1 files changed, 314 insertions, 0 deletions
diff --git a/lib/trace-cmd/trace-plugin.c b/lib/trace-cmd/trace-plugin.c
new file mode 100644
index 00000000..127771ea
--- /dev/null
+++ b/lib/trace-cmd/trace-plugin.c
@@ -0,0 +1,314 @@
+// SPDX-License-Identifier: LGPL-2.1
+/*
+ * Copyright (C) 2009, 2010 Red Hat Inc, Steven Rostedt <srostedt@redhat.com>
+ *
+ */
+#include <stdlib.h>
+#include <unistd.h>
+#include <dlfcn.h>
+#include <sys/stat.h>
+#include <libgen.h>
+#include "trace-cmd.h"
+#include "trace-local.h"
+#include "trace-cmd-local.h"
+
+#define LOCAL_PLUGIN_DIR ".local/lib/trace-cmd/plugins/"
+
+struct trace_plugin_list {
+	struct trace_plugin_list	*next;
+	char				*name;
+	void				*handle;
+};
+
+struct trace_plugin_context {
+	enum tracecmd_context context;
+	enum tracecmd_plugin_flag flags;
+	union {
+		void				*data;
+		struct tracecmd_input		*trace_input;
+		struct tracecmd_output		*trace_output;
+	};
+};
+
+/**
+ * tracecmd_plugin_context_create - Create and initialize tracecmd plugins context.
+ * @context: Context of the trace-cmd command.
+ * @data: Pointer to the context specific data, which will be passed to plugins.
+ *
+ * Returns a pointer to created tracecmd plugins context, or NULL in case memory
+ * allocation fails. The returned pointer should be freed by free ().
+ */
+struct trace_plugin_context *
+tracecmd_plugin_context_create(enum tracecmd_context context, void *data)
+{
+	struct trace_plugin_context *trace;
+
+	trace = calloc(1, sizeof(struct trace_plugin_context));
+	if (!trace)
+		return NULL;
+	trace->context = context;
+	trace->data = data;
+	return trace;
+}
+
+/**
+ * tracecmd_plugin_set_flag - Set a flag to tracecmd plugins context.
+ * @context: Context of the trace-cmd command.
+ * @flag: Flag, whil will be set.
+ *
+ */
+void tracecmd_plugin_set_flag(struct trace_plugin_context *context,
+			      enum tracecmd_plugin_flag flag)
+{
+	if (context)
+		context->flags |= flag;
+}
+
+/**
+ * tracecmd_plugin_context_input - Get a tracecmd_input plugin context.
+ * @context: Context of the trace-cmd command.
+ *
+ * Returns pointer to tracecmd_input, if such context is available or
+ * NULL otherwise.
+ */
+struct tracecmd_input *
+tracecmd_plugin_context_input(struct trace_plugin_context *context)
+{
+	if (!context || context->context != TRACECMD_INPUT)
+		return NULL;
+	return context->trace_input;
+}
+
+/**
+ * tracecmd_plugin_context_output - Get a tracecmd_output plugin context
+ * @context: Context of the trace-cmd command.
+ *
+ * Returns pointer to tracecmd_output, if such context is available or
+ * NULL otherwise.
+ */
+struct tracecmd_output *
+tracecmd_plugin_context_output(struct trace_plugin_context *context)
+{
+	if (!context || context->context != TRACECMD_OUTPUT)
+		return NULL;
+	return context->trace_output;
+}
+
+static void
+load_plugin(struct trace_plugin_context *trace, const char *path,
+	    const char *file, void *data)
+{
+	struct trace_plugin_list **plugin_list = data;
+	tracecmd_plugin_load_func func;
+	struct trace_plugin_list *list;
+	const char *alias;
+	char *plugin;
+	void *handle;
+	int ret;
+
+	ret = asprintf(&plugin, "%s/%s", path, file);
+	if (ret < 0) {
+		tracecmd_warning("could not allocate plugin memory");
+		return;
+	}
+
+	handle = dlopen(plugin, RTLD_NOW | RTLD_GLOBAL);
+	if (!handle) {
+		tracecmd_warning("could not load plugin '%s'\n%s", plugin, dlerror());
+		goto out_free;
+	}
+
+	alias = dlsym(handle, TRACECMD_PLUGIN_ALIAS_NAME);
+	if (!alias)
+		alias = file;
+
+	func = dlsym(handle, TRACECMD_PLUGIN_LOADER_NAME);
+	if (!func) {
+		tracecmd_warning("could not find func '%s' in plugin '%s'\n%s",
+				 TRACECMD_PLUGIN_LOADER_NAME, plugin, dlerror());
+		goto out_free;
+	}
+
+	list = malloc(sizeof(*list));
+	if (!list) {
+		tracecmd_warning("could not allocate plugin memory");
+		goto out_free;
+	}
+
+	list->next = *plugin_list;
+	list->handle = handle;
+	list->name = plugin;
+	*plugin_list = list;
+
+	tracecmd_info("registering plugin: %s", plugin);
+	func(trace);
+	return;
+
+ out_free:
+	free(plugin);
+}
+
+static void
+load_plugins_dir(struct trace_plugin_context *trace, const char *suffix,
+		 const char *path,
+		 void (*load_plugin)(struct trace_plugin_context *trace,
+				     const char *path,
+				     const char *name,
+				     void *data),
+		 void *data)
+{
+	struct dirent *dent;
+	struct stat st;
+	DIR *dir;
+	int ret;
+
+	ret = stat(path, &st);
+	if (ret < 0)
+		return;
+
+	if (!S_ISDIR(st.st_mode))
+		return;
+
+	dir = opendir(path);
+	if (!dir)
+		return;
+
+	while ((dent = readdir(dir))) {
+		const char *name = dent->d_name;
+
+		if (strcmp(name, ".") == 0 ||
+		    strcmp(name, "..") == 0)
+			continue;
+
+		/* Only load plugins that end in suffix */
+		if (strcmp(name + (strlen(name) - strlen(suffix)), suffix) != 0)
+			continue;
+
+		load_plugin(trace, path, name, data);
+	}
+
+	closedir(dir);
+}
+
+static char *get_source_plugins_dir(void)
+{
+	char *p, path[PATH_MAX+1];
+	int ret;
+
+	ret = readlink("/proc/self/exe", path, PATH_MAX);
+	if (ret > PATH_MAX || ret < 0)
+		return NULL;
+
+	path[ret] = 0;
+	dirname(path);
+	p = strrchr(path, '/');
+	if (!p)
+		return NULL;
+	/* Check if we are in the the source tree */
+	if (strcmp(p, "/tracecmd") != 0)
+		return NULL;
+
+	strcpy(p, "/lib/trace-cmd/plugins");
+	return strdup(path);
+}
+
+static void
+load_plugins_hook(struct trace_plugin_context *trace, const char *suffix,
+		  void (*load_plugin)(struct trace_plugin_context *trace,
+				      const char *path,
+				      const char *name,
+				      void *data),
+		  void *data)
+{
+	char *home;
+	char *path;
+	char *envdir;
+	int ret;
+
+	if (trace && trace->flags & TRACECMD_DISABLE_PLUGINS)
+		return;
+
+	/*
+	 * If a system plugin directory was defined,
+	 * check that first.
+	 */
+#ifdef PLUGIN_TRACECMD_DIR
+	if (!trace || !(trace->flags & TRACECMD_DISABLE_SYS_PLUGINS))
+		load_plugins_dir(trace, suffix, PLUGIN_TRACECMD_DIR,
+				 load_plugin, data);
+#endif
+
+	/*
+	 * Next let the environment-set plugin directory
+	 * override the system defaults.
+	 */
+	envdir = getenv("TRACECMD_PLUGIN_DIR");
+	if (envdir)
+		load_plugins_dir(trace, suffix, envdir, load_plugin, data);
+
+	/*
+	 * Now let the home directory override the environment
+	 * or system defaults.
+	 */
+	home = getenv("HOME");
+	if (!home)
+		return;
+
+	ret = asprintf(&path, "%s/%s", home, LOCAL_PLUGIN_DIR);
+	if (ret < 0) {
+		tracecmd_warning("could not allocate plugin memory");
+		return;
+	}
+
+	load_plugins_dir(trace, suffix, path, load_plugin, data);
+
+	free(path);
+
+	path = get_source_plugins_dir();
+	if (path) {
+		load_plugins_dir(trace, suffix, path, load_plugin, data);
+		free(path);
+	}
+}
+
+/**
+ * tracecmd_load_plugins - Load trace-cmd specific plugins.
+ * @context: Context of the trace-cmd command, will be passed to the plugins
+ *	     at load time.
+ *
+ * Returns a list of loaded plugins
+ */
+struct trace_plugin_list*
+tracecmd_load_plugins(struct trace_plugin_context *trace)
+{
+	struct trace_plugin_list *list = NULL;
+
+	load_plugins_hook(trace, ".so", load_plugin, &list);
+	return list;
+}
+
+/**
+ * tracecmd_unload_plugins - Unload trace-cmd specific plugins.
+ * @plugin_list - List of plugins, previously loaded with tracecmd_load_plugins.
+ * @context: Context of the trace-cmd command, will be passed to the plugins
+ *	     at unload time.
+ *
+ */
+void
+tracecmd_unload_plugins(struct trace_plugin_list *plugin_list,
+			struct trace_plugin_context *trace)
+{
+	tracecmd_plugin_unload_func func;
+	struct trace_plugin_list *list;
+
+	while (plugin_list) {
+		list = plugin_list;
+		plugin_list = list->next;
+		func = dlsym(list->handle, TRACECMD_PLUGIN_UNLOADER_NAME);
+		if (func)
+			func(trace);
+		dlclose(list->handle);
+		free(list->name);
+		free(list);
+	}
+}