dockertar-sha256-helper: Error without arg

Provide a human understandable error when an argument is not provided. Signed-off-by: Steve Milner <[email protected]> Closes: #1117 Approved by: giuseppe
projectatomic · Oct 16, 2017 · eced7be · eced7be
1 parent d2c4ee8
commit eced7be
Showing 1 changed file with 7 additions and 3 deletions.
diff --git a/dockertar-sha256-helper.go b/dockertar-sha256-helper.go
@@ -1,14 +1,18 @@
 package main
 
 import (
-	"fmt"
 	"compress/gzip"
-	"os"
-	"io"
 	"crypto/sha256"
+	"fmt"
+	"io"
+	"os"
 )
 
 func main() {
+	// Require one positional argument
+	if len(os.Args) != 2 {
+		panic("One positional argument is required")
+	}
 	reader, err := os.Open(os.Args[1])
 	if err != nil {
 		os.Exit(1)