init

main.go

@@ -0,0 +1,55 @@
+package main
+
+import (
+	"crypto/sha1"
+	"crypto/sha256"
+	"crypto/sha512"
+	"flag"
+	"fmt"
+	"io"
+	"os"
+)
+
+var algo = flag.String("a", "sha256", "algorithm to use")
+
+func main() {
+	flag.Parse()
+	files := flag.Args()
+	h := sha256.New()
+	switch *algo {
+	case "sha1", "1":
+		h = sha1.New()
+	case "sha256", "256":
+		h = sha256.New()
+	case "sha512", "512":
+		h = sha512.New()
+	default:
+		fmt.Fprintf(os.Stderr, "unsupported algorithm: %v\n", *algo)
+		os.Exit(1)
+	}
+
+	if len(files) == 0 {
+		_, err := io.Copy(h, os.Stdin)
+		if err != nil {
+			fmt.Fprintf(os.Stderr, "%v\n", err)
+			os.Exit(1)
+		}
+		fmt.Printf("%x  -\n", h.Sum(nil))
+	} else {
+		for _, name := range files {
+			f, err := os.Open(name)
+			if err != nil {
+				fmt.Fprintf(os.Stderr, "%v\n", err)
+				continue
+			}
+			h.Reset()
+			_, err = io.Copy(h, f)
+			f.Close()
+			if err != nil {
+				fmt.Fprintf(os.Stderr, "%v\n", err)
+				continue
+			}
+			fmt.Printf("%x  %s\n", h.Sum(nil), name)
+		}
+	}
+}