 
-		files = append(files, tplPath)
+			files = append(files, tplPath)
+		}()
 	}
 
 	return files, nil