drivers/syslog/syslog_putc.c

/****************************************************************************
 * drivers/syslog/syslog_putc.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/types.h>
#include <assert.h>
#include <errno.h>

#include <nuttx/arch.h>
#include <nuttx/sched.h>
#include <nuttx/syslog/syslog.h>

#include "syslog.h"

/****************************************************************************
 * Public Functions
 ****************************************************************************/

/****************************************************************************
 * Name: syslog_putc
 *
 * Description:
 *   This is the low-level system logging interface.
 *
 * Input Parameters:
 *   ch - The character to add to the SYSLOG (must be positive).
 *
 * Returned Value:
 *   On success, the character is echoed back to the caller.  A negated
 *   errno value is returned on any failure.
 *
 ****************************************************************************/

int syslog_putc(int ch)
{
  int i;

  /* Is this an attempt to do SYSLOG output from an interrupt handler? */

  if (up_interrupt_context() || sched_idletask())
    {
#if defined(CONFIG_SYSLOG_INTBUFFER)
      if (up_interrupt_context())
        {
          /* Buffer the character in the interrupt buffer.
           * The interrupt buffer will be flushed before the next
           * normal,non-interrupt SYSLOG output.
           */

          return syslog_add_intbuffer(ch);
        }
      else
#endif
        {
          /* Force the character to the SYSLOG device immediately
           * (if possible).
           * This means that the interrupt data may not be in
           * synchronization with output data that may have been
           * buffered by sc_putc().
           */

          for (i = 0; i < CONFIG_SYSLOG_MAX_CHANNELS; i++)
            {
              FAR struct syslog_channel_s *channel = g_syslog_channel[i];

              if (channel == NULL)
                {
                  break;
                }

#ifdef CONFIG_SYSLOG_IOCTL
              if (channel->sc_disable)
                {
                  continue;
                }
#endif

              if (channel->sc_ops->sc_force != NULL)
                {
                  channel->sc_ops->sc_force(channel,  ch);
                }
              else
                {
                  char tmp = ch;

                  DEBUGASSERT(channel->sc_ops->sc_write_force != NULL);
                  channel->sc_ops->sc_write_force(channel, &tmp, 1);
                }
            }
        }
    }
  else
    {
#ifdef CONFIG_SYSLOG_INTBUFFER
      /* Flush any characters that may have been added to the interrupt
       * buffer.
       */

      syslog_flush_intbuffer(false);
#endif

      for (i = 0; i < CONFIG_SYSLOG_MAX_CHANNELS; i++)
        {
          FAR struct syslog_channel_s *channel = g_syslog_channel[i];

          if (channel == NULL)
            {
              break;
            }

#ifdef CONFIG_SYSLOG_IOCTL
          if (channel->sc_disable)
            {
              continue;
            }
#endif

          if (channel->sc_ops->sc_putc != NULL)
            {
              channel->sc_ops->sc_putc(channel, ch);
            }
          else
            {
              char tmp = ch;
              DEBUGASSERT(channel->sc_ops->sc_write != NULL);
              channel->sc_ops->sc_write(channel, &tmp, 1);
            }
        }
    }

  return ch;
}