Add initial plugin header

This patch adds the first preliminary draft plugin description. It is
missing many things, most importantly documentation.

More importantly it is likely not yet complete.

Signed-off-by: Olliver Schinagl <oliver@schinagl.nl>

7 files changed, 164 insertions, 3 deletions

diff --git a/configure.ac b/configure.ac
index e8b8193..4396242 100644
--- a/configure.ac
+++ b/configure.ac
@@ -94,6 +94,7 @@ packaging/pkgbuild/Makefile
 po/Makefile.in
 src/Makefile
 src/bin/Makefile
+src/include/Makefile
 src/lib/Makefile
 src/tests/Makefile
 doc/engagement.1
diff --git a/po/POTFILES.in b/po/POTFILES.in
index 2708812..7269d3e 100644
--- a/po/POTFILES.in
+++ b/po/POTFILES.in
@@ -1,2 +1,3 @@
 src/bin/engagement.c
 src/bin/engagement_private.h
+src/lib/plugin.c
diff --git a/src/Makefile.am b/src/Makefile.am
index 15871c9..b52407c 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -1,4 +1,4 @@
 MAINTAINERCLEANFILES = Makefile.in
 
-SUBDIRS = lib bin tests
+SUBDIRS = include lib bin tests
 
diff --git a/src/include/Makefile.am b/src/include/Makefile.am
new file mode 100644
index 0000000..6a1282d
--- /dev/null
+++ b/src/include/Makefile.am
@@ -0,0 +1,6 @@
+MAINTAINERCLEANFILES = Makefile.in
+
+includesdir = $(includedir)/engagement
+includes_HEADERS = engagement/plugin.h
+
+EXTRA_DIST = gettext.h
diff --git a/src/include/engagement/plugin.h b/src/include/engagement/plugin.h
new file mode 100644
index 0000000..7bd7fa6
--- /dev/null
+++ b/src/include/engagement/plugin.h
@@ -0,0 +1,78 @@
+/*
+ * (c) Copyright 2016 Olliver Schinagl
+ * Author: Olliver Schinagl <oliver@schinagl.nl>
+ *
+ * SPDX-License-Identifier:	AGPL-3.0+
+ */
+
+/** \file
+ * Common header to describe the generic plugin API.
+ */
+#ifndef _PLUGIN_H_
+#define _PLUGIN_H_
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#include <stdbool.h>
+#include <stdint.h>
+
+/**
+ * @defgroup Plugins
+ * @ingroup engagement
+ *
+ * Generic plugin API
+ */
+
+#define PLUGIN_MAGIC 0		/* TODO pick plugin magic */
+#define PLUGIN_VERSION_MAJOR 0	/* TODO replace with version from src? @ENGAGEMENT_VERSION_MAJOR@ */
+#define PLUGIN_VERSION_MINOR 0	/* TODO replace with version from src? */
+
+#define PLUGIN_SYMBOL "calendar_plugin" /* TODO use generic name */
+
+#define PLUGIN_INIT(plugin)
+
+enum plugin_type {
+	PLUGIN_TYPE_CALENDAR,
+	PLUGIN_TYPE_DIRECTORY,
+};
+
+struct plugin_info {
+	const char *name;
+	const char *summary;
+	const char *description;
+	const char *help;
+	const char *author;
+	const char *email;
+	const char *url;
+};
+
+struct plugin_version {
+	uint8_t major;
+	uint8_t minor;
+	uint32_t micro;
+};
+
+struct plugin {
+	uint32_t magic;
+	void *_handle;
+	enum plugin_type type;
+	const char *id;
+	struct plugin_version version;
+	struct plugin_info info;
+	void *dependencies; /* Unused/reserved */
+	bool (*load)(void);
+	bool (*unload)(void);
+	void *ui; /* struct plugin_ui ui; Unused/reserved */
+	void *ops;
+	void *priv;
+};
+
+struct plugin *plugin_load(const char *path);
+int plugin_unload(struct plugin *plugin);
+
+#ifdef __cplusplus
+}
+#endif
+#endif /* _PLUGIN_H_ */
diff --git a/src/lib/Makefile.am b/src/lib/Makefile.am
index 0eaf568..fc64133 100644
--- a/src/lib/Makefile.am
+++ b/src/lib/Makefile.am
@@ -3,6 +3,7 @@ MAINTAINERCLEANFILES = Makefile.in
 AM_CPPFLAGS = \
 -I$(top_srcdir)/src/lib \
 -I$(top_builddir)/src/lib \
+-I$(top_srcdir)/src/include \
 -DPACKAGE_LIB_DIR=\"$(libdir)\" \
 -DPACKAGE_DATA_DIR=\"$(datadir)/$(PACKAGE)\" \
 @EFL_CFLAGS@ \
@@ -13,6 +14,6 @@ lib_LTLIBRARIES = libengagement.la
 includes_HEADERS = engagement.h
 includesdir = $(includedir)/engagement-@VMAJ@
 
-libengagement_la_SOURCES = engagement.c
-libengagement_la_LIBADD = @EFL_LIBS@ -lm
+libengagement_la_SOURCES = engagement.c plugin.c
+libengagement_la_LIBADD = @EFL_LIBS@ @LIBDL@
 libengagement_la_LDFLAGS = @EFL_LTLIBRARY_FLAGS@
diff --git a/src/lib/plugin.c b/src/lib/plugin.c
new file mode 100644
index 0000000..09df8de
--- /dev/null
+++ b/src/lib/plugin.c
@@ -0,0 +1,74 @@
+/*
+ * (c) Copyright 2016 Olliver Schinagl
+ * Author: Olliver Schinagl <oliver@schinagl.nl>
+ *
+ * SPDX-License-Identifier:	AGPL-3.0+
+ */
+
+#include <errno.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <dlfcn.h>
+
+#include <engagement/plugin.h>
+
+struct plugin *plugin_load(const char *path)
+{
+	struct plugin *plugin;
+	void *handle;
+
+	handle = dlopen(path, RTLD_LAZY); /* TODO check if RTLD_LAZY is what we want */
+	if (!handle) {
+		// TODO EINA_LOG
+		fprintf(stderr, "dlopen failed: %s\n", dlerror());
+		return NULL;
+	}
+
+	/* TODO use macro's to allow for static inclusion */
+	/* TODO use dlvsym() if available */
+	plugin = (struct plugin *)dlsym(handle, PLUGIN_SYMBOL);
+	if(!plugin) {
+		// TODO EINA_LOG
+		fprintf(stderr, "dlsym failed%s\n", dlerror());
+		return NULL;
+	}
+
+	if (plugin->magic != PLUGIN_MAGIC) {
+		// TODO EINA_LOG
+		fprintf(stderr, "Failed to init plugin, magic mismatch, plugin corrupt?\n");
+		return NULL;
+	}
+	plugin->_handle = handle;
+
+	if (plugin->load)
+		plugin->load();
+
+	return plugin;
+}
+
+int plugin_unload(struct plugin *plugin)
+{
+	int error;
+
+	if (!plugin) {
+		// TODO EINA_LOG
+		fprintf(stderr, "Cannot unload plugin %p.\n", plugin);
+		return -EFAULT;
+	}
+	
+	if (plugin->unload)
+		plugin->unload();
+
+	if (!plugin->_handle) {
+		// TODO EINA_LOG
+		fprintf(stderr, "Error, no handle for plugin %s\n",
+			       plugin->info.name);
+		return -EFAULT;
+	}
+	error = dlclose(plugin->_handle);
+	if (error)
+		// TODO EINA_LOG
+		fprintf(stderr, "Failed to close %s\n", dlerror());
+
+	return error;
+}