main: check directories for existence early

This prevents that the user enters the password only to get an error
later.

1 files changed, 33 insertions, 0 deletions

diff --git a/checkdir.go b/checkdir.go
new file mode 100644
index 0000000..182bf97
--- /dev/null
+++ b/checkdir.go
@@ -0,0 +1,33 @@
+package main
+
+import (
+	"io/ioutil"
+	"fmt"
+	"os"
+)
+
+func checkDirEmpty(dir string) error {
+	err := checkDir(dir)
+	if err != nil {
+		return err
+	}
+	entries, err := ioutil.ReadDir(dir)
+	if err != nil {
+		return err
+	}
+	if len(entries) == 0 {
+		return nil
+	}
+	return fmt.Errorf("directory %s not empty", dir)
+}
+
+func checkDir(dir string) error {
+	fi, err := os.Stat(dir)
+	if err != nil {
+		return err
+	}
+	if ! fi.IsDir() {
+		return fmt.Errorf("%s is not a directory")
+	}
+	return nil
+}