cmd/sharefs: improve help message

This improves consistency with the fuse_main help message.

Signed-off-by: Ophestra <cat@gensokyo.uk>

cmd/sharefs/fuse.go

@@ -108,13 +108,17 @@ func sharefs_destroy(private_data unsafe.Pointer) {
 }
 
 // showHelp prints the help message.
-func showHelp() {
+func showHelp(args *C.struct_fuse_args) {
 	fmt.Printf("usage: %s [options] <mountpoint>\n\n", executableName)
-	C.fuse_cmdline_help()
-	C.fuse_lowlevel_help()
+
+	fmt.Println("Filesystem options:")
 	fmt.Println("    -o source=/data/media  source directory to be mounted")
 	fmt.Println("    -o setuid=1023         uid to run as when starting as root")
 	fmt.Println("    -o setgid=1023         gid to run as when starting as root")
+
+	fmt.Println("\nFUSE options:")
+	C.fuse_cmdline_help()
+	C.fuse_lib_help(args)
 }
 
 // parseOpts parses fuse options via fuse_opt_parse.
@@ -155,7 +159,7 @@ func parseOpts(args *C.struct_fuse_args) (
 	}
 
 	if unsafeOpts.source == nil || *unsafeOpts.source == 0 {
-		showHelp()
+		showHelp(args)
 		ret = 1
 		return
 	} else {