kvm tools: Improve 'lkvm sandbox' syntax

This patch adds the possibility to run commands using the default parameter
in 'lkvm sandbox'. For example, a user would now be able to run:

	'lkvm sandbox firefox'

And have a sandboxed firefox instance start in the guest.

For commands with parameters, we still need to use dashdash to pass the
parameters (similar to 'git bisect run'). For example:

	'lkvm sandbox -- ls -al /bin

Suggested-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Sasha Levin <levinsasha928@gmail.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>

builtin-run.c

@@ -114,6 +114,7 @@ static const char * const run_usage[] = {
 };
 
 enum {
+	KVM_RUN_DEFAULT,
 	KVM_RUN_SANDBOX,
 };
 
@@ -904,16 +905,27 @@ int kvm_cmd_run(int argc, const char **argv, const char *prefix)
 				}
 			}
 
-			if (kernel_filename) {
+			if ((kvm_run_wrapper == KVM_RUN_DEFAULT && kernel_filename) ||
+				(kvm_run_wrapper == KVM_RUN_SANDBOX && sandbox)) {
 				fprintf(stderr, "Cannot handle parameter: "
 						"%s\n", argv[0]);
 				usage_with_options(run_usage, options);
 				return EINVAL;
 			}
-			/* first unhandled parameter is treated as a kernel
-			   image
-			 */
-			kernel_filename = argv[0];
+			if (kvm_run_wrapper == KVM_RUN_SANDBOX) {
+				/*
+				 * first unhandled parameter is treated as
+				 * sandbox command
+				 */
+				sandbox = DEFAULT_SANDBOX_FILENAME;
+				kvm_run_write_sandbox_cmd(argv, argc);
+			} else {
+				/*
+				 * first unhandled parameter is treated as a kernel
+				 * image
+				 */
+				kernel_filename = argv[0];
+			}
 			argv++;
 			argc--;
 		}