nuttx/net/net_procfs.c

/****************************************************************************
 * net/net_procfs.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>

#include <sys/types.h>
#include <sys/statfs.h>
#include <sys/stat.h>

#include <stdint.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <fcntl.h>
#include <assert.h>
#include <errno.h>
#include <debug.h>

#include <nuttx/arch.h>
#include <nuttx/sched.h>
#include <nuttx/kmalloc.h>
#include <nuttx/fs/fs.h>
#include <nuttx/fs/procfs.h>
#include <nuttx/fs/dirent.h>
#include <nuttx/net/netstats.h>

#include <arch/irq.h>

#if !defined(CONFIG_DISABLE_MOUNTPOINT) && defined(CONFIG_FS_PROCFS)

/****************************************************************************
 * Pre-processor Definitions
 ****************************************************************************/
/* Determines the size of an intermediate buffer that must be large enough
 * to handle the longest line generated by this logic.
 */

#define NET_LINELEN 64

/****************************************************************************
 * Private Types
 ****************************************************************************/

/* This enumeration identifies all of the thread attributes that can be
 * accessed via the procfs file system.
 */

/* This structure describes one open "file" */

struct netprocfs_file_s
{
  struct procfs_file_s base;         /* Base open file structure */
  uint8_t lineno;                    /* Line number */
  uint8_t linesize;                  /* Number of valid characters in line[] */
  uint8_t offset;                    /* Offset to first valid character in line[] */
  char line[NET_LINELEN];            /* Pre-allocated buffer for formatted lines */
};

/* Level 1 is the directory of attributes */

struct netprocfs_level1_s
{
  struct procfs_dir_priv_s  base;    /* Base directory private data */
};

/* Line generating function type */

typedef int (*linegen_t)(FAR struct netprocfs_file_s *netfile);

/****************************************************************************
 * Private Function Prototypes
 ****************************************************************************/
/* Line generating functions */

#ifdef CONFIG_NET_STATISTICS
static int     netprocfs_header(FAR struct netprocfs_file_s *netfile);
static int     netprocfs_received(FAR struct netprocfs_file_s *netfile);
static int     netprocfs_dropped(FAR struct netprocfs_file_s *netfile);
#ifdef CONFIG_NET_IPv4
static int     netprocfs_ipv4_dropped(FAR struct netprocfs_file_s *netfile);
#endif /* CONFIG_NET_IPv4 */
#ifdef CONFIG_NET_IPv6
static int     netprocfs_ipv6_dropped(FAR struct netprocfs_file_s *netfile);
#endif /* CONFIG_NET_IPv4 */
static int     netprocfs_checksum(FAR struct netprocfs_file_s *netfile);
#ifdef CONFIG_NET_TCP
static int     netprocfs_tcp_dropped_1(FAR struct netprocfs_file_s *netfile);
static int     netprocfs_tcp_dropped_2(FAR struct netprocfs_file_s *netfile);
#endif /* CONFIG_NET_TCP */
static int     netprocfs_prototype(FAR struct netprocfs_file_s *netfile);
static int     netprocfs_sent(FAR struct netprocfs_file_s *netfile);
#ifdef CONFIG_NET_TCP
static int     netprocfs_retransmissions(FAR struct netprocfs_file_s *netfile);
#endif /* CONFIG_NET_TCP */
#endif /* CONFIG_NET_STATISTICS */

/* File system methods */

static int     netprocfs_open(FAR struct file *filep, FAR const char *relpath,
                 int oflags, mode_t mode);
static int     netprocfs_close(FAR struct file *filep);
static ssize_t netprocfs_read(FAR struct file *filep, FAR char *buffer,
                 size_t buflen);

static int     netprocfs_dup(FAR const struct file *oldp,
                 FAR struct file *newp);

static int     netprocfs_opendir(FAR const char *relpath,
                 FAR struct fs_dirent_s *dir);
static int     netprocfs_closedir(FAR struct fs_dirent_s *dir);
static int     netprocfs_readdir(FAR struct fs_dirent_s *dir);
static int     netprocfs_rewinddir(FAR struct fs_dirent_s *dir);

static int     netprocfs_stat(FAR const char *relpath, FAR struct stat *buf);

/****************************************************************************
 * Private Data
 ****************************************************************************/

/* Line generating functions */

#ifdef CONFIG_NET_STATISTICS
static const linegen_t g_linegen[] =
{
  netprocfs_header,
  netprocfs_received,
  netprocfs_dropped,

#ifdef CONFIG_NET_IPv4
  netprocfs_ipv4_dropped,
#endif /* CONFIG_NET_IPv4 */

#ifdef CONFIG_NET_IPv6
  netprocfs_ipv6_dropped,
#endif /* CONFIG_NET_IPv4 */

  netprocfs_checksum,

#ifdef CONFIG_NET_TCP
  netprocfs_tcp_dropped_1,
  netprocfs_tcp_dropped_2,
#endif /* CONFIG_NET_TCP */

  netprocfs_prototype,
  netprocfs_sent

#ifdef CONFIG_NET_TCP
  , netprocfs_retransmissions
#endif /* CONFIG_NET_TCP */
};

#define NSTAT_LINES (sizeof(g_linegen) / sizeof(linegen_t))
#endif /* CONFIG_NET_STATISTICS */

/****************************************************************************
 * Public Data
 ****************************************************************************/

/* See include/nutts/fs/procfs.h
 * We use the old-fashioned kind of initializers so that this will compile
 * with any compiler.
 */

const struct procfs_operations net_procfsoperations =
{
  netprocfs_open,       /* open */
  netprocfs_close,      /* close */
  netprocfs_read,       /* read */
  NULL,                 /* write */
  netprocfs_dup,        /* dup */

  netprocfs_opendir,    /* opendir */
  netprocfs_closedir,   /* closedir */
  netprocfs_readdir,    /* readdir */
  netprocfs_rewinddir,  /* rewinddir */

  netprocfs_stat        /* stat */
};

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

/****************************************************************************
 * Name: netprocfs_header
 ****************************************************************************/

#ifdef CONFIG_NET_STATISTICS
static int netprocfs_header(FAR struct netprocfs_file_s *netfile)
{
  int len = 0;

  len += snprintf(&netfile->line[len], NET_LINELEN - len, "           ");
#ifdef CONFIG_NET_IPv4
  len += snprintf(&netfile->line[len], NET_LINELEN - len, "  IPv4");
#endif
#ifdef CONFIG_NET_IPv6
  len += snprintf(&netfile->line[len], NET_LINELEN - len, "  IPv6");
#endif
#ifdef CONFIG_NET_TCP
  len += snprintf(&netfile->line[len], NET_LINELEN - len, "   TCP");
#endif
#ifdef CONFIG_NET_UDP
  len += snprintf(&netfile->line[len], NET_LINELEN - len, "   UDP");
#endif
#ifdef CONFIG_NET_ICMP
  len += snprintf(&netfile->line[len], NET_LINELEN - len, "  ICMP");
#endif
#ifdef CONFIG_NET_ICMPv6
  len += snprintf(&netfile->line[len], NET_LINELEN - len, "  ICMPv6");
#endif

  len += snprintf(&netfile->line[len], NET_LINELEN - len, "\n");
  return len;
}
#endif /* CONFIG_NET_STATISTICS */

/****************************************************************************
 * Name: netprocfs_received
 ****************************************************************************/

#ifdef CONFIG_NET_STATISTICS
static int netprocfs_received(FAR struct netprocfs_file_s *netfile)
{
  int len = 0;

  len += snprintf(&netfile->line[len], NET_LINELEN - len, "Received   ");
#ifdef CONFIG_NET_IPv4
  len += snprintf(&netfile->line[len], NET_LINELEN - len, "  %04x",
                  g_netstats.ipv4.recv);
#endif
#ifdef CONFIG_NET_IPv6
  len += snprintf(&netfile->line[len], NET_LINELEN - len, "  %04x",
                  g_netstats.ipv6.recv);
#endif
#ifdef CONFIG_NET_TCP
  len += snprintf(&netfile->line[len], NET_LINELEN - len, "  %04x",
                  g_netstats.tcp.recv);
#endif
#ifdef CONFIG_NET_UDP
  len += snprintf(&netfile->line[len], NET_LINELEN - len, "  %04x",
                  g_netstats.udp.recv);
#endif
#ifdef CONFIG_NET_ICMP
  len += snprintf(&netfile->line[len], NET_LINELEN - len, "  %04x",
                  g_netstats.icmp.recv);
#endif
#ifdef CONFIG_NET_ICMPv6
  len += snprintf(&netfile->line[len], NET_LINELEN - len, "  %04x",
                  g_netstats.icmpv6.recv);
#endif

  len += snprintf(&netfile->line[len], NET_LINELEN - len, "\n");
  return len;
}
#endif /* CONFIG_NET_STATISTICS */

/****************************************************************************
 * Name: netprocfs_dropped
 ****************************************************************************/

#ifdef CONFIG_NET_STATISTICS
static int netprocfs_dropped(FAR struct netprocfs_file_s *netfile)
{
  int len = 0;

  len += snprintf(&netfile->line[len], NET_LINELEN - len, "Dropped    ");
#ifdef CONFIG_NET_IPv4
  len += snprintf(&netfile->line[len], NET_LINELEN - len, "  %04x",
                  g_netstats.ipv4.drop);
#endif
#ifdef CONFIG_NET_IPv6
  len += snprintf(&netfile->line[len], NET_LINELEN - len, "  %04x",
                  g_netstats.ipv6.drop);
#endif
#ifdef CONFIG_NET_TCP
  len += snprintf(&netfile->line[len], NET_LINELEN - len, "  %04x",
                  g_netstats.tcp.drop);
#endif
#ifdef CONFIG_NET_UDP
  len += snprintf(&netfile->line[len], NET_LINELEN - len, "  %04x",
                  g_netstats.udp.drop);
#endif
#ifdef CONFIG_NET_ICMP
  len += snprintf(&netfile->line[len], NET_LINELEN - len, "  %04x",
                  g_netstats.icmp.drop);
#endif
#ifdef CONFIG_NET_ICMPv6
  len += snprintf(&netfile->line[len], NET_LINELEN - len, "  %04x",
                  g_netstats.icmpv6.drop);
#endif

  len += snprintf(&netfile->line[len], NET_LINELEN - len, "\n");
  return len;
}
#endif /* CONFIG_NET_STATISTICS */

/****************************************************************************
 * Name: netprocfs_ipv4_dropped
 ****************************************************************************/

#if defined(CONFIG_NET_STATISTICS) && defined(CONFIG_NET_IPv4)
static int netprocfs_ipv4_dropped(FAR struct netprocfs_file_s *netfile)
{
  return snprintf(netfile->line, NET_LINELEN,
                  "  IPv4        VHL: %04x   Frg: %04x\n",
                  g_netstats.ipv4.vhlerr, g_netstats.ipv4.fragerr);
}
#endif /* CONFIG_NET_STATISTICS && CONFIG_NET_IPv4 */

/****************************************************************************
 * Name: netprocfs_ipv6_dropped
 ****************************************************************************/

#if defined(CONFIG_NET_STATISTICS) && defined(CONFIG_NET_IPv6)
static int netprocfs_ipv6_dropped(FAR struct netprocfs_file_s *netfile)
{
  return snprintf(netfile->line, NET_LINELEN,
                  "  IPv6        VHL: %04x\n",
                  g_netstats.ipv6.vhlerr);
}
#endif /* CONFIG_NET_STATISTICS && CONFIG_NET_IPv6 */

/****************************************************************************
 * Name: netprocfs_checksum
 ****************************************************************************/

#ifdef CONFIG_NET_STATISTICS
static int netprocfs_checksum(FAR struct netprocfs_file_s *netfile)
{
  int len = 0;

  len += snprintf(&netfile->line[len], NET_LINELEN - len, "  Checksum ");
#ifdef CONFIG_NET_IPv4
  len += snprintf(&netfile->line[len], NET_LINELEN - len, "  %04x",
                  g_netstats.ipv4.chkerr);
#endif
#ifdef CONFIG_NET_IPv6
  len += snprintf(&netfile->line[len], NET_LINELEN - len, "  ----");
#endif
#ifdef CONFIG_NET_TCP
  len += snprintf(&netfile->line[len], NET_LINELEN - len, "  %04x",
                  g_netstats.tcp.chkerr);
#endif
#ifdef CONFIG_NET_UDP
  len += snprintf(&netfile->line[len], NET_LINELEN - len, "  %04x",
                  g_netstats.udp.chkerr);
#endif
#ifdef CONFIG_NET_ICMP
  len += snprintf(&netfile->line[len], NET_LINELEN - len, "  ----");
#endif
#ifdef CONFIG_NET_ICMPv6
  len += snprintf(&netfile->line[len], NET_LINELEN - len, "  ----");
#endif

  len += snprintf(&netfile->line[len], NET_LINELEN - len, "\n");
  return len;
}
#endif /* CONFIG_NET_STATISTICS  */

/****************************************************************************
 * Name: netprocfs_tcp_dropped_1
 ****************************************************************************/

#if defined(CONFIG_NET_STATISTICS) && defined(CONFIG_NET_TCP)
static int netprocfs_tcp_dropped_1(FAR struct netprocfs_file_s *netfile)
{
  return snprintf(netfile->line, NET_LINELEN,
                  "  TCP         ACK: %04x   SYN: %04x\n",
                  g_netstats.tcp.ackerr, g_netstats.tcp.syndrop);
}
#endif /* CONFIG_NET_STATISTICS && CONFIG_NET_TCP */

/****************************************************************************
 * Name: netprocfs_tcp_dropped_2
 ****************************************************************************/

#if defined(CONFIG_NET_STATISTICS) && defined(CONFIG_NET_TCP)
static int netprocfs_tcp_dropped_2(FAR struct netprocfs_file_s *netfile)
{
  return snprintf(netfile->line, NET_LINELEN,
                  "              RST: %04x  %04x\n",
                  g_netstats.tcp.rst, g_netstats.tcp.synrst);
}
#endif /* CONFIG_NET_STATISTICS && CONFIG_NET_TCP */

/****************************************************************************
 * Name: netprocfs_prototype
 ****************************************************************************/

#ifdef CONFIG_NET_STATISTICS
static int netprocfs_prototype(FAR struct netprocfs_file_s *netfile)
{
  int len = 0;

  len += snprintf(&netfile->line[len], NET_LINELEN - len, "  Type     ");
#ifdef CONFIG_NET_IPv4
  len += snprintf(&netfile->line[len], NET_LINELEN - len, "  %04x",
                  g_netstats.ipv4.protoerr);
#endif
#ifdef CONFIG_NET_IPv6
  len += snprintf(&netfile->line[len], NET_LINELEN - len, "  %04x",
                  g_netstats.ipv6.protoerr);
#endif
#ifdef CONFIG_NET_TCP
  len += snprintf(&netfile->line[len], NET_LINELEN - len, "  ----");
#endif
#ifdef CONFIG_NET_UDP
  len += snprintf(&netfile->line[len], NET_LINELEN - len, "  ----");
#endif
#ifdef CONFIG_NET_ICMP
  len += snprintf(&netfile->line[len], NET_LINELEN - len, "  %04x",
                  g_netstats.icmp.typeerr);
#endif
#ifdef CONFIG_NET_ICMPv6
  len += snprintf(&netfile->line[len], NET_LINELEN - len, "  %04x",
                  g_netstats.icmpv6.typeerr);
#endif

  len += snprintf(&netfile->line[len], NET_LINELEN - len, "\n");
  return len;
}
#endif /* CONFIG_NET_STATISTICS */

/****************************************************************************
 * Name: netprocfs_sent
 ****************************************************************************/

#ifdef CONFIG_NET_STATISTICS
static int netprocfs_sent(FAR struct netprocfs_file_s *netfile)
{
  int len = 0;

  len += snprintf(&netfile->line[len], NET_LINELEN - len, "Sent       ");
#ifdef CONFIG_NET_IPv4
  len += snprintf(&netfile->line[len], NET_LINELEN - len, "  %04x",
                  g_netstats.ipv4.sent);
#endif
#ifdef CONFIG_NET_IPv6
  len += snprintf(&netfile->line[len], NET_LINELEN - len, "  %04x",
                  g_netstats.ipv6.sent);
#endif
#ifdef CONFIG_NET_TCP
  len += snprintf(&netfile->line[len], NET_LINELEN - len, "  %04x",
                  g_netstats.tcp.sent);
#endif
#ifdef CONFIG_NET_UDP
  len += snprintf(&netfile->line[len], NET_LINELEN - len, "  %04x",
                  g_netstats.udp.sent);
#endif
#ifdef CONFIG_NET_ICMP
  len += snprintf(&netfile->line[len], NET_LINELEN - len, "  %04x",
                  g_netstats.icmp.sent);
#endif
#ifdef CONFIG_NET_ICMPv6
  len += snprintf(&netfile->line[len], NET_LINELEN - len, "  %04x",
                  g_netstats.icmpv6.sent);
#endif

  len += snprintf(&netfile->line[len], NET_LINELEN - len, "\n");
  return len;
}
#endif /* CONFIG_NET_STATISTICS */

/****************************************************************************
 * Name: netprocfs_retransmissions
 ****************************************************************************/

#if defined(CONFIG_NET_STATISTICS) && defined(CONFIG_NET_TCP)
static int netprocfs_retransmissions(FAR struct netprocfs_file_s *netfile)
{
  int len = 0;

  len += snprintf(&netfile->line[len], NET_LINELEN - len, "  Rexmit   ");
#ifdef CONFIG_NET_IPv4
  len += snprintf(&netfile->line[len], NET_LINELEN - len, "  ----");
#endif
#ifdef CONFIG_NET_IPv6
  len += snprintf(&netfile->line[len], NET_LINELEN - len, "  ----");
#endif
  len += snprintf(&netfile->line[len], NET_LINELEN - len, "  %04x",
                  g_netstats.tcp.rexmit);
#ifdef CONFIG_NET_UDP
  len += snprintf(&netfile->line[len], NET_LINELEN - len, "  ----");
#endif
#ifdef CONFIG_NET_ICMP
   len += snprintf(&netfile->line[len], NET_LINELEN - len, "  ----");
#endif
#ifdef CONFIG_NET_ICMPv6
   len += snprintf(&netfile->line[len], NET_LINELEN - len, "  ----");
#endif

  len += snprintf(&netfile->line[len], NET_LINELEN - len, "\n");
  return len;
}
#endif /* CONFIG_NET_STATISTICS && CONFIG_NET_TCP */

/****************************************************************************
 * Name: netprocfs_open
 ****************************************************************************/

static int netprocfs_open(FAR struct file *filep, FAR const char *relpath,
                          int oflags, mode_t mode)
{
  FAR struct netprocfs_file_s *priv;

  fvdbg("Open '%s'\n", relpath);

  /* PROCFS is read-only.  Any attempt to open with any kind of write
   * access is not permitted.
   *
   * REVISIT:  Write-able proc files could be quite useful.
   */

  if (((oflags & O_WRONLY) != 0 || (oflags & O_RDONLY) == 0) &&
      (net_procfsoperations.write == NULL))
    {
      fdbg("ERROR: Only O_RDONLY supported\n");
      return -EACCES;
    }

  /* "net/stat" is the only acceptable value for the relpath */

  if (strcmp(relpath, "net/stat") != 0)
    {
      fdbg("ERROR: relpath is '%s'\n", relpath);
      return -ENOENT;
    }

  /* Allocate a container to hold the task and attribute selection */

  priv = (FAR struct netprocfs_file_s *)kmm_zalloc(sizeof(struct netprocfs_file_s));
  if (!priv)
    {
      fdbg("ERROR: Failed to allocate file attributes\n");
      return -ENOMEM;
    }

  /* Save the index as the open-specific state in filep->f_priv */

  filep->f_priv = (FAR void *)priv;
  return OK;
}

/****************************************************************************
 * Name: netprocfs_close
 ****************************************************************************/

static int netprocfs_close(FAR struct file *filep)
{
  FAR struct netprocfs_file_s *priv;

  /* Recover our private data from the struct file instance */

  priv = (FAR struct netprocfs_file_s *)filep->f_priv;
  DEBUGASSERT(priv);

  /* Release the file attributes structure */

  kmm_free(priv);
  filep->f_priv = NULL;
  return OK;
}

/****************************************************************************
 * Name: netprocfs_read
 ****************************************************************************/

static ssize_t netprocfs_read(FAR struct file *filep, FAR char *buffer,
                              size_t buflen)
{
#ifdef CONFIG_NET_STATISTICS
  FAR struct netprocfs_file_s *priv;
  size_t xfrsize;
  ssize_t nreturned;

  fvdbg("buffer=%p buflen=%d\n", buffer, (int)buflen);

  /* Recover our private data from the struct file instance */

  priv = (FAR struct netprocfs_file_s *)filep->f_priv;
  DEBUGASSERT(priv);

  /* Is there line data already buffered? */

  nreturned = 0;
  if (priv->linesize > 0)
    {
      /* Yes, how much can we transfer now? */

      xfrsize = priv->linesize;
      if (xfrsize > buflen)
        {
          xfrsize = buflen;
        }

      /* Transfer the data to the user buffer */

      memcpy(buffer, &priv->line[priv->offset], xfrsize);

      /* Update pointers, sizes, and offsets */

      buffer         += xfrsize;
      buflen         -= xfrsize;

      priv->linesize -= xfrsize;
      priv->offset   += xfrsize;
      nreturned       = xfrsize;
    }

  /* Loop until the user buffer is full or until all of the network
   * statistics have been transferred.  At this point we know that
   * either:
   *
   * 1. The user buffer is full, and/or
   * 2. All of the current line data has been transferred.
   */

  while (buflen > 0 && priv->lineno < NSTAT_LINES)
    {
      int len;

      /* Read the next line into the working buffer */

      len = g_linegen[priv->lineno](priv);

      /* Update line-related information */

      priv->lineno++;
      priv->linesize = len;
      priv->offset = 0;

      /* Transfer data to the user buffer */

      xfrsize = priv->linesize;
      if (xfrsize > buflen)
        {
          xfrsize = buflen;
        }

      memcpy(buffer, &priv->line[priv->offset], xfrsize);

      /* Update pointers, sizes, and offsets */

      buffer         += xfrsize;
      buflen         -= xfrsize;

      priv->linesize -= xfrsize;
      priv->offset   += xfrsize;
      nreturned      += xfrsize;
    }

  /* Update the file offset */

  if (nreturned > 0)
    {
      filep->f_pos += nreturned;
    }

  return nreturned;
#else
  return 0;
#endif
}

/****************************************************************************
 * Name: netprocfs_dup
 *
 * Description:
 *   Duplicate open file data in the new file structure.
 *
 ****************************************************************************/

static int netprocfs_dup(FAR const struct file *oldp, FAR struct file *newp)
{
  FAR struct netprocfs_file_s *oldpriv;
  FAR struct netprocfs_file_s *newpriv;

  fvdbg("Dup %p->%p\n", oldp, newp);

  /* Recover our private data from the old struct file instance */

  oldpriv = (FAR struct netprocfs_file_s *)oldp->f_priv;
  DEBUGASSERT(oldpriv);

  /* Allocate a new container to hold the task and attribute selection */

  newpriv = (FAR struct netprocfs_file_s *)kmm_zalloc(sizeof(struct netprocfs_file_s));
  if (!newpriv)
    {
      fdbg("ERROR: Failed to allocate file attributes\n");
      return -ENOMEM;
    }

  /* The copy the file attribtes from the old attributes to the new */

  memcpy(newpriv, oldpriv, sizeof(struct netprocfs_file_s));

  /* Save the new attributes in the new file structure */

  newp->f_priv = (FAR void *)newpriv;
  return OK;
}

/****************************************************************************
 * Name: netprocfs_opendir
 *
 * Description:
 *   Open a directory for read access
 *
 ****************************************************************************/

static int netprocfs_opendir(FAR const char *relpath,
                             FAR struct fs_dirent_s *dir)
{
  FAR struct netprocfs_level1_s *level1;

  fvdbg("relpath: \"%s\"\n", relpath ? relpath : "NULL");
  DEBUGASSERT(relpath && dir && !dir->u.procfs);

  /* The path refers to the 1st level sbdirectory.  Allocate the level1
   * dirent structure.
   */

  level1 = (FAR struct netprocfs_level1_s *)
     kmm_zalloc(sizeof(struct netprocfs_level1_s));

  if (!level1)
    {
      fdbg("ERROR: Failed to allocate the level1 directory structure\n");
      return -ENOMEM;
    }

  /* Initialze base structure components */

  level1->base.level    = 1;
  level1->base.nentries = 1;
  level1->base.index    = 0;

  dir->u.procfs = (FAR void *) level1;
  return OK;
}

/****************************************************************************
 * Name: netprocfs_closedir
 *
 * Description: Close the directory listing
 *
 ****************************************************************************/

static int netprocfs_closedir(FAR struct fs_dirent_s *dir)
{
  FAR struct netprocfs_level1_s *priv;

  DEBUGASSERT(dir && dir->u.procfs);
  priv = dir->u.procfs;

  if (priv)
    {
      kmm_free(priv);
    }

  dir->u.procfs = NULL;
  return OK;
}

/****************************************************************************
 * Name: netprocfs_readdir
 *
 * Description: Read the next directory entry
 *
 ****************************************************************************/

static int netprocfs_readdir(FAR struct fs_dirent_s *dir)
{
  FAR struct netprocfs_level1_s *level1;
  int index;
  int ret;

  DEBUGASSERT(dir && dir->u.procfs);
  level1 = dir->u.procfs;

  /* Have we reached the end of the directory */

  index = level1->base.index;
  if (index >= level1->base.nentries)
    {
      /* We signal the end of the directory by returning the special
       * error -ENOENT
       */

      fvdbg("Entry %d: End of directory\n", index);
      ret = -ENOENT;
    }

  /* Currently only one element in the directory */

  else
    {
      DEBUGASSERT(level1->base.level == 1);
      DEBUGASSERT(level1->base.index <= 1);

      /* Copy the one supported directory entry */

      dir->fd_dir.d_type = DTYPE_FILE;
      strncpy(dir->fd_dir.d_name, "stat", NAME_MAX + 1);

      /* Set up the next directory entry offset.  NOTE that we could use the
       * standard f_pos instead of our own private index.
       */

      level1->base.index = index + 1;
      ret = OK;
    }

  return ret;
}

/****************************************************************************
 * Name: netprocfs_rewindir
 *
 * Description: Reset directory read to the first entry
 *
 ****************************************************************************/

static int netprocfs_rewinddir(FAR struct fs_dirent_s *dir)
{
  FAR struct netprocfs_level1_s *priv;

  DEBUGASSERT(dir && dir->u.procfs);
  priv = dir->u.procfs;

  priv->base.index = 0;
  return OK;
}

/****************************************************************************
 * Name: netprocfs_stat
 *
 * Description: Return information about a file or directory
 *
 ****************************************************************************/

static int netprocfs_stat(FAR const char *relpath, FAR struct stat *buf)
{
  /* "net" and "net/stat" are the only acceptable values for the relpath */

  if (strcmp(relpath, "net") == 0)
    {
      buf->st_mode = S_IFDIR | S_IROTH | S_IRGRP | S_IRUSR;
    }
  else if (strcmp(relpath, "net/stat") == 0)
    {
      buf->st_mode = S_IFREG | S_IROTH | S_IRGRP | S_IRUSR;
    }
  else
    {
      fdbg("ERROR: relpath is '%s'\n", relpath);
      return -ENOENT;
    }

  /* File/directory size, access block size */

  buf->st_size    = 0;
  buf->st_blksize = 512;
  buf->st_blocks  = 0;

  return OK;
}

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

#endif /* !CONFIG_DISABLE_MOUNTPOINT && CONFIG_FS_PROCFS */