nuttx/libs/libc/syslog/lib_setlogmask.c
Gregory Nutt 2b5ff17a85 setlogmask(): Add comments
In include/syslog.h and libs/libc/syslog/lib_setlogmask.c, add comments indicating tht setlogmask() is not thread-safe.
2020-05-11 11:32:55 -04:00

86 lines
3.4 KiB
C

/****************************************************************************
* lib/syslog/lib_setlogmask.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 <stdint.h>
#include <syslog.h>
#include "syslog/syslog.h"
/****************************************************************************
* Public Data
****************************************************************************/
/* The currently enabled set of syslog priorities */
uint8_t g_syslog_mask = LOG_ALL;
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: setlogmask
*
* Description:
* The setlogmask() function sets the logmask and returns the previous
* mask. If the mask argument is 0, the current logmask is not modified.
*
* The SYSLOG priorities are: LOG_EMERG, LOG_ALERT, LOG_CRIT, LOG_ERR,
* LOG_WARNING, LOG_NOTICE, LOG_INFO, and LOG_DEBUG. The bit corresponding
* to a priority p is LOG_MASK(p); LOG_UPTO(p) provides the mask of all
* priorities in the above list up to and including p.
*
* Per OpenGroup.org "If the maskpri argument is 0, the current log mask
* is not modified." In this implementation, the value zero is permitted
* in order to disable all syslog levels.
*
* NOTE: setlogmask is not a thread-safe, re-entrant function. Concurrent
* use of setlogmask() will have undefined behavior.
*
* REVISIT: Per POSIX the syslog mask should be a per-process value but in
* NuttX, the scope of the mask is dependent on the nature of the build:
*
* Flat Build: There is one, global SYSLOG mask that controls all output.
* Protected Build: There are two SYSLOG masks. One within the kernel
* that controls only kernel output. And one in user-space that controls
* only user SYSLOG output.
* Kernel Build: The kernel build is compliant with the POSIX requirement:
* There will be one mask for each user process, controlling the SYSLOG
* output only form that process. There will be a separate mask
* accessible only in the kernel code to control kernel SYSLOG output.
*
****************************************************************************/
int setlogmask(int mask)
{
uint8_t oldmask;
oldmask = g_syslog_mask;
g_syslog_mask = (uint8_t)mask;
return oldmask;
}