lws_system

include/libwebsockets.h

@@ -1,7 +1,7 @@
 /*
  * libwebsockets - small server side websockets and web server implementation
  *
- * Copyright (C) 2010-2018 Andy Green <andy@warmcat.com>
+ * Copyright (C) 2010-2019 Andy Green <andy@warmcat.com>
  *
  *  This library is free software; you can redistribute it and/or
  *  modify it under the terms of the GNU Lesser General Public
@@ -517,6 +517,7 @@ struct lws_tokens;
 struct lws_vhost;
 struct lws;
 
+#include <libwebsockets/lws-system.h>
 #include <libwebsockets/lws-ws-close.h>
 #include <libwebsockets/lws-callbacks.h>
 #include <libwebsockets/lws-ws-state.h>

include/libwebsockets/lws-context-vhost.h

@@ -673,6 +673,9 @@ struct lws_context_creation_info {
 	 * on a unix socket, you can give a "username:groupname" string here
 	 * to control the owner:group it's created with.  It's always created
 	 * with 0660 mode. */
+	const lws_system_ops_t *system_ops;
+	/**< CONTEXT: hook up lws_system_ apis to system-specific
+	 * implementations */
 
 	/* Add new things just above here ---^
 	 * This is part of the ABI, don't needlessly break compatibility

include/libwebsockets/lws-system.h

@@ -0,0 +1,84 @@
+/*
+ * libwebsockets - small server side websockets and web server implementation
+ *
+ * Copyright (C) 2010-2019 Andy Green <andy@warmcat.com>
+ *
+ *  This library is free software; you can redistribute it and/or
+ *  modify it under the terms of the GNU Lesser General Public
+ *  License as published by the Free Software Foundation:
+ *  version 2.1 of the License.
+ *
+ *  This library is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ *  Lesser General Public License for more details.
+ *
+ *  You should have received a copy of the GNU Lesser General Public
+ *  License along with this library; if not, write to the Free Software
+ *  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
+ *  MA  02110-1301  USA
+ *
+ * included from libwebsockets.h
+ *
+ * This provides a clean way to interface lws user code to be able to
+ * work unchanged on different systems for fetching common system information,
+ * and performing common system operations like reboot.
+ *
+ * An ops struct with the system-specific implementations is set at
+ * context creation time, and apis are provided that call through to
+ * those where they exist.
+ */
+
+typedef enum {
+	LWS_SYSI_HRS_DEVICE_MODEL = 1,
+	LWS_SYSI_HRS_DEVICE_SERIAL,
+	LWS_SYSI_HRS_FIRMWARE_VERSION,
+
+	LWS_SYSI_USER_BASE = 100
+} lws_system_item_t;
+
+typedef union {
+	const char	*hrs;	/* human readable string */
+	void		*data;
+	time_t		t;
+} lws_system_arg_t;
+
+typedef struct lws_system_ops {
+	int (*get_info)(lws_system_item_t i, lws_system_arg_t arg, size_t *len);
+	int (*reboot)(void);
+} lws_system_ops_t;
+
+/* wrappers handle NULL members or no ops struct set at all cleanly */
+
+/**
+ * lws_system_get_info() - get standardized system information
+ *
+ * \param context: the lws_context
+ * \param item: which information to fetch
+ * \param arg: where to place the result
+ * \param len: incoming: max length of result, outgoing: used length of result
+ *
+ * This queries a standardized information-fetching ops struct that can be
+ * applied to the context... the advantage is it allows you to get common items
+ * of information like a device serial number writing the code once, even if the
+ * actual serial number muse be fetched in wildly different ways depending on
+ * the exact platform it's running on.
+ *
+ * Set arg and *len on entry to be the result location and the max length that
+ * can be used there, on seccessful exit *len is set to the actual length and
+ * 0 is returned.  On error, 1 is returned.
+ */
+LWS_EXTERN LWS_VISIBLE int
+lws_system_get_info(struct lws_context *context, lws_system_item_t item,
+		    lws_system_arg_t arg, size_t *len);
+
+
+/**
+ * lws_system_reboot() - if provided, use the lws_system ops to reboot
+ *
+ * \param context: the lws_context
+ *
+ * If possible, the system will reboot.  Otherwise returns 1.
+ */
+LWS_EXTERN LWS_VISIBLE int
+lws_system_reboot(struct lws_context *context);

lib/core/context.c

@@ -120,6 +120,7 @@ lws_create_context(const struct lws_context_creation_info *info)
 	context->gid = info->gid;
 	context->username = info->username;
 	context->groupname = info->groupname;
+	context->system_ops = info->system_ops;
 
 	/* if he gave us names, set the uid / gid */
 	if (lws_plat_drop_app_privileges(context, 0))

lib/core/libwebsockets.c

@@ -934,3 +934,22 @@ lws_humanize(char *p, int len, uint64_t v, const lws_humanize_unit_t *schema)
 
 	return 0;
 }
+
+int
+lws_system_get_info(struct lws_context *context, lws_system_item_t item,
+		    lws_system_arg_t arg, size_t *len)
+{
+	if (!context->system_ops || !context->system_ops->get_info)
+		return 1;
+
+	return context->system_ops->get_info(item, arg, len);
+}
+
+int
+lws_system_reboot(struct lws_context *context)
+{
+	if (!context->system_ops || !context->system_ops->reboot)
+		return 1;
+
+	return context->system_ops->reboot();
+}

lib/core/private.h

@@ -308,6 +308,7 @@ struct lws_context {
 	time_t next_cull;
 #endif
 
+	const lws_system_ops_t *system_ops;
 	void *external_baggage_free_on_destroy;
 	const struct lws_token_limits *token_limits;
 	void *user_space;