/*
 * Copyright (C) 2009, 2010 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 Lesser General Public
 * License as published by the Free Software Foundation;
 * version 2.1 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 Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this program; if not,  see <http://www.gnu.org/licenses>
 *
 * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 */

#include <stdio.h>
#include <string.h>
#include <dlfcn.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <dirent.h>
#include "event-parse.h"
#include "event-utils.h"

#define LOCAL_PLUGIN_DIR ".traceevent/plugins"

static struct registered_plugin_options {
        struct registered_plugin_options        *next;
        struct pevent_plugin_option             *options;
} *registered_options;

static struct trace_plugin_options {
        struct trace_plugin_options     *next;
        char                            *plugin;
        char                            *option;
        char                            *value;
} *trace_plugin_options;

struct plugin_list {
        struct plugin_list      *next;
        char                    *name;
        void                    *handle;
};

/**
 * traceevent_plugin_list_options - get list of plugin options
 *
 * Returns an array of char strings that list the currently registered
 * plugin options in the format of <plugin>:<option>. This list can be
 * used by toggling the option.
 *
 * Returns NULL if there's no options registered. On error it returns
 * INVALID_PLUGIN_LIST_OPTION
 *
 * Must be freed with traceevent_plugin_free_options_list().
 */
char **traceevent_plugin_list_options(void)
{
        struct registered_plugin_options *reg;
        struct pevent_plugin_option *op;
        char **list = NULL;
        char *name;
        int count = 0;

        for (reg = registered_options; reg; reg = reg->next) {
                for (op = reg->options; op->name; op++) {
                        char *alias = op->plugin_alias ? op->plugin_alias : op->file;
                        char **temp = list;

                        name = malloc(strlen(op->name) + strlen(alias) + 2);
                        if (!name)
                                goto err;

                        sprintf(name, "%s:%s", alias, op->name);
                        list = realloc(list, count + 2);
                        if (!list) {
                                list = temp;
                                free(name);
                                goto err;
                        }
                        list[count++] = name;
                        list[count] = NULL;
                }
        }
        return list;

 err:
        while (--count >= 0)
                free(list[count]);
        free(list);

        return INVALID_PLUGIN_LIST_OPTION;
}

void traceevent_plugin_free_options_list(char **list)
{
        int i;

        if (!list)
                return;

        if (list == INVALID_PLUGIN_LIST_OPTION)
                return;

        for (i = 0; list[i]; i++)
                free(list[i]);

        free(list);
}

static int
update_option(const char *file, struct pevent_plugin_option *option)
{
        struct trace_plugin_options *op;
        char *plugin;

        if (option->plugin_alias) {
                plugin = strdup(option->plugin_alias);
                if (!plugin)
                        return -1;
        } else {
                char *p;
                plugin = strdup(file);
                if (!plugin)
                        return -1;
                p = strstr(plugin, ".");
                if (p)
                        *p = '\0';
        }

        /* first look for named options */
        for (op = trace_plugin_options; op; op = op->next) {
                if (!op->plugin)
                        continue;
                if (strcmp(op->plugin, plugin) != 0)
                        continue;
                if (strcmp(op->option, option->name) != 0)
                        continue;

                option->value = op->value;
                option->set ^= 1;
                goto out;
        }

        /* first look for unnamed options */
        for (op = trace_plugin_options; op; op = op->next) {
                if (op->plugin)
                        continue;
                if (strcmp(op->option, option->name) != 0)
                        continue;

                option->value = op->value;
                option->set ^= 1;
                break;
        }

 out:
        free(plugin);
        return 0;
}

/**
 * traceevent_plugin_add_options - Add a set of options by a plugin
 * @name: The name of the plugin adding the options
 * @options: The set of options being loaded
 *
 * Sets the options with the values that have been added by user.
 */
int traceevent_plugin_add_options(const char *name,
                                  struct pevent_plugin_option *options)
{
        struct registered_plugin_options *reg;

        reg = malloc(sizeof(*reg));
        if (!reg)
                return -1;
        reg->next = registered_options;
        reg->options = options;
        registered_options = reg;

        while (options->name) {
                update_option(name, options);
                options++;
        }
        return 0;
}

/**
 * traceevent_plugin_remove_options - remove plugin options that were registered
 * @options: Options to removed that were registered with traceevent_plugin_add_options
 */
void traceevent_plugin_remove_options(struct pevent_plugin_option *options)
{
        struct registered_plugin_options **last;
        struct registered_plugin_options *reg;

        for (last = &registered_options; *last; last = &(*last)->next) {
                if ((*last)->options == options) {
                        reg = *last;
                        *last = reg->next;
                        free(reg);
                        return;
                }
        }
}

/**
 * traceevent_print_plugins - print out the list of plugins loaded
 * @s: the trace_seq descripter to write to
 * @prefix: The prefix string to add before listing the option name
 * @suffix: The suffix string ot append after the option name
 * @list: The list of plugins (usually returned by traceevent_load_plugins()
 *
 * Writes to the trace_seq @s the list of plugins (files) that is
 * returned by traceevent_load_plugins(). Use @prefix and @suffix for formating:
 * @prefix = "  ", @suffix = "\n".
 */
void traceevent_print_plugins(struct trace_seq *s,
                              const char *prefix, const char *suffix,
                              const struct plugin_list *list)
{
        while (list) {
                trace_seq_printf(s, "%s%s%s", prefix, list->name, suffix);
                list = list->next;
        }
}

static void
load_plugin(struct pevent *pevent, const char *path,
            const char *file, void *data)
{
        struct plugin_list **plugin_list = data;
        pevent_plugin_load_func func;
        struct plugin_list *list;
        const char *alias;
        char *plugin;
        void *handle;

        plugin = malloc(strlen(path) + strlen(file) + 2);
        if (!plugin) {
                warning("could not allocate plugin memory\n");
                return;
        }

        strcpy(plugin, path);
        strcat(plugin, "/");
        strcat(plugin, file);

        handle = dlopen(plugin, RTLD_NOW | RTLD_GLOBAL);
        if (!handle) {
                warning("could not load plugin '%s'\n%s\n",
                        plugin, dlerror());
                goto out_free;
        }

        alias = dlsym(handle, PEVENT_PLUGIN_ALIAS_NAME);
        if (!alias)
                alias = file;

        func = dlsym(handle, PEVENT_PLUGIN_LOADER_NAME);
        if (!func) {
                warning("could not find func '%s' in plugin '%s'\n%s\n",
                        PEVENT_PLUGIN_LOADER_NAME, plugin, dlerror());
                goto out_free;
        }

        list = malloc(sizeof(*list));
        if (!list) {
                warning("could not allocate plugin memory\n");
                goto out_free;
        }

        list->next = *plugin_list;
        list->handle = handle;
        list->name = plugin;
        *plugin_list = list;

        pr_stat("registering plugin: %s", plugin);
        func(pevent);
        return;

 out_free:
        free(plugin);
}

static void
load_plugins_dir(struct pevent *pevent, const char *suffix,
                 const char *path,
                 void (*load_plugin)(struct pevent *pevent,
                                     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(pevent, path, name, data);
        }

        closedir(dir);
}

static void
load_plugins(struct pevent *pevent, const char *suffix,
             void (*load_plugin)(struct pevent *pevent,
                                 const char *path,
                                 const char *name,
                                 void *data),
             void *data)
{
        char *home;
        char *path;
        char *envdir;

        if (pevent->flags & PEVENT_DISABLE_PLUGINS)
                return;

        /*
         * If a system plugin directory was defined,
         * check that first.
         */
#ifdef PLUGIN_DIR
        if (!(pevent->flags & PEVENT_DISABLE_SYS_PLUGINS))
                load_plugins_dir(pevent, suffix, PLUGIN_DIR,
                                 load_plugin, data);
#endif

        /*
         * Next let the environment-set plugin directory
         * override the system defaults.
         */
        envdir = getenv("TRACEEVENT_PLUGIN_DIR");
        if (envdir)
                load_plugins_dir(pevent, suffix, envdir, load_plugin, data);

        /*
         * Now let the home directory override the environment
         * or system defaults.
         */
        home = getenv("HOME");
        if (!home)
                return;

        path = malloc(strlen(home) + strlen(LOCAL_PLUGIN_DIR) + 2);
        if (!path) {
                warning("could not allocate plugin memory\n");
                return;
        }

        strcpy(path, home);
        strcat(path, "/");
        strcat(path, LOCAL_PLUGIN_DIR);

        load_plugins_dir(pevent, suffix, path, load_plugin, data);

        free(path);
}

struct plugin_list*
traceevent_load_plugins(struct pevent *pevent)
{
        struct plugin_list *list = NULL;

        load_plugins(pevent, ".so", load_plugin, &list);
        return list;
}

void
traceevent_unload_plugins(struct plugin_list *plugin_list, struct pevent *pevent)
{
        pevent_plugin_unload_func func;
        struct plugin_list *list;

        while (plugin_list) {
                list = plugin_list;
                plugin_list = list->next;
                func = dlsym(list->handle, PEVENT_PLUGIN_UNLOADER_NAME);
                if (func)
                        func(pevent);
                dlclose(list->handle);
                free(list->name);
                free(list);
        }
}