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git-svn-id: http://svn.code.sf.net/p/nuttx/code/trunk@5153 42af7a65-404d-4744-a932-0658087f49c3
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patacongo
2012-09-17 18:18:44 +00:00
commit 57623d42eb
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nuttx/fs/fs_poll.c
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/****************************************************************************
* fs/fs_poll.c
*
* Copyright (C) 2008-2009, 2012 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 <stdint.h>
#include <stdbool.h>
#include <poll.h>
#include <wdog.h>
#include <errno.h>
#include <assert.h>
#include <debug.h>
#include <nuttx/fs/fs.h>
#include <nuttx/sched.h>
#include <nuttx/clock.h>
#include "fs_internal.h"
#ifndef CONFIG_DISABLE_POLL
/****************************************************************************
* Pre-processor Definitions
****************************************************************************/
#define poll_semgive(sem) sem_post(sem)
/****************************************************************************
* Private Functions
****************************************************************************/
/****************************************************************************
* Name: poll_semtake
****************************************************************************/
static void poll_semtake(FAR sem_t *sem)
{
/* Take the semaphore (perhaps waiting) */
while (sem_wait(sem) != 0)
{
/* The only case that an error should occur here is if
* the wait was awakened by a signal.
*/
ASSERT(get_errno() == EINTR);
}
}
/****************************************************************************
* Name: poll_fdsetup
*
* Description:
* Configure (or unconfigure) one file/socket descriptor for the poll
* operation. If fds and sem are non-null, then the poll is being setup.
* if fds and sem are NULL, then the poll is being torn down.
*
****************************************************************************/
#if CONFIG_NFILE_DESCRIPTORS > 0
static int poll_fdsetup(int fd, FAR struct pollfd *fds, bool setup)
{
FAR struct filelist *list;
FAR struct file *this_file;
FAR struct inode *inode;
int ret = -ENOSYS;
/* Check for a valid file descriptor */
if ((unsigned int)fd >= CONFIG_NFILE_DESCRIPTORS)
{
/* Perform the socket ioctl */
#if defined(CONFIG_NET) && CONFIG_NSOCKET_DESCRIPTORS > 0
if ((unsigned int)fd < (CONFIG_NFILE_DESCRIPTORS+CONFIG_NSOCKET_DESCRIPTORS))
{
return net_poll(fd, fds, setup);
}
else
#endif
{
return -EBADF;
}
}
/* Get the thread-specific file list */
list = sched_getfiles();
if (!list)
{
return -EMFILE;
}
/* Is a driver registered? Does it support the poll method?
* If not, return -ENOSYS
*/
this_file = &list->fl_files[fd];
inode = this_file->f_inode;
if (inode && inode->u.i_ops && inode->u.i_ops->poll)
{
/* Yes, then setup the poll */
ret = (int)inode->u.i_ops->poll(this_file, fds, setup);
}
return ret;
}
#endif
/****************************************************************************
* Name: poll_setup
*
* Description:
* Setup the poll operation for each descriptor in the list.
*
****************************************************************************/
#if CONFIG_NFILE_DESCRIPTORS > 0
static inline int poll_setup(FAR struct pollfd *fds, nfds_t nfds, sem_t *sem)
{
int ret;
int i;
/* Process each descriptor in the list */
for (i = 0; i < nfds; i++)
{
/* Setup the poll descriptor */
fds[i].sem = sem;
fds[i].revents = 0;
fds[i].priv = NULL;
/* Set up the poll */
ret = poll_fdsetup(fds[i].fd, &fds[i], true);
if (ret < 0)
{
return ret;
}
}
return OK;
}
#endif
/****************************************************************************
* Name: poll_teardown
*
* Description:
* Teardown the poll operation for each descriptor in the list and return
* the count of non-zero poll events.
*
****************************************************************************/
#if CONFIG_NFILE_DESCRIPTORS > 0
static inline int poll_teardown(FAR struct pollfd *fds, nfds_t nfds, int *count)
{
int status;
int ret = OK;
int i;
/* Process each descriptor in the list */
*count = 0;
for (i = 0; i < nfds; i++)
{
/* Teardown the poll */
status = poll_fdsetup(fds[i].fd, &fds[i], false);
if (status < 0)
{
ret = status;
}
/* Check if any events were posted */
if (fds[i].revents != 0)
{
(*count)++;
}
/* Un-initialize the poll structure */
fds[i].sem = NULL;
}
return ret;
}
#endif
/****************************************************************************
* Name: poll_timeout
*
* Description:
* The wdog expired before any other events were received.
*
****************************************************************************/
static void poll_timeout(int argc, uint32_t isem, ...)
{
/* Wake up the poller */
FAR sem_t *sem = (FAR sem_t *)isem;
poll_semgive(sem);
}
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: poll
*
* Description:
* poll() waits for one of a set of file descriptors to become ready to
* perform I/O. If none of the events requested (and no error) has
* occurred for any of the file descriptors, then poll() blocks until
* one of the events occurs.
*
* Inputs:
* fds - List of structures describing file descriptors to be monitored
* nfds - The number of entries in the list
* timeout - Specifies an upper limit on the time for which poll() will
* block in milliseconds. A negative value of timeout means an infinite
* timeout.
*
* Return:
* On success, the number of structures that have nonzero revents fields.
* A value of 0 indicates that the call timed out and no file descriptors
* were ready. On error, -1 is returned, and errno is set appropriately:
*
* EBADF - An invalid file descriptor was given in one of the sets.
* EFAULT - The fds address is invalid
* EINTR - A signal occurred before any requested event.
* EINVAL - The nfds value exceeds a system limit.
* ENOMEM - There was no space to allocate internal data structures.
* ENOSYS - One or more of the drivers supporting the file descriptor
* does not support the poll method.
*
****************************************************************************/
int poll(FAR struct pollfd *fds, nfds_t nfds, int timeout)
{
WDOG_ID wdog;
sem_t sem;
int count = 0;
int ret;
sem_init(&sem, 0, 0);
ret = poll_setup(fds, nfds, &sem);
if (ret >= 0)
{
if (timeout >= 0)
{
/* Wait for the poll event with a timeout. Note that the
* millisecond timeout has to be converted to system clock
* ticks for wd_start
*/
wdog = wd_create();
wd_start(wdog, MSEC2TICK(timeout), poll_timeout, 1, (uint32_t)&sem);
poll_semtake(&sem);
wd_delete(wdog);
}
else
{
/* Wait for the poll event with no timeout */
poll_semtake(&sem);
}
/* Teardown the poll operation and get the count of events */
ret = poll_teardown(fds, nfds, &count);
}
sem_destroy(&sem);
/* Check for errors */
if (ret < 0)
{
set_errno(-ret);
return ERROR;
}
return count;
}
#endif /* CONFIG_DISABLE_POLL */