nuttx/net/local/local_fifo.c

/****************************************************************************
 * net/local/local_fifo.c
 *
 *   Copyright (C) 2015 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>
#if defined(CONFIG_NET) && defined(CONFIG_NET_LOCAL)

#include <sys/stat.h>
#include <sys/ioctl.h>

#include <stdbool.h>
#include <stdio.h>
#include <unistd.h>
#include <fcntl.h>
#include <string.h>
#include <errno.h>
#include <assert.h>

#include "local/local.h"

/****************************************************************************
 * Private Functions
 ****************************************************************************/

#define LOCAL_CS_SUFFIX    "CS"  /* Name of the client-to-server FIFO */
#define LOCAL_SC_SUFFIX    "SC"  /* Name of the server-to-client FIFO */
#define LOCAL_HD_SUFFIX    "HD"  /* Name of the half duplex datagram FIFO */
#define LOCAL_SUFFIX_LEN   2

#define LOCAL_FULLPATH_LEN (UNIX_PATH_MAX + LOCAL_SUFFIX_LEN)

/****************************************************************************
 * Private Functions
 ****************************************************************************/

/****************************************************************************
 * Name: local_cs_name
 *
 * Description:
 *   Create the name of the client-to-server FIFO.
 *
 ****************************************************************************/

#ifdef CONFIG_NET_LOCAL_STREAM
static inline void local_cs_name(FAR struct local_conn_s *conn,
                                 FAR char *path)
{
  (void)snprintf(path, LOCAL_FULLPATH_LEN-1, "%s" LOCAL_CS_SUFFIX,
                 conn->lc_path);
  path[LOCAL_FULLPATH_LEN-1] = '\0';
}
#endif /* CONFIG_NET_LOCAL_STREAM */

/****************************************************************************
 * Name: local_sc_name
 *
 * Description:
 *   Create the name of the server-to-client FIFO.
 *
 ****************************************************************************/

#ifdef CONFIG_NET_LOCAL_STREAM
static inline void local_sc_name(FAR struct local_conn_s *conn,
                                 FAR char *path)
{
  (void)snprintf(path, LOCAL_FULLPATH_LEN-1, "%s" LOCAL_SC_SUFFIX,
                 conn->lc_path);
  path[LOCAL_FULLPATH_LEN-1] = '\0';
}
#endif /* CONFIG_NET_LOCAL_STREAM */

/****************************************************************************
 * Name: local_hd_name
 *
 * Description:
 *   Create the name of the half duplex, datagram FIFO.
 *
 ****************************************************************************/

#ifdef CONFIG_NET_LOCAL_DGRAM
static inline void local_hd_name(FAR const char *inpath, FAR char *outpath)
{
  (void)snprintf(outpath, LOCAL_FULLPATH_LEN-1, "%s" LOCAL_HD_SUFFIX, inpath);
  outpath[LOCAL_FULLPATH_LEN-1] = '\0';
}
#endif /* CONFIG_NET_LOCAL_DGRAM */

/****************************************************************************
 * Name: local_fifo_exists
 *
 * Description:
 *   Check if a FIFO exists.
 *
 ****************************************************************************/

static bool local_fifo_exists(FAR const char *path)
{
  struct stat buf;
  int ret;

  /* Create the client-to-server FIFO */

  ret = stat(path, &buf);
  if (ret < 0)
    {
      return false;
    }

  /* FIFOs are character devices in NuttX.  Return true if what we found
   * is a FIFO.  What if it is something else?  In that case, we will
   * return false and mkfifo() will fail.
   */

  return (bool)S_ISCHR(buf.st_mode);
}

/****************************************************************************
 * Name: local_create_fifo
 *
 * Description:
 *   Create the one FIFO.
 *
 ****************************************************************************/

static int local_create_fifo(FAR const char *path)
{
  int ret;

  /* Create the client-to-server FIFO if it does not already exist. */

  if (!local_fifo_exists(path))
    {
      ret = mkfifo(path, 0644);
      if (ret < 0)
        {
          int errcode = errno;
          DEBUGASSERT(errcode > 0);

          ndbg("ERROR: Failed to create FIFO %s: %d\n", path, errcode);
          return -errcode;
        }
    }

  /* The FIFO (or some character driver) exists at PATH or we successfully
   * created the FIFO at that location.
   */

  return OK;
}

/****************************************************************************
 * Name: local_release_fifo
 *
 * Description:
 *   Release a reference from one of the FIFOs used in a connection.
 *
 ****************************************************************************/

static int local_release_fifo(FAR const char *path)
{
  int ret;

  /* Unlink the client-to-server FIFO if it exists. */

  if (local_fifo_exists(path))
    {
      /* Un-linking the FIFO removes the FIFO from the namespace.  It will
       * also mark the FIFO device "unlinked".  When all of the open
       * references to the FIFO device are closed, the resources consumed
       * by the device instance will also be freed.
       */

      ret = unlink(path);
      if (ret < 0)
        {
          int errcode = errno;
          DEBUGASSERT(errcode > 0);

          ndbg("ERROR: Failed to unlink FIFO %s: %d\n", path, errcode);
          return -errcode;
        }
    }

  /* The FIFO does not exist or we successfully unlinked it. */

  return OK;
}

/****************************************************************************
 * Name: local_rx_open
 *
 * Description:
 *   Open a FIFO for read-only access.
 *
 ****************************************************************************/

static int local_rx_open(FAR struct local_conn_s *conn, FAR const char *path,
                         bool nonblock)
{
  int oflags = nonblock ? O_RDONLY | O_NONBLOCK : O_RDONLY;

  conn->lc_infd = open(path, oflags);
  if (conn->lc_infd < 0)
    {
      int errcode = errno;
      DEBUGASSERT(errcode > 0);

      ndbg("ERROR: Failed on open %s for reading: %d\n",
           path, errcode);

      /* Map the errcode to something consistent with the return
       * error codes from connect():
       *
       * If errcode is ENOENT, meaning that the FIFO does exist,
       * return EFAULT meaning that the socket structure address is
       * outside the user's address space.
       */

      return errcode == ENOENT ? -EFAULT : -errcode;
    }

  return OK;
}

/****************************************************************************
 * Name: local_tx_open
 *
 * Description:
 *   Open a FIFO for write-only access.
 *
 ****************************************************************************/

static int local_tx_open(FAR struct local_conn_s *conn, FAR const char *path,
                         bool nonblock)
{
  int oflags = nonblock ? O_WRONLY | O_NONBLOCK : O_WRONLY;

  conn->lc_outfd = open(path, oflags);
  if (conn->lc_outfd < 0)
    {
      int errcode = errno;
      DEBUGASSERT(errcode > 0);

      ndbg("ERROR: Failed on open %s for writing: %d\n",
           path, errcode);

      /* Map the errcode to something consistent with the return
       * error codes from connect():
       *
       * If errcode is ENOENT, meaning that the FIFO does exist,
       * return EFAULT meaning that the socket structure address is
       * outside the user's address space.
       */

      return errcode == ENOENT ? -EFAULT : -errcode;
    }

  return OK;
}

/****************************************************************************
 * Name: local_set_policy
 *
 * Description:
 *   Set the FIFO buffer policy:
 *
 *     0=Free FIFO resources when the last reference is closed
 *     1=Free FIFO resources when the buffer is empty.
 *
 ****************************************************************************/

static int local_set_policy(int fd, unsigned long policy)
{
  int ret;

  /* Set the buffer policy */

  ret = ioctl(fd, PIPEIOC_POLICY, policy);
  if (ret < 0)
    {
      int errcode = get_errno();
      DEBUGASSERT(errcode > 0);

      ndbg("ERROR: Failed to set FIFO buffer policty: %d\n", errcode);
      return -errcode;
    }

  return OK;
}

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

/****************************************************************************
 * Name: local_create_fifos
 *
 * Description:
 *   Create the FIFO pair needed for a SOCK_STREAM connection.
 *
 ****************************************************************************/

#ifdef CONFIG_NET_LOCAL_STREAM
int local_create_fifos(FAR struct local_conn_s *conn)
{
  char path[LOCAL_FULLPATH_LEN];
  int ret;

  /* Create the client-to-server FIFO if it does not already exist. */

  local_cs_name(conn, path);
  ret = local_create_fifo(path);
  if (ret >= 0)
    {
      /* Create the server-to-client FIFO if it does not already exist. */

      local_sc_name(conn, path);
      ret = local_create_fifo(path);
    }

  return ret;
}
#endif /* CONFIG_NET_LOCAL_STREAM */

/****************************************************************************
 * Name: local_create_halfduplex
 *
 * Description:
 *   Create the half-duplex FIFO needed for SOCK_DGRAM communication.
 *
 ****************************************************************************/

#ifdef CONFIG_NET_LOCAL_DGRAM
int local_create_halfduplex(FAR struct local_conn_s *conn, FAR const char *path)
{
  char fullpath[LOCAL_FULLPATH_LEN];

  /* Create the half duplex FIFO if it does not already exist. */

  local_hd_name(path, fullpath);
  return local_create_fifo(fullpath);
}
#endif /* CONFIG_NET_LOCAL_DGRAM */

/****************************************************************************
 * Name: local_release_fifos
 *
 * Description:
 *   Release references to the FIFO pair used for a SOCK_STREAM connection.
 *
 ****************************************************************************/

#ifdef CONFIG_NET_LOCAL_STREAM
int local_release_fifos(FAR struct local_conn_s *conn)
{
  char path[LOCAL_FULLPATH_LEN];
  int ret1;
  int ret2;

  /* Destroy the client-to-server FIFO if it exists. */

  local_sc_name(conn, path);
  ret1 = local_release_fifo(path);

  /* Destroy the server-to-client FIFO if it exists. */

  local_cs_name(conn, path);
  ret2 = local_create_fifo(path);

  /* Return a failure if one occurred. */

  return ret1 < 0 ? ret1 : ret2;
}
#endif /* CONFIG_NET_LOCAL_STREAM */

/****************************************************************************
 * Name: local_release_halfduplex
 *
 * Description:
 *   Release a reference to the FIFO used for SOCK_DGRAM communication
 *
 ****************************************************************************/

#ifdef CONFIG_NET_LOCAL_DGRAM
int local_release_halfduplex(FAR struct local_conn_s *conn)
{
  char path[LOCAL_FULLPATH_LEN];

  /* Destroy the half duplex FIFO if it exists. */

  local_hd_name(conn->lc_path, path);
  return local_release_fifo(path);
}
#endif /* CONFIG_NET_LOCAL_DGRAM */

/****************************************************************************
 * Name: local_open_client_rx
 *
 * Description:
 *   Open the client-side of the server-to-client FIFO.
 *
 ****************************************************************************/

#ifdef CONFIG_NET_LOCAL_STREAM
int local_open_client_rx(FAR struct local_conn_s *client, bool nonblock)
{
#if 1
  /* REVIST: We need to think about this carefully.  Unlike the connection-
   * oriented Unix domain socket, we don't really know the best time to
   * release the FIFO resource.  It would be extremely inefficient to create
   * and destroy the FIFO on each packet. But, on the other hand, failing
   * to destory the FIFO will leave the FIFO resources in place after the
   * communications have completed.
   *
   * I am thinking that ther should be something like a timer.  The timer
   * would be started at the completion of each transfer and cancelled at
   * the beginning of each transfer.  If the timer expires, then the FIFO
   * would be destroyed.
   */

#  warning Missing logic
  return OK;

#else
  char path[LOCAL_FULLPATH_LEN];
  int ret;

  /* Get the server-to-client path name */

  local_sc_name(client, path);

  /* Then open the file for read-only access */

  ret = local_rx_open(client, path, nonblock);
  if (ret == OK)
    {
      /* Policy: Free FIFO resources when the last reference is closed */

      ret = local_set_policy(client->lc_infd, 0);
    }

  return ret;
#endif
}
#endif /* CONFIG_NET_LOCAL_STREAM */

/****************************************************************************
 * Name: local_open_client_tx
 *
 * Description:
 *   Open the client-side of the client-to-server FIFO.
 *
 ****************************************************************************/

#ifdef CONFIG_NET_LOCAL_STREAM
int local_open_client_tx(FAR struct local_conn_s *client, bool nonblock)
{
  char path[LOCAL_FULLPATH_LEN];
  int ret;

  /* Get the client-to-server path name */

  local_cs_name(client, path);

  /* Then open the file for write-only access */

  ret = local_tx_open(client, path, nonblock);
  if (ret == OK)
    {
      /* Policy: Free FIFO resources when the last reference is closed */

      ret = local_set_policy(client->lc_outfd, 0);
    }

  return ret;
}
#endif /* CONFIG_NET_LOCAL_STREAM */

/****************************************************************************
 * Name: local_open_server_rx
 *
 * Description:
 *   Open the server-side of the client-to-server FIFO.
 *
 ****************************************************************************/

#ifdef CONFIG_NET_LOCAL_STREAM
int local_open_server_rx(FAR struct local_conn_s *server, bool nonblock)
{
  char path[LOCAL_FULLPATH_LEN];
  int ret;

  /* Get the client-to-server path name */

  local_cs_name(server, path);

  /* Then open the file for write-only access */

  ret = local_rx_open(server, path, nonblock);
  if (ret == OK)
    {
      /* Policy: Free FIFO resources when the last reference is closed */

      ret = local_set_policy(server->lc_infd, 0);
    }

  return ret;
}
#endif /* CONFIG_NET_LOCAL_STREAM */

/****************************************************************************
 * Name: local_open_server_tx
 *
 * Description:
 *   Only the server-side of the server-to-client FIFO.
 *
 ****************************************************************************/

#ifdef CONFIG_NET_LOCAL_STREAM
int local_open_server_tx(FAR struct local_conn_s *server, bool nonblock)
{
  char path[LOCAL_FULLPATH_LEN];
  int ret;

  /* Get the server-to-client path name */

  local_sc_name(server, path);

  /* Then open the file for read-only access */

  ret = local_tx_open(server, path, nonblock);
  if (ret == OK)
    {
      /* Policy: Free FIFO resources when the last reference is closed */

      ret = local_set_policy(server->lc_outfd, 0);
    }

  return ret;
}
#endif /* CONFIG_NET_LOCAL_STREAM */

/****************************************************************************
 * Name: local_open_receiver
 *
 * Description:
 *   Only the receiving side of the half duplex FIFO.
 *
 ****************************************************************************/

#ifdef CONFIG_NET_LOCAL_DGRAM
int local_open_receiver(FAR struct local_conn_s *conn, bool nonblock)
{
  char path[LOCAL_FULLPATH_LEN];
  int ret;

  /* Get the server-to-client path name */

  local_hd_name(conn->lc_path, path);

  /* Then open the file for read-only access */

  ret = local_rx_open(conn, path, nonblock);
  if (ret == OK)
    {
      /* Policy: Free FIFO resources when the buffer is empty. */

      ret = local_set_policy(conn->lc_infd, 1);
    }

  return ret;
}
#endif /* CONFIG_NET_LOCAL_DGRAM */

/****************************************************************************
 * Name: local_open_sender
 *
 * Description:
 *   Only the sending side of the half duplex FIFO.
 *
 ****************************************************************************/

#ifdef CONFIG_NET_LOCAL_DGRAM
int local_open_sender(FAR struct local_conn_s *conn, FAR const char *path,
                      bool nonblock)
{
  char fullpath[LOCAL_FULLPATH_LEN];
  int ret;

  /* Get the server-to-client path name */

  local_hd_name(path, fullpath);

  /* Then open the file for read-only access */

  ret = local_tx_open(conn, fullpath, nonblock);
  if (ret == OK)
    {
      /* Policy: Free FIFO resources when the buffer is empty. */

      ret = local_set_policy(conn->lc_outfd, 1);
    }

  return ret;
}
#endif /* CONFIG_NET_LOCAL_DGRAM */

#endif /* CONFIG_NET && CONFIG_NET_LOCAL */