nuttx/sched/module/mod_modsym.c

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/****************************************************************************
* sched/module/mod_modsym.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 <assert.h>
#include <errno.h>
#include <debug.h>
#include <nuttx/module.h>
#include <nuttx/symtab.h>
#include <nuttx/lib/modlib.h>
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* 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.
*
* NOTE: This means that the address zero can never be a valid return
* value.
*
****************************************************************************/
FAR const void *modsym(FAR void *handle, FAR const char *name)
{
FAR struct module_s *modp = (FAR struct module_s *)handle;
FAR const struct symtab_s *symbol;
int err;
int ret;
/* Verify that the module is in the registry */
modlib_registry_lock();
ret = modlib_registry_verify(modp);
if (ret < 0)
{
berr("ERROR: Failed to verify module: %d\n", ret);
err = -ret;
goto errout_with_lock;
}
/* Does the module have a symbol table? */
if (modp->modinfo.exports == NULL || modp->modinfo.nexports == 0)
{
berr("ERROR: Module has no symbol table\n");
err = ENOENT;
goto errout_with_lock;
}
/* Search the symbol table for the matching symbol */
symbol = symtab_findbyname(modp->modinfo.exports, name,
modp->modinfo.nexports);
if (symbol == NULL)
{
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berr("ERROR: Failed to find symbol in symbol \"%s\" in table\n", name);
err = ENOENT;
goto errout_with_lock;
}
/* Return the address within the module associated with the symbol */
modlib_registry_unlock();
DEBUGASSERT(symbol->sym_value != NULL);
return symbol->sym_value;
errout_with_lock:
modlib_registry_unlock();
set_errno(err);
return NULL;
}