/*

   Unix SMB/CIFS implementation.

   functions to calculate the free disk space

   Copyright (C) Andrew Tridgell 1998

   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 3 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, see <http://www.gnu.org/licenses/>.

*/

#include "includes.h"

#include "smbd/smbd.h"

#include "smbd/globals.h"

#include "lib/util/util_file.h"

#include "lib/util/memcache.h"

/****************************************************************************

 Normalise for DOS usage.

****************************************************************************/

static void disk_norm(uint64_t *bsize, uint64_t *dfree, uint64_t *dsize)

{

  /* check if the disk is beyond the max disk size */

  uint64_t maxdisksize = lp_max_disk_size();

  if (maxdisksize) {

    /* convert to blocks - and don't overflow */

    maxdisksize = ((maxdisksize*1024)/(*bsize))*1024;

    if (*dsize > maxdisksize) {

      *dsize = maxdisksize;

    }

    if (*dfree > maxdisksize) {

      *dfree = maxdisksize - 1;

    }

    /* the -1 should stop applications getting div by 0

       errors */

  }

}

/****************************************************************************

 Return number of 1K blocks available on a path and total number.

****************************************************************************/

static bool handle_dfree_command(connection_struct *conn,

         struct smb_filename *fname,

         uint64_t *bsize,

         uint64_t *dfree,

         uint64_t *dsize)

{

  const struct loadparm_substitution *lp_sub =

    loadparm_s3_global_substitution();

  const char *dfree_command = NULL;

  char *path = fname->base_name;

  char **lines = NULL;

  char **argl = NULL;

  char *line = NULL;

  int ret;

  dfree_command = lp_dfree_command(talloc_tos(), lp_sub, SNUM(conn));

  if (!dfree_command || !*dfree_command) {

    return false;

  }

  argl = str_list_make_empty(talloc_tos());

  str_list_add_printf(&argl, "%s", dfree_command);

  str_list_add_printf(&argl, "%s", path);

  if (argl == NULL) {

    return false;

  }

  DBG_NOTICE("Running command '%s %s'\n",

    dfree_command,

    path);

  lines = file_lines_ploadv(talloc_tos(), argl, NULL);

  TALLOC_FREE(argl);

  if ((lines == NULL) || (lines[0] == NULL)) {

    DBG_ERR("file_lines_ploadv() failed for "

      "command '%s %s'. Error was : %s\n",

      dfree_command, path, strerror(errno));

    TALLOC_FREE(lines);

    return false;

  }

  line = lines[0];

  DBG_NOTICE("Read input from dfree, \"%s\"\n", line);

  ret = sscanf(

    line, "%" SCNu64 " %" SCNu64 " %" SCNu64, dsize, dfree, bsize);

  TALLOC_FREE(lines);

  if (ret < 3) {

    *bsize = 1024;

  }

  if (ret < 2) {

    *dfree = 1024;

  }

  if (ret < 1) {

    *dsize = 2048;

  }

  DBG_NOTICE("Parsed output of dfree, ret=%d, dsize=%" PRIu64 ", "

       "dfree=%" PRIu64 ", bsize=%" PRIu64 "\n",

       ret,

       *dsize,

       *dfree,

       *bsize);

  return true;

}

static uint64_t sys_disk_free(struct files_struct *fsp,

            uint64_t *bsize,

            uint64_t *dfree,

            uint64_t *dsize)

{

  struct connection_struct *conn = fsp->conn;

  struct smb_filename *fname = fsp->fsp_name;

  uint64_t dfree_retval;

  uint64_t dfree_q = 0;

  uint64_t bsize_q = 0;

  uint64_t dsize_q = 0;

  static bool dfree_broken = false;

  bool ok;

  (*dfree) = (*dsize) = 0;

  (*bsize) = 512;

  /*

   * If external disk calculation specified, use it.

   */

  ok = handle_dfree_command(conn, fname, bsize, dfree, dsize);

  if (ok) {

    goto dfree_done;

  }

  if (SMB_VFS_DISK_FREE(conn, fsp, bsize, dfree, dsize) == (uint64_t)-1)

  {

    DBG_ERR("VFS disk_free failed. Error was : %s\n",

      strerror(errno));

    return (uint64_t)-1;

  }

  if (disk_quotas(conn, fsp, &bsize_q, &dfree_q, &dsize_q)) {

    uint64_t min_bsize = MIN(*bsize, bsize_q);

    (*dfree) = (*dfree) * (*bsize) / min_bsize;

    (*dsize) = (*dsize) * (*bsize) / min_bsize;

    dfree_q = dfree_q * bsize_q / min_bsize;

    dsize_q = dsize_q * bsize_q / min_bsize;

    (*bsize) = min_bsize;

    (*dfree) = MIN(*dfree,dfree_q);

    (*dsize) = MIN(*dsize,dsize_q);

  }

  /* FIXME : Any reason for this assumption ? */

  if (*bsize < 256) {

    DBG_INFO("Warning: bsize == %"PRIu64" < 256 . "

       "Changing to assumed correct bsize = 512\n",

       *bsize);

    *bsize = 512;

  }

  if ((*dsize)<1) {

    if (!dfree_broken) {

      DEBUG(0,("WARNING: dfree is broken on this system\n"));

      dfree_broken=true;

    }

    *dsize = 20*1024*1024/(*bsize);

    *dfree = MAX(1,*dfree);

  }

dfree_done:

  disk_norm(bsize, dfree, dsize);

  if ((*bsize) < 1024) {

    dfree_retval = (*dfree)/(1024/(*bsize));

  } else {

    dfree_retval = ((*bsize)/1024)*(*dfree);

  }

  return(dfree_retval);

}

/****************************************************************************

 Potentially returned cached dfree info.

 Depending on the file system layout and file system features, the free space

 information can be different for different sub directories underneath a SMB

 share. Store the cache information in memcache using the query path as the

 key to accommodate this.

****************************************************************************/

struct dfree_cached_info {

  time_t last_dfree_time;

  uint64_t dfree_ret;

  uint64_t bsize;

  uint64_t dfree;

  uint64_t dsize;

};

uint64_t get_dfree_info(struct files_struct *fsp,

      uint64_t *bsize,

      uint64_t *dfree,

      uint64_t *dsize)

{

  struct connection_struct *conn = fsp->conn;

  struct smb_filename *fname = fsp->fsp_name;

  int dfree_cache_time = lp_dfree_cache_time(SNUM(conn));

  struct dfree_cached_info *dfc = NULL;

  struct dfree_cached_info dfc_new = { 0 };

  uint64_t dfree_ret;

  char tmpbuf[PATH_MAX];

  char *full_path = NULL;

  char *to_free = NULL;

  char *key_path = NULL;

  size_t len;

  DATA_BLOB key, value;

  bool found;

  if (!dfree_cache_time) {

    return sys_disk_free(fsp, bsize, dfree, dsize);

  }

  len = full_path_tos(conn->connectpath,

          fname->base_name,

          tmpbuf,

          sizeof(tmpbuf),

          &full_path,

          &to_free);

  if (len == -1) {

    errno = ENOMEM;

    return -1;

  }

  if (VALID_STAT(fname->st) && S_ISREG(fname->st.st_ex_mode)) {

    /*

     * In case of a file use the parent directory to reduce number

     * of cache entries.

     */

    bool ok;

    ok = parent_dirname(talloc_tos(),

            full_path,

            &key_path,

            NULL);

    TALLOC_FREE(to_free); /* We're done with full_path */

    if (!ok) {

      errno = ENOMEM;

      return -1;

    }

    /*

     * key_path is always a talloced object.

     */

    to_free = key_path;

  } else {

    /*

     * key_path might not be a talloced object; rely on

     * to_free set from full_path_tos.

     */

    key_path = full_path;

  }

  key = data_blob_const(key_path, strlen(key_path));

  found = memcache_lookup(smbd_memcache(),

        DFREE_CACHE,

        key,

        &value);

  dfc = found ? (struct dfree_cached_info *)value.data : NULL;

  if (dfc && (conn->lastused - dfc->last_dfree_time < dfree_cache_time)) {

    DBG_DEBUG("Returning dfree cache entry for %s\n", key_path);

    *bsize = dfc->bsize;

    *dfree = dfc->dfree;

    *dsize = dfc->dsize;

    dfree_ret = dfc->dfree_ret;

    goto out;

  }

  dfree_ret = sys_disk_free(fsp, bsize, dfree, dsize);

  if (dfree_ret == (uint64_t)-1) {

    /* Don't cache bad data. */

    goto out;

  }

  DBG_DEBUG("Creating dfree cache entry for %s\n", key_path);

  dfc_new.bsize = *bsize;

  dfc_new.dfree = *dfree;

  dfc_new.dsize = *dsize;

  dfc_new.dfree_ret = dfree_ret;

  dfc_new.last_dfree_time = conn->lastused;

  memcache_add(smbd_memcache(),

         DFREE_CACHE,

         key,

         data_blob_const(&dfc_new, sizeof(dfc_new)));

out:

  TALLOC_FREE(to_free);

  return dfree_ret;

}

void flush_dfree_cache(void)

{

  memcache_flush(smbd_memcache(), DFREE_CACHE);

}