/****************************************************************************
 * include/nuttx/module.h
 *
 * SPDX-License-Identifier: Apache-2.0
 *
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.  The
 * ASF licenses this file to you 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.
 *
 ****************************************************************************/

#ifndef __INCLUDE_NUTTX_MODULE_H
#define __INCLUDE_NUTTX_MODULE_H

/****************************************************************************
 * Included Files
 ****************************************************************************/

#include <nuttx/config.h>

#include <sys/types.h>

/****************************************************************************
 * Public Function Prototypes
 ****************************************************************************/

#undef EXTERN
#if defined(__cplusplus)
#define EXTERN extern "C"
extern "C"
{
#else
#define EXTERN extern
#endif

/****************************************************************************
 * Name: insmod
 *
 * Description:
 *   Verify that the file is an ELF module binary and, if so, load the
 *   module into kernel memory and initialize it for use.
 *
 *   NOTE:
 *   libelf_setsymtab had to have been called in board-specific OS logic
 *   prior to calling this function from application logic (perhaps via
 *   boardctl(BOARDIOC_OS_SYMTAB).  Otherwise, insmod will be unable to
 *   resolve symbols in the OS module.
 *
 * Input Parameters:
 *
 *   filename - Full path to the module binary to be loaded
 *   modname  - The name that can be used to refer to the module after
 *     it has been loaded.
 *
 * Returned Value:
 *   A non-NULL module handle that can be used on subsequent calls to other
 *   module interfaces is returned on success.  If insmod() was unable to
 *   load the module insmod() will return a NULL handle and the errno
 *   variable will be set appropriately.
 *
 ****************************************************************************/

FAR void *insmod(FAR const char *filename, FAR const char *modname);

/****************************************************************************
 * Name: rmmod
 *
 * Description:
 *   Remove a previously installed module from memory.
 *
 * Input Parameters:
 *   handle - The module handler previously returned by insmod().
 *
 * Returned Value:
 *   Zero (OK) on success.  On any failure, -1 (ERROR) is returned the
 *   errno value is set appropriately.
 *
 ****************************************************************************/

int rmmod(FAR void *handle);

/****************************************************************************
 * Name: modsym
 *
 * Description:
 *   modsym() returns the address of a symbol defined within the object that
 *   was previously made accessible through a insmod() call.  handle is the
 *   value returned from a call to insmod() (and which has not since been
 *   released via a call to rmmod()), name is the symbol's name as a
 *   character string.
 *
 *   The returned symbol address will remain valid until rmmod() is called.
 *
 * Input Parameters:
 *   handle - The opaque, non-NULL value returned by a previous successful
 *            call to insmod().
 *   name   - A pointer to the symbol name string.
 *
 * Returned Value:
 *   The address associated with the symbol is returned on success.
 *   If handle does not refer to a valid module opened by insmod(), or if
 *   the named symbol cannot be found within any of the objects associated
 *   with handle, modsym() will return NULL and the errno variable will be
 *   set appropriately.
 *
 ****************************************************************************/

FAR const void *modsym(FAR void *handle, FAR const char *name);

/****************************************************************************
 * Name: modhandle
 *
 * Description:
 *   modhandle() returns the module handle for the installed module with the
 *   provided name.  A secondary use of this function is to determine if a
 *   module has been loaded or not.
 *
 * Input Parameters:
 *   name   - A pointer to the module name string.
 *
 * Returned Value:
 *   The non-NULL module handle previously returned by insmod() is returned
 *   on success.  If no module with that name is installed, modhandle() will
 *   return a NULL handle and the errno variable will be set appropriately.
 *
 ****************************************************************************/

FAR void *modhandle(FAR const char *name);

#undef EXTERN
#if defined(__cplusplus)
}
#endif

#endif /* __INCLUDE_NUTTX_MODULE_H */
