conky/src/setting.cc

/*
 *
 * Conky, a system monitor, based on torsmo
 *
 * Please see COPYING for details
 *
 * Copyright (C) 2010 Pavel Labath et al.
 *
 * 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, either version 3 of the License, or
 * (at your option) any later version.
 *
 * 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/>.
 *
 */

#include <config.h>

#include "setting.hh"

#include <algorithm>
#include <memory>
#include <unordered_map>
#include <utility>
#include <vector>

namespace conky {

namespace {
typedef std::unordered_map<std::string, priv::config_setting_base *>
    settings_map;
using settings_vector = std::vector<priv::config_setting_base *>;

/*
 * We cannot construct this object statically, because order of object
 * construction in different modules is not defined, so config_setting_base
 * could be called before this object is constructed. Therefore, we create it on
 * the first call to config_setting_base constructor.
 */
settings_map *settings;

/*
 * Returns the setting record corresponding to the value at the specified index.
 * If the value is not valid, returns nullptr and prints an error.
 */
priv::config_setting_base *get_setting(lua::state &l, int index) {
  lua::Type type = l.type(index);
  if (type != lua::TSTRING) {
    NORM_ERR("invalid setting of type '%s'", l.type_name(type));
    return nullptr;
  }

  const std::string &name = l.tostring(index);
  auto iter = settings->find(name);
  if (iter == settings->end()) {
    NORM_ERR("Unknown setting '%s'", name.c_str());
    return nullptr;
  }

  return iter->second;
}

// returns a vector of all settings, sorted in order of registration
settings_vector make_settings_vector() {
  settings_vector ret;
  ret.reserve(settings->size());

  for (auto &setting : *settings) {
    ret.push_back(setting.second);
  }
  sort(ret.begin(), ret.end(), &priv::config_setting_base::seq_compare);

  return ret;
}

/*
 * Returns the seq_no for the new setting object. Also constructs settings
 * object if needed.
 */
size_t get_next_seq_no() {
  struct settings_constructor {
    settings_constructor() { settings = new settings_map; }
    ~settings_constructor() {
      delete settings;
      settings = nullptr;
    }
  };
  static settings_constructor constructor;

  return settings->size();
}
}  // namespace

namespace priv {

config_setting_base::config_setting_base(std::string name_)
    : name(std::move(name_)), seq_no(get_next_seq_no()) {
  bool inserted = settings->insert({name, this}).second;
  if (not inserted) {
    throw std::logic_error("Setting with name '" + name +
                           "' already registered");
  }
}

void config_setting_base::lua_set(lua::state &l) {
  std::lock_guard<lua::state> guard(l);
  lua::stack_sentry s(l, -1);
  l.checkstack(2);

  l.getglobal("conky");
  l.rawgetfield(-1, "config");
  l.replace(-2);
  l.insert(-2);

  l.setfield(-2, name.c_str());
  l.pop();
}

/*
 * Performs the actual assignment of settings. Calls the setting-specific setter
 * after some sanity-checking. stack on entry: | ..., new_config_table, key,
 * value, old_value | stack on exit:  | ..., new_config_table |
 */
void config_setting_base::process_setting(lua::state &l, bool init) {
  lua::stack_sentry s(l, -3);

  config_setting_base *ptr = get_setting(l, -3);
  if (ptr == nullptr) {
    return;
  }

  ptr->lua_setter(l, init);
  l.pushvalue(-2);
  l.insert(-2);
  l.rawset(-4);
}

/*
 * Called when user sets a new value for a setting
 * stack on entry: | config_table, key, value |
 * stack on exit:  | |
 */
int config_setting_base::config__newindex(lua::state *l) {
  lua::stack_sentry s(*l, -3);
  l->checkstack(1);

  l->getmetatable(-3);
  l->replace(-4);

  l->pushvalue(-2);
  l->rawget(-4);
  process_setting(*l, false);

  return 0;
}

/*
 * conky.config will not be a table, but a userdata with some metamethods we do
 * this because we want to control access to the settings we use the metatable
 * for storing the settings, that means having a setting whose name starts with
 * "__" is a bad idea stack on entry: | ... | stack on exit:  | ...
 * new_config_table |
 */
void config_setting_base::make_conky_config(lua::state &l) {
  lua::stack_sentry s(l);
  l.checkstack(3);

  l.newuserdata(1);

  l.newtable();
  {
    l.pushboolean(false);
    l.rawsetfield(-2, "__metatable");

    l.pushvalue(-1);
    l.rawsetfield(-2, "__index");

    l.pushfunction(&priv::config_setting_base::config__newindex);
    l.rawsetfield(-2, "__newindex");
  }
  l.setmetatable(-2);

  ++s;
}
}  // namespace priv

void set_config_settings(lua::state &l) {
  lua::stack_sentry s(l);
  l.checkstack(6);

  // Force creation of settings map. In the off chance we have no settings.
  get_next_seq_no();

  l.getglobal("conky");
  {
    if (l.type(-1) != lua::TTABLE) {
      throw std::runtime_error("conky must be a table");
    }

    l.rawgetfield(-1, "config");
    {
      if (l.type(-1) != lua::TTABLE) {
        throw std::runtime_error("conky.config must be a table");
      }

      priv::config_setting_base::make_conky_config(l);
      l.rawsetfield(-3, "config");

      l.rawgetfield(-2, "config");
      l.getmetatable(-1);
      l.replace(-2);
      {
        const settings_vector &v = make_settings_vector();

        for (auto i : v) {
          l.pushstring(i->name);
          l.rawgetfield(-3, i->name.c_str());
          l.pushnil();
          priv::config_setting_base::process_setting(l, true);
        }
      }
      l.pop();

      // print error messages for unknown settings
      l.pushnil();
      while (l.next(-2)) {
        l.pop();
        get_setting(l, -1);
      }
    }
    l.pop();
  }
  l.pop();
}

void cleanup_config_settings(lua::state &l) {
  lua::stack_sentry s(l);
  l.checkstack(2);

  l.getglobal("conky");
  l.rawgetfield(-1, "config");
  l.replace(-2);

  const settings_vector &v = make_settings_vector();
  for (size_t i = v.size(); i > 0; --i) {
    l.getfield(-1, v[i - 1]->name.c_str());
    v[i - 1]->cleanup(l);
  }

  l.pop();
}

/////////// example settings, remove after real settings are available ///////
range_config_setting<int> asdf("asdf", 42, 47, 45, true);
}  // namespace conky