mroe argv checks

Signed-off-by: Jeff Carr <jcarr@wit.com>

Makefile

@@ -5,6 +5,9 @@ run: clean build
 	make -C testautogen/ all
 	make -C testSort/
 
+test:
+	./autogenpb --proto test.proto
+
 vet:
 	@GO111MODULE=off go vet
 	@echo this go library package builds okay

main.go

@@ -21,7 +21,23 @@ func main() {
 	// for very new users or users unfamilar with the command line, this may help them
 	if argv.Base == "help" || argv.Base == "?" {
 		pp.WriteHelp(os.Stdout)
-		os.Exit(0)
+		os.Exit(-1)
+	}
+
+	// you need a proto file
+	if argv.Proto == "" {
+		log.Info("you must provide --proto <filename>")
+		os.Exit(-1)
+	}
+
+	if !shell.Exists(argv.Proto) {
+		log.Info("protobuf", argv.Proto, "is missing")
+		os.Exit(-1)
+	}
+
+	if ! strings.HasSuffix(argv.Proto, ".proto") {
+		log.Info("protobuf", argv.Proto, "must end in .proto")
+		os.Exit(-1)
 	}
 
 	cmd := []string{"go", "list", "-f", "'{{.Name}}'"}
@@ -32,7 +48,9 @@ func main() {
 	packageName = strings.Trim(packageName, "'")
 	log.Info("packageName == ", packageName)
 
-	f, _ := os.OpenFile("test.sort.pb.go", os.O_WRONLY|os.O_CREATE, 0600)
+	protobase := strings.TrimSuffix(argv.Proto, ".proto")
+
+	f, _ := os.OpenFile(protobase + ".sort.pb.go", os.O_WRONLY|os.O_CREATE, 0600)
 
 	sortmap := make(map[string]string)
 	sortmap["package"] = packageName

testautogen/Makefile

@@ -6,7 +6,7 @@ test: vet
 all: clean test.pb.go run goimports vet
 
 run:
-	../autogenpb
+	../autogenpb --proto test.proto
 
 vet:
 	@GO111MODULE=off go vet