source: src/router/proftpd/contrib/mod_quotatab.c @ 17876

/*
 * ProFTPD: mod_quotatab -- a module for managing FTP byte/file quotas via
 *                          centralized tables
 *
 * Copyright (c) 2001-2011 TJ Saunders
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Suite 500, Boston, MA 02110-1335, USA.
 *
 * As a special exemption, TJ Saunders gives permission to link this program
 * with OpenSSL, and distribute the resulting executable, without including
 * the source code for OpenSSL in the source distribution.
 *
 * This is mod_quotatab, contrib software for proftpd 1.2 and above.
 * For more information contact TJ Saunders <tj@castaglia.org>.  It is based
 * the ideas in Eric Estabrook's mod_quota, available from
 * ftp://pooh.urbanrage.com/pub/c/.  This module, however, has been written
 * from scratch to implement quotas in a different way.
 *
 * $Id: mod_quotatab.c,v 1.76 2011/05/26 23:14:01 castaglia Exp $
 */

#include "mod_quotatab.h"

typedef struct regtab_obj {
  struct regtab_obj *prev, *next;
 
  /* Table source type name */
  const char *regtab_name;

  /* Initialization function for this type of table source */
  quota_table_t *(*regtab_open)(pool *, quota_tabtype_t, const char *);

  /* Flags for this type of table: QUOTATAB_LIMIT_SRC, QUOTATAB_TALLY_SRC.
   * Used to restrict some sources to only certain table types (ie
   * LDAP to limit tables).
   */
  unsigned int regtab_srcs;

} quota_regtab_t;

module quotatab_module;

/* Quota objects for the current session */
static quota_table_t *limit_tab = NULL;
static quota_limit_t sess_limit;

static quota_table_t *tally_tab = NULL;
static quota_tally_t sess_tally;

/* Memory pools for this module */
static pool *quotatab_pool = NULL;
static pool *quotatab_backend_pool = NULL;

/* List of registered quotatab sources */
static quota_regtab_t *quotatab_backends = NULL;
static unsigned int quotatab_nbackends = 0;

/* Logging data */
static int quota_logfd = -1; 
static char *quota_logname = NULL;

static unsigned char allow_site_quota = TRUE;
static unsigned char use_dirs = FALSE;
static unsigned char use_quotas = FALSE;
static unsigned char have_quota_entry = FALSE;
static unsigned char have_quota_limit_table = FALSE;
static unsigned char have_quota_tally_table = FALSE;

static unsigned long have_quota_update = 0;
#define QUOTA_HAVE_READ_UPDATE                  10000
#define QUOTA_HAVE_WRITE_UPDATE                 20000

#ifdef PR_USE_REGEX
static pr_regex_t *quota_exclude_pre = NULL;
static const char *quota_exclude_filter = NULL;
#endif

static quota_units_t byte_units = BYTE;

/* For transmitting number of bytes/files from PRE_CMD to POST_CMD handlers
 * (for use by APPE, DELE, MKD, RMD, RNTO, STOR, STOU, XMKD, and XRMD
 * commands)
 */
static off_t quotatab_disk_nbytes;
static unsigned int quotatab_disk_nfiles;

/* For handling deletes of files which not belong to us. */
static struct stat quotatab_dele_st;
static int quotatab_have_dele_st = FALSE;

/* For locking (e.g. during tally creation). */
static int quota_lockfd = -1;

#define QUOTA_MAX_LOCK_ATTEMPTS         10

/* Used to indicate whether a transfer was aborted via the ABORT command.
 * This is needed, in conjunction with checking the SF_ABORT/SF_POST_ABORT
 * session flags, since it is possible for clients to abort transfers without
 * using the OOB signal byte.
 */
static unsigned char have_aborted_transfer = FALSE;

/* It is the case where sometimes a command may be denied by a PRE_CMD
 * handler of this module, in which case an appropriate error response is
 * added to the response chain.  When the matching POST_CMD_ERR handler
 * then runs, it will add another response.  Sometimes, however, the
 * POST_CMD_ERR handlers may be run for other reasons, and the response
 * added is not a duplicate.  Use this flag to signal when a response has
 * already been added.
 */
static unsigned char have_err_response = FALSE;

/* convenience macros */
#define DISPLAY_BYTES_IN(x) \
    quota_display_bytes((x)->tmp_pool, \
    sess_tally.bytes_in_used, sess_limit.bytes_in_avail, IN)

#define DISPLAY_BYTES_OUT(x) \
    quota_display_bytes((x)->tmp_pool, \
    sess_tally.bytes_out_used, sess_limit.bytes_out_avail, OUT)

#define DISPLAY_BYTES_XFER(x) \
    quota_display_bytes((x)->tmp_pool, \
    sess_tally.bytes_xfer_used, sess_limit.bytes_xfer_avail, XFER)

#define DISPLAY_FILES_IN(x) \
    quota_display_files((x)->tmp_pool, \
    sess_tally.files_in_used, sess_limit.files_in_avail, IN)

#define DISPLAY_FILES_OUT(x) \
    quota_display_files((x)->tmp_pool, \
    sess_tally.files_out_used, sess_limit.files_out_avail, OUT)

#define DISPLAY_FILES_XFER(x) \
    quota_display_files((x)->tmp_pool, \
    sess_tally.files_xfer_used, sess_limit.files_xfer_avail, XFER)

#define QUOTATAB_TALLY_READ \
  if (!sess_limit.quota_per_session) { \
    if (quotatab_read(&sess_tally) < 0) { \
      quotatab_log("error: unable to read tally: %s", strerror(errno)); \
    } \
  }

#define QUOTATAB_TALLY_WRITE(bi, bo, bx, fi, fo, fx) \
  { \
    if (quotatab_write(&sess_tally, (bi), (bo), (bx), (fi), (fo), (fx)) < 0) { \
      quotatab_log("error: unable to write tally: %s", strerror(errno)); \
    } \
    have_quota_update = 0; \
  }

static unsigned long quotatab_opts = 0UL;
#define QUOTA_OPT_SCAN_ON_LOGIN         0x0001

#define QUOTA_SCAN_FL_VERBOSE           0x0001

/* necessary prototypes */
MODRET quotatab_pre_stor(cmd_rec *);
MODRET quotatab_post_stor(cmd_rec *);
MODRET quotatab_post_stor_err(cmd_rec *);

static int quotatab_rlock(quota_table_t *);
static int quotatab_runlock(quota_table_t *);
static int quotatab_wlock(quota_table_t *);
static int quotatab_wunlock(quota_table_t *);

/* Support routines
 */

/* Returns the most appropriate errno value for indicating a "quota exceeded"
 * state, or -1 if there is no such appropriate errno.
 */
static int get_quota_exceeded_errno(int default_errno, char **errstr) {
  int res;

#if defined(EDQUOT)
  res = EDQUOT;

#elif defined(EFBIG)
  res = EFBIG;

#elif defined(ENOSPC)
  res = ENOSPC;

#else
  res = default_errno;
#endif

  if (errstr != NULL) {
    *errstr = strerror(res);
  }

  return res;
}

/* Quota units routines */

static char *quota_display_bytes(pool *p, double bytes_used,
    double bytes_avail, quota_xfer_t xfer_type) {
  double adj_used = 0.0, adj_avail = 0.0;
  char *display = NULL, *xferstr = NULL;
  unsigned int display_len = 80;

  display = pcalloc(p, display_len);

  switch (xfer_type) {
    case IN:
      xferstr = _("upload");
      break;

    case OUT:
      xferstr = _("download");
      break;

    case XFER:
      xferstr = _("transfer");
      break;

    default:
      break;
  }

  switch (byte_units) {

    case BYTE:
      /* no manipulation needed */
      snprintf(display, display_len - 1, _("%.2f of %.2f %s %s"), bytes_used,
        bytes_avail, xferstr, bytes_avail > 1.0 ? _("bytes") : _("byte"));
      break;

    case KILO:
      /* divide by 1024.0 */
      adj_used = (bytes_used / 1024.0);
      adj_avail = (bytes_avail / 1024.0);
      snprintf(display, display_len - 1, _("%.2f of %.2f %s Kb"), adj_used,
        adj_avail, xferstr);
      break;

    case MEGA:
      /* divide by 1024.0 * 1024.0 */
      adj_used = (bytes_used / (1024.0 * 1024.0));
      adj_avail = (bytes_avail / (1024.0 * 1024.0));
      snprintf(display, display_len -1 , _("%.2f of %.2f %s Mb"), adj_used,
        adj_avail, xferstr);
      break;

    case GIGA:
      /* divide by 1024.0 * 1024.0 * 1024.0 */
      adj_used = (bytes_used / (1024.0 * 1024.0 * 1024.0));
      adj_avail = (bytes_avail / (1024.0 * 1024.0 * 1024.0));
      snprintf(display, display_len - 1, _("%.2f of %.2f %s Gb"), adj_used,
        adj_avail, xferstr);
      break;

    /* Always have a fallthrough case, even if it _should_ never be reached. */
    default:
      quotatab_log("warning: unknown QuotaDisplayUnits");
      break;
  }

  return display;
}

static char *quota_display_files(pool *p, unsigned int files_used,
    unsigned int files_avail, quota_xfer_t xfer_type) {
  char *display = NULL, *xferstr = NULL;
  unsigned int display_len = 80;

  display = pcalloc(p, display_len);

  switch (xfer_type) {
    case IN:
      xferstr = _("upload");
      break;

    case OUT:
      xferstr = _("download");
      break;

    case XFER:
      xferstr = _("transfer");
      break;

    default:
      break;
  }

  snprintf(display, display_len - 1, _("%u of %u %s %s"), files_used,
    files_avail, xferstr, files_avail > 1.0 ? _("files") : _("file"));

  return display;
}

static char *quota_display_site_bytes(pool *p, double bytes_used,
    double bytes_avail, quota_xfer_t xfer_type) {
  double adj_used = 0.0, adj_avail = 0.0;
  char *display = NULL;
  unsigned int display_len = 80;

  display = pcalloc(p, display_len);

  switch (byte_units) {
    case BYTE:
      /* no calculation needed */

      if (bytes_avail > 0.0)
        snprintf(display, display_len - 1, _("bytes:\t%.2f/%.2f"), bytes_used,
          bytes_avail);
      else
        snprintf(display, display_len - 1, _("bytes:\tunlimited"));
      break;

    case KILO:
      /* divide by 1024.0 */
      adj_used = (bytes_used / 1024.0);
      adj_avail = (bytes_avail / 1024.0);

      if (adj_avail > 0.0)
        snprintf(display, display_len - 1, _("Kb:\t%s%.2f/%.2f"),
          xfer_type != IN ? "" : "\t", adj_used, adj_avail);
      else
        snprintf(display, display_len - 1, _("Kb:\tunlimited"));
      break;

    case MEGA:
      /* divide by 1024.0 * 1024.0 */
      adj_used = (bytes_used / (1024.0 * 1024.0));
      adj_avail = (bytes_avail / (1024.0 * 1024.0));

      if (adj_avail > 0.0)
        snprintf(display, display_len - 1, _("Mb:\t%s%.2f/%.2f"),
          xfer_type != IN ? "" : "\t", adj_used, adj_avail);
      else
        snprintf(display, display_len - 1, _("Mb:\tunlimited"));
      break;

    case GIGA:
      /* divide by 1024.0 * 1024.0 * 1024.0 */
      adj_used = (bytes_used / (1024.0 * 1024.0 * 1024.0));
      adj_avail = (bytes_avail / (1024.0 * 1024.0 * 1024.0));

      if (adj_avail > 0.0)
        snprintf(display, display_len - 1, _("Gb:\t%s%.2f/%.2f"),
          xfer_type != IN ? "" : "\t", adj_used, adj_avail);
      else
        snprintf(display, display_len - 1, _("Gb:\tunlimited"));
      break;

    default:
      quotatab_log("warning: unknown QuotaDisplayUnits");
      break;
  }

  return display;
}

static char *quota_display_site_files(pool *p, unsigned int files_used,
    unsigned int files_avail, quota_xfer_t xfer_type) {
  char *display = NULL;
  unsigned int display_len = 80;

  display = pcalloc(p, display_len);

  if (files_avail != 0)
    snprintf(display, display_len - 1, _("files:\t%u/%u"), files_used,
      files_avail);
  else
    snprintf(display, display_len - 1, _("files:\tunlimited"));

  return display;
}

/* Quota logging routines */
static int quotatab_closelog(void) {
  /* sanity check */
  if (quota_logfd != -1) {
    close(quota_logfd);
    quota_logfd = -1;
    quota_logname = NULL;
  }

  return 0;
}

int quotatab_log(const char *fmt, ...) {
  va_list msg;
  int res;

  /* sanity check */
  if (!quota_logname)
    return 0;

  va_start(msg, fmt);
  res = pr_log_vwritefile(quota_logfd, MOD_QUOTATAB_VERSION, fmt, msg);
  va_end(msg);

  return res;
}

int quotatab_openlog(void) {
  int res = 0;

  /* Sanity checks. */
  if (quota_logname)
    return 0;

  quota_logname = get_param_ptr(main_server->conf, "QuotaLog", FALSE);
  if (quota_logname == NULL)
    return 0;

  /* check for "none" */
  if (strcasecmp(quota_logname, "none") == 0) {
    quota_logname = NULL;
    return 0;
  }

  pr_signals_block();
  PRIVS_ROOT
  res = pr_log_openfile(quota_logname, &quota_logfd, 0640);
  PRIVS_RELINQUISH
  pr_signals_unblock();

  switch (res) {
    case -1:
      pr_log_pri(LOG_NOTICE, MOD_QUOTATAB_VERSION
        ": unable to open QuotaLog '%s': %s", quota_logname, strerror(errno));
      break;

    case PR_LOG_WRITABLE_DIR:
      pr_log_pri(LOG_NOTICE, MOD_QUOTATAB_VERSION
        ": unable to open QuotaLog '%s': %s", quota_logname,
        "World-writable directory");
      break;

    case PR_LOG_SYMLINK:
      pr_log_pri(LOG_NOTICE, MOD_QUOTATAB_VERSION
        ": unable to open QuotaLog '%s': %s", quota_logname, "Symbolic link");
      break;
  }

  return res;
}

static int quotatab_close(quota_tabtype_t tab_type) {
  int res = 0;

  if (tab_type == TYPE_TALLY) {
    res = tally_tab->tab_close(tally_tab);
    tally_tab = NULL;

  } else if (tab_type == TYPE_LIMIT) {
    res = limit_tab->tab_close(limit_tab); 
    limit_tab = NULL;
  }

  return res;
}

static int quotatab_verify(quota_tabtype_t tab_type) {

  /* Request the table source object to verify itself */
  if (tab_type == TYPE_TALLY) {
    if (tally_tab->tab_verify(tally_tab))
      return TRUE;
    else
      quotatab_log("error: unable to use QuotaTallyTable: bad table header");

  } else if (tab_type == TYPE_LIMIT) {
    if (limit_tab->tab_verify(limit_tab))
      return TRUE;
    else
      quotatab_log("error: unable to use QuotaLimitTable: bad table header");
  }

  return FALSE;
}

static int quotatab_create(quota_tally_t *tally) {

  /* Creation of an entry only ever occurs in the tally table -- the limit
   * table is considered read-only.
   */

  /* Obtain a writer lock for the entry in question. */
  if (quotatab_wlock(tally_tab) < 0)
    return FALSE;

  if (tally_tab->tab_create(tally_tab, tally) < 0) {
    quotatab_wunlock(tally_tab);
    return FALSE;
  }

  /* Release the lock */
  if (quotatab_wunlock(tally_tab) < 0)
    return FALSE;

  return TRUE;
}

static int quotatab_create_tally(void) {
  int res = TRUE;

  memset(sess_tally.name, '\0', sizeof(sess_tally.name));
  snprintf(sess_tally.name, sizeof(sess_tally.name), "%s",
    sess_limit.name);
  sess_tally.name[sizeof(sess_tally.name)-1] = '\0';

  sess_tally.quota_type = sess_limit.quota_type;

  /* Initial tally values. */
  sess_tally.bytes_in_used = 0.0F;
  sess_tally.bytes_out_used = 0.0F;
  sess_tally.bytes_xfer_used = 0.0F;
  sess_tally.files_in_used = 0U;
  sess_tally.files_out_used = 0U;
  sess_tally.files_xfer_used = 0U;

  quotatab_log("creating new tally entry to match limit entry");

  res = quotatab_create(&sess_tally);
  if (res == FALSE) {
    quotatab_log("error: unable to create tally entry: %s",
      strerror(errno));
  }

  return res;
}

static quota_regtab_t *quotatab_get_backend(const char *backend,
    unsigned int srcs) {
  quota_regtab_t *regtab;

  for (regtab = quotatab_backends; regtab; regtab = regtab->next) {
    if ((regtab->regtab_srcs & srcs) &&
        strcmp(regtab->regtab_name, backend) == 0) {
      return regtab;
    }
  }

  errno = ENOENT;
  return NULL;
}

/* Returns TRUE if the given path is to be ignored, FALSE otherwise. */
static int quotatab_ignore_path(pool *p, const char *path) {
  char *abs_path;

  if (path == NULL) {
    return FALSE;
  }

#ifdef PR_USE_REGEX
  if (quota_exclude_pre == NULL) {
    return FALSE;
  }

  /* Always apply the filter to the absolute path. */
  abs_path = dir_abs_path(p, path, TRUE);
  if (abs_path == NULL) {
    quotatab_log("unable to resolve absolute path for '%s': %s", path,
      strerror(errno));
    abs_path = (char *) path;
  }

  if (pr_regexp_exec(quota_exclude_pre, abs_path, 0, NULL, 0, 0, 0) == 0) {
    return TRUE;
  }

  return FALSE;
#else
  return FALSE;
#endif
}

static int quotatab_scan_dir(pool *p, const char *path, uid_t uid,
    gid_t gid, int flags, double *nbytes, unsigned int *nfiles) {
  struct stat st;
  DIR *dirh;
  struct dirent *dent;

  if (!nbytes ||
      !nfiles) {
    errno = EINVAL;
    return -1;
  }

  if (quotatab_ignore_path(p, path)) {
    quotatab_log("path '%s' matches QuotaExcludeFilter '%s', ignoring",
      path, quota_exclude_filter);
    return 0;
  }

  if (pr_fsio_lstat(path, &st) < 0) {
    return -1;
  }

  if (!S_ISDIR(st.st_mode)) {
    errno = EINVAL;
    return -1;
  }

  dirh = pr_fsio_opendir(path);
  if (dirh == NULL) {
    return -1;
  }

  if (use_dirs) {
    if (uid != (uid_t) -1 ||
        gid != (gid_t) -1) {

      if (uid != (uid_t) -1 &&
          st.st_uid == uid) {
        *nbytes += st.st_size;
        *nfiles += 1;

      } else if (gid != (gid_t) -1 &&
                 st.st_gid == gid) {
        *nbytes += st.st_size;
        *nfiles += 1;
      }

    } else {
      *nbytes += st.st_size;
      *nfiles += 1;
    }
  }

  while ((dent = pr_fsio_readdir(dirh)) != NULL) {
    char *file;

    pr_signals_handle();

    if (strcmp(dent->d_name, ".") == 0 ||
        strcmp(dent->d_name, "..") == 0) {
      continue;
    }

    file = pdircat(p, path, dent->d_name, NULL);

    memset(&st, 0, sizeof(st));
    if (pr_fsio_lstat(file, &st) < 0) {
      quotatab_log("unable to lstat '%s': %s", file, strerror(errno));
      continue;
    }

    if (S_ISREG(st.st_mode) ||
        S_ISLNK(st.st_mode)) {

      if (uid != (uid_t) -1 ||
          gid != (gid_t) -1) {
        if (uid != (uid_t) -1 &&
            st.st_uid == uid) {
          *nbytes += st.st_size;
          *nfiles += 1;
  
        } else if (gid != (gid_t) -1 &&
                   st.st_gid == gid) {
          *nbytes += st.st_size;
          *nfiles += 1;
        }

      } else {
        *nbytes += st.st_size;
        *nfiles += 1;
      }

    } else if (S_ISDIR(st.st_mode)) {
      pool *sub_pool;

      sub_pool = make_sub_pool(p);

      if (quotatab_scan_dir(sub_pool, file, uid, gid, flags, nbytes,
          nfiles) < 0) {
        quotatab_log("error scanning '%s': %s", file, strerror(errno));
      }

      destroy_pool(sub_pool);

    } else {
      if (flags & QUOTA_SCAN_FL_VERBOSE) {
        quotatab_log("file '%s' is not a file, symlink, or directory; skipping",
          file);
      }
    }
  }

  pr_fsio_closedir(dirh); 
  return 0;
}

static int quotatab_open(quota_tabtype_t tab_type) {

  if (tab_type == TYPE_TALLY) {
    register config_rec *c = NULL;
    register quota_regtab_t *regtab = NULL;

    c = find_config(main_server->conf, CONF_PARAM, "QuotaTallyTable", FALSE);
    if (!c) {
      quotatab_log("notice: no QuotaTallyTable configured");
      return -1;
    }

    regtab = quotatab_get_backend(c->argv[0], QUOTATAB_TALLY_SRC);
    if (regtab) {
      tally_tab = regtab->regtab_open(quotatab_pool, TYPE_TALLY, c->argv[1]);
      if (!tally_tab)
        return -1;

    } else {
      quotatab_log("error: unsupported tally table type: '%s'",
        (const char *) c->argv[0]);
      return -1;
    }

  } else if (tab_type == TYPE_LIMIT) {
    register config_rec *c = NULL;
    register quota_regtab_t *regtab = NULL;

    c = find_config(main_server->conf, CONF_PARAM, "QuotaLimitTable", FALSE);
    if (!c) {
      quotatab_log("notice: no QuotaLimitTable configured");
      return -1;
    }

    /* Look up the table source open routine by name, and invoke it */
    regtab = quotatab_get_backend(c->argv[0], QUOTATAB_LIMIT_SRC);
    if (regtab) {
      limit_tab = regtab->regtab_open(quotatab_pool, TYPE_LIMIT, c->argv[1]);
      if (!limit_tab)
        return -1;

    } else {
      quotatab_log("error: unsupported limit table type: '%s'",
        (const char *) c->argv[0]);
      return -1;
    }
  }

  return 0;
}

/* Reads via this function are only ever done on tally tables.  Limit tables
 * are read via the quotatab_lookup() function.
 */
int quotatab_read(quota_tally_t *tally) {
  int bread = 0;

  /* Make sure the tally table can support reads. */
  if (!tally_tab || !tally_tab->tab_read) {
    errno = EPERM;
    return -1;
  }

  /* Obtain a reader lock for the entry in question. */
  if (quotatab_rlock(tally_tab) < 0) {
    quotatab_log("error: unable to obtain read lock: %s", strerror(errno));
    return -1;
  }

  /* Read from the current point in the stream enough information to populate
   * the quota structs.
   */
  bread = tally_tab->tab_read(tally_tab, tally);
  if (bread < 0) {
    quotatab_runlock(tally_tab);
    return -1;
  }

  /* Release the lock */
  if (quotatab_runlock(tally_tab) < 0) {
    quotatab_log("error: unable to release read lock: %s", strerror(errno));
    return -1;
  }

  return bread;
}

/* This function is used by mod_quotatab backends, to register their
 * individual backend table function pointers with the main mod_quotatab
 * module.
 */
int quotatab_register_backend(const char *backend,
    quota_table_t *(*srcopen)(pool *, quota_tabtype_t, const char *),
    unsigned int srcs) {
  quota_regtab_t *regtab;

  if (!backend || !srcopen) {
    errno = EINVAL;
    return -1;
  }

  if (!quotatab_backend_pool) {
    quotatab_backend_pool = make_sub_pool(permanent_pool);
    pr_pool_tag(quotatab_backend_pool, MOD_QUOTATAB_VERSION ": Backend Pool");
  }

  /* Check to see if this backend has already been registered. */
  regtab = quotatab_get_backend(backend, srcs);
  if (regtab) {
    errno = EEXIST;
    return -1;
  }

  regtab = pcalloc(quotatab_backend_pool, sizeof(quota_regtab_t));
  regtab->regtab_name = pstrdup(quotatab_backend_pool, backend);
  regtab->regtab_open = srcopen;
  regtab->regtab_srcs = srcs;

  /* Add this object to the list. */
  if (quotatab_backends) {
    quotatab_backends->prev = regtab;
    regtab->next = quotatab_backends;
  }

  quotatab_backends = regtab;
  quotatab_nbackends++;

  return 0;
}

/* Used by mod_quotatab backends to unregister their backend function pointers
 * from the main mod_quotatab module.
 */
int quotatab_unregister_backend(const char *backend, unsigned int srcs) {
  quota_regtab_t *regtab;

  if (!backend) {
    errno = EINVAL;
    return -1;
  }

  /* Check to see if this backend has been registered. */
  regtab = quotatab_get_backend(backend, srcs);
  if (!regtab) {
    errno = ENOENT;
    return -1;
  }

#if !defined(PR_SHARED_MODULE)
  /* If there is only one registered backend, it cannot be removed.
   */
  if (quotatab_nbackends == 1) {
    errno = EPERM;
    return -1;
  }
#endif

  /* Remove this backend from the linked list. */
  if (regtab->prev)
    regtab->prev->next = regtab->next;
  else
    /* This backend is the start of the quotatab_backends list (prev is NULL),
     * so we need to update the list head pointer as well.
     */
    quotatab_backends = regtab->next;

  if (regtab->next)
    regtab->next->prev = regtab->prev;

  regtab->prev = regtab->next = NULL;

  quotatab_nbackends--;

  /* NOTE: a counter should be kept of the number of unregistrations,
   * as the memory for a registration is not freed on unregistration.
   */

  return 0;
}

/* Note: this function will only find the first occurrence of the given
 *  name and type in the table.  This means that if there is a malformed
 *  quota table, with duplicate name/type pairs, the duplicates will be
 *  ignored.
 */
unsigned char quotatab_lookup(quota_tabtype_t tab_type, void *ptr,
    const char *name, quota_type_t quota_type) {

  if (tab_type == TYPE_TALLY) {

    /* Make sure the requested table can do lookups. */
    if (!tally_tab ||
        !tally_tab->tab_lookup) {
      errno = EPERM;
      return FALSE;
    }

    return tally_tab->tab_lookup(tally_tab, ptr, name, quota_type);
  
  } else if (tab_type == TYPE_LIMIT) {

    /* Make sure the requested table can do lookups. */
    if (!limit_tab ||
        !limit_tab->tab_lookup) {
      errno = EPERM;
      return FALSE;
    }

    return limit_tab->tab_lookup(limit_tab, ptr, name, quota_type);
  }

  errno = ENOENT;
  return FALSE;
}

static int quotatab_mutex_lock(int lock_type) {
  const char *lock_desc;
  struct flock lock;
  unsigned int nattempts = 1;

  if (quota_lockfd < 0)
    return 0;

  lock.l_type = lock_type;
  lock.l_whence = SEEK_SET;
  lock.l_start = 0;
  lock.l_len = 0;

  lock_desc = (lock.l_type == F_WRLCK ? "write-lock" : "unlock");

  pr_trace_msg("lock", 9, "attempting to %s QuotaLock fd %d", lock_desc,
    quota_lockfd);

  while (fcntl(quota_lockfd, F_SETLK, &lock) < 0) {
    int xerrno = errno;

    if (xerrno == EINTR) {
      pr_signals_handle();
      continue;
    }

    pr_trace_msg("lock", 3, "%s of QuotaLock fd %d failed: %s",
      lock_desc, quota_lockfd, strerror(xerrno));
  
    if (xerrno == EACCES) {
      struct flock locker;

      /* Get the PID of the process blocking this lock. */
      if (fcntl(quota_lockfd, F_GETLK, &locker) == 0) {
        pr_trace_msg("lock", 3, "process ID %lu has blocking %s on "
          "QuotaLock fd %d", (unsigned long) locker.l_pid,
          (locker.l_type == F_WRLCK ? "write-lock" :
           locker.l_type == F_RDLCK ? "read-lock" : "unlock"),
          quota_lockfd);
      }
    }

    if (xerrno == EAGAIN ||
        xerrno == EACCES) {
      /* Treat this as an interrupted call, call pr_signals_handle() (which
       * will delay for a few msecs because of EINTR), and try again.
       * After QUOTA_MAX_LOCK_ATTEMPTS attempts, give up altogether.
       */

      nattempts++;
      if (nattempts <= QUOTA_MAX_LOCK_ATTEMPTS) {
        errno = EINTR;

        pr_signals_handle();

        errno = 0;
        continue;
      }

      quotatab_log("unable to acquire %s lock on QuotaLock for user '%s': %s",
        lock_desc, session.user, strerror(xerrno));
      errno = xerrno;
      return -1;
    }
  }

  pr_trace_msg("lock", 9, "%s of QuotaLock fd %d succeeded", lock_desc,
    quota_lockfd);
  return 0;
}

static int quotatab_rlock(quota_table_t *tab) {

  if (tab->rlock_count == 0 &&
      tab->wlock_count == 0) {
    unsigned int nattempts = 1;

    tab->tab_lockfd = quota_lockfd;

    pr_trace_msg("lock", 9, "attempting to read-lock QuotaLock fd %d",
      quota_lockfd);
   
    while (tab->tab_rlock(tab) < 0) { 
      int xerrno = errno;

      if (xerrno == EINTR) {
        pr_signals_handle();
        continue;
      }

      if (xerrno == EACCES) {
        struct flock locker;

        /* Get the PID of the process blocking this lock. */
        if (fcntl(quota_lockfd, F_GETLK, &locker) == 0) {
          pr_trace_msg("lock", 3, "process ID %lu has blocking %s on "
            "QuotaLock fd %d", (unsigned long) locker.l_pid,
            (locker.l_type == F_WRLCK ? "write-lock" :
             locker.l_type == F_RDLCK ? "read-lock" : "unlock"),
            quota_lockfd);
        }
      }

      if (xerrno == EAGAIN ||
          xerrno == EACCES) {
        /* Treat this as an interrupted call, call pr_signals_handle() (which
         * will delay for a few msecs because of EINTR), and try again.
         * After QUOTA_MAX_LOCK_ATTEMPTS attempts, give up altogether.
         */

        nattempts++;
        if (nattempts <= QUOTA_MAX_LOCK_ATTEMPTS) {
          errno = EINTR;

          pr_signals_handle();

          errno = 0;
          continue;
        }
      }

      quotatab_log("unable to acquire read lock on QuotaLock for user '%s': %s",
        session.user, strerror(xerrno));
      errno = xerrno;
      return -1;
    }
  }

  tab->rlock_count++;
  return 0;
}

static int quotatab_runlock(quota_table_t *tab) {
  int res = 0;

  if (tab->rlock_count == 1 &&
      tab->wlock_count == 0) {
    tab->tab_lockfd = quota_lockfd;

    while (tab->tab_unlock(tab) < 0) {
      int xerrno = errno;

      if (xerrno == EINTR) {
        pr_signals_handle();
        continue;
      }

      res = -1;
      break;
    }
  }

  if (res == 0 &&
      tab->rlock_count > 0) {
    tab->rlock_count--;
  }

  return res;
}

static int quotatab_wlock(quota_table_t *tab) {

  if (tab->wlock_count == 0) {
    unsigned int nattempts = 1;

    tab->tab_lockfd = quota_lockfd;

    pr_trace_msg("lock", 9, "attempting to write-lock QuotaLock fd %d",
      quota_lockfd);

    while (tab->tab_wlock(tab) < 0) {
      int xerrno = errno;

      if (xerrno == EINTR) {
        pr_signals_handle();
        continue;
      }

      if (xerrno == EACCES) {
        struct flock locker;

        /* Get the PID of the process blocking this lock. */
        if (fcntl(quota_lockfd, F_GETLK, &locker) == 0) {
          pr_trace_msg("lock", 3, "process ID %lu has blocking %s on "
            "QuotaLock fd %d", (unsigned long) locker.l_pid,
            (locker.l_type == F_WRLCK ? "write-lock" :
             locker.l_type == F_RDLCK ? "read-lock" : "unlock"),
            quota_lockfd);
        }
      }

      if (xerrno == EAGAIN ||
          xerrno == EACCES) {
        /* Treat this as an interrupted call, call pr_signals_handle() (which
         * will delay for a few msecs because of EINTR), and try again.
         * After QUOTA_MAX_LOCK_ATTEMPTS attempts, give up altogether.
         */

        nattempts++;
        if (nattempts <= QUOTA_MAX_LOCK_ATTEMPTS) {
          errno = EINTR;

          pr_signals_handle();

          errno = 0;
          continue;
        }
      }

      quotatab_log("unable to acquire write lock on QuotaLock for "
        "user '%s': %s", session.user, strerror(xerrno));
      errno = xerrno;
      return -1;
    }
  }

  tab->wlock_count++;
  return 0;
}

static int quotatab_wunlock(quota_table_t *tab) {
  int res = 0;

  /* A write-lock may need to be "downgraded" into a read-lock, depending
   * on the other lock attempts that have been made.
   */
  if (tab->wlock_count == 1) {
    tab->tab_lockfd = quota_lockfd;

    if (tab->rlock_count == 0) {
      /* The write-lock is the only lock left on the table; do a full unlock. */
      while (tab->tab_unlock(tab) < 0) {
        int xerrno = errno;

        if (xerrno == EINTR) {
          pr_signals_handle();
          continue;
        }

        res = -1;
        break;
      }

    } else {
      /* We have some read-locks on the table; downgrade the write-lock to
       * a read-lock.  The call to the tab_rlock() callback does NOT go
       * through the quotatab_rlock() function, which means it does not affect
       * the table lock counters; this is by design.
       */
      res = tab->tab_rlock(tab);
    }
  }

  if (res == 0 &&
      tab->wlock_count > 0) {
    tab->wlock_count--;
  }

  return res;
}

int quotatab_write(quota_tally_t *tally,
    double bytes_in_inc, double bytes_out_inc, double bytes_xfer_inc,
    int files_in_inc, int files_out_inc, int files_xfer_inc) {

  /* Make sure the tally table can support writes. */
  if (!tally_tab || !tally_tab->tab_write) {
    errno = EPERM;
    return -1;
  }

  /* Obtain a writer lock for the entry in question */
  if (quotatab_wlock(tally_tab) < 0) {
    quotatab_log("error: unable to obtain write lock: %s", strerror(errno));
    return -1;
  }

  /* Make sure the deltas are cleared. */
  memset(&quotatab_deltas, '\0', sizeof(quotatab_deltas));

  /* Read in the tally (to catch any possible updates by other processes). */
  QUOTATAB_TALLY_READ

  /* Only update the tally if the value is not "unlimited". */
  if (sess_limit.bytes_in_avail > 0.0) {
    sess_tally.bytes_in_used += bytes_in_inc;

    /* Prevent underflows. */
    if (sess_tally.bytes_in_used < 0.0)
      sess_tally.bytes_in_used = 0.0;

    quotatab_deltas.bytes_in_delta = bytes_in_inc;
  }

  /* Only update the tally if the value is not "unlimited". */
  if (sess_limit.bytes_out_avail > 0.0) {
    sess_tally.bytes_out_used += bytes_out_inc;

    /* Prevent underflows. */
    if (sess_tally.bytes_out_used < 0.0)
      sess_tally.bytes_out_used = 0.0;

    quotatab_deltas.bytes_out_delta = bytes_out_inc;
  }

  /* Only update the tally if the value is not "unlimited". */
  if (sess_limit.bytes_xfer_avail > 0.0) {
    sess_tally.bytes_xfer_used += bytes_xfer_inc;

    /* Prevent underflows. */
    if (sess_tally.bytes_xfer_used < 0.0)
      sess_tally.bytes_xfer_used = 0.0;

    quotatab_deltas.bytes_xfer_delta = bytes_xfer_inc;
  }

  /* Only update the tally if the value is not "unlimited". */
  if (sess_limit.files_in_avail != 0) {

    /* Prevent underflows. As this is an unsigned data type, the 
     * underflow check is not as straightforward as checking for a value
     * less than zero.
     */
    if (!(sess_tally.files_in_used == 0 && files_in_inc < 0))
      sess_tally.files_in_used += files_in_inc;

    quotatab_deltas.files_in_delta = files_in_inc;
  }

  /* Only update the tally if the value is not "unlimited". */
  if (sess_limit.files_out_avail != 0) {

    /* Prevent underflows. As this is an unsigned data type, the
     * underflow check is not as straightforward as checking for a value
     * less than zero.
     */
    if (!(sess_tally.files_out_used == 0 && files_out_inc < 0))
      sess_tally.files_out_used += files_out_inc;

    quotatab_deltas.files_out_delta = files_out_inc;
  }

  /* Only update the tally if the value is not "unlimited". */
  if (sess_limit.files_xfer_avail != 0) {

    /* Prevent underflows. As this is an unsigned data type, the
     * underflow check is not as straightforward as checking for a value
     * less than zero.
     */
    if (!(sess_tally.files_xfer_used == 0 && files_xfer_inc < 0))
      sess_tally.files_xfer_used += files_xfer_inc;

    quotatab_deltas.files_xfer_delta = files_xfer_inc;
  }

  /* No need to write out to the stream if per-session quotas are in effect. */
  if (sess_limit.quota_per_session) {
    memset(&quotatab_deltas, '\0', sizeof(quotatab_deltas));
    quotatab_wunlock(tally_tab);
    return 0;
  }

  if (tally_tab->tab_write(tally_tab, tally) < 0) {
    quotatab_log("error: unable to update tally entry: %s", strerror(errno));
    quotatab_wunlock(tally_tab);
    memset(&quotatab_deltas, '\0', sizeof(quotatab_deltas));
    return -1;
  }

  /* Release the lock */
  if (quotatab_wunlock(tally_tab) < 0) {
    quotatab_log("error: unable to release write lock: %s", strerror(errno));
    memset(&quotatab_deltas, '\0', sizeof(quotatab_deltas));
    return -1;
  }

  memset(&quotatab_deltas, '\0', sizeof(quotatab_deltas));
  return 0;
}

/* FSIO handlers
 */

static int quotatab_fsio_write(pr_fh_t *fh, int fd, const char *buf,
    size_t bufsz) {
  int res;

  res = write(fd, buf, bufsz);
  if (res < 0)
    return res;

  /* Check to see if we've exceeded our upload limit.  mod_xfer will
   * have called pr_data_xfer(), which will have updated
   * session.xfer.total_bytes, before calling pr_fsio_write(), so
   * we do not have to worry about updated/changing session.xfer.total_bytes
   * ourselves.
   *
   * Note that there is a race condition here: it is possible for the same
   * user to be writing to the same file in chunks from multiple
   * simultaneous connections.
   */

  if (sess_limit.bytes_in_avail > 0.0 &&
      sess_tally.bytes_in_used + session.xfer.total_bytes > sess_limit.bytes_in_avail) {
    int xerrno;
    char *errstr = NULL;

    xerrno = get_quota_exceeded_errno(EIO, &errstr);
    quotatab_log("quotatab write(): limit exceeded, returning %s", errstr);

    errno = xerrno;
    return -1;
  }

  if (sess_limit.bytes_xfer_avail > 0.0 &&
      sess_tally.bytes_xfer_used + session.xfer.total_bytes > sess_limit.bytes_xfer_avail) {
    int xerrno;
    char *errstr = NULL;

    xerrno = get_quota_exceeded_errno(EIO, &errstr);
    quotatab_log("quotatab write(): transfer limit exceeded, returning %s",
      errstr);

    errno = xerrno;
    return -1;
  }

  return res;
}

/* Configuration handlers
 */

/* usage: QuotaDirectoryTally <on|off> */
MODRET set_quotadirtally(cmd_rec *cmd) {
  int bool = -1;
  config_rec *c = NULL;

  CHECK_ARGS(cmd, 1);
  CHECK_CONF(cmd, CONF_ROOT|CONF_VIRTUAL|CONF_GLOBAL);

  bool = get_boolean(cmd, 1);
  if (bool == -1)
    CONF_ERROR(cmd, "expected boolean argument");

  c = add_config_param(cmd->argv[0], 1, NULL);
  c->argv[0] = pcalloc(c->pool, sizeof(unsigned char));
  *((unsigned char *) c->argv[0]) = (unsigned char) bool;

  return PR_HANDLED(cmd);
}

/* usage: QuotaDisplayUnits <b|Kb|Mb|Gb> */
MODRET set_quotadisplayunits(cmd_rec *cmd) {
  quota_units_t units = BYTE;
  config_rec *c = NULL;

  CHECK_ARGS(cmd, 1);
  CHECK_CONF(cmd, CONF_ROOT|CONF_VIRTUAL|CONF_GLOBAL);

  if (strcasecmp(cmd->argv[1], "b") == 0) {
    /* No need to assign to the units variable, as it defaults to
     * displaying bytes
     */
    ;

  } else if (strcasecmp(cmd->argv[1], "Kb") == 0) {
    units = KILO;

  } else if (strcasecmp(cmd->argv[1], "Mb") == 0) {
    units = MEGA;

  } else if (strcasecmp(cmd->argv[1], "Gb") == 0) {
    units = GIGA;

  } else
    CONF_ERROR(cmd, pstrcat(cmd->tmp_pool, ": unknown display units: ",
      cmd->argv[1], NULL));

  c = add_config_param(cmd->argv[0], 1, NULL);
  c->argv[0] = palloc(c->pool, sizeof(quota_units_t));
  *((quota_units_t *) c->argv[0]) = units;

  return PR_HANDLED(cmd);
}

/* usage: QuotaEngine <on|off> */
MODRET set_quotaengine(cmd_rec *cmd) {
  int bool = -1;
  config_rec *c = NULL;

  CHECK_ARGS(cmd, 1);
  CHECK_CONF(cmd, CONF_ROOT|CONF_VIRTUAL|CONF_GLOBAL);

  bool = get_boolean(cmd, 1);
  if (bool == -1)
    CONF_ERROR(cmd, "expected boolean argument");

  c = add_config_param(cmd->argv[0], 1, NULL);
  c->argv[0] = pcalloc(c->pool, sizeof(unsigned char));
  *((unsigned char *) c->argv[0]) = (unsigned char) bool;

  return PR_HANDLED(cmd);
}

/* usage: QuotaExcludeFilter regex|"none" */
MODRET set_quotaexcludefilter(cmd_rec *cmd) {
#ifdef PR_USE_REGEX
  pr_regex_t *pre = NULL;
  config_rec *c;
  int res;

  CHECK_ARGS(cmd, 1);
  CHECK_CONF(cmd, CONF_ROOT|CONF_VIRTUAL|CONF_GLOBAL);

  if (strcasecmp(cmd->argv[1], "none") == 0) {
    add_config_param(cmd->argv[0], 0);
    return PR_HANDLED(cmd);
  }

  pre = pr_regexp_alloc(&quotatab_module);

  res = pr_regexp_compile(pre, cmd->argv[1], REG_EXTENDED|REG_NOSUB);
  if (res != 0) {
    char errstr[256] = {'\0'};

    pr_regexp_error(res, pre, errstr, sizeof(errstr));
    pr_regexp_free(NULL, pre);

    CONF_ERROR(cmd, pstrcat(cmd->tmp_pool, "'", cmd->argv[1], "' failed regex "
      "compilation: ", errstr, NULL));
  }

  c = add_config_param(cmd->argv[0], 2, NULL, NULL);
  c->argv[0] = pstrdup(c->pool, cmd->argv[1]);
  c->argv[1] = (void *) pre;
  return PR_HANDLED(cmd);

#else
  CONF_ERROR(cmd, "The QuotaExcludeFilter directive cannot be used on this "
    "system, as you do not have POSIX compliant regex support");
#endif
}

/* usage: QuotaLock file */
MODRET set_quotalock(cmd_rec *cmd) {
  CHECK_ARGS(cmd, 1);
  CHECK_CONF(cmd, CONF_ROOT|CONF_VIRTUAL|CONF_GLOBAL);

  /* Check for non-absolute paths */
  if (*cmd->argv[1] != '/')
    CONF_ERROR(cmd, "absolute path required");

  add_config_param_str(cmd->argv[0], 1, cmd->argv[1]);

  return PR_HANDLED(cmd);
}

/* usage: QuotaLog path|"none" */
MODRET set_quotalog(cmd_rec *cmd) {
  CHECK_ARGS(cmd, 1);
  CHECK_CONF(cmd, CONF_ROOT|CONF_VIRTUAL|CONF_GLOBAL);

  add_config_param_str(cmd->argv[0], 1, cmd->argv[1]);

  return PR_HANDLED(cmd);
}

/* usage: QuotaOptions opt1 opt2 ... */
MODRET set_quotaoptions(cmd_rec *cmd) {
  config_rec *c;
  register unsigned int i;
  unsigned long opts = 0UL;

  if (cmd->argc-1 == 0)
    CONF_ERROR(cmd, "wrong number of parameters");

  CHECK_CONF(cmd, CONF_ROOT|CONF_VIRTUAL|CONF_GLOBAL);

  c = add_config_param(cmd->argv[0], 1, NULL);

  for (i = 1; i < cmd->argc; i++) {
    if (strcmp(cmd->argv[i], "ScanOnLogin") == 0) {
      opts |= QUOTA_OPT_SCAN_ON_LOGIN;

    } else {
      CONF_ERROR(cmd, pstrcat(cmd->tmp_pool, ": unknown QuotaOption: '",
        cmd->argv[i], "'", NULL));
    }
  }

  c->argv[0] = pcalloc(c->pool, sizeof(unsigned long));
  *((unsigned long *) c->argv[0]) = opts;

  return PR_HANDLED(cmd);
}

/* usage: QuotaShowQuotas <on|off> */
MODRET set_quotashowquotas(cmd_rec *cmd) {
  int bool = -1;
  config_rec *c = NULL;

  CHECK_ARGS(cmd, 1);
  CHECK_CONF(cmd, CONF_ROOT|CONF_VIRTUAL|CONF_GLOBAL);

  bool = get_boolean(cmd, 1);
  if (bool == -1)
    CONF_ERROR(cmd, "expected boolean argument");

  c = add_config_param(cmd->argv[0], 1, NULL);
  c->argv[0] = pcalloc(c->pool, sizeof(unsigned char));
  *((unsigned char *) c->argv[0]) = (unsigned char) bool;

  return PR_HANDLED(cmd);
}

/* usage: Quota{Limit,Tally}Table <source-type:source-info> */
MODRET set_quotatable(cmd_rec *cmd) {
  char *tmp = NULL;
  unsigned int tabflag = 0;
#if !defined(PR_SHARED_MODULE)
  register quota_regtab_t *regtab = NULL;
#endif /* PR_SHARED_MODULE */

  CHECK_ARGS(cmd, 1);
  CHECK_CONF(cmd, CONF_ROOT|CONF_VIRTUAL|CONF_GLOBAL);

  /* Separate the parameter into the separate pieces.  The parameter is 
   * given as one string to enhance its similarity to URL syntax.
   */
  tmp = strchr(cmd->argv[1], ':');
  if (tmp == NULL)
    CONF_ERROR(cmd, "badly formatted parameter");

  *tmp++ = '\0';

  /* Verify that the requested source type has been registered, and supports
   * the table type (limit or tally).
   */
  if (strcasecmp(cmd->argv[0], "QuotaLimitTable") == 0)
    tabflag = QUOTATAB_LIMIT_SRC;

  else if (strcasecmp(cmd->argv[0], "QuotaTallyTable") == 0)
    tabflag = QUOTATAB_TALLY_SRC;

#if !defined(PR_SHARED_MODULE)
  regtab = quotatab_get_backend(cmd->argv[1], tabflag);
  if (!regtab)
    CONF_ERROR(cmd, pstrcat(cmd->tmp_pool, "unsupported table source type: '",
      cmd->argv[1], "'", NULL));
#endif /* PR_SHARED_MODULE */

  add_config_param_str(cmd->argv[0], 2, cmd->argv[1], tmp);
  return PR_HANDLED(cmd);
}

/* Variable handlers
 */

static const char *quota_get_bytes_str(void *data, size_t datasz) {
  const char *res = NULL;
  double adj = 0.0, bytes = *((double *) data);

  switch (byte_units) {
    case BYTE:
      /* no calculation needed */

      if (bytes > 0.0) {
        char buf[PR_TUNABLE_BUFFER_SIZE];
        memset(buf, '\0', sizeof(buf));
        snprintf(buf, sizeof(buf), "%.2f", bytes);
        res = pstrdup(session.pool, buf);

      } else
        res = pstrdup(session.pool, "(unlimited)");

      break;

    case KILO:
      /* Divide by 1024.0 */
      adj = (bytes / 1024.0);

      if (adj > 0.0) {
        char buf[PR_TUNABLE_BUFFER_SIZE];
        memset(buf, '\0', sizeof(buf));
        snprintf(buf, sizeof(buf), "%.2f KB", adj);
        res = pstrdup(session.pool, buf);

      } else
        res = pstrdup(session.pool, "(unlimited)");

      break;

    case MEGA:
      /* Divide by 1024.0 * 1024.0 */
      adj = (bytes / (1024.0 * 1024.0));

      if (adj > 0.0) {
        char buf[PR_TUNABLE_BUFFER_SIZE];
        memset(buf, '\0', sizeof(buf));
        snprintf(buf, sizeof(buf), "%.2f MB", adj);
        res = pstrdup(session.pool, buf);

      } else
        res = pstrdup(session.pool, "(unlimited)");

      break;

    case GIGA:
      /* Divide by 1024.0 * 1024.0 * 1024.0 */
      adj = (bytes / (1024.0 * 1024.0 * 1024.0));

      if (adj > 0.0) {
        char buf[PR_TUNABLE_BUFFER_SIZE];
        memset(buf, '\0', sizeof(buf));
        snprintf(buf, sizeof(buf), "%.2f GB", adj);
        res = pstrdup(session.pool, buf);

      } else
        res = pstrdup(session.pool, "(unlimited)");

      break;

    default:
      quotatab_log("warning: unknown QuotaDisplayUnits");
      break;
  }

  return res;
}

static const char *quota_get_files_str(void *data, size_t datasz) {
  const char *res;
  unsigned int files = *((unsigned int *) data);

  if (files != 0) {
    char buf[PR_TUNABLE_BUFFER_SIZE];
    memset(buf, '\0', sizeof(buf));
    snprintf(buf, sizeof(buf), "%u", files);
    res = pstrdup(session.pool, buf);

  } else
    res = pstrdup(session.pool, "(unlimited)");

  return res;
}

/* Command handlers
 */

MODRET quotatab_post_abor(cmd_rec *cmd) {
  have_aborted_transfer = TRUE;
  return PR_DECLINED(cmd);
}

MODRET quotatab_pre_appe(cmd_rec *cmd) {
  struct stat st;

  have_aborted_transfer = FALSE;
  have_err_response = FALSE;

  /* Sanity check */
  if (!use_quotas)
    return PR_DECLINED(cmd);

  if (quotatab_ignore_path(cmd->tmp_pool, cmd->arg)) {
    quotatab_log("%s: path '%s' matched QuotaExcludeFilter '%s', ignoring",
      cmd->argv[0], cmd->arg, quota_exclude_filter);
    return PR_DECLINED(cmd);
  }

  /* Refresh the tally */
  QUOTATAB_TALLY_READ

  /* Check quotas to see if bytes upload or total quota has been reached.
   * Block command if so.
   */
  if (sess_limit.bytes_in_avail > 0.0 &&
      sess_tally.bytes_in_used >= sess_limit.bytes_in_avail) {

    /* Report the exceeding of the threshold. */
    quotatab_log("%s denied: quota exceeded: used %s", cmd->argv[0],
      DISPLAY_BYTES_IN(cmd));
    pr_response_add_err(R_552, _("%s denied: quota exceeded: used %s"),
      cmd->argv[0], DISPLAY_BYTES_IN(cmd));
    have_err_response = TRUE;

    /* Set an appropriate errno value. */
    errno = get_quota_exceeded_errno(EPERM, NULL);

    return PR_ERROR(cmd);

  } else if (sess_limit.bytes_xfer_avail > 0.0 &&
      sess_tally.bytes_xfer_used >= sess_limit.bytes_xfer_avail) {

    /* Report the exceeding of the threshold. */
    quotatab_log("%s denied: quota exceeded: used %s", cmd->argv[0],
      DISPLAY_BYTES_XFER(cmd));
    pr_response_add_err(R_552, _("%s denied: quota exceeded: used %s"),
      cmd->argv[0], DISPLAY_BYTES_XFER(cmd));
    have_err_response = TRUE;

    /* Set an appropriate errno value. */
    errno = get_quota_exceeded_errno(EPERM, NULL);

    return PR_ERROR(cmd);
  }

  /* Briefly cache the size (in bytes) of the file being appended to, so that
   * if successful, the byte counts can be adjusted correctly.
   */
  pr_fs_clear_cache();
  if (pr_fsio_lstat(cmd->arg, &st) < 0) {
    quotatab_disk_nbytes = 0;

  } else {
    quotatab_disk_nbytes = st.st_size;
  }

  have_quota_update = QUOTA_HAVE_WRITE_UPDATE;
  return PR_DECLINED(cmd);
}

MODRET quotatab_post_appe(cmd_rec *cmd) {
  struct stat st;
  off_t append_bytes = session.xfer.total_bytes;

  /* sanity check */
  if (!use_quotas) {
    have_quota_update = 0;
    return PR_DECLINED(cmd);
  }

  if (quotatab_ignore_path(cmd->tmp_pool, cmd->arg)) {
    quotatab_log("%s: path '%s' matched QuotaExcludeFilter '%s', ignoring",
      cmd->argv[0], cmd->arg, quota_exclude_filter);
    have_quota_update = 0;
    return PR_DECLINED(cmd);
  }

  /* Check on the size of the appended-to file again, and use the difference
   * in file size as the increment.  Make sure that no caching effects 
   * mess with the stat.
   */
  pr_fs_clear_cache();
  if (pr_fsio_lstat(cmd->arg, &st) >= 0) {
    append_bytes = st.st_size - quotatab_disk_nbytes;

  } else {
    if (errno == ENOENT) {
      append_bytes = 0;

    } else {
      quotatab_log("%s: error checking '%s': %s", cmd->argv[0], cmd->arg,
        strerror(errno));
    }
  }

  /* Write out an updated quota entry. */
  QUOTATAB_TALLY_WRITE(append_bytes, 0, session.xfer.total_bytes, 0, 0, 0)

  /* Check the bytes quotas to see if any have been reached.  Report this
   * to the user if so.
   */
  if (sess_limit.bytes_in_avail > 0.0 &&
      sess_tally.bytes_in_used >= sess_limit.bytes_in_avail) {

    if (!have_err_response) {
      quotatab_log("%s: quota reached: used %s", cmd->argv[0],
        DISPLAY_BYTES_IN(cmd));
      pr_response_add(R_DUP, _("%s: notice: quota reached: used %s"),
        cmd->argv[0], DISPLAY_BYTES_IN(cmd));
    }

    if (sess_tally.bytes_in_used > sess_limit.bytes_in_avail &&
        sess_limit.quota_limit_type == HARD_LIMIT) {
      int res;

      res = pr_fsio_unlink(cmd->arg);
      if (res < 0 &&
          errno == EISDIR &&
          use_dirs == TRUE) {
        res = pr_fsio_rmdir(cmd->arg);
      }

      if (res < 0) {
        quotatab_log("notice: unable to unlink '%s': %s", cmd->arg,
          strerror(errno));

      } else {
        QUOTATAB_TALLY_WRITE(-append_bytes, 0, -session.xfer.total_bytes,
          -1, 0, -1);

        /* Report the removal of the file. */
        quotatab_log("%s: quota reached: '%s' removed", cmd->argv[0], cmd->arg);
        pr_response_add(R_DUP, _("%s: notice: quota reached: '%s' removed"),
          cmd->argv[0], cmd->arg);
      }
    }

  } else if (sess_limit.bytes_xfer_avail > 0.0 &&
      sess_tally.bytes_xfer_used >= sess_limit.bytes_xfer_avail) {

    if (!have_err_response) {
      quotatab_log("%s: quota reached: used %s", cmd->argv[0],
        DISPLAY_BYTES_XFER(cmd));
      pr_response_add(R_DUP, _("%s: notice: quota reached: used %s"),
        cmd->argv[0], DISPLAY_BYTES_XFER(cmd));
    }

    if (sess_tally.bytes_xfer_used > sess_limit.bytes_xfer_avail &&
        sess_limit.quota_limit_type == HARD_LIMIT) {
      if (pr_fsio_unlink(cmd->arg) < 0) {
        quotatab_log("notice: unable to unlink '%s': %s", cmd->arg,
          strerror(errno));

      } else {
        QUOTATAB_TALLY_WRITE(-append_bytes, 0, -session.xfer.total_bytes,
          -1, 0, -1);

        /* Report the removal of the file. */
        quotatab_log("%s: quota reached: '%s' removed", cmd->argv[0], cmd->arg);
        pr_response_add(R_DUP, _("%s: notice: quota reached: '%s' removed"),
          cmd->argv[0], cmd->arg);
      }
    }
  }

  have_quota_update = 0;
  return PR_DECLINED(cmd);
}

MODRET quotatab_post_appe_err(cmd_rec *cmd) {
  struct stat st;
  off_t append_bytes = session.xfer.total_bytes;

  /* sanity check */
  if (!use_quotas) {
    have_quota_update = 0;
    return PR_DECLINED(cmd);
  }

  if (quotatab_ignore_path(cmd->tmp_pool, cmd->arg)) {
    quotatab_log("%s: path '%s' matched QuotaExcludeFilter '%s', ignoring",
      cmd->argv[0], cmd->arg, quota_exclude_filter);
    have_quota_update = 0;
    return PR_DECLINED(cmd);
  }

  /* Check on the size of the appended-to file again, and use the difference
   * in file size as the increment.  Make sure that no caching effects 
   * mess with the stat.
   */
  pr_fs_clear_cache();
  if (pr_fsio_lstat(cmd->arg, &st) >= 0) {
    append_bytes = st.st_size - quotatab_disk_nbytes;

  } else {
    if (errno == ENOENT) {
      append_bytes = 0;

    } else {
      quotatab_log("%s: error checking '%s': %s", cmd->argv[0], cmd->arg,
        strerror(errno));
    }
  }

  /* Write out an updated quota entry */
  QUOTATAB_TALLY_WRITE(append_bytes, 0, session.xfer.total_bytes, 0, 0, 0)

  /* Check the bytes quotas to see if any have been reached.  Report this
   * to the user if so.
   */
  if (sess_limit.bytes_in_avail > 0.0 &&
      sess_tally.bytes_in_used >= sess_limit.bytes_in_avail) {

    if (!have_err_response) {
      quotatab_log("%s: quota reached: used %s", cmd->argv[0],
        DISPLAY_BYTES_IN(cmd));
      pr_response_add_err(R_DUP, _("%s: notice: quota reached: used %s"),
        cmd->argv[0], DISPLAY_BYTES_IN(cmd));
    }

    if (sess_tally.bytes_in_used > sess_limit.bytes_in_avail &&
        sess_limit.quota_limit_type == HARD_LIMIT) {
      int res;

      res = pr_fsio_unlink(cmd->arg);
      if (res < 0 &&
          errno == EISDIR &&
          use_dirs == TRUE) {
        res = pr_fsio_rmdir(cmd->arg);
      }

      if (res < 0) {
        quotatab_log("notice: unable to unlink '%s': %s", cmd->arg,
          strerror(errno));

      } else {
        QUOTATAB_TALLY_WRITE(-append_bytes, 0, -session.xfer.total_bytes,
          -1, 0, -1);

        /* Report the removal of the file. */
        quotatab_log("%s: quota reached: '%s' removed", cmd->argv[0], cmd->arg);
        pr_response_add(R_DUP, _("%s: notice: quota reached: '%s' removed"),
          cmd->argv[0], cmd->arg);
      }
    }

  } else if (sess_limit.bytes_xfer_avail > 0.0 &&
      sess_tally.bytes_xfer_used >= sess_limit.bytes_xfer_avail) {

    if (!have_err_response) {
      quotatab_log("%s: quota reached: used %s", cmd->argv[0],
        DISPLAY_BYTES_XFER(cmd));
      pr_response_add_err(R_DUP, _("%s: notice: quota reached: used %s"),
        cmd->argv[0], DISPLAY_BYTES_XFER(cmd));
    }

    if (sess_tally.bytes_xfer_used > sess_limit.bytes_xfer_avail &&
        sess_limit.quota_limit_type == HARD_LIMIT) {
      int res;

      res = pr_fsio_unlink(cmd->arg);
      if (res < 0 &&
          errno == EISDIR &&
          use_dirs == TRUE) {
        res = pr_fsio_rmdir(cmd->arg);
      }

      if (res < 0) {
        quotatab_log("notice: unable to unlink '%s': %s", cmd->arg,
          strerror(errno));

      } else {
        QUOTATAB_TALLY_WRITE(-append_bytes, 0, -session.xfer.total_bytes,
          -1, 0, -1);

        /* Report the removal of the file. */
        quotatab_log("%s: quota reached: '%s' removed", cmd->argv[0], cmd->arg);
        pr_response_add(R_DUP, _("%s: notice: quota reached: '%s' removed"),
          cmd->argv[0], cmd->arg);
      }
    }
  }

  have_quota_update = 0;
  return PR_DECLINED(cmd);
}

MODRET quotatab_pre_copy(cmd_rec *cmd) {
  struct stat st;

  have_aborted_transfer = FALSE;
  have_err_response = FALSE;

  /* Sanity check */
  if (!use_quotas)
    return PR_DECLINED(cmd);

  if (quotatab_ignore_path(cmd->tmp_pool, cmd->argv[1])) {
    quotatab_log("%s: path '%s' matched QuotaExcludeFilter '%s', ignoring",
      cmd->argv[0], cmd->argv[1], quota_exclude_filter);
    return PR_DECLINED(cmd);
  }

  /* Refresh the tally */
  QUOTATAB_TALLY_READ

  /* Check quotas to see if bytes upload or total quota has been reached.
   * Block command if so.
   */
  if (sess_limit.bytes_in_avail > 0.0 &&
      sess_tally.bytes_in_used >= sess_limit.bytes_in_avail) {

    /* Report the exceeding of the threshold. */
    quotatab_log("%s denied: quota exceeded: used %s", cmd->argv[0],
      DISPLAY_BYTES_IN(cmd));
    pr_response_add_err(R_552, _("%s denied: quota exceeded: used %s"),
      cmd->argv[0], DISPLAY_BYTES_IN(cmd));
    have_err_response = TRUE;

    /* Set an appropriate errno value. */
    errno = get_quota_exceeded_errno(EPERM, NULL);

    return PR_ERROR(cmd);

  } else if (sess_limit.bytes_xfer_avail > 0.0 &&
             sess_tally.bytes_xfer_used >= sess_limit.bytes_xfer_avail) {

    /* Report the exceeding of the threshold. */
    quotatab_log("%s denied: quota exceeded: used %s", cmd->argv[0],
      DISPLAY_BYTES_XFER(cmd));
    pr_response_add_err(R_552, _("%s denied: quota exceeded: used %s"),
      cmd->argv[0], DISPLAY_BYTES_XFER(cmd));
    have_err_response = TRUE;

    /* Set an appropriate errno value. */
    errno = get_quota_exceeded_errno(EPERM, NULL);

    return PR_ERROR(cmd);
  }

  /* Briefly cache the size (in bytes) of the file being overwritten, so that
   * if successful, the byte counts can be adjusted correctly.
   */
  pr_fs_clear_cache();
  if (pr_fsio_stat(cmd->argv[2], &st) < 0) {
    quotatab_disk_nbytes = 0;

    if (errno == ENOENT) {
      quotatab_disk_nfiles = 1;

    } else {
      quotatab_disk_nfiles = 0;
    }

  } else {

    if (!S_ISDIR(st.st_mode) ||
        (S_ISDIR(st.st_mode) && use_dirs == TRUE)) {
      quotatab_disk_nbytes = st.st_size;
      quotatab_disk_nfiles = 0;
    }
  }

  if (quotatab_disk_nfiles == 1) {
    /* Check quotas to see if files upload or total quota has been reached,
     * but only if the destination file did not already exist.  Block the
     * command if the file quotas were exceeded.
     */
    if (sess_limit.files_in_avail != 0 &&
        sess_tally.files_in_used >= sess_limit.files_in_avail) {

      /* Report the exceeding of the threshold. */
      quotatab_log("%s denied: quota exceeded: used %s", cmd->argv[0],
        DISPLAY_FILES_IN(cmd));
      pr_response_add_err(R_552, _("%s denied: quota exceeded: used %s"),
        cmd->argv[0], DISPLAY_FILES_IN(cmd));
      have_err_response = TRUE;

      /* Set an appropriate errno value. */
      errno = get_quota_exceeded_errno(EPERM, NULL);

      return PR_ERROR(cmd);

    } else if (sess_limit.files_xfer_avail != 0 &&
               sess_tally.files_xfer_used >= sess_limit.files_xfer_avail) {

      /* Report the exceeding of the threshold. */
      quotatab_log("%s denied: quota exceeded: used %s", cmd->argv[0],
        DISPLAY_FILES_XFER(cmd));
      pr_response_add_err(R_552, _("%s denied: quota exceeded: used %s"),
        cmd->argv[0], DISPLAY_FILES_XFER(cmd));
      have_err_response = TRUE;

      /* Set an appropriate errno value. */
      errno = get_quota_exceeded_errno(EPERM, NULL);

      return PR_ERROR(cmd);
    }
  }

  have_quota_update = 0;
  return PR_DECLINED(cmd);
}

MODRET quotatab_post_copy(cmd_rec *cmd) {
  struct stat st;
  off_t copy_bytes = 0;
  int dst_truncated = FALSE;

  /* Sanity check */
  if (!use_quotas)
    return PR_DECLINED(cmd);

  if (quotatab_ignore_path(cmd->tmp_pool, cmd->argv[2])) {
    quotatab_log("%s: path '%s' matched QuotaExcludeFilter '%s', ignoring",
      cmd->argv[0], cmd->argv[2], quota_exclude_filter);
    return PR_DECLINED(cmd);
  }

  pr_fs_clear_cache();
  if (pr_fsio_stat(cmd->argv[2], &st) == 0) {
    if (quotatab_disk_nfiles == 0) {

      if (!S_ISDIR(st.st_mode) ||
          (S_ISDIR(st.st_mode) && use_dirs == TRUE)) {
        /* If the destination file already existed, the number of bytes
         * copied is the current size less its previous size.  Unless its
         * current size is smaller than its previous size...
         */ 

        if (st.st_size >= quotatab_disk_nbytes) {
          copy_bytes = st.st_size - quotatab_disk_nbytes;

        } else {
          copy_bytes = quotatab_disk_nbytes - st.st_size;
          dst_truncated = TRUE;
        }
      }
 
    } else {
      if (!S_ISDIR(st.st_mode) ||
          (S_ISDIR(st.st_mode) && use_dirs == TRUE)) {
        /* ... otherwise, its the entire size of the destination file. */
        copy_bytes = st.st_size;
      }
    }
  }

  /* Write out an updated quota entry.  If the destination file was truncated
   * (i.e. made smaller) because of this copy, then we need to write
   * negative byte values, not positive.
   */
  if (!dst_truncated) {
    QUOTATAB_TALLY_WRITE(copy_bytes, 0, copy_bytes,
      quotatab_disk_nfiles, 0, quotatab_disk_nfiles)

  } else {
    QUOTATAB_TALLY_WRITE(-copy_bytes, 0, -copy_bytes,
      quotatab_disk_nfiles, 0, quotatab_disk_nfiles)
  }

  /* Check quotas to see if bytes upload or total quota has been reached.
   * Report this to user if so.  If it is a hard bytes limit, delete the
   * uploaded file.
   */
  if (sess_limit.bytes_in_avail > 0.0 &&
      sess_tally.bytes_in_used >= sess_limit.bytes_in_avail) {

    if (!have_err_response) {
      /* Report the reaching of the threshold. */
      quotatab_log("%s: quota reached: used %s", cmd->argv[0],
        DISPLAY_BYTES_IN(cmd));
      pr_response_add(R_DUP, _("%s: notice: quota reached: used %s"),
        cmd->argv[0], DISPLAY_BYTES_IN(cmd));
    }

    if (sess_tally.bytes_in_used > sess_limit.bytes_in_avail &&
        sess_limit.quota_limit_type == HARD_LIMIT) {
      int res;

      res = pr_fsio_unlink(cmd->argv[2]);
      if (res < 0 &&
          errno == EISDIR &&
          use_dirs == TRUE) {
        res = pr_fsio_rmdir(cmd->argv[2]);
      }

      if (res < 0) {
        quotatab_log("notice: unable to unlink '%s': %s", cmd->argv[2],
          strerror(errno));

      } else {
        QUOTATAB_TALLY_WRITE(-copy_bytes, 0, -copy_bytes,
          -quotatab_disk_nfiles, 0, -quotatab_disk_nfiles);

        /* Report the removal of the file. */
        quotatab_log("%s: quota reached: '%s' removed", cmd->argv[0],
          cmd->argv[2]);
        pr_response_add(R_DUP, _("%s: notice: quota reached: '%s' removed"),
          cmd->argv[0], cmd->argv[2]);
      }
    }

  } else if (sess_limit.bytes_xfer_avail > 0.0 &&
             sess_tally.bytes_xfer_used >= sess_limit.bytes_xfer_avail) {

    if (!have_err_response) {
      /* Report the reaching of the threshold. */
      quotatab_log("%s: quota reached: used %s", cmd->argv[0],
        DISPLAY_BYTES_XFER(cmd));
      pr_response_add(R_DUP, _("%s: notice: quota reached: used %s"),
        cmd->argv[0], DISPLAY_BYTES_XFER(cmd));
    }

    if (sess_tally.bytes_xfer_used > sess_limit.bytes_xfer_avail &&
        sess_limit.quota_limit_type == HARD_LIMIT) {
      int res;

      res = pr_fsio_unlink(cmd->argv[2]);
      if (res < 0 &&
          errno == EISDIR &&
          use_dirs == TRUE) {
        res = pr_fsio_rmdir(cmd->argv[2]);
      }

      if (res < 0) {
        quotatab_log("notice: unable to unlink '%s': %s", cmd->argv[2],
          strerror(errno));

      } else {
        QUOTATAB_TALLY_WRITE(-copy_bytes, 0, -copy_bytes,
          -quotatab_disk_nfiles, 0, -quotatab_disk_nfiles);

        /* Report the removal of the file. */
        quotatab_log("%s: quota reached: '%s' removed", cmd->argv[0],
          cmd->argv[2]);
        pr_response_add(R_DUP, _("%s: notice: quota reached: '%s' removed"),
          cmd->argv[0], cmd->argv[2]);
      }
    }
  }

  if (quotatab_disk_nfiles == 1) {
    /* Check quotas to see if files upload or total quota has been reached,
     * but only if the destination file did not already exist.  Report this
     * to user if the file quotas were exceeded.
     */
    if (sess_limit.files_in_avail != 0 &&
        sess_tally.files_in_used >= sess_limit.files_in_avail) {

      if (!have_err_response) {
        /* Report the reaching of the threshold. */
        quotatab_log("%s: quota reached: used %s", cmd->argv[0],
          DISPLAY_FILES_IN(cmd));
        pr_response_add(R_DUP, _("%s: notice: quota reached: used %s"),
          cmd->argv[0], DISPLAY_FILES_IN(cmd));
      }

    } else if (sess_limit.files_xfer_avail != 0 &&
               sess_tally.files_xfer_used >= sess_limit.files_xfer_avail) {

      if (!have_err_response) {
        /* Report the reaching of the threshold. */
        quotatab_log("%s: quota reached: used %s", cmd->argv[0],
          DISPLAY_FILES_XFER(cmd));
        pr_response_add(R_DUP, _("%s: notice: quota reached: used %s"),
          cmd->argv[0], DISPLAY_FILES_XFER(cmd));
      }
    }
  }

  /* Clear the cached bytes/files. */
  quotatab_disk_nbytes = 0;
  quotatab_disk_nfiles = 0;
  
  return PR_DECLINED(cmd);
}

MODRET quotatab_post_copy_err(cmd_rec *cmd) {
  /* Sanity check */
  if (!use_quotas)
    return PR_DECLINED(cmd);

  /* Clear the cached bytes/files. */
  quotatab_disk_nbytes = 0;
  quotatab_disk_nfiles = 0;
  
  return PR_DECLINED(cmd);
}

MODRET quotatab_pre_dele(cmd_rec *cmd) {
  char *path;

  /* sanity check */
  if (!use_quotas)
    return PR_DECLINED(cmd);

  /* The real DELE handler makes sure that, if a symlink is being deleted,
   * only the symlink (and not the pointed-to file) is deleted.  We need
   * to do the same here, so that the bytes are correct.
   */
  path = dir_canonical_path(cmd->tmp_pool,
    pr_fs_decode_path(cmd->tmp_pool, cmd->arg));

  quotatab_have_dele_st = FALSE;

  if (path) {
    if (quotatab_ignore_path(cmd->tmp_pool, cmd->arg)) {
      quotatab_log("%s: path '%s' matched QuotaExcludeFilter '%s', ignoring",
        cmd->argv[0], cmd->arg, quota_exclude_filter);
      return PR_DECLINED(cmd);
    }

    /* Briefly cache the size (in bytes) of the file to be deleted, so that
     * if successful, the byte counts can be adjusted correctly.
     */
    pr_fs_clear_cache();
    if (pr_fsio_lstat(path, &quotatab_dele_st) < 0) {
      quotatab_disk_nbytes = 0;

    } else {
      quotatab_disk_nbytes = quotatab_dele_st.st_size;
      quotatab_have_dele_st = TRUE;
      have_quota_update = QUOTA_HAVE_WRITE_UPDATE;
    }

  } else {
    quotatab_disk_nbytes = 0;
  }

  return PR_DECLINED(cmd);
}

MODRET quotatab_post_dele(cmd_rec *cmd) {

  /* sanity check */
  if (!use_quotas)
    return PR_DECLINED(cmd); 

  if (quotatab_ignore_path(cmd->tmp_pool, cmd->arg)) {
    quotatab_log("%s: path '%s' matched QuotaExcludeFilter '%s', ignoring",
      cmd->argv[0], cmd->arg, quota_exclude_filter);
    return PR_DECLINED(cmd);
  }

  if (quotatab_have_dele_st) {

    /* Check the ownership of the deleted file against the currently
     * logged-in user/group.  If the file belongs to us, we can update
     * our tally as normal.  Otherwise, we try to give the credit for the
     * deleted bytes to the owner of the file.
     */

    if (quotatab_dele_st.st_uid == session.uid) {
      /* Write out an updated quota entry. */
      QUOTATAB_TALLY_WRITE(-quotatab_disk_nbytes, 0, 0, -1, 0, 0)

    } else {
      const char *group_owner, *user_owner, *path;
      quota_limit_t dele_limit;
      quota_tally_t dele_tally;

      path = dir_canonical_path(cmd->tmp_pool,
        pr_fs_decode_path(cmd->tmp_pool, cmd->arg));

      /* 1. Get the user name for the st.st_uid.
       * 2. Check for a USER_QUOTA limit for this user.
       * 3. If have limit, check for USER_QUOTA tally.
       * 4. If have tally, update _that_ tally.
       *
       * Do the same check for the st.st_gid, too.
       */

      user_owner = pr_auth_uid2name(cmd->tmp_pool, quotatab_dele_st.st_uid);
      group_owner = pr_auth_gid2name(cmd->tmp_pool, quotatab_dele_st.st_gid);

      quotatab_log("deleted file '%s' belongs to user '%s' (UID %lu), "
        "not the current user '%s' (UID %lu); attempting to credit user '%s' "
        "for the deleted bytes", path, user_owner,
        (unsigned long) quotatab_dele_st.st_uid, session.user,
        (unsigned long) session.uid, user_owner);

      quotatab_mutex_lock(F_WRLCK);

      if (quotatab_lookup(TYPE_LIMIT, &dele_limit, user_owner, USER_QUOTA)) {
        quotatab_log("found limit entry for user '%s'", user_owner);

        if (quotatab_lookup(TYPE_TALLY, &dele_tally, user_owner, USER_QUOTA)) {
          quotatab_log("found tally entry for user '%s'", user_owner);
          quotatab_mutex_lock(F_UNLCK);

          if (quotatab_write(&dele_tally, -quotatab_disk_nbytes, 0, 0, -1,
              0, 0) < 0) {
            quotatab_log("error: unable to write tally: %s", strerror(errno));

          } else {
            quotatab_log("credited user '%s' for the deleted file/bytes",
              user_owner);
          }

          have_quota_update = 0;

        } else {
          quotatab_log("no tally entry found for user '%s'", user_owner);
          quotatab_mutex_lock(F_UNLCK);

          /* Credit the current user for these bytes anyway; that's the
           * default behavior anyway.
           */
          QUOTATAB_TALLY_WRITE(-quotatab_disk_nbytes, 0, 0, -1, 0, 0)
        }

      } else {
        quotatab_log("no limit entry found for user '%s'", user_owner);

        /* Look for a quota for the group owner, too. */
        if (quotatab_lookup(TYPE_LIMIT, &dele_limit, group_owner,
            GROUP_QUOTA)) {
          quotatab_log("found limit entry for group '%s'", group_owner);

          if (quotatab_lookup(TYPE_TALLY, &dele_tally, group_owner,
              GROUP_QUOTA)) {
            quotatab_log("found tally entry for group '%s'", group_owner);
            quotatab_mutex_lock(F_UNLCK);

            if (quotatab_write(&dele_tally, -quotatab_disk_nbytes, 0, 0, -1,
                0, 0) < 0) {
              quotatab_log("error: unable to write tally: %s", strerror(errno));

            } else {
              quotatab_log("credited group '%s' for the deleted file/bytes",
                group_owner);
            }

            have_quota_update = 0;

          } else {
            quotatab_log("no tally entry found for group '%s'", group_owner);
            quotatab_mutex_lock(F_UNLCK);

            /* Credit the current user for these bytes anyway; that's the
             * default behavior anyway.
             */
            QUOTATAB_TALLY_WRITE(-quotatab_disk_nbytes, 0, 0, -1, 0, 0)
          }

        } else {
          quotatab_mutex_lock(F_UNLCK);

          /* Credit the current user for these bytes anyway; that's the
           * default behavior anyway.
           */
          QUOTATAB_TALLY_WRITE(-quotatab_disk_nbytes, 0, 0, -1, 0, 0)
        }
      }
    }
  }

  /* NOTE: if use_dirs is TRUE, also take into consideration the decreased
   * disk usage caused by any decrease in the size of the containing directory.
   */

  /* Clear the cached bytes. */
  quotatab_disk_nbytes = 0;

  /* Clear the update flag as well. */
  have_quota_update = 0;

  return PR_DECLINED(cmd);
}

MODRET quotatab_post_dele_err(cmd_rec *cmd) {

  /* sanity check */
  if (!use_quotas)
    return PR_DECLINED(cmd); 

  /* Clear the cached bytes. */
  quotatab_disk_nbytes = 0;

  /* Clear the update flag as well. */
  have_quota_update = 0;

  return PR_DECLINED(cmd);
}

MODRET quotatab_pre_mkd(cmd_rec *cmd) {

  /* Sanity check. */
  if (!use_dirs)
    return PR_DECLINED(cmd);

  /* Use quotatab_pre_stor() for most of the work. */
  return quotatab_pre_stor(cmd);
}

MODRET quotatab_post_mkd(cmd_rec *cmd) {

  /* Sanity check. */
  if (!use_dirs)
    return PR_DECLINED(cmd);

  /* Use quotatab_post_stor() for most of the work. */
  return quotatab_post_stor(cmd);
}

MODRET quotatab_post_mkd_err(cmd_rec *cmd) {

  /* Sanity check. */
  if (!use_dirs)
    return PR_DECLINED(cmd);

  /* Use quotatab_post_stor_err() for most of the work. */
  return quotatab_post_stor_err(cmd);
}

MODRET quotatab_post_pass(cmd_rec *cmd) {
  unsigned char have_limit_entry = FALSE;
  have_quota_entry = FALSE;

  /* Be done now if there is no quota table */
  if (!use_quotas ||
      !have_quota_limit_table ||
      !have_quota_tally_table) {
    use_quotas = FALSE;
    quotatab_log("turning QuotaEngine off");
    return PR_DECLINED(cmd);
  }

  quotatab_mutex_lock(F_WRLCK);

  /* Check for a limit and a tally entry for this user. */
  if (quotatab_lookup(TYPE_LIMIT, &sess_limit, session.user, USER_QUOTA)) {
    quotatab_log("found limit entry for user '%s'", session.user);
    have_limit_entry = TRUE;

    if (quotatab_lookup(TYPE_TALLY, &sess_tally, session.user, USER_QUOTA)) {
      quotatab_log("found tally entry for user '%s'", session.user);
      have_quota_entry = TRUE;

    } else {
      if (quotatab_create_tally()) {
        quotatab_log("created tally entry for user '%s'", session.user);
        have_quota_entry = TRUE;
      }
    }

    quotatab_mutex_lock(F_UNLCK);

    if (have_quota_entry) {
      if ((quotatab_opts & QUOTA_OPT_SCAN_ON_LOGIN) &&
          (sess_limit.bytes_in_avail > 0 ||
           sess_limit.files_in_avail > 0)) {
        double byte_count = 0;
        unsigned int file_count = 0;
        time_t then;

        quotatab_log("ScanOnLogin enabled, scanning current directory '%s' "
          "for files owned by user '%s'", pr_fs_getcwd(), session.user);

        time(&then);
        if (quotatab_scan_dir(cmd->tmp_pool, pr_fs_getcwd(), session.uid, -1,
            0, &byte_count, &file_count) < 0) {
          quotatab_log("unable to scan '%s': %s", pr_fs_getcwd(),
            strerror(errno));

        } else {
          double bytes_diff = (double)
            (byte_count - sess_tally.bytes_in_used);
          int files_diff = file_count - sess_tally.files_in_used;

          quotatab_log("found %0.2lf bytes in %u %s for user '%s' "
            "in %lu secs", byte_count, file_count,
            file_count != 1 ? "files" : "file", session.user,
            (unsigned long) time(NULL) - then);

          quotatab_log("updating tally (%0.2lf bytes, %d %s difference)",
            bytes_diff, files_diff, files_diff != 1 ? "files" : "file");

          /* Write out an updated quota entry */
          QUOTATAB_TALLY_WRITE(bytes_diff, 0, 0, files_diff, 0, 0);
        }
      }
    }
  }

  /* Check for a limit and a tally entry for these groups. */
  if (!have_limit_entry) {
    char *group_name = session.group;
    gid_t group_id = session.gid;

    if (quotatab_lookup(TYPE_LIMIT, &sess_limit, group_name, GROUP_QUOTA)) {
      quotatab_log("found limit entry for group '%s'", group_name);
      have_limit_entry = TRUE;

    } else {
      if (session.groups) {
        register int i = 0;

        char **group_names = session.groups->elts;
        gid_t *group_ids = session.gids->elts;

        /* Scan the list of supplemental group memberships for this user. */
        for (i = 0; i < session.groups->nelts; i++) {
          group_name = group_names[i];
          group_id = group_ids[i];

          if (quotatab_lookup(TYPE_LIMIT, &sess_limit, group_name,
              GROUP_QUOTA)) {
            quotatab_log("found limit entry for group '%s'", group_name);
            have_limit_entry = TRUE;
            break;
          }
        }
      }
    }

    if (have_limit_entry) {
      if (quotatab_lookup(TYPE_TALLY, &sess_tally, group_name, GROUP_QUOTA)) {
        quotatab_log("found tally entry for group '%s'", group_name);
        have_quota_entry = TRUE;

      } else {
        if (quotatab_create_tally()) {
          quotatab_log("created tally entry for group '%s'", group_name);
          have_quota_entry = TRUE;
        }
      }

      quotatab_mutex_lock(F_UNLCK);

      if (have_quota_entry) {
        if ((quotatab_opts & QUOTA_OPT_SCAN_ON_LOGIN) &&
            (sess_limit.bytes_in_avail > 0 ||
             sess_limit.files_in_avail > 0)) {
          double byte_count = 0;
          unsigned int file_count = 0;
          time_t then;

          quotatab_log("ScanOnLogin enabled, scanning current directory '%s' "
            "for files owned by group '%s'", pr_fs_getcwd(), group_name);

          time(&then);
          if (quotatab_scan_dir(cmd->tmp_pool, pr_fs_getcwd(), -1, group_id,
              0, &byte_count, &file_count) < 0) {
            quotatab_log("unable to scan '%s': %s", pr_fs_getcwd(),
              strerror(errno));

          } else {
            double bytes_diff = byte_count - sess_tally.bytes_in_used;
            int files_diff = file_count - sess_tally.files_in_used;

            quotatab_log("found %0.2lf bytes in %u %s for group '%s' "
              "in %lu secs", byte_count, file_count,
              file_count != 1 ? "files" : "file", group_name,
              (unsigned long) time(NULL) - then);

            quotatab_log("updating tally (%0.2lf bytes, %d %s difference)",
              bytes_diff, files_diff, files_diff != 1 ? "files" : "file");

            /* Write out an updated quota entry */
            QUOTATAB_TALLY_WRITE(bytes_diff, 0, 0, files_diff, 0, 0);
          }
        }
      }
    }
  }

  /* Check for a limit and a tally entry for this class. */
  if (!have_limit_entry &&
      session.class) {
    if (quotatab_lookup(TYPE_LIMIT, &sess_limit, session.class->cls_name,
        CLASS_QUOTA)) {
      quotatab_log("found limit entry for class '%s'", session.class->cls_name);
      have_limit_entry = TRUE;

      if (quotatab_lookup(TYPE_TALLY, &sess_tally, session.class->cls_name,
          CLASS_QUOTA)) {
        quotatab_log("found tally entry for class '%s'",
          session.class->cls_name);
        have_quota_entry = TRUE;

      } else {
        if (quotatab_create_tally()) {
          quotatab_log("created tally entry for class '%s'",
            session.class->cls_name);
          have_quota_entry = TRUE;
        }
      }

      quotatab_mutex_lock(F_UNLCK);

      if (have_quota_entry) {
        if ((quotatab_opts & QUOTA_OPT_SCAN_ON_LOGIN) &&
            (sess_limit.bytes_in_avail > 0 ||
             sess_limit.files_in_avail > 0)) {
          double byte_count = 0;
          unsigned int file_count = 0;
          time_t then;

          quotatab_log("ScanOnLogin enabled, scanning current directory '%s' "
            "for files owned by class '%s'", pr_fs_getcwd(),
            session.class->cls_name);

          time(&then);
          if (quotatab_scan_dir(cmd->tmp_pool, pr_fs_getcwd(), -1, -1, 0,
              &byte_count, &file_count) < 0) {
            quotatab_log("unable to scan '%s': %s", pr_fs_getcwd(),
            strerror(errno));

          } else {
            double bytes_diff = (double)
              (byte_count - sess_tally.bytes_in_used);
            int files_diff = file_count - sess_tally.files_in_used;

            quotatab_log("found %0.2lf bytes in %u %s for class '%s' "
              "in %lu secs", byte_count, file_count,
              file_count != 1 ? "files" : "file", session.class->cls_name,
              (unsigned long) time(NULL) - then);

            quotatab_log("updating tally (%0.2lf bytes, %d %s difference)",
              bytes_diff, files_diff, files_diff != 1 ? "files" : "file");

            /* Write out an updated quota entry */
            QUOTATAB_TALLY_WRITE(bytes_diff, 0, 0, files_diff, 0, 0);
          }
        }
      }
    }
  }

  /* Check for a limit and a tally entry for everyone. */
  if (!have_limit_entry) {
    if (quotatab_lookup(TYPE_LIMIT, &sess_limit, NULL, ALL_QUOTA)) {
      quotatab_log("found limit entry for all");
      have_limit_entry = TRUE;

      if (quotatab_lookup(TYPE_TALLY, &sess_tally, NULL, ALL_QUOTA)) {
        quotatab_log("found tally entry for all");
        have_quota_entry = TRUE;

      } else {
        if (quotatab_create_tally()) {
          quotatab_log("created tally entry for all");
          have_quota_entry = TRUE;
        }
      }

      quotatab_mutex_lock(F_UNLCK);

      if (have_quota_entry) {
        if ((quotatab_opts & QUOTA_OPT_SCAN_ON_LOGIN) &&
            (sess_limit.bytes_in_avail > 0 ||
             sess_limit.files_in_avail > 0)) {
          double byte_count = 0;
          unsigned int file_count = 0;
          time_t then;

          quotatab_log("ScanOnLogin enabled, scanning current directory '%s' "
            "for files owned by all", pr_fs_getcwd());

          time(&then);
          if (quotatab_scan_dir(cmd->tmp_pool, pr_fs_getcwd(), -1, -1, 0,
              &byte_count, &file_count) < 0) {
            quotatab_log("unable to scan '%s': %s", pr_fs_getcwd(),
            strerror(errno));

          } else {
            double bytes_diff = (double)
              (byte_count - sess_tally.bytes_in_used);
            int files_diff = file_count - sess_tally.files_in_used;

            quotatab_log("found %0.2lf bytes in %u %s for all "
              "in %lu secs", byte_count, file_count,
              file_count != 1 ? "files" : "file",
              (unsigned long) time(NULL) - then);

            quotatab_log("updating tally (%0.2lf bytes, %d %s difference)",
              bytes_diff, files_diff, files_diff != 1 ? "files" : "file");

            /* Write out an updated quota entry */
            QUOTATAB_TALLY_WRITE(bytes_diff, 0, 0, files_diff, 0, 0);
          }
        }
      }
    }
  }

  /* Note: We _could_ close the limit table here.  However, we keep it
   * open anyway, in order to look up limits for _other_ users (e.g. when
   * handling deleted files).
   */

  if (have_quota_entry) {

    /* Assume that quotatab_lookup() does the reading in of the necessary
     * data from the quota source table as well.
     */

    /* If per-session quotas are in effect, zero the tally record now */
    if (sess_limit.quota_per_session) {
      sess_tally.bytes_in_used = 0.0F;
      sess_tally.bytes_out_used = 0.0F;
      sess_tally.bytes_xfer_used = 0.0F;
      sess_tally.files_in_used = 0U;
      sess_tally.files_out_used = 0U;
      sess_tally.files_xfer_used = 0U;

      quotatab_log("per session setting in effect: updates will not be "
        "tracked in the QuotaTallyTable");
    }

    /* If the limit for this user is a hard limit, install our own FS handler,
     * one that provides a custom write() function.  We will use this to
     * return an error when writing a file causes a limit to be reached.
     */
    if (sess_limit.quota_limit_type == HARD_LIMIT) {
      pr_fs_t *fs = pr_register_fs(main_server->pool, "quotatab", "/");
      if (fs) {
        quotatab_log("quotatab fs registered");

        fs->write = quotatab_fsio_write;

      } else
        quotatab_log("error registering quotatab fs: %s", strerror(errno));
    }

  } else {
    /* If we didn't even find a limit entry, then make sure that we
     * release the QuotaLock.
     */
    if (!have_limit_entry) {
      quotatab_mutex_lock(F_UNLCK);
    }

    /* No quota entry for this user.  Make sure the quotas are not used. */
    quotatab_log("no quota entry found, turning QuotaEngine off");
    use_quotas = FALSE;
  }

  /* Register some Variable entries, for Display files. */
  if (pr_var_set(quotatab_pool, "%{mod_quotatab.limit.bytes_in}",
      "Maximum number of uploadable bytes", PR_VAR_TYPE_FUNC,
      quota_get_bytes_str, &(sess_limit.bytes_in_avail),
      sizeof(double *)) < 0)
    quotatab_log("error setting %%{mod_quotatab.limit.bytes_in} variable: %s",
      strerror(errno));

  if (pr_var_set(quotatab_pool, "%{mod_quotatab.limit.bytes_out}",
      "Maximum number of downloadable bytes", PR_VAR_TYPE_FUNC,
      quota_get_bytes_str, &(sess_limit.bytes_out_avail),
      sizeof(double *)) < 0)
    quotatab_log("error setting %%{mod_quotatab.limit.bytes_out} variable: %s",
      strerror(errno));

  if (pr_var_set(quotatab_pool, "%{mod_quotatab.limit.bytes_xfer}",
      "Maximum number of transferble bytes", PR_VAR_TYPE_FUNC,
      quota_get_bytes_str, &(sess_limit.bytes_xfer_avail),
      sizeof(double *)) < 0)
    quotatab_log("error setting %%{mod_quotatab.limit.bytes_xfer} variable: %s",
      strerror(errno));

  if (pr_var_set(quotatab_pool, "%{mod_quotatab.limit.files_in}",
      "Maximum number of uploadable files", PR_VAR_TYPE_FUNC,
      quota_get_files_str, &(sess_limit.files_in_avail),
      sizeof(unsigned int *)) < 0)
    quotatab_log("error setting %%{mod_quotatab.limit.files_in} variable: %s",
      strerror(errno));

  if (pr_var_set(quotatab_pool, "%{mod_quotatab.limit.files_out}",
      "Maximum number of downloadable files", PR_VAR_TYPE_FUNC,
      quota_get_files_str, &(sess_limit.files_out_avail),
      sizeof(unsigned int *)) < 0)
    quotatab_log("error setting %%{mod_quotatab.limit.files_out} variable: %s",
      strerror(errno));

  if (pr_var_set(quotatab_pool, "%{mod_quotatab.limit.files_xfer}",
      "Maximum number of transferable files", PR_VAR_TYPE_FUNC,
      quota_get_files_str, &(sess_limit.files_xfer_avail),
      sizeof(unsigned int *)) < 0)
    quotatab_log("error setting %%{mod_quotatab.limit.files_xfer} variable: %s",
      strerror(errno));

  if (pr_var_set(quotatab_pool, "%{mod_quotatab.tally.bytes_in}",
      "Current number of uploaded bytes", PR_VAR_TYPE_FUNC,
      quota_get_bytes_str, &(sess_tally.bytes_in_used),
      sizeof(double *)) < 0)
    quotatab_log("error setting %%{mod_quotatab.tally.bytes_in} variable: %s",
      strerror(errno));

  if (pr_var_set(quotatab_pool, "%{mod_quotatab.tally.bytes_out}",
      "Current number of downloaded bytes", PR_VAR_TYPE_FUNC,
      quota_get_bytes_str, &(sess_tally.bytes_out_used),
      sizeof(double *)) < 0)
    quotatab_log("error setting %%{mod_quotatab.limit.bytes_out} variable: %s",
      strerror(errno));

  if (pr_var_set(quotatab_pool, "%{mod_quotatab.tally.bytes_xfer}",
      "Current number of transferred bytes", PR_VAR_TYPE_FUNC,
      quota_get_bytes_str, &(sess_tally.bytes_xfer_used),
      sizeof(double *)) < 0)
    quotatab_log("error setting %%{mod_quotatab.tally.bytes_xfer} variable: %s",
      strerror(errno));

  if (pr_var_set(quotatab_pool, "%{mod_quotatab.tally.files_in}",
      "Current number of uploaded files", PR_VAR_TYPE_FUNC,
      quota_get_files_str, &(sess_tally.files_in_used),
      sizeof(unsigned int *)) < 0)
    quotatab_log("error setting %%{mod_quotatab.tally.files_in} variable: %s",
      strerror(errno));

  if (pr_var_set(quotatab_pool, "%{mod_quotatab.tally.files_out}",
      "Current number of downloaded files", PR_VAR_TYPE_FUNC,
      quota_get_files_str, &(sess_tally.files_out_used),
      sizeof(unsigned int *)) < 0)
    quotatab_log("error setting %%{mod_quotatab.tally.files_out} variable: %s",
      strerror(errno));

  if (pr_var_set(quotatab_pool, "%{mod_quotatab.tally.files_xfer}",
      "Current number of transferred files", PR_VAR_TYPE_FUNC,
      quota_get_files_str, &(sess_tally.files_xfer_used),
      sizeof(unsigned int *)) < 0)
    quotatab_log("error setting %%{mod_quotatab.tally.files_xfer} variable: %s",
      strerror(errno));

  return PR_DECLINED(cmd);
}

MODRET quotatab_pre_retr(cmd_rec *cmd) {
  have_aborted_transfer = FALSE;
  have_err_response = FALSE;

  /* Sanity check */
  if (!use_quotas)
    return PR_DECLINED(cmd);

  if (quotatab_ignore_path(cmd->tmp_pool, cmd->arg)) {
    quotatab_log("%s: path '%s' matched QuotaExcludeFilter '%s', ignoring",
      cmd->argv[0], cmd->arg, quota_exclude_filter);
    return PR_DECLINED(cmd);
  }

  /* Refresh the tally */
  QUOTATAB_TALLY_READ

  /* Check quotas to see if bytes download or total quota has been reached.
   * Block command if so.
   */
  if (sess_limit.bytes_out_avail > 0.0 &&
      sess_tally.bytes_out_used >= sess_limit.bytes_out_avail) {

    /* Report the exceeding of the threshold. */
    quotatab_log("%s denied: quota exceeded: used %s", cmd->argv[0],
      DISPLAY_BYTES_OUT(cmd));
    pr_response_add_err(R_451, _("%s denied: quota exceeded: used %s"),
      cmd->argv[0], DISPLAY_BYTES_OUT(cmd));
    have_err_response = TRUE;

    /* Set an appropriate errno value. */
    errno = get_quota_exceeded_errno(EPERM, NULL);

    return PR_ERROR(cmd);

  } else if (sess_limit.bytes_xfer_avail > 0.0 &&
      sess_tally.bytes_xfer_used >= sess_limit.bytes_xfer_avail) {

    /* Report the exceeding of the threshold. */
    quotatab_log("%s denied: quota exceeded: used %s", cmd->argv[0],
      DISPLAY_BYTES_XFER(cmd));
    pr_response_add_err(R_451, _("%s denied: quota exceeded: used %s"),
      cmd->argv[0], DISPLAY_BYTES_XFER(cmd));
    have_err_response = TRUE;

    /* Set an appropriate errno value. */
    errno = get_quota_exceeded_errno(EPERM, NULL);

    return PR_ERROR(cmd);
  }

  /* Check quotas to see if files download or total quota has been reached.
   * Block command if so.
   */
  if (sess_limit.files_out_avail != 0 &&
      sess_tally.files_out_used >= sess_limit.files_out_avail) {

    /* Report the exceeding of the threshold. */
    quotatab_log("%s denied: quota exceeded: used %s", cmd->argv[0],
      DISPLAY_FILES_OUT(cmd));
    pr_response_add_err(R_451, _("%s denied: quota exceeded: used %s"),
      cmd->argv[0], DISPLAY_FILES_OUT(cmd));
    have_err_response = TRUE;

    /* Set an appropriate errno value. */
    errno = get_quota_exceeded_errno(EPERM, NULL);

    return PR_ERROR(cmd);

  } else if (sess_limit.files_xfer_avail != 0 &&
      sess_tally.files_xfer_used >= sess_limit.files_xfer_avail) {

    /* Report the exceeding of the threshold. */
    quotatab_log("%s: denied: quota exceeded: used %s", cmd->argv[0],
      DISPLAY_FILES_XFER(cmd));
    pr_response_add(R_451, _("%s denied: quota exceeded: used %s"),
      cmd->argv[0], DISPLAY_FILES_XFER(cmd));
    have_err_response = TRUE;

    /* Set an appropriate errno value. */
    errno = get_quota_exceeded_errno(EPERM, NULL);

    return PR_ERROR(cmd);
  }

  have_quota_update = QUOTA_HAVE_READ_UPDATE;
  return PR_DECLINED(cmd);
}

MODRET quotatab_post_retr(cmd_rec *cmd) {

  /* Sanity check */
  if (!use_quotas)
    return PR_DECLINED(cmd);

  if (quotatab_ignore_path(cmd->tmp_pool, cmd->arg)) {
    quotatab_log("%s: path '%s' matched QuotaExcludeFilter '%s', ignoring",
      cmd->argv[0], cmd->arg, quota_exclude_filter);
    return PR_DECLINED(cmd);
  }

  /* Write out an updated tally */
  QUOTATAB_TALLY_WRITE(0, session.xfer.total_bytes, session.xfer.total_bytes,
    0, 1, 1)

  /* Check quotas to see if bytes download or total quota has been reached.
   * Report this to user if so.
   */
  if (sess_limit.bytes_out_avail > 0.0 &&
      sess_tally.bytes_out_used >= sess_limit.bytes_out_avail) {

    /* Report the reaching of the threshold. */
    quotatab_log("%s: quota reached: used %s", cmd->argv[0],
      DISPLAY_BYTES_OUT(cmd));
    pr_response_add(R_DUP, _("%s: notice: quota reached: used %s"),
      cmd->argv[0], DISPLAY_BYTES_OUT(cmd));

  } else if (sess_limit.bytes_xfer_avail > 0.0 &&
      sess_tally.bytes_xfer_used >= sess_limit.bytes_xfer_avail) {

    /* Report the reaching of the threshold. */
    quotatab_log("%s: quota reached: used %s", cmd->argv[0],
      DISPLAY_BYTES_XFER(cmd));
    pr_response_add(R_DUP, _("%s: notice: quota reached: used %s"),
      cmd->argv[0], DISPLAY_BYTES_XFER(cmd));
  }

  /* Check quotas to see if files download or total quota has been reached.
   * Report this to user if so.
   */
  if (sess_limit.files_out_avail != 0 && 
      sess_tally.files_out_used >= sess_limit.files_out_avail) {

    /* Report the reaching of the threshold. */
    quotatab_log("%s: quota reached: used %s", cmd->argv[0],
      DISPLAY_FILES_OUT(cmd));
    pr_response_add(R_DUP, _("%s: notice: quota reached: used %s"),
      cmd->argv[0], DISPLAY_FILES_OUT(cmd));

  } else if (sess_limit.files_xfer_avail != 0 &&
    sess_tally.files_xfer_used >= sess_limit.files_xfer_avail) {

    /* Report the reaching of the threshold. */
    quotatab_log("%s: quota reached: used %s", cmd->argv[0],
      DISPLAY_FILES_XFER(cmd));
    pr_response_add(R_DUP, _("%s: notice: quota reached: used %s"),
      cmd->argv[0], DISPLAY_FILES_XFER(cmd));
  }

  return PR_DECLINED(cmd);
}

MODRET quotatab_post_retr_err(cmd_rec *cmd) {

  /* Sanity check */
  if (!use_quotas)
    return PR_DECLINED(cmd);

  if (quotatab_ignore_path(cmd->tmp_pool, cmd->arg)) {
    quotatab_log("%s: path '%s' matched QuotaExcludeFilter '%s', ignoring",
      cmd->argv[0], cmd->arg, quota_exclude_filter);
    return PR_DECLINED(cmd);
  }

  /* Write out an updated tally */
  QUOTATAB_TALLY_WRITE(0, session.xfer.total_bytes, session.xfer.total_bytes,
    0, 0, 0)

  /* Check quotas to see if bytes download or total quota has been reached.
   * Report this to user if so (if not already reported).
   */
  if (sess_limit.bytes_out_avail > 0.0 &&
      sess_tally.bytes_out_used >= sess_limit.bytes_out_avail) {

    if (!have_err_response) {

      /* Report the reaching of the threshold. */
      quotatab_log("%s: quota reached: used %s", cmd->argv[0],
        DISPLAY_BYTES_OUT(cmd));
      pr_response_add_err(R_DUP, _("%s: notice: quota reached: used %s"),
        cmd->argv[0], DISPLAY_BYTES_OUT(cmd));
    }

  } else if (sess_limit.bytes_xfer_avail > 0.0 &&
      sess_tally.bytes_xfer_used >= sess_limit.bytes_xfer_avail) {

    if (!have_err_response) {

      /* Report the reaching of the threshold. */
      quotatab_log("%s: quota reached: used %s", cmd->argv[0],
        DISPLAY_BYTES_XFER(cmd));
      pr_response_add_err(R_DUP, _("%s: notice: quota reached: used %s"),
        cmd->argv[0], DISPLAY_BYTES_XFER(cmd));
    }
  }

  /* Check quotas to see if files download or total quota has been reached.
   * Report this to user if so (if not already reported).
   */
  if (sess_limit.files_out_avail != 0 &&
      sess_tally.files_out_used >= sess_limit.files_out_avail) {

    if (!have_err_response) {

      /* Report the reaching of the treshold. */
      quotatab_log("%s: quota reached: used %s", cmd->argv[0],
        DISPLAY_FILES_OUT(cmd));
      pr_response_add_err(R_DUP, _("%s: notice: quota reached: used %s"),
        cmd->argv[0], DISPLAY_FILES_OUT(cmd));
    }

  } else if (sess_limit.files_xfer_avail != 0 &&
    sess_tally.files_xfer_used >= sess_limit.files_xfer_avail) {

    if (!have_err_response) {

      /* Report the reaching of the treshold. */
      quotatab_log("%s: quota reached: used %s", cmd->argv[0],
        DISPLAY_FILES_XFER(cmd));
      pr_response_add_err(R_DUP, _("%s: notice: quota reached: used %s"),
        cmd->argv[0], DISPLAY_FILES_XFER(cmd));
    }
  }

  have_err_response = FALSE;
  return PR_DECLINED(cmd);
}

MODRET quotatab_pre_rmd(cmd_rec *cmd) {
  struct stat st;

  /* Sanity check. */
  if (!use_quotas || !use_dirs)
    return PR_DECLINED(cmd);

  /* Briefly cache the size (in bytes) of the directory to be deleted, so that
   * if successful, the byte counts can be adjusted correctly.
   */
  pr_fs_clear_cache();
  if (pr_fsio_lstat(cmd->arg, &st) < 0) {
    quotatab_disk_nbytes = 0;

  } else {
    quotatab_disk_nbytes = st.st_size;
  }

  return PR_DECLINED(cmd);
}

MODRET quotatab_post_rmd(cmd_rec *cmd) {

  /* Sanity check. */
  if (!use_quotas || !use_dirs)
    return PR_DECLINED(cmd);

  if (quotatab_ignore_path(cmd->tmp_pool, cmd->arg)) {
    quotatab_log("%s: path '%s' matched QuotaExcludeFilter '%s', ignoring",
      cmd->argv[0], cmd->arg, quota_exclude_filter);
    return PR_DECLINED(cmd);
  }

  /* Write out an updated quota entry. */
  QUOTATAB_TALLY_WRITE(-quotatab_disk_nbytes, 0, 0, -1, 0, -1)

  /* Clear the cached bytes. */
  quotatab_disk_nbytes = 0;

  return PR_DECLINED(cmd);
}

MODRET quotatab_pre_rnto(cmd_rec *cmd) {
  struct stat st;

  /* Sanity check */
  if (!use_quotas)
    return PR_DECLINED(cmd);

  if (quotatab_ignore_path(cmd->tmp_pool, cmd->arg)) {
    quotatab_log("%s: path '%s' matched QuotaExcludeFilter '%s', ignoring",
      cmd->argv[0], cmd->arg, quota_exclude_filter);
    return PR_DECLINED(cmd);
  }

  /* Briefly cache the size (in bytes) of the file being overwritten, so that
   * if successful, the byte counts can be adjusted correctly.
   */
  pr_fs_clear_cache();
  if (pr_fsio_lstat(cmd->arg, &st) < 0) {
    quotatab_disk_nbytes = 0;
    quotatab_disk_nfiles = 0;

  } else {
    quotatab_disk_nbytes = st.st_size;
    quotatab_disk_nfiles = 1;
  }

  return PR_DECLINED(cmd);
}

MODRET quotatab_post_rnto(cmd_rec *cmd) {

  /* Sanity check */
  if (!use_quotas)
    return PR_DECLINED(cmd);

  if (quotatab_ignore_path(cmd->tmp_pool, cmd->arg)) {
    quotatab_log("%s: path '%s' matched QuotaExcludeFilter '%s', ignoring",
      cmd->argv[0], cmd->arg, quota_exclude_filter);
    return PR_DECLINED(cmd);
  }

  /* Write out an updated quota entry. */
  QUOTATAB_TALLY_WRITE(-quotatab_disk_nbytes, 0, -quotatab_disk_nbytes,
    -quotatab_disk_nfiles, 0, -quotatab_disk_nfiles)

  /* Clear the cached bytes/files. */
  quotatab_disk_nbytes = 0;
  quotatab_disk_nfiles = 0;
  
  return PR_DECLINED(cmd);
}

MODRET quotatab_pre_stor(cmd_rec *cmd) {
  struct stat st;
 
  have_aborted_transfer = FALSE;
  have_err_response = FALSE;

  /* Sanity check */
  if (!use_quotas) {
    have_quota_update = 0;
    return PR_DECLINED(cmd);
  }

  if (quotatab_ignore_path(cmd->tmp_pool, cmd->arg)) {
    quotatab_log("%s: path '%s' matched QuotaExcludeFilter '%s', ignoring",
      cmd->argv[0], cmd->arg, quota_exclude_filter);
    have_quota_update = 0;
    return PR_DECLINED(cmd);
  }

  /* Refresh the tally */
  QUOTATAB_TALLY_READ

  /* Check quotas to see if bytes upload or total quota has been reached.
   * Block command if so.
   */
  if (sess_limit.bytes_in_avail > 0.0 &&
      sess_tally.bytes_in_used >= sess_limit.bytes_in_avail) {

    /* Report the exceeding of the threshold. */
    quotatab_log("%s denied: quota exceeded: used %s", cmd->argv[0],
      DISPLAY_BYTES_IN(cmd));
    pr_response_add_err(R_552, _("%s denied: quota exceeded: used %s"),
      cmd->argv[0], DISPLAY_BYTES_IN(cmd));
    have_err_response = TRUE;

    /* Set an appropriate errno value. */
    errno = get_quota_exceeded_errno(EPERM, NULL);

    return PR_ERROR(cmd);

  } else if (sess_limit.bytes_xfer_avail > 0.0 &&
      sess_tally.bytes_xfer_used >= sess_limit.bytes_xfer_avail) {

    /* Report the exceeding of the threshold. */
    quotatab_log("%s denied: quota exceeded: used %s", cmd->argv[0],
      DISPLAY_BYTES_XFER(cmd));
    pr_response_add_err(R_552, _("%s denied: quota exceeded: used %s"),
      cmd->argv[0], DISPLAY_BYTES_XFER(cmd));
    have_err_response = TRUE;

    /* Set an appropriate errno value. */
    errno = get_quota_exceeded_errno(EPERM, NULL);

    return PR_ERROR(cmd);
  }

  /* Check quotas to see if files upload or total quota has been reached.
   * Block the command if so.
   */
  if (sess_limit.files_in_avail != 0 &&
      sess_tally.files_in_used >= sess_limit.files_in_avail) {

    /* Report the exceeding of the threshold. */
    quotatab_log("%s denied: quota exceeded: used %s", cmd->argv[0],
      DISPLAY_FILES_IN(cmd));
    pr_response_add_err(R_552, _("%s denied: quota exceeded: used %s"),
      cmd->argv[0], DISPLAY_FILES_IN(cmd));
    have_err_response = TRUE;

    /* Set an appropriate errno value. */
    errno = get_quota_exceeded_errno(EPERM, NULL);

    return PR_ERROR(cmd);

  } else if (sess_limit.files_xfer_avail != 0 &&
      sess_tally.files_xfer_used >= sess_limit.files_xfer_avail) {

    /* Report the exceeding of the threshold. */
    quotatab_log("%s denied: quota exceeded: used %s", cmd->argv[0],
      DISPLAY_FILES_XFER(cmd));
    pr_response_add_err(R_552, _("%s denied: quota exceeded: used %s"),
      cmd->argv[0], DISPLAY_FILES_XFER(cmd));
    have_err_response = TRUE;

    /* Set an appropriate errno value. */
    errno = get_quota_exceeded_errno(EPERM, NULL);

    return PR_ERROR(cmd);
  }

  /* Briefly cache the size (in bytes) of the file being appended to, so that
   * if successful, the byte counts can be adjusted correctly.  If the
   * stat fails, it means that a new file is being uploaded, so set the
   * disk_nbytes to be zero. 
   */
  pr_fs_clear_cache();
  if (pr_fsio_lstat(cmd->arg, &st) < 0) {
    quotatab_disk_nbytes = 0;

  } else {
    quotatab_disk_nbytes = st.st_size;
  }

  have_quota_update = QUOTA_HAVE_WRITE_UPDATE;
  return PR_DECLINED(cmd);
}

MODRET quotatab_post_stor(cmd_rec *cmd) {
  struct stat st;
  off_t store_bytes = session.xfer.total_bytes;

  /* Sanity check */
  if (!use_quotas) {
    have_quota_update = 0;
    return PR_DECLINED(cmd);
  }

  if (quotatab_ignore_path(cmd->tmp_pool, cmd->arg)) {
    quotatab_log("%s: path '%s' matched QuotaExcludeFilter '%s', ignoring",
      cmd->argv[0], cmd->arg, quota_exclude_filter);
    have_quota_update = 0;
    return PR_DECLINED(cmd);
  }

  /* If the transfer was aborted, AND if DeleteAbortedStores is on, then
   * don't update the tally (Bug#3621).
   */
  if (have_aborted_transfer ||
      (session.sf_flags & (SF_ABORT|SF_POST_ABORT))) {
    unsigned char *delete_stores;

    delete_stores = get_param_ptr(CURRENT_CONF, "DeleteAbortedStores", FALSE);
    if (delete_stores != NULL &&
        *delete_stores == TRUE) {
      quotatab_log("%s: upload aborted and DeleteAbortedStores on, "
        "skipping tally update", cmd->argv[0]);
      have_quota_update = 0;
      return PR_DECLINED(cmd);
    }
  }

  /* Check on the size of the stored file again, and use the difference
   * in file size as the increment.  Make sure that no caching effects
   * mess with the stat.
   */
  pr_fs_clear_cache();
  if (pr_fsio_lstat(cmd->arg, &st) >= 0) {
    store_bytes = st.st_size - quotatab_disk_nbytes;

  } else {
    if (errno == ENOENT) {
      store_bytes = 0;

    } else {
      quotatab_log("%s: error checking '%s': %s", cmd->argv[0], cmd->arg,
        strerror(errno));
    }
  }

  /* NOTE: if use_dirs is TRUE, also take into consideration the increased
   * disk usage caused by any increase in the size of the containing directory.
   */

  /* Write out an updated quota entry */
  QUOTATAB_TALLY_WRITE(store_bytes, 0, session.xfer.total_bytes,
    quotatab_disk_nbytes ? 0 : 1, 0, 1)

  /* Check quotas to see if bytes upload or total quota has been reached.
   * Report this to user if so.  If it is a hard bytes limit, delete the
   * uploaded file.
   */
  if (sess_limit.bytes_in_avail > 0.0 &&
      sess_tally.bytes_in_used >= sess_limit.bytes_in_avail) {

    if (!have_err_response) {
      /* Report the reaching of the threshold. */
      quotatab_log("%s: quota reached: used %s", cmd->argv[0],
        DISPLAY_BYTES_IN(cmd));
      pr_response_add(R_DUP, _("%s: notice: quota reached: used %s"),
        cmd->argv[0], DISPLAY_BYTES_IN(cmd));
    }

    if (sess_tally.bytes_in_used > sess_limit.bytes_in_avail &&
        sess_limit.quota_limit_type == HARD_LIMIT) {
      int res;

      res = pr_fsio_unlink(cmd->arg);
      if (res < 0 &&
          errno == EISDIR &&
          use_dirs == TRUE) {
        res = pr_fsio_rmdir(cmd->arg);
      }

      if (res < 0) {
        quotatab_log("notice: unable to unlink '%s': %s", cmd->arg,
          strerror(errno));

      } else {
        QUOTATAB_TALLY_WRITE(-store_bytes, 0, -session.xfer.total_bytes,
          -1, 0, -1);
        
        /* Report the removal of the file. */
        quotatab_log("%s: quota reached: '%s' removed", cmd->argv[0], cmd->arg);
        pr_response_add(R_DUP, _("%s: notice: quota reached: '%s' removed"),
          cmd->argv[0], cmd->arg);
      }
    }

  } else if (sess_limit.bytes_xfer_avail > 0.0 &&
      sess_tally.bytes_xfer_used >= sess_limit.bytes_xfer_avail) {

    if (!have_err_response) {
      /* Report the reaching of the threshold. */ 
      quotatab_log("%s: quota reached: used %s", cmd->argv[0],
        DISPLAY_BYTES_XFER(cmd));
      pr_response_add(R_DUP, _("%s: notice: quota reached: used %s"),
        cmd->argv[0], DISPLAY_BYTES_XFER(cmd));
    }

    if (sess_tally.bytes_xfer_used > sess_limit.bytes_xfer_avail &&
        sess_limit.quota_limit_type == HARD_LIMIT) {
      int res;

      res = pr_fsio_unlink(cmd->arg);
      if (res < 0 &&
          errno == EISDIR &&
          use_dirs == TRUE) {
        res = pr_fsio_rmdir(cmd->arg);
      }

      if (res < 0) {
        quotatab_log("notice: unable to unlink '%s': %s", cmd->arg,
          strerror(errno));

      } else {
        QUOTATAB_TALLY_WRITE(-store_bytes, 0, -session.xfer.total_bytes,
          -1, 0, -1);

        /* Report the removal of the file. */
        quotatab_log("%s: quota reached: '%s' removed", cmd->argv[0], cmd->arg);
        pr_response_add(R_DUP, _("%s: notice: quota reached: '%s' removed"),
          cmd->argv[0], cmd->arg);
      }
    }
  }

  /* Check quotas to see if files upload or total quota has been reached.
   * Report this to user if so.
   */
  if (sess_limit.files_in_avail != 0 &&
      sess_tally.files_in_used >= sess_limit.files_in_avail) {

    if (!have_err_response) {
      /* Report the reaching of the threshold. */
      quotatab_log("%s: quota reached: used %s", cmd->argv[0],
        DISPLAY_FILES_IN(cmd));
      pr_response_add(R_DUP, _("%s: notice: quota reached: used %s"),
        cmd->argv[0], DISPLAY_FILES_IN(cmd));
    }

  } else if (sess_limit.files_xfer_avail != 0 &&
      sess_tally.files_xfer_used >= sess_limit.files_xfer_avail) {

    if (!have_err_response) {
      /* Report the reaching of the threshold. */
      quotatab_log("%s: quota reached: used %s", cmd->argv[0],
        DISPLAY_FILES_XFER(cmd));
      pr_response_add(R_DUP, _("%s: notice: quota reached: used %s"),
        cmd->argv[0], DISPLAY_FILES_XFER(cmd));
    }
  }

  have_quota_update = 0;
  return PR_DECLINED(cmd);
}

MODRET quotatab_post_stor_err(cmd_rec *cmd) {
  struct stat st;
  off_t store_bytes = session.xfer.total_bytes;

  /* Sanity check */
  if (!use_quotas) {
    have_quota_update = 0;
    return PR_DECLINED(cmd);
  }

  if (quotatab_ignore_path(cmd->tmp_pool, cmd->arg)) {
    quotatab_log("%s: path '%s' matched QuotaExcludeFilter '%s', ignoring",
      cmd->argv[0], cmd->arg, quota_exclude_filter);
    have_quota_update = 0;
    return PR_DECLINED(cmd);
  }

  /* Check on the size of the stored file again, and use the difference
   * in file size as the increment.  Make sure that no caching effects 
   * mess with the stat.
   */
  pr_fs_clear_cache();
  if (pr_fsio_lstat(cmd->arg, &st) >= 0) {
    store_bytes = st.st_size - quotatab_disk_nbytes;

  } else {
    if (errno == ENOENT) {
      store_bytes = 0;

    } else {
      quotatab_log("%s: error checking '%s': %s", cmd->argv[0], cmd->arg,
        strerror(errno));
    }
  }

  /* Write out an updated quota entry */
  QUOTATAB_TALLY_WRITE(store_bytes, 0, session.xfer.total_bytes, 0, 0, 0)

  /* Check quotas to see if bytes upload or total quota has been reached.
   * Report this to user if so (if not already reported).  If it is a hard
   * bytes limit, delete the uploaded file.
   */
  if (sess_limit.bytes_in_avail > 0.0 &&
      sess_tally.bytes_in_used >= sess_limit.bytes_in_avail) {

    if (!have_err_response) {

      /* Report the reaching of the threshold. */
      quotatab_log("%s: quota reached: used %s", cmd->argv[0],
        DISPLAY_BYTES_IN(cmd));
      pr_response_add_err(R_DUP, _("%s: notice: quota reached: used %s"),
        cmd->argv[0], DISPLAY_BYTES_IN(cmd));
    }

    if (sess_tally.bytes_in_used > sess_limit.bytes_in_avail) {
      if (sess_limit.quota_limit_type == HARD_LIMIT) {
        int res;

        res = pr_fsio_unlink(cmd->arg);
        if (res < 0 &&
            errno == EISDIR &&
            use_dirs == TRUE) {
          res = pr_fsio_rmdir(cmd->arg);
        }

        if (res < 0) {
          quotatab_log("notice: unable to unlink '%s': %s", cmd->arg,
            strerror(errno));

        } else {

          /* Report the removal of the file. */
          quotatab_log("%s: quota reached: '%s' removed", cmd->argv[0],
            cmd->arg);
          pr_response_add_err(R_DUP,
            _("%s: notice: quota reached: '%s' removed"), cmd->argv[0],
            cmd->arg);
        }
      }

      QUOTATAB_TALLY_WRITE(-store_bytes, 0, -session.xfer.total_bytes, 0, 0, 0);
    }

  } else if (sess_limit.bytes_xfer_avail > 0.0 &&
      sess_tally.bytes_xfer_used >= sess_limit.bytes_xfer_avail) {

    if (!have_err_response) {

      /* Report the reaching of the threshold. */
      quotatab_log("%s: quota reached: used %s", cmd->argv[0],
        DISPLAY_BYTES_XFER(cmd));
      pr_response_add_err(R_DUP, _("%s: notice: quota reached: used %s"),
        cmd->argv[0], DISPLAY_BYTES_XFER(cmd));
    }

    if (sess_tally.bytes_xfer_used > sess_limit.bytes_xfer_avail) {
      if (sess_limit.quota_limit_type == HARD_LIMIT) {
        int res;

        res = pr_fsio_unlink(cmd->arg);
        if (res < 0 &&
            errno == EISDIR &&
            use_dirs == TRUE) {
          res = pr_fsio_rmdir(cmd->arg);
        }

        if (res < 0) {
          quotatab_log("notice: unable to unlink '%s': %s", cmd->arg,
            strerror(errno));

        } else {

          /* Report the removal of the file. */
          quotatab_log("%s: quota reached: '%s' removed", cmd->argv[0],
            cmd->arg);
          pr_response_add_err(R_DUP,
            _("%s: notice: quota reached: '%s' removed"), cmd->argv[0],
            cmd->arg);
        }
      }

      QUOTATAB_TALLY_WRITE(-store_bytes, 0, -session.xfer.total_bytes, 0, 0, 0);
    }
  }

  /* Check quotas to see if files upload or total quota has been reached.
   * Report this to user if so.
   */
  if (sess_limit.files_in_avail != 0 &&
      sess_tally.files_in_used >= sess_limit.files_in_avail) {

    /* Report the reaching of the threshold. */
    quotatab_log("%s: quota reached: used %s", cmd->argv[0],
      DISPLAY_FILES_IN(cmd));
    pr_response_add_err(R_DUP, _("%s: notice: quota reached: used %s"),
      cmd->argv[0], DISPLAY_FILES_IN(cmd));

  } else if (sess_limit.files_xfer_avail != 0 &&
      sess_tally.files_xfer_used >= sess_limit.files_xfer_avail) {

    /* Report the reaching of the threshold. */
    quotatab_log("%s: quota reached: used %s", cmd->argv[0],
      DISPLAY_FILES_XFER(cmd));
    pr_response_add_err(R_DUP, _("%s: notice: quota reached: used %s"),
      cmd->argv[0], DISPLAY_FILES_XFER(cmd));
  }

  have_quota_update = 0;
  return PR_DECLINED(cmd);
}

MODRET quotatab_pre_site(cmd_rec *cmd) {

  /* Make sure it's a valid SITE command */
  if (cmd->argc < 2)
    return PR_DECLINED(cmd);

  if (strncasecmp(cmd->argv[1], "COPY", 5) == 0) {
    cmd_rec *copy_cmd;

    copy_cmd = pr_cmd_alloc(cmd->tmp_pool, 3, cmd->argv[1], cmd->argv[2],
      cmd->argv[3]);
    return quotatab_pre_copy(copy_cmd);

  } else if (strncasecmp(cmd->argv[1], "CPTO", 5) == 0) {
    register unsigned int i;
    cmd_rec *copy_cmd;
    char *from, *to = "";

    if (cmd->argc < 3)
      return PR_DECLINED(cmd);

    from = pr_table_get(session.notes, "mod_copy.cpfr-path", NULL);
    if (from == NULL) {
      pr_response_add_err(R_503, _("Bad sequence of commands"));
      return PR_ERROR(cmd);
    }

    /* Construct the target file name by concatenating all the parameters after
     * the "SITE CPTO", separating them with spaces.
     */
    for (i = 2; i <= cmd->argc-1; i++) {
      to = pstrcat(cmd->tmp_pool, to, *to ? " " : "",
        pr_fs_decode_path(cmd->tmp_pool, cmd->argv[i]), NULL);
    }

    copy_cmd = pr_cmd_alloc(cmd->tmp_pool, 3, "COPY", from, to);
    return quotatab_pre_copy(copy_cmd);
  }

  have_quota_update = 0;
  return PR_DECLINED(cmd);
}

MODRET quotatab_site(cmd_rec *cmd) {

  /* Make sure it's a valid SITE QUOTA command */
  if (cmd->argc < 2)
    return PR_DECLINED(cmd);

  if (strncasecmp(cmd->argv[1], "QUOTA", 6) == 0) {
    char *cmd_name;
    unsigned char *authenticated = get_param_ptr(cmd->server->conf,
      "authenticated", FALSE);

    /* The user is required to be authenticated/logged in, first */
    if (!authenticated || *authenticated == FALSE) {
      pr_response_send(R_530, _("Please login with USER and PASS"));
      return PR_ERROR(cmd);
    }

    /* Is showing of the user's quota barred by configuration? */
    if (!allow_site_quota) {
      pr_response_add_err(R_500, _("'SITE QUOTA' not understood."));
      return PR_ERROR(cmd);
    }

    /* Check for <Limit> restrictions. */
    cmd_name = cmd->argv[0];
    cmd->argv[0] = "SITE_QUOTA";
    if (!dir_check(cmd->tmp_pool, cmd, "NONE", session.cwd, NULL)) {
      cmd->argv[0] = cmd_name;
      pr_response_add_err(R_550, "%s: %s", cmd->arg, strerror(EPERM));
      return PR_ERROR(cmd);
    }
    cmd->argv[0] = cmd_name;

    /* Log that the user requested their quota. */
    quotatab_log("SITE QUOTA requested by user %s", session.user);

    /* If quotas are not in use, no need to do anything. */
    if (!use_quotas || !have_quota_entry) {
      pr_response_add(R_202, _("No quotas in effect"));
      return PR_HANDLED(cmd);
    }

    /* Refresh the tally. */
    QUOTATAB_TALLY_READ

    pr_response_add(R_200,
      _("The current quota for this session are [current/limit]:"));

    pr_response_add(R_DUP, _("Name: %s"), sess_limit.name);
    pr_response_add(R_DUP, _("Quota Type: %s"),
      (sess_limit.quota_type == USER_QUOTA ? _("User") :
       sess_limit.quota_type == GROUP_QUOTA ? _("Group") :
       sess_limit.quota_type == CLASS_QUOTA ? _("Class") :
       sess_limit.quota_type == ALL_QUOTA ? _("All") : _("(unknown)")));

    pr_response_add(R_DUP, _("Per Session: %s"),
      sess_limit.quota_per_session ? _("True") : _("False"));

    pr_response_add(R_DUP, _("Limit Type: %s"),
      (sess_limit.quota_limit_type == HARD_LIMIT ? _("Hard") :
       sess_limit.quota_limit_type == SOFT_LIMIT ? _("Soft") :
       _("(unknown)")));

    pr_response_add(R_DUP, _("  Uploaded %s"),
      quota_display_site_bytes(cmd->tmp_pool, sess_tally.bytes_in_used,
      sess_limit.bytes_in_avail, IN));
    pr_response_add(R_DUP, _("  Downloaded %s"),
      quota_display_site_bytes(cmd->tmp_pool, sess_tally.bytes_out_used,
      sess_limit.bytes_out_avail, OUT));
    pr_response_add(R_DUP, _("  Transferred %s"),
      quota_display_site_bytes(cmd->tmp_pool, sess_tally.bytes_xfer_used,
      sess_limit.bytes_xfer_avail, XFER));

    pr_response_add(R_DUP, _("  Uploaded %s"),
      quota_display_site_files(cmd->tmp_pool, sess_tally.files_in_used,
      sess_limit.files_in_avail, IN));
    pr_response_add(R_DUP, _("  Downloaded %s"),
      quota_display_site_files(cmd->tmp_pool, sess_tally.files_out_used,
      sess_limit.files_out_avail, OUT));
    pr_response_add(R_DUP, _("  Transferred %s"),
      quota_display_site_files(cmd->tmp_pool, sess_tally.files_xfer_used,
      sess_limit.files_xfer_avail, XFER));

    /* Add one final line to preserve the spacing. */
    pr_response_add(R_DUP,
      _("Please contact %s if these entries are inaccurate"),
      cmd->server->ServerAdmin ? cmd->server->ServerAdmin : _("ftp-admin"));

    return PR_HANDLED(cmd);
  }

  if (strncasecmp(cmd->argv[1], "HELP", 5) == 0) {

    /* Add a description of SITE QUOTA to the output. */
    pr_response_add(R_214, "QUOTA");
  }

  return PR_DECLINED(cmd);
}

MODRET quotatab_post_site(cmd_rec *cmd) {

  /* Make sure it's a valid SITE command */
  if (cmd->argc < 2)
    return PR_DECLINED(cmd);

  if (strncasecmp(cmd->argv[1], "COPY", 5) == 0) {
    cmd_rec *copy_cmd;

    copy_cmd = pr_cmd_alloc(cmd->tmp_pool, 3, cmd->argv[1], cmd->argv[2],
      cmd->argv[3]);
    return quotatab_post_copy(copy_cmd);

  } else if (strncasecmp(cmd->argv[1], "CPTO", 5) == 0) {
    register unsigned int i;
    cmd_rec *copy_cmd;
    char *from, *to = "";

    if (cmd->argc < 3)
      return PR_DECLINED(cmd);

    from = pr_table_get(session.notes, "mod_copy.cpfr-path", NULL);
    if (from == NULL) {
      pr_response_add_err(R_503, _("Bad sequence of commands"));
      return PR_ERROR(cmd);
    }

    /* Construct the target file name by concatenating all the parameters after
     * the "SITE CPTO", separating them with spaces.
     */
    for (i = 2; i <= cmd->argc-1; i++) {
      to = pstrcat(cmd->tmp_pool, to, *to ? " " : "",
        pr_fs_decode_path(cmd->tmp_pool, cmd->argv[i]), NULL);
    }

    copy_cmd = pr_cmd_alloc(cmd->tmp_pool, 3, "COPY", from, to);
    return quotatab_post_copy(copy_cmd);
  }

  return PR_DECLINED(cmd);
}

MODRET quotatab_post_site_err(cmd_rec *cmd) {

  /* Make sure it's a valid SITE command */
  if (cmd->argc < 2)
    return PR_DECLINED(cmd);

  if (strncasecmp(cmd->argv[1], "COPY", 5) == 0) {
    cmd_rec *copy_cmd;

    copy_cmd = pr_cmd_alloc(cmd->tmp_pool, 3, cmd->argv[1], cmd->argv[2],
      cmd->argv[3]);
    return quotatab_post_copy_err(copy_cmd);

  } else if (strncasecmp(cmd->argv[1], "CPTO", 5) == 0) {
    register unsigned int i;
    cmd_rec *copy_cmd;
    char *from, *to = "";

    from = pr_table_get(session.notes, "mod_copy.cpfr-path", NULL);
    if (from == NULL) {
      pr_response_add_err(R_503, _("Bad sequence of commands"));
      return PR_ERROR(cmd);
    }

    /* Construct the target file name by concatenating all the parameters after
     * the "SITE CPTO", separating them with spaces.
     */
    for (i = 2; i <= cmd->argc-1; i++) {
      to = pstrcat(cmd->tmp_pool, to, *to ? " " : "",
        pr_fs_decode_path(cmd->tmp_pool, cmd->argv[i]), NULL);
    }

    copy_cmd = pr_cmd_alloc(cmd->tmp_pool, 3, "COPY", from, to);
    return quotatab_post_copy_err(copy_cmd);
  }

  have_quota_update = 0;
  return PR_DECLINED(cmd);
}

/* Event handlers
 */

static void quotatab_exit_ev(const void *event_data, void *user_data) {

  if (have_quota_update) {
    /* The session may be ending abruptly, aborted or somesuch in mid-transfer,
     * before the change of quota state has been persisted.
     *
     * Note that it is IMPORTANT that the have_quota_update flag be cleared
     * BEFORE writing to the tally table; see Bug#3328.
     */

    switch (have_quota_update) {
      case QUOTA_HAVE_READ_UPDATE:
        have_quota_update = 0;
        QUOTATAB_TALLY_WRITE(0, session.xfer.total_bytes,
          session.xfer.total_bytes, 0, 1, 1)
        break;

      case QUOTA_HAVE_WRITE_UPDATE:
        have_quota_update = 0;
        QUOTATAB_TALLY_WRITE(session.xfer.total_bytes, 0,
          session.xfer.total_bytes, 1, 0, 1)
        break;
    }
  }

  if (use_quotas &&
      have_quota_tally_table) {
    if (quotatab_close(TYPE_TALLY) < 0)
      quotatab_log("error: unable to close QuotaTallyTable: %s",
        strerror(errno));
  }

  quotatab_closelog();
  return;
}

#if defined(PR_SHARED_MODULE)
static void quotatab_mod_unload_ev(const void *event_data, void *user_data) {
  if (strcmp("mod_quotatab.c", (const char *) event_data) == 0) {
    pr_event_unregister(&quotatab_module, NULL, NULL);
    pr_regex_free(NULL, quota_exclude_pre);

    if (quotatab_pool) {
      destroy_pool(quotatab_pool);
      quotatab_pool = NULL;
    }

    close(quota_logfd);
    quota_logfd = -1;
    quota_logname = NULL;
  }
}
#endif

static void quotatab_restart_ev(const void *event_data, void *user_data) {

  /* Reset the module's memory pool. */
  destroy_pool(quotatab_pool);
  quotatab_pool = make_sub_pool(permanent_pool);
  pr_pool_tag(quotatab_pool, MOD_QUOTATAB_VERSION);

  return;
}

/* Initialization routines
 */

static int quotatab_init(void) {

  /* Initialize the module's memory pool. */
  if (!quotatab_pool) {
    quotatab_pool = make_sub_pool(permanent_pool);
    pr_pool_tag(quotatab_pool, MOD_QUOTATAB_VERSION);
  }

#if defined(PR_SHARED_MODULE)
  pr_event_register(&quotatab_module, "core.module-unload",
    quotatab_mod_unload_ev, NULL);
#endif
  pr_event_register(&quotatab_module, "core.restart", quotatab_restart_ev,
    NULL); 

  return 0;
}

static int quotatab_sess_init(void) {
  config_rec *c;
  unsigned char *quotatab_engine = NULL, *quotatab_showquotas = NULL,
    *quotatab_usedirs = NULL;
  quota_units_t *units = NULL;

  /* Check to see if quotas are enabled for this server. */
  quotatab_engine = get_param_ptr(main_server->conf, "QuotaEngine", FALSE);
  if (quotatab_engine != NULL &&
      *quotatab_engine == TRUE) {
    use_quotas = TRUE;

  } else {
    use_quotas = FALSE;
    return 0;
  }

  /* Check to see if SITE QUOTA enabled for this server. */
  quotatab_showquotas = get_param_ptr(main_server->conf, "QuotaShowQuotas",
    FALSE);
  if (quotatab_showquotas != NULL &&
      *quotatab_showquotas == FALSE) {
    allow_site_quota = FALSE;

 } else {
    allow_site_quota = TRUE;
  }

  quotatab_openlog();

  /* Open the quota limit and tally tables.  This is being done while the
   * proces still has root privs, so the tables _can_ be opened.  In the case
   * of file quotastreams, the file descriptor is cached, so that this process,
   * once root privs are dropped, is still able to read from and write to the
   * streams.  Other confstream mechanisms may need to cache something
   * similarly.
   */
  PRIVS_ROOT
  if (quotatab_open(TYPE_LIMIT) < 0) {
    PRIVS_RELINQUISH
    quotatab_log("error: unable to open QuotaLimitTable: %s", strerror(errno));
    have_quota_limit_table = FALSE;

  } else {
    PRIVS_RELINQUISH

    /* Verify that it's a valid limit table */
    if (quotatab_verify(TYPE_LIMIT))
      have_quota_limit_table = TRUE;
    else
      use_quotas = FALSE;
  }

  PRIVS_ROOT
  if (quotatab_open(TYPE_TALLY) < 0) {
    PRIVS_RELINQUISH
    quotatab_log("error: unable to open QuotaTallyTable: %s", strerror(errno));
    have_quota_tally_table = FALSE;

  } else {
    PRIVS_RELINQUISH

    /* Verify that it's a valid tally table */
    if (quotatab_verify(TYPE_TALLY))
      have_quota_tally_table = TRUE;
    else
      use_quotas = FALSE;
  }

  /* Make sure the tables will be closed when the child exits. */
  pr_event_register(&quotatab_module, "core.exit", quotatab_exit_ev, NULL);

  /* Check for the units to display for byte quotas. */
  units = get_param_ptr(main_server->conf, "QuotaDisplayUnits", FALSE);
  byte_units = units ? *units : BYTE;

  /* Check to see if directories are to be used for tallies for this server. */
  quotatab_usedirs = get_param_ptr(main_server->conf, "QuotaDirectoryTally",
    FALSE);
  if (quotatab_usedirs != NULL &&
      *quotatab_usedirs == TRUE) {
    use_dirs = TRUE;

  } else {
    use_dirs = FALSE;
  }

  c = find_config(main_server->conf, CONF_PARAM, "QuotaExcludeFilter", FALSE);
  if (c &&
      c->argc == 2) {
     quota_exclude_filter = c->argv[0];
     quota_exclude_pre = c->argv[1];
  }

  c = find_config(main_server->conf, CONF_PARAM, "QuotaOptions", FALSE);
  if (c) {
    quotatab_opts = *((unsigned long *) c->argv[0]);
  }

  c = find_config(main_server->conf, CONF_PARAM, "QuotaLock", FALSE);
  if (c) {
    int fd;
    const char *path;

    path = c->argv[0];

    /* Make sure the QuotaLock file exists. */
    PRIVS_ROOT
    fd = open(path, O_RDWR|O_CREAT, 0600);
    PRIVS_RELINQUISH

    if (fd < 0) {
      quotatab_log("unable to open QuotaLock '%s': %s", path, strerror(errno));

    } else {
      /* Make sure that this fd is not one of the main three. */
      if (fd <= STDERR_FILENO) {
        int res;

        res = pr_fs_get_usable_fd(fd);
        if (res < 0) {
          quotatab_log("warning: unable to find usable fd for lockfd %d: %s",
            fd, strerror(errno));

        } else {
          quota_lockfd = fd;
        }

      } else {
        quota_lockfd = fd;
      }
    }
  }

  return 0;
}

/* Module API tables
 */

static conftable quotatab_conftab[] = {
  { "QuotaDirectoryTally",      set_quotadirtally,      NULL },
  { "QuotaDisplayUnits",        set_quotadisplayunits,  NULL },
  { "QuotaEngine",              set_quotaengine,        NULL },
  { "QuotaExcludeFilter",       set_quotaexcludefilter, NULL },
  { "QuotaLimitTable",          set_quotatable,         NULL },
  { "QuotaLock",                set_quotalock,          NULL },
  { "QuotaLog",                 set_quotalog,           NULL },
  { "QuotaOptions",             set_quotaoptions,       NULL },
  { "QuotaShowQuotas",          set_quotashowquotas,    NULL },
  { "QuotaTallyTable",          set_quotatable,         NULL },
  { NULL }
};

static cmdtable quotatab_cmdtab[] = {
  { POST_CMD,           C_ABOR, G_NONE, quotatab_post_abor,     FALSE,  FALSE },
  { PRE_CMD,            C_APPE, G_NONE, quotatab_pre_appe,      FALSE,  FALSE },
  { POST_CMD,           C_APPE, G_NONE, quotatab_post_appe,     FALSE,  FALSE },
  { POST_CMD_ERR,       C_APPE, G_NONE, quotatab_post_appe_err, FALSE,  FALSE },
  { PRE_CMD,            C_DELE, G_NONE, quotatab_pre_dele,      FALSE,  FALSE },
  { POST_CMD,           C_DELE, G_NONE, quotatab_post_dele,     FALSE,  FALSE },
  { POST_CMD_ERR,       C_DELE, G_NONE, quotatab_post_dele_err, FALSE,  FALSE },
  { PRE_CMD,            C_MKD,  G_NONE, quotatab_pre_mkd,       FALSE,  FALSE },
  { POST_CMD,           C_MKD,  G_NONE, quotatab_post_mkd,      FALSE,  FALSE },
  { POST_CMD_ERR,       C_MKD,  G_NONE, quotatab_post_mkd_err,  FALSE,  FALSE },
  { POST_CMD,           C_PASS, G_NONE, quotatab_post_pass,     FALSE,  FALSE },
  { PRE_CMD,            C_RETR, G_NONE, quotatab_pre_retr,      FALSE,  FALSE },
  { POST_CMD,           C_RETR, G_NONE, quotatab_post_retr,     FALSE,  FALSE },
  { POST_CMD_ERR,       C_RETR, G_NONE, quotatab_post_retr_err, FALSE,  FALSE },
  { PRE_CMD,            C_RMD,  G_NONE, quotatab_pre_rmd,       FALSE,  FALSE },
  { POST_CMD,           C_RMD,  G_NONE, quotatab_post_rmd,      FALSE,  FALSE },
  { PRE_CMD,            C_RNTO, G_NONE, quotatab_pre_rnto,      FALSE,  FALSE },
  { POST_CMD,           C_RNTO, G_NONE, quotatab_post_rnto,     FALSE,  FALSE },
  { PRE_CMD,            C_STOR, G_NONE, quotatab_pre_stor,      FALSE,  FALSE },
  { POST_CMD,           C_STOR, G_NONE, quotatab_post_stor,     FALSE,  FALSE },
  { POST_CMD_ERR,       C_STOR, G_NONE, quotatab_post_stor_err, FALSE,  FALSE },
  { PRE_CMD,            C_STOU, G_NONE, quotatab_pre_stor,      FALSE,  FALSE },
  { POST_CMD,           C_STOU, G_NONE, quotatab_post_stor,     FALSE,  FALSE },
  { POST_CMD_ERR,       C_STOU, G_NONE, quotatab_post_stor_err, FALSE,  FALSE },
  { PRE_CMD,            C_XMKD, G_NONE, quotatab_pre_mkd,       FALSE,  FALSE },
  { POST_CMD,           C_XMKD, G_NONE, quotatab_post_mkd,      FALSE,  FALSE },
  { POST_CMD_ERR,       C_XMKD, G_NONE, quotatab_post_mkd_err,  FALSE,  FALSE },
  { PRE_CMD,            C_XRMD, G_NONE, quotatab_pre_rmd,       FALSE,  FALSE },
  { POST_CMD,           C_XRMD, G_NONE, quotatab_post_rmd,      FALSE,  FALSE },

  { PRE_CMD,            C_SITE, G_NONE, quotatab_pre_site,      FALSE,  FALSE, CL_MISC },
  { CMD,                C_SITE, G_NONE, quotatab_site,          FALSE,  FALSE, CL_MISC },
  { POST_CMD,           C_SITE, G_NONE, quotatab_post_site,     FALSE,  FALSE, CL_MISC },
  { POST_CMD_ERR,       C_SITE, G_NONE, quotatab_post_site_err, FALSE,  FALSE, CL_MISC },

  /* Should this be a single HOOK instead of being in the CMD namespace? */
  { PRE_CMD,            "COPY", G_NONE, quotatab_pre_copy,      FALSE,  FALSE },
  { POST_CMD,           "COPY", G_NONE, quotatab_post_copy,     FALSE,  FALSE },
  { POST_CMD_ERR,       "COPY", G_NONE, quotatab_post_copy_err, FALSE,  FALSE },

  { 0, NULL }
};

module quotatab_module = {
  NULL, NULL,

  /* Module API version 2.0 */
  0x20,

  /* Module name */
  "quotatab",

  /* Module configuration handler table */
  quotatab_conftab,

  /* Module command handler table */
  quotatab_cmdtab,

  /* Module authentication handler table */
  NULL,

  /* Module initialization function */
  quotatab_init,

  /* Session initialization function */
  quotatab_sess_init,

  /* Module version */
  MOD_QUOTATAB_VERSION
};