incubator-nuttx/drivers/syslog/syslog_intbuffer.c

343 lines
10 KiB
C

/****************************************************************************
* drivers/syslog/syslog_intbuffer.c
*
* Copyright (C) 2016 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>
#include <stdbool.h>
#include <stdio.h>
#include <assert.h>
#include <errno.h>
#include <nuttx/syslog/syslog.h>
#include <nuttx/irq.h>
#include "syslog.h"
#ifdef CONFIG_SYSLOG_INTBUFFER
/****************************************************************************
* Pre-processor Definitions
****************************************************************************/
/* Extend the size of the interrupt buffer so that a "[truncated]\n"
* indication can be append to the end.
*
* The usable capacity of the interrupt buffer is (CONFIG_SYSLOG_INTBUFSIZE - 1).
*/
#define SYSLOG_BUFOVERRUN_MESSAGE "[truncated]\n"
#define SYSLOG_BUFOVERRUN_SIZE 13
#if CONFIG_SYSLOG_INTBUFSIZE > (65535 - SYSLOG_BUFOVERRUN_SIZE)
# undef CONFIG_SYSLOG_INTBUFSIZE
# define CONFIG_SYSLOG_INTBUFSIZE (65535 - SYSLOG_BUFOVERRUN_SIZE)
# define SYSLOG_INTBUFSIZE 65535
#else
# define SYSLOG_INTBUFSIZE \
(CONFIG_SYSLOG_INTBUFSIZE + SYSLOG_BUFOVERRUN_SIZE)
#endif
#define USABLE_INTBUFSIZE (CONFIG_SYSLOG_INTBUFSIZE - 1)
/****************************************************************************
* Private Types
****************************************************************************/
/* This structure encapsulates the interrupt buffer state */
struct g_syslog_intbuffer_s
{
volatile uint16_t si_inndx;
volatile uint16_t si_outndx;
uint8_t si_buffer[SYSLOG_INTBUFSIZE];
};
/****************************************************************************
* Private Data
****************************************************************************/
static struct g_syslog_intbuffer_s g_syslog_intbuffer;
static const char g_overrun_msg[SYSLOG_BUFOVERRUN_SIZE] = SYSLOG_BUFOVERRUN_MESSAGE;
/****************************************************************************
* Private Data
****************************************************************************/
/****************************************************************************
* Name: syslog_remove_intbuffer
*
* Description:
* Extract any characters that may have been added to the interrupt buffer
* to the SYSLOG device.
*
* Input Parameters:
* None
*
* Returned Value:
* On success, the extracted character is returned. EOF is returned if
* the interrupt buffer is empty.
*
* Assumptions:
* Interrupts may or may not be disabled.
*
****************************************************************************/
int syslog_remove_intbuffer(void)
{
irqstate_t flags;
uint32_t inndx;
uint32_t outndx;
uint32_t endndx;
int inuse = 0;
int ch;
/* Extraction of the character and adjustment of the circular buffer
* indices must be performed in a critical section to protect from
* concurrent modification from interrupt handlers.
*/
flags = enter_critical_section();
/* How much space is left in the inbuffer? */
inndx = (uint32_t)g_syslog_intbuffer.si_inndx;
outndx = (uint32_t)g_syslog_intbuffer.si_outndx;
if (inndx != outndx)
{
/* Handle the case where the inndx has wrapped around */
endndx = inndx;
if (endndx < outndx)
{
endndx += SYSLOG_INTBUFSIZE;
}
inuse = (int)(endndx - outndx);
/* Take the next character from the interrupt buffer */
ch = g_syslog_intbuffer.si_buffer[outndx];
/* Increment the OUT index, handling wrap-around */
if (++outndx >= SYSLOG_INTBUFSIZE)
{
outndx -= SYSLOG_INTBUFSIZE;
}
g_syslog_intbuffer.si_outndx = (uint16_t)outndx;
}
leave_critical_section(flags);
/* Now we can send the extracted character to the SYSLOG device */
return (inuse > 0) ? ch : EOF;
}
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: syslog_add_intbuffer
*
* Description:
* Add one more character to the interrupt buffer. In the event of
* buffer overlowed, the character will be dropped. The indication
* "[truncated]\n" will be appended to the end of the interrupt buffer.
*
* Input Parameters:
* ch - The character to add to the interrupt buffer (must be positive).
*
* Returned Value:
* Zero success, the character is echoed back to the caller. A negated
* errno value is returned on any failure.
*
* Assumptions:
* - Called either from (1) interrupt handling logic with interrupts
* disabled or from an IDLE thread with interrupts enabled.
* - Requires caution because there may be an interrupted execution of
* syslog_flush_intbuffer(): Only the outndx can be modified.
*
****************************************************************************/
int syslog_add_intbuffer(int ch)
{
irqstate_t flags;
uint32_t inndx;
uint32_t outndx;
uint32_t endndx;
unsigned int inuse;
int ret;
int i;
/* Disable concurrent modification from interrupt handling logic */
flags = enter_critical_section();
/* How much space is left in the inbuffer? */
inndx = (uint32_t)g_syslog_intbuffer.si_inndx;
outndx = (uint32_t)g_syslog_intbuffer.si_outndx;
endndx = inndx;
if (endndx < outndx)
{
endndx += SYSLOG_INTBUFSIZE;
}
inuse = (unsigned int)(endndx - outndx);
/* Is there space for another character (reserving space for the overrun
* message)?
*/
if (inuse == USABLE_INTBUFSIZE)
{
/* Copy the truncated message one character at a time, handing index
* wrap-around on each character.
*/
for (i = 0; i < SYSLOG_BUFOVERRUN_SIZE; i++)
{
/* Copy one character */
g_syslog_intbuffer.si_buffer[inndx] = (uint8_t)g_overrun_msg[i];
/* Increment the IN index, handling wrap-around */
if (++inndx >= SYSLOG_INTBUFSIZE)
{
inndx -= SYSLOG_INTBUFSIZE;
}
DEBUGASSERT(inndx != outndx);
}
g_syslog_intbuffer.si_inndx = (uint16_t)inndx;
ret = -ENOSPC;
}
else if (inuse < USABLE_INTBUFSIZE)
{
/* Copy one character */
g_syslog_intbuffer.si_buffer[inndx] = (uint8_t)ch;
/* Increment the IN index, handling wrap-around */
if (++inndx >= SYSLOG_INTBUFSIZE)
{
inndx -= SYSLOG_INTBUFSIZE;
}
g_syslog_intbuffer.si_inndx = (uint16_t)inndx;
ret = OK;
}
else
{
/* This character goes to the bit bucket. We have already copied
* the overrun message so there is nothing else to do.
*/
ret = -ENOSPC;
}
leave_critical_section(flags);
return ret;
}
/****************************************************************************
* Name: syslog_flush_intbuffer
*
* Description:
* Flush any characters that may have been added to the interrupt buffer
* to the SYSLOG device.
*
* Input Parameters:
* channel - The syslog channel to use in performing the flush operation.
* force - Use the force() method of the channel vs. the putc() method.
*
* Returned Value:
* On success, the character is echoed back to the caller. A negated
* errno value is returned on any failure.
*
* Assumptions:
* Interrupts may or may not be disabled.
*
****************************************************************************/
int syslog_flush_intbuffer(FAR const struct syslog_channel_s *channel,
bool force)
{
syslog_putc_t putfunc;
int ch;
int ret = OK;
/* Select which putc function to use for this flush */
putfunc = force ? channel->sc_putc : channel->sc_force;
/* This logic is performed with the scheduler disabled to protect from
* concurrent modification by other tasks.
*/
sched_lock();
do
{
/* Transfer one character to time. This is inefficient, but is
* done in this way to: (1) Deal with concurrent modification of
* the interrupt buffer from interrupt activity, (2) Avoid keeper
* interrupts disabled for a long time, and (3) to handler
* wraparound of the circular buffer indices.
*/
ch = syslog_remove_intbuffer();
if (ch != EOF)
{
ret = putfunc(ch);
}
}
while (ch != EOF && ret >= 0);
sched_unlock();
return ret;
}
#endif /* CONFIG_SYSLOG_INTBUFFER */