incubator-nuttx/libs/libc/unistd/lib_getpriority.c

93 lines
2.8 KiB
C

/****************************************************************************
* libs/libc/unistd/lib_getpriority.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>
#include <sys/resource.h>
#include <sched.h>
#include <unistd.h>
#include <errno.h>
#include <nuttx/sched.h>
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: getpriority
*
* Description:
* The getpriority() function shall obtain the nice value of a process,
* process group, or user.
*
* Input Parameters:
* which - PRIO_PROCESS, PRIO_PGRP, or PRIO_USER, ignored in current
* implementation.
* who - Process id is interpreted relative to "which"
*
* Returned Value:
* Upon successful completion, getpriority() shall return an integer in
* the range -{NZERO} to {NZERO}-1. Otherwise, -1 shall be returned and
* errno set to indicate the error. The following errors may be
* reported:
*
* - ESRCH: No process was located using the which and who values
* specified.
* - EINVAL: which was not one of PRIO_PROCESS, PRIO_PGRP, or
* PRIO_USER.
*
* Assumptions:
*
****************************************************************************/
int getpriority(int which, id_t who)
{
struct sched_param param;
int ret;
if (which > PRIO_USER || which < PRIO_PROCESS)
{
set_errno(EINVAL);
return ERROR;
}
if (who == 0)
{
who = _SCHED_GETTID();
}
ret = sched_getparam(who, &param);
if (ret < 0)
{
return ret;
}
/* Since -1 is a legal return value, clear errno to avoid the chaos */
set_errno(0);
return NZERO - param.sched_priority;
}