nuttx/sched/environ/env_dup.c

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/****************************************************************************
* sched/environ/env_dup.c
*
* Copyright (C) 2007, 2009, 2011, 2013, 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>
#ifndef CONFIG_DISABLE_ENVIRON
#include <sys/types.h>
#include <sched.h>
#include <string.h>
#include <errno.h>
#include <nuttx/kmalloc.h>
#include "sched/sched.h"
#include "environ/environ.h"
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: env_dup
*
* Description:
* Copy the internal environment structure of a task. This is the action
* that is performed when a new task is created: The new task has a private,
* exact duplicate of the parent task's environment.
*
* Input Parameters:
* group The child task group to receive the newly allocated copy of the
* parent task groups environment structure.
*
* Returned Value:
* zero on success
*
* Assumptions:
* Not called from an interrupt handler.
*
****************************************************************************/
int env_dup(FAR struct task_group_s *group)
{
FAR struct tcb_s *ptcb = this_task();
FAR char *envp = NULL;
size_t envlen;
int ret = OK;
DEBUGASSERT(group != NULL && ptcb != NULL && ptcb->group != NULL);
/* Pre-emption must be disabled throughout the following because the
* environment may be shared.
*/
sched_lock();
/* Does the parent task have an environment? */
if (ptcb->group != NULL && ptcb->group->tg_envp != NULL)
{
/* Yes.. The parent task has an environment allocation. */
envlen = ptcb->group->tg_envsize;
envp = NULL;
/* A special case is that the parent has an "empty" environment
* allocation, i.e., there is an allocation in place but it
* contains no variable definitions and, hence, envlen == 0.
*/
if (envlen > 0)
{
/* There is an environment, duplicate it */
envp = (FAR char *)kumm_malloc(envlen);
if (envp == NULL)
{
/* The parent's environment can not be inherited due to a
* failure in the allocation of the child environment.
*/
envlen = 0;
ret = -ENOMEM;
}
else
{
/* Duplicate the parent environment. */
memcpy(envp, ptcb->group->tg_envp, envlen);
}
}
/* Save the size and child environment allocation. */
group->tg_envsize = envlen;
group->tg_envp = envp;
}
sched_unlock();
return ret;
}
#endif /* CONFIG_DISABLE_ENVIRON */