add memory tag example

examples/memtag/.gitignore

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+*.o
+.flavor
+.objs
+memtag.so
+assets.h
+cert

examples/memtag/conf/build.conf

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+# memtag build config
+# You can switch flavors using: kodev flavor [newflavor]
+
+# Set to yes if you wish to produce a single binary instead
+# of a dynamic library. If you set this to yes you must also
+# set kore_source together with kore_flavor.
+#single_binary=no
+#kore_source=/home/joris/src/kore
+#kore_flavor=
+
+# The flags below are shared between flavors
+cflags=-Wall -Wmissing-declarations -Wshadow
+cflags=-Wstrict-prototypes -Wmissing-prototypes
+cflags=-Wpointer-arith -Wcast-qual -Wsign-compare
+
+cxxflags=-Wall -Wmissing-declarations -Wshadow
+cxxflags=-Wpointer-arith -Wcast-qual -Wsign-compare
+
+# Mime types for assets served via the builtin asset_serve_*
+#mime_add=txt:text/plain; charset=utf-8
+#mime_add=png:image/png
+#mime_add=html:text/html; charset=utf-8
+
+dev {
+	# These flags are added to the shared ones when
+	# you build the "dev" flavor.
+	cflags=-g
+	cxxflags=-g
+}
+
+#prod {
+#	You can specify additional flags here which are only
+#	included if you build with the "prod" flavor.
+#}

examples/memtag/conf/memtag.conf

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+# memtag configuration
+
+bind		127.0.0.1 8888
+load		./memtag.so init
+
+tls_dhparam	dh2048.pem
+
+domain * {
+	certfile	cert/server.pem
+	certkey		cert/key.pem
+
+	static	/	page
+}

examples/memtag/src/memtag.c

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+/*
+ * Copyright (c) 2017 Joris Vink <joris@coders.se>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#include <kore/kore.h>
+#include <kore/http.h>
+
+/*
+ * This example demonstrates how dynamically reloadable modules
+ * can use the memory tagging system in Kore in order to restore
+ * the global pointers in the module.
+ */
+
+/* Some unique value. */
+#define MEM_TAG_HELLO		100
+
+int		init(int);
+int		page(struct http_request *);
+
+/* Global pointer, gets initialized to NULL when module loads/reloads. */
+char		*fixed_ptr = NULL;
+
+int
+init(int state)
+{
+	/* Ignore unload(s). */
+	if (state == KORE_MODULE_UNLOAD)
+		return (KORE_RESULT_OK);
+
+	printf("fixed_ptr: %p\n", (void *)fixed_ptr);
+
+	/* Attempt to lookup the original pointer. */
+	if ((fixed_ptr = kore_mem_lookup(MEM_TAG_HELLO)) == NULL) {
+		/* Failed, grab a new chunk of memory and tag it. */
+		printf("  allocating fixed_ptr for the first time\n");
+		fixed_ptr = kore_malloc_tagged(6, MEM_TAG_HELLO);
+		kore_strlcpy(fixed_ptr, "hello", 6);
+	} else {
+		printf("  fixed_ptr address resolved\n");
+	}
+
+	printf("  fixed_ptr: %p\n", (void *)fixed_ptr);
+	printf("  value    : %s\n", fixed_ptr);
+
+	return (KORE_RESULT_OK);
+}
+
+int
+page(struct http_request *req)
+{
+	http_response(req, 200, fixed_ptr, strlen(fixed_ptr));
+	return (KORE_RESULT_OK);
+}