config: preserve ownership and permissions on configfile

cli/config/configfile/file.go

@@ -196,6 +196,9 @@ func (configFile *ConfigFile) Save() error {
 		os.Remove(temp.Name())
 		return err
 	}
+	// Try copying the current config file (if any) ownership and permissions
+	copyFilePermissions(configFile.Filename, temp.Name())
+
 	return os.Rename(temp.Name(), configFile.Filename)
 }
 

cli/config/configfile/file_unix.go

@@ -0,0 +1,35 @@
+// +build !windows
+
+package configfile
+
+import (
+	"os"
+	"syscall"
+)
+
+// copyFilePermissions copies file ownership and permissions from "src" to "dst",
+// ignoring any error during the process.
+func copyFilePermissions(src, dst string) {
+	var (
+		mode     os.FileMode = 0600
+		uid, gid int
+	)
+
+	fi, err := os.Stat(src)
+	if err != nil {
+		return
+	}
+	if fi.Mode().IsRegular() {
+		mode = fi.Mode()
+	}
+	if err := os.Chmod(dst, mode); err != nil {
+		return
+	}
+
+	uid = int(fi.Sys().(*syscall.Stat_t).Uid)
+	gid = int(fi.Sys().(*syscall.Stat_t).Gid)
+
+	if uid > 0 && gid > 0 {
+		_ = os.Chown(dst, uid, gid)
+	}
+}

cli/config/configfile/file_windows.go

@@ -0,0 +1,5 @@
+package configfile
+
+func copyFilePermissions(src, dst string) {
+	// TODO implement for Windows
+}