api: doxygen: Add Doxygen sections

Add a Doxygen introduction to seccomp.h.in and add an
API section to api.c.

Signed-off-by: Tom Hromatka <tom.hromatka@oracle.com>

Author: drakenclimber

include/seccomp.h.in

@@ -1,6 +1,8 @@
-/**
+/*
  * Seccomp Library
  *
+ * Copyright (c) 2021,2022 Microsoft corporation <paulmoore@microsoft.com>
+ * Copyright (c) 2018-2022 Oracle <tom.hromatka@oracle.com>
  * Copyright (c) 2019 Cisco Systems <pmoore2@cisco.com>
  * Copyright (c) 2012,2013 Red Hat <pmoore@redhat.com>
  * Author: Paul Moore <paul@paul-moore.com>
@@ -35,6 +37,24 @@
 extern "C" {
 #endif
 
+/*! \mainpage libseccomp
+ *
+ * \section intro_sec Introduction
+ *
+ * @c The libseccomp library provides an easy to use, platform independent,
+ * interface to the Linux Kernel's syscall filtering mechanism. The libseccomp
+ * API is designed to abstract away the underlying BPF based syscall filter
+ * language and present a more conventional function-call based filtering 
+ * interface that should be familiar to, and easily adopted by, application
+ * developers.
+ *
+ * View the entire
+ * <a href="https://github.com/seccomp/libseccomp/blob/main/README.md">README</a>
+ * for more information.
+ *
+ * Libseccomp's C APIs are outlined in the @ref APIs "APIs" section.
+ */
+
 /*
  * version information
  */

src/api.c

@@ -38,6 +38,11 @@
 #include "helper.h"
 #include "system.h"
 
+/**
+ * @defgroup APIs
+ * @{
+ */
+
 #define API	__attribute__((visibility("default")))
 
 const struct scmp_version library_version = {
@@ -765,3 +770,7 @@ API int seccomp_export_bpf_mem(const scmp_filter_ctx ctx, void *buf,
 
 	return rc;
 }
+
+/**
+ * @}
+ */