px4-firmware/nuttx/sched/env_share.c

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/****************************************************************************
* sched/env_share.c
*
* Copyright (C) 2007, 2009 Gregory Nutt. All rights reserved.
* Author: Gregory Nutt <spudmonkey@racsa.co.cr>
*
* 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>
#ifndef CONFIG_DISABLE_ENVIRON
#include <sched.h>
#include <errno.h>
#include "os_internal.h"
#include "env_internal.h"
/****************************************************************************
* Private Data
****************************************************************************/
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Function: env_share
*
* Description:
* Increment the reference count on the internal environment structure of
* a task. This is the action that is performed when a new pthread is
* created: The new pthread shares the environment with its parent.
*
* Parameters:
* ptcb The new TCB to receive the shared environment.
*
* Return Value:
* A pointer to a specified TCB's environment structure with an incremented
* reference count.
*
* Assumptions:
* Not called from an interrupt handler.
*
****************************************************************************/
int env_share(FAR _TCB *ptcb)
{
int ret = OK;
if (!ptcb)
{
ret = -EINVAL;
}
else
{
FAR _TCB *parent = (FAR _TCB*)g_readytorun.head;
environ_t *envp = parent->envp;
/* Pre-emption must be disabled throughout the following because the
* environment is shared.
*/
sched_lock();
/* Does the parent task have an environment? */
if (envp)
{
/* Yes.. increment the reference count on the environment */
envp->ev_crefs++;
}
/* Then share the environment */
ptcb->envp = envp;
sched_unlock();
}
return ret;
}
#endif /* CONFIG_DISABLE_ENVIRON */