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nuttx/drivers/syslog/syslog_device.c

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/****************************************************************************
* drivers/syslog/syslog_device.c
*
* Copyright (C) 2012, 2016-2017 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 <sys/types.h>
#include <stdint.h>
#include <stdio.h>
#include <unistd.h>
#include <string.h>
#include <sched.h>
#include <fcntl.h>
#include <semaphore.h>
#include <errno.h>
#include <assert.h>
#include <nuttx/arch.h>
#include <nuttx/kmalloc.h>
#include <nuttx/fs/fs.h>
#include <nuttx/syslog/syslog.h>
#include "syslog.h"
#if CONFIG_NFILE_DESCRIPTORS > 0
/****************************************************************************
* Pre-processor Definitions
****************************************************************************/
/* Open the device/file write-only, try to create (file) it if it doesn't
* exist, if the file that already exists, then append the new log data to
* end of the file.
*/
#define SYSLOG_OFLAGS (O_WRONLY | O_CREAT | O_APPEND)
/* An invalid thread ID */
#define NO_HOLDER ((pid_t)-1)
/****************************************************************************
* Private Types
****************************************************************************/
/* This enumeration represents the state of the SYSLOG device interface */
enum syslog_dev_state
{
SYSLOG_UNINITIALIZED = 0, /* SYSLOG has not been initialized */
SYSLOG_INITIALIZING, /* SYSLOG is being initialized */
SYSLOG_REOPEN, /* SYSLOG open failed... try again later */
SYSLOG_FAILURE, /* SYSLOG open failed... don't try again */
SYSLOG_OPENED, /* SYSLOG device is open and ready to use */
};
/* This structure contains all SYSLOGing state information */
struct syslog_dev_s
{
uint8_t sl_state; /* See enum syslog_dev_state */
uint8_t sl_oflags; /* Saved open mode (for re-open) */
uint16_t sl_mode; /* Saved open flags (for re-open) */
sem_t sl_sem; /* Enforces mutually exclusive access */
pid_t sl_holder; /* PID of the thread that holds the semaphore */
struct file sl_file; /* The syslog file structure */
FAR char *sl_devpath; /* Full path to the character device */
};
/****************************************************************************
* Private Data
****************************************************************************/
/* This is the device structure for the console or syslogging function. */
static struct syslog_dev_s g_syslog_dev;
static const uint8_t g_syscrlf[2] =
{
'\r', '\n'
};
/****************************************************************************
* Private Functions
****************************************************************************/
/****************************************************************************
* Name: syslog_dev_takesem
*
* Description:
* Write to the syslog device
*
****************************************************************************/
static inline int syslog_dev_takesem(void)
{
pid_t me = getpid();
int ret;
/* Does this thread already hold the semaphore? That could happen if
* we were called recursively, i.e., if the logic kicked off by
* file_write() where to generate more debug output. Return an
* error in that case.
*/
if (g_syslog_dev.sl_holder == me)
{
/* Return an error (instead of deadlocking) */
return -EWOULDBLOCK;
}
/* Either the semaphore is available or is currently held by another
* thread. Wait for it to become available.
*/
ret = nxsem_wait(&g_syslog_dev.sl_sem);
if (ret < 0)
{
return ret;
}
/* We hold the semaphore. We can safely mark ourself as the holder
* of the semaphore.
*/
g_syslog_dev.sl_holder = me;
return OK;
}
/****************************************************************************
* Name: syslog_dev_givesem
*
* Description:
* Write to the syslog device
*
****************************************************************************/
static inline void syslog_dev_givesem(void)
{
#ifdef CONFIG_DEBUG_ASSERTIONS
pid_t me = getpid();
DEBUGASSERT(g_syslog_dev.sl_holder == me);
#endif
/* Relinquish the semaphore */
g_syslog_dev.sl_holder = NO_HOLDER;
nxsem_post(&g_syslog_dev.sl_sem);
}
/****************************************************************************
* Name: syslog_dev_outputready
*
* Description:
* Ignore any output:
*
* (1) Before the SYSLOG device has been initialized. This could happen
* from debug output that occurs early in the boot sequence before
* syslog_dev_initialize() is called (SYSLOG_UNINITIALIZED).
* (2) While the device is being initialized. The case could happen if
* debug output is generated while syslog_dev_initialize() executes
* (SYSLOG_INITIALIZING).
* (3) While we are generating SYSLOG output. The case could happen if
* debug output is generated while syslog_dev_putc() executes
* (This case is actually handled inside of syslog_semtake()).
* (4) Any debug output generated from interrupt handlers. A disadvantage
* of using the generic character device for the SYSLOG is that it
* cannot handle debug output generated from interrupt level handlers.
* (5) Any debug output generated from the IDLE loop. The character
* driver interface is blocking and the IDLE thread is not permitted
* to block.
* (6) If an irrecoverable failure occurred during initialization. In
* this case, we won't ever bother to try again (ever).
*
* NOTE: That the third case is different. It applies only to the thread
* that currently holds the sl_sem sempaphore. Other threads should wait.
* that is why that case is handled in syslog_semtake().
*
* 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.
*
****************************************************************************/
static int syslog_dev_outputready(void)
{
int ret;
/* Cases (4) and (5) */
if (up_interrupt_context() || getpid() == 0)
{
return -ENOSYS;
}
/* We can save checks in the usual case: That after the SYSLOG device
* has been successfully opened.
*/
if (g_syslog_dev.sl_state != SYSLOG_OPENED)
{
/* Case (1) and (2) */
if (g_syslog_dev.sl_state == SYSLOG_UNINITIALIZED ||
g_syslog_dev.sl_state == SYSLOG_INITIALIZING)
{
return -EAGAIN; /* Can't access the SYSLOG now... maybe next time? */
}
/* Case (6) */
if (g_syslog_dev.sl_state == SYSLOG_FAILURE)
{
return -ENXIO; /* There is no SYSLOG device */
}
/* syslog_dev_initialize() is called as soon as enough of the operating
* system is in place to support the open operation... but it is
* possible that the SYSLOG device is not yet registered at that time.
* In this case, we know that the system is sufficiently initialized
* to support an attempt to re-open the SYSLOG device.
*
* NOTE that the scheduler is locked. That is because we do not have
* fully initialized semaphore capability until the SYSLOG device is
* successfully initialized
*/
sched_lock();
if (g_syslog_dev.sl_state == SYSLOG_REOPEN)
{
/* Try again to initialize the device. We may do this repeatedly
* because the log device might be something that was not ready
* the first time that syslog_dev_initializee() was called (such as a
* USB serial device that has not yet been connected or a file in
* an NFS mounted file system that has not yet been mounted).
*/
DEBUGASSERT(g_syslog_dev.sl_devpath != NULL);
ret = syslog_dev_initialize(g_syslog_dev.sl_devpath,
(int)g_syslog_dev.sl_oflags,
(int)g_syslog_dev.sl_mode);
if (ret < 0)
{
sched_unlock();
return ret;
}
}
sched_unlock();
DEBUGASSERT(g_syslog_dev.sl_state == SYSLOG_OPENED);
}
return OK;
}
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: syslog_dev_initialize
*
* Description:
* Initialize to use the character device (or file) at
* CONFIG_SYSLOG_DEVPATH as the SYSLOG sink.
*
* One power up, the SYSLOG facility is non-existent or limited to very
* low-level output. This function may be called later in the
* intialization sequence after full driver support has been initialized.
* (via syslog_initialize()) It installs the configured SYSLOG drivers
* and enables full SYSLOGing capability.
*
* NOTE that this implementation excludes using a network connection as
* SYSLOG device. That would be a good extension.
*
* Input Parameters:
* devpath - The full path to the character device to be used.
* oflags - File open flags
* mode - File open mode (only if oflags include O_CREAT)
*
* Returned Value:
* Zero (OK) is returned on success; a negated errno value is returned on
* any failure.
*
****************************************************************************/
int syslog_dev_initialize(FAR const char *devpath, int oflags, int mode)
{
int ret;
/* At this point, the only expected states are SYSLOG_UNINITIALIZED or
* SYSLOG_REOPEN.. Not SYSLOG_INITIALIZING, SYSLOG_FAILURE, SYSLOG_OPENED.
*/
DEBUGASSERT(g_syslog_dev.sl_state == SYSLOG_UNINITIALIZED ||
g_syslog_dev.sl_state == SYSLOG_REOPEN);
/* Save the path to the device in case we have to re-open it.
* If we get here and sl_devpath is not equal to NULL, that is a clue
* that we will are re-openingthe file.
*/
if (g_syslog_dev.sl_state == SYSLOG_REOPEN)
{
/* Re-opening: Then we should already have a copy of the path to the
* device.
*/
DEBUGASSERT(g_syslog_dev.sl_devpath != NULL &&
strcmp(g_syslog_dev.sl_devpath, devpath) == 0);
}
else
{
/* Initializing. Copy the device path so that we can use it if we
* have to re-open the file.
*/
DEBUGASSERT(g_syslog_dev.sl_devpath == NULL);
g_syslog_dev.sl_oflags = oflags;
g_syslog_dev.sl_mode = mode;
g_syslog_dev.sl_devpath = strdup(devpath);
DEBUGASSERT(g_syslog_dev.sl_devpath != NULL);
}
g_syslog_dev.sl_state = SYSLOG_INITIALIZING;
/* Open the device driver. */
ret = file_open(&g_syslog_dev.sl_file, devpath, oflags, mode);
if (ret < 0)
{
/* We failed to open the file. Perhaps it does exist? Perhaps it
* exists, but is not ready because it depends on insertion of a
* removable device?
*
* In any case we will attempt to re-open the device repeatedly.
* The assumption is that the device path is valid but that the
* driver has not yet been registered or a removable device has
* not yet been installed.
*/
g_syslog_dev.sl_state = SYSLOG_REOPEN;
return ret;
}
/* The SYSLOG device is open and ready for writing. */
nxsem_init(&g_syslog_dev.sl_sem, 0, 1);
g_syslog_dev.sl_holder = NO_HOLDER;
g_syslog_dev.sl_state = SYSLOG_OPENED;
return OK;
}
/****************************************************************************
* Name: syslog_dev_uninitialize
*
* Description:
* Called to disable the last device/file channel in preparation to use
* a different SYSLOG device. Currently only used for CONFIG_SYSLOG_FILE.
*
* Input Parameters:
* None
*
* Returned Value:
* Zero (OK) is returned on success; a negated errno value is returned on
* any failure.
*
* Assumptions:
* The caller has already switched the SYSLOG source to some safe channel
* (the default channel).
*
****************************************************************************/
#ifdef CONFIG_SYSLOG_FILE /* Currently only used in this configuration */
int syslog_dev_uninitialize(void)
{
/* Attempt to flush any buffered data */
sched_lock();
(void)syslog_dev_flush();
/* Close the detached file instance */
(void)file_close(&g_syslog_dev.sl_file);
/* Free the device path */
if (g_syslog_dev.sl_devpath != NULL)
{
kmm_free(g_syslog_dev.sl_devpath);
}
/* Destroy the semaphore */
nxsem_destroy(&g_syslog_dev.sl_sem);
/* Reset the state structure */
memset(&g_syslog_dev, 0, sizeof(struct syslog_dev_s));
sched_unlock();
return OK;
}
#endif /* CONFIG_SYSLOG_FILE */
/****************************************************************************
* Name: syslog_dev_write
*
* Description:
* This is the low-level, multile byte, system logging interface provided
* for the character driver interface.
*
* Input Parameters:
* buffer - The buffer containing the data to be output
* buflen - The number of bytes in the buffer
*
* Returned Value:
* On success, the character is echoed back to the caller. A negated errno
* value is returned on any failure.
*
****************************************************************************/
ssize_t syslog_dev_write(FAR const char *buffer, size_t buflen)
{
FAR const char *endptr;
ssize_t nwritten;
size_t writelen;
size_t remaining;
int ret;
/* Check if the system is ready to do output operations */
ret = syslog_dev_outputready();
if (ret < 0)
{
return ret;
}
/* The syslog device is ready for writing */
ret = syslog_dev_takesem();
if (ret < 0)
{
/* We probably already hold the semaphore and were probably
* re-entered by the logic kicked off by file_write().
* We might also have been interrupted by a signal. Either
* way, we are outta here.
*/
return ret;
}
/* Loop until we have output all characters */
for (endptr = buffer, remaining = buflen;
remaining > 0;
endptr++, remaining--)
{
/* Check for carriage return or line feed */
if (*endptr == '\r' || *endptr == '\n')
{
/* Check for pre-formatted CR-LF sequence */
if (remaining > 1 &&
((endptr[0] == '\r' && endptr[1] == '\n') ||
(endptr[0] == '\n' && endptr[1] == '\r')))
{
/* Just skip over pre-formatted CR-LF or LF-CR sequence */
endptr++;
remaining--;
}
else
{
/* Write everything up to the position of the special
* character.
*
* - buffer points to next byte to output.
* - endptr points to the special character.
*/
writelen = (size_t)((uintptr_t)endptr - (uintptr_t)buffer);
if (writelen > 0)
{
nwritten = file_write(&g_syslog_dev.sl_file, buffer, writelen);
if (nwritten < 0)
{
ret = (int)nwritten;
goto errout_with_sem;
}
}
/* Ignore the carriage return, but for the linefeed, output
* both a carriage return and a linefeed.
*/
if (*endptr == '\n')
{
nwritten = file_write(&g_syslog_dev.sl_file, g_syscrlf, 2);
if (nwritten < 0)
{
ret = (int)nwritten;
goto errout_with_sem;
}
}
/* Adjust pointers */
writelen++; /* Skip the special character */
buffer += writelen; /* Points past the special character */
}
}
}
/* Write any unterminated data at the end of the buffer.
*
* - buffer points to next byte to output.
* - endptr points to the end of the buffer plus 1.
*/
writelen = (size_t)((uintptr_t)endptr - (uintptr_t)buffer);
if (writelen > 0)
{
nwritten = file_write(&g_syslog_dev.sl_file, buffer, writelen);
if (nwritten < 0)
{
ret = (int)nwritten;
goto errout_with_sem;
}
}
syslog_dev_givesem();
return buflen;
errout_with_sem:
syslog_dev_givesem();
return ret;
}
/****************************************************************************
* Name: syslog_dev_putc
*
* Description:
* This is the low-level, single character, system logging interface
* provided for the character driver 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. Minus one
* is returned on any failure with the errno set correctly.
*
****************************************************************************/
int syslog_dev_putc(int ch)
{
ssize_t nbytes;
uint8_t uch;
int ret;
/* Check if the system is ready to do output operations */
ret = syslog_dev_outputready();
if (ret < 0)
{
return ret;
}
/* Ignore carriage returns */
if (ch == '\r')
{
return ch;
}
/* The syslog device is ready for writing and we have something of
* value to write.
*/
ret = syslog_dev_takesem();
if (ret < 0)
{
/* We probably already hold the semaphore and were probably
* re-entered by the logic kicked off by file_write().
* We might also have been interrupted by a signal. Either
* way, we are outta here.
*/
return ret;
}
/* Pre-pend a newline with a carriage return. */
if (ch == '\n')
{
/* Write the CR-LF sequence */
nbytes = file_write(&g_syslog_dev.sl_file, g_syscrlf, 2);
/* Synchronize the file when each CR-LF is encountered (i.e.,
* implements line buffering always).
*/
#ifndef CONFIG_DISABLE_MOUNTPOINT
if (nbytes > 0)
{
(void)syslog_dev_flush();
}
#endif
}
else
{
/* Write the non-newline character (and don't flush) */
uch = (uint8_t)ch;
nbytes = file_write(&g_syslog_dev.sl_file, &uch, 1);
}
syslog_dev_givesem();
/* Check if the write was successful. If not, nbytes will be
* a negated errno value.
*/
if (nbytes < 0)
{
return (int)nbytes;
}
return ch;
}
/****************************************************************************
* Name: syslog_dev_flush
*
* Description:
* Flush any buffer data in the file system to media.
*
* Input Parameters:
* None
*
* Returned Value:
* Zero (OK) on success; a negated errno value is returned on any failure.
*
****************************************************************************/
int syslog_dev_flush(void)
{
#if defined(CONFIG_SYSLOG_FILE) && !defined(CONFIG_DISABLE_MOUNTPOINT)
/* Ignore return value, always return success. file_fsync() could fail
* because the file is not open, the inode is not a mountpoint, or the
* mountpoint does not support the sync() method.
*/
(void)file_fsync(&g_syslog_dev.sl_file);
#endif
return OK;
}
#endif /* CONFIG_NFILE_DESCRIPTORS > 0 */
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