nuttx/libs/libc/modlib/modlib_depend.c

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/****************************************************************************
* libs/libc/modlib/modlib_depend.c
*
* Copyright (C) 2017 Gregory Nutt. All rights reserved.
* Author: Gregory Nutt <gnutt@nuttx.org>
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
* 3. Neither the name NuttX nor the names of its contributors may be
* used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*
****************************************************************************/
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/config.h>
#include <stdlib.h>
#include <errno.h>
#include <debug.h>
#include <nuttx/lib/modlib.h>
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: modlib_depend
*
* Description:
* Set up module dependencies between the exporter and the importer of a
* symbol. The happens when the module is installed via insmod and a
* symbol is imported from another module.
*
* Returned Value:
* 0 (OK) is returned on success and a negated errno is returned on
* failure.
*
* Assumptions:
* Caller holds the registry lock.
*
****************************************************************************/
int modlib_depend(FAR struct module_s *importer,
FAR struct module_s *exporter)
{
#if CONFIG_MODLIB_MAXDEPEND > 0
int freendx;
int i;
DEBUGASSERT(importer != NULL && exporter != NULL);
/* First checker if the exported is already in our list if dependencies.
* This would happen if we are importing multiple symbols from the same
* exporting module. In that case, the module would already be in the
* list of dependencies.
*
* The list dependency list is a a dumb, upacked array of pointers. This
* should not be too inefficient if the number of CONFIG_MODLIB_MAXDEPEND
* is small. Otherwise, a more dynamic data structure would be in order.
*/
for (i = 0, freendx = -1; i < CONFIG_MODLIB_MAXDEPEND; i++)
{
FAR const struct module_s *modp;
/* Check if this dependency slot is available. */
modp = importer->dependencies[i];
if (modp == NULL)
{
/* Remember this slot for use the module is NOT already in the
* list of dependencies.
*/
freendx = i;
}
else if (modp == exporter)
{
/* Yes, we are already importing symbols from this module. Nothing
* more needs to be done.
*/
return OK;
}
}
/* If we get here, then (1) this is a new exporting module that does not
* already appear in the list of dependencies, and (2) freendx is the
* index to the last free slot in the dependency list. If freendx is
* negative, then the dependency list is full.
*/
if (freendx >= 0)
{
/* Increment the count of dependencies on the exporter module */
DEBUGASSERT(exporter->dependents < UINT8_MAX);
if (exporter->dependents >= UINT8_MAX)
{
return -ENOSPC;
}
exporter->dependents++;
/* And remember the exporter so that we can decrement the count of
* dependents if the importer is removed.
*/
DEBUGASSERT(importer->dependencies[freendx] == NULL);
importer->dependencies[freendx] = exporter;
return OK;
}
/* If we get there then the list of dependencies is full. */
DEBUGPANIC();
return -ENFILE;
#else
return OK;
#endif
}
/****************************************************************************
* Name: modlib_undepend
*
* Description:
* Tear down module dependencies between the exporters and the importer of
* symbols. This happens when the module is removed via rmmod (and on
* error handling cases in insmod).
*
* Returned Value:
* 0 (OK) is returned on success and a negated errno is returned on
* failure.
*
* Assumptions:
* Caller holds the registry lock.
*
****************************************************************************/
int modlib_undepend(FAR struct module_s *importer)
{
#if CONFIG_MODLIB_MAXDEPEND > 0
FAR struct module_s *exporter;
int i;
DEBUGASSERT(importer != NULL && importer->dependents == 0);
/* Decrement the dependency count on each of exporters of symbols used by
* this importer module. This is an upacked array of pointers. This
* should not be too inefficient if the number of CONFIG_MODLIB_MAXDEPEND
* is small. Otherwise, a more dynamic data structure would be in order.
*/
for (i = 0; i < CONFIG_MODLIB_MAXDEPEND; i++)
{
exporter = importer->dependencies[i];
if (exporter != NULL)
{
DEBUGASSERT(exporter->dependents > 0);
if (exporter->dependents > 0)
{
exporter->dependents--;
}
importer->dependencies[i] = NULL;
}
}
#endif
return OK;
}