incubator-nuttx/sched/environ/env_findvar.c

113 lines
3.3 KiB
C

/****************************************************************************
* sched/environ/env_findvar.c
*
* 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.
*
****************************************************************************/
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/config.h>
#ifndef CONFIG_DISABLE_ENVIRON
#include <stdbool.h>
#include <string.h>
#include <sched.h>
#include <assert.h>
#include "environ/environ.h"
/****************************************************************************
* Private Functions
****************************************************************************/
/****************************************************************************
* Name: env_cmpname
****************************************************************************/
static bool env_cmpname(const char *pszname, const char *peqname)
{
/* Search until we find anything different in the two names */
for (; *pszname == *peqname; pszname++, peqname++)
{
}
/* On success, pszname will end with '\0' and peqname with '=' */
if (*pszname == '\0' && *peqname == '=')
{
return true;
}
return false;
}
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: env_findvar
*
* Description:
* Search the provided environment structure for the variable of the
* specified name.
*
* Input Parameters:
* group - The task group containing environment array to be searched.
* pname - The variable name to find
*
* Returned Value:
* A index to the name=value string in the environment
*
* Assumptions:
* - Not called from an interrupt handler
* - Pre-emption is disabled by caller
*
****************************************************************************/
ssize_t env_findvar(FAR struct task_group_s *group, FAR const char *pname)
{
ssize_t i;
/* Verify input parameters */
DEBUGASSERT(group != NULL && pname != NULL);
if (group->tg_envp == NULL)
{
return -ENOENT;
}
/* Search for a name=value string with matching name */
for (i = 0; group->tg_envp[i] != NULL; i++)
{
if (env_cmpname(pname, group->tg_envp[i]))
{
return i;
}
}
return -ENOENT;
}
#endif /* CONFIG_DISABLE_ENVIRON */