/*
 * plugin.c: plugin handling
 *
 * Copyright (c) 2011 Cisco and/or its affiliates.
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at:
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include <vlib/unix/plugin.h>
#include <dlfcn.h>
#include <dirent.h>

plugin_main_t vlib_plugin_main;

void vlib_set_get_handoff_structure_cb (void *cb)
{
  plugin_main_t * pm = &vlib_plugin_main;
  pm->handoff_structure_get_cb = cb;
}

static void * vnet_get_handoff_structure (void)
{
  void * (*fp)(void);

  fp = vlib_plugin_main.handoff_structure_get_cb;
  if (fp == 0)
    return 0;
  else
    return (*fp)();
}

static int 
load_one_plugin (plugin_main_t *pm, plugin_info_t *pi, int from_early_init)
{
  void *handle, *register_handle;
  clib_error_t * (*fp)(vlib_main_t *, void *, int);
  clib_error_t * error;
  void *handoff_structure;
  
  handle = dlopen ((char *)pi->name, RTLD_LAZY);

  /* 
   * Note: this can happen if the plugin has an undefined symbol reference,
   * so print a warning. Otherwise, the poor slob won't know what happened.
   * Ask me how I know that...
   */
  if (handle == 0)
    {
      clib_warning ("%s", dlerror());
      return -1;
    }
  
  pi->handle = handle;

  register_handle = dlsym (pi->handle, "vlib_plugin_register");
  if (register_handle == 0)
    {
      dlclose (handle);
      return 0;
    }

  fp = register_handle;

  handoff_structure = vnet_get_handoff_structure();

  if (handoff_structure == 0)
    error = clib_error_return (0, "handoff structure callback returned 0");
  else
    error = (*fp)(pm->vlib_main, handoff_structure, from_early_init);

  if (error)
    {
      clib_error_report (error);
      dlclose (handle);
      return 1;
    }

  clib_warning ("Loaded plugin: %s", pi->name);

  return 0;
}

static u8 **split_plugin_path (plugin_main_t *pm)
{
  int i;
  u8 **rv = 0;
  u8 *path = pm->plugin_path;
  u8 *this = 0;

  for (i = 0; i < vec_len (pm->plugin_path); i++)
    {
      if (path[i] != ':')
        {
          vec_add1(this, path[i]);
          continue;
        }
      vec_add1(this, 0);
      vec_add1 (rv, this);
      this = 0;
    }
  if (this)
    {
      vec_add1 (this, 0);
      vec_add1 (rv, this);
    }
  return rv;
}

int vlib_load_new_plugins (plugin_main_t *pm, int from_early_init)
{
  DIR *dp;
  struct dirent *entry;
  struct stat statb;
  uword *p;
  plugin_info_t *pi;
  u8 **plugin_path;
  int i;

  plugin_path = split_plugin_path (pm);
  
  for (i = 0; i < vec_len (plugin_path); i++)
    {
      dp = opendir ((char *)plugin_path[i]);
  
      if (dp == 0)
        continue;
      
      while ((entry = readdir (dp)))
        {
          u8 *plugin_name;
          
          if (pm->plugin_name_filter)
            {
              int j;
              for (j = 0; j < vec_len (pm->plugin_name_filter); j++)
                if (entry->d_name[j] != pm->plugin_name_filter[j])
                  goto next;
            }

          plugin_name = format (0, "%s/%s%c", plugin_path[i],
                                entry->d_name, 0);
          
          /* unreadable */
          if (stat ((char *)plugin_name, &statb) < 0)
            {
            ignore:
              vec_free (plugin_name);
              continue;
            }
          
          /* a dir or other things which aren't plugins */
          if (!S_ISREG(statb.st_mode))
            goto ignore;
          
          p = hash_get_mem (pm->plugin_by_name_hash, plugin_name);
          if (p == 0) 
            {
              vec_add2 (pm->plugin_info, pi, 1);
              pi->name = plugin_name;
              pi->file_info = statb;
              
              if (load_one_plugin (pm, pi, from_early_init))
                {
                  vec_free (plugin_name);
                  _vec_len (pm->plugin_info) = vec_len (pm->plugin_info) - 1;
                  continue;
                }
              memset (pi, 0, sizeof (*pi));
              hash_set_mem (pm->plugin_by_name_hash, plugin_name, 
                            pi - pm->plugin_info);
            }
        next:
          ;
        }
      closedir (dp);
      vec_free (plugin_path[i]);
    }
  vec_free (plugin_path);
  return 0;
}
char *vlib_plugin_path __attribute__((weak));
char *vlib_plugin_path = "";
char *vlib_plugin_name_filter __attribute__((weak));
char *vlib_plugin_name_filter = 0;

int vlib_plugin_early_init (vlib_main_t *vm)
{
  plugin_main_t *pm = &vlib_plugin_main;

  pm->plugin_path = format (0, "%s%c", vlib_plugin_path, 0);

  clib_warning ("plugin path %s", pm->plugin_path);

  if (vlib_plugin_name_filter)
    pm->plugin_name_filter = format (0, "%s%c", vlib_plugin_name_filter, 0);

  pm->plugin_by_name_hash = hash_create_string (0, sizeof (uword));
  pm->vlib_main = vm;
  
  return vlib_load_new_plugins (pm, 1 /* from_early_init */);
}