kernelshark: Add infrastructure to allow kernelshark to have plugins

Add a -p plugin command line option for kernelshark to accept a plugin that
can modify how kernelshark works. This is just adds a loader, currently
nothing uses it yet.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

2 files changed, 94 insertions, 1 deletions

diff --git a/kernel-shark.c b/kernel-shark.c
index 58ab9d63..a7a75a80 100644
--- a/kernel-shark.c
+++ b/kernel-shark.c
@@ -29,12 +29,14 @@
 #include <errno.h>
 #include <getopt.h>
 #include <libgen.h>
+#include <dlfcn.h>
 
 #include "trace-compat.h"
 #include "trace-capture.h"
 #include "trace-cmd.h"
 #include "trace-gui.h"
 #include "kernel-shark.h"
+#include "kshark-plugin.h"
 #include "event-utils.h"
 #include "version.h"
 
@@ -1799,6 +1801,57 @@ button_press_event(GtkWidget *widget, GdkEventButton *event, gpointer data)
 	return FALSE;
 }
 
+static struct plugin_list {
+	struct plugin_list		*next;
+	const char			*file;
+} *plugins;
+static struct plugin_list **plugin_next = &plugins;
+
+static void add_plugin(const char *file)
+{
+	struct stat st;
+	int ret;
+
+	ret = stat(default_input_file, &st);
+	if (ret < 0) {
+		warning("plugin %s not found", file);
+		return;
+	}
+
+	*plugin_next = calloc(sizeof(struct plugin_list), 1);
+	if (!*plugin_next)
+		die("failed to allocat memory for plugin");
+
+	(*plugin_next)->file = file;
+	plugin_next = &(*plugin_next)->next;
+}
+
+static void handle_plugins(struct shark_info *info)
+{
+	kshark_plugin_load_func func;
+	struct plugin_list *plugin;
+	void *handle;
+
+	while ((plugin = plugins)) {
+		plugins = plugin->next;
+
+		handle = dlopen(plugin->file, RTLD_NOW | RTLD_GLOBAL);
+		free(plugin);
+		if (!handle) {
+			warning("cound not load plugin '%s'\n%s\n",
+				plugin->file, dlerror());
+			continue;
+		}
+		func = dlsym(handle, KSHARK_PLUGIN_LOADER_NAME);
+		if (!func) {
+			warning("cound not find func '%s' in plugin '%s'\n%s\n",
+				KSHARK_PLUGIN_LOADER_NAME, plugin->file, dlerror());
+			continue;
+		}
+		func(info);
+	}
+}
+
 static void sig_end(int sig)
 {
 	fprintf(stderr, "kernelshark: Received SIGINT\n");
@@ -1835,7 +1888,7 @@ void kernel_shark(int argc, char **argv)
 
 	gtk_init(&argc, &argv);
 
-	while ((c = getopt(argc, argv, "hvi:")) != -1) {
+	while ((c = getopt(argc, argv, "hvi:p:")) != -1) {
 		switch(c) {
 		case 'h':
 			usage(basename(argv[0]));
@@ -1848,6 +1901,9 @@ void kernel_shark(int argc, char **argv)
 		case 'i':
 			input_file = optarg;
 			break;
+		case 'p':
+			add_plugin(optarg);
+			break;
 		default:
 			/* assume the other options are for gtk */
 			break;
@@ -2435,6 +2491,8 @@ void kernel_shark(int argc, char **argv)
 
 	gtk_widget_set_size_request(window, TRACE_WIDTH, TRACE_HEIGHT);
 
+	handle_plugins(info);
+
 	gdk_threads_enter();
 
 	/*
diff --git a/kshark-plugin.h b/kshark-plugin.h
new file mode 100644
index 00000000..95ba797a
--- /dev/null
+++ b/kshark-plugin.h
@@ -0,0 +1,35 @@
+/*
+ * Copyright (C) 2016 Red Hat Inc, Steven Rostedt <srostedt@redhat.com>
+ *
+ * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License (not later!)
+ *
+ * This program 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not,  see <http://www.gnu.org/licenses>
+ *
+ * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ */
+#ifndef _KSHARK_PLUGIN_H
+#define _KSHARK_PLUGIN_H
+
+#define KSHARK_PLUGIN_LOADER kshark_plugin_loader
+#define KSHARK_PLUGIN_UNLOADER kshark_plugin_unloader
+
+#define _MAKE_STR(x)	#x
+#define MAKE_STR(x)	_MAKE_STR(x)
+#define KSHARK_PLUGIN_LOADER_NAME MAKE_STR(KSHARK_PLUGIN_LOADER)
+#define KSHARK_PLUGIN_UNLOADER_NAME MAKE_STR(KSHARK_PLUGIN_UNLOADER)
+
+typedef int (*kshark_plugin_load_func)(void *info);
+typedef int (*kshark_plugin_unload_func)(void *info);
+
+
+#endif