fix ptrace (maybe)

src/misc/ptrace.c

@@ -8,11 +8,18 @@ long ptrace(int req, ...)
 	va_list ap;
 	pid_t pid;
 	void *addr, *data, *addr2;
+	long ret, result;
+
 	va_start(ap, req);
 	pid = va_arg(ap, pid_t);
 	addr = va_arg(ap, void *);
 	data = va_arg(ap, void *);
 	addr2 = va_arg(ap, void *);
 	va_end(ap);
-	return syscall(SYS_ptrace, req, pid, addr, data, addr2);
+
+	if (req<4U) data = &result;
+	ret = syscall(SYS_ptrace, req, pid, addr, data, addr2);
+
+	if (ret<0 || req>=4U) return ret;
+	return result;
 }