Use one binary with subcommands

1 files changed, 48 insertions, 0 deletions

diff --git a/sym.go b/sym.go
new file mode 100644
index 0000000..2405feb
--- /dev/null
+++ b/sym.go
@@ -0,0 +1,48 @@
+package main
+
+import (
+	"flag"
+	"fmt"
+	"os"
+	"path/filepath"
+)
+
+type subcommand interface {
+	registerFlags(*flag.FlagSet)
+	run(...string) error
+}
+
+func whichSubcommand(name string) (subcommand, bool) {
+	switch filepath.Base(name) {
+	case "enc":
+		return &defaultEncryptOptions, true
+	case "dec":
+		return &defaultDecryptOptions, true
+	default:
+		return nil, false
+	}
+}
+
+func run(args []string) error {
+	cmd, ok := whichSubcommand(args[0])
+	if !ok {
+		if len(args) < 2 {
+			return fmt.Errorf("missing subcommand")
+		}
+		cmd, ok = whichSubcommand(args[1])
+		if !ok {
+			return fmt.Errorf("invalid subcommand %q", args[1])
+		}
+		args = args[1:]
+	}
+	cmd.registerFlags(flag.CommandLine)
+	flag.CommandLine.Parse(args[1:])
+	return cmd.run(flag.Args()...)
+}
+
+func main() {
+	if err := run(os.Args); err != nil {
+		fmt.Fprintln(os.Stderr, err)
+		os.Exit(1)
+	}
+}