/*
 * Copyright (c) 1997-2011 Erez Zadok
 * Copyright (c) 1990 Jan-Simon Pendry
 * Copyright (c) 1990 Imperial College of Science, Technology & Medicine
 * Copyright (c) 1990 The Regents of the University of California.
 * All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Jan-Simon Pendry at Imperial College, London.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgment:
 *      This product includes software developed by the University of
 *      California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *
 * File: am-utils/amd/nfs_subr.c
 *
 */

#ifdef HAVE_CONFIG_H
# include <config.h>
#endif /* HAVE_CONFIG_H */
#include <am_defs.h>
#include <amd.h>

/*
 * Convert from UN*X to NFS error code.
 * Some systems like linux define their own (see
 * conf/mount/mount_linux.h).
 */
#ifndef nfs_error
# define nfs_error(e) ((nfsstat)(e))
#endif /* nfs_error */

/*
 * File Handle structure
 *
 * This is interpreted by indexing the exported array
 * by fhh_id (for old-style filehandles), or by retrieving
 * the node name from fhh_path (for new-style filehandles).
 *
 * The whole structure is mapped onto a standard fhandle_t
 * when transmitted.
 */
struct am_fh {
  u_int fhh_gen;				/* generation number */
  union {
    struct {
      int fhh_type;				/* old or new am_fh */
      pid_t fhh_pid;				/* process id */
      int fhh_id;				/* map id */
    } s;
    char fhh_path[NFS_FHSIZE-sizeof(u_int)];	/* path to am_node */
  } u;
};


/* forward declarations */
/* converting am-filehandles to mount-points */
static am_node *fh_to_mp3(am_nfs_fh *fhp, int *rp, int vop);
static am_node *fh_to_mp(am_nfs_fh *fhp);
static void count_map_entries(const am_node *mp, u_int *out_blocks, u_int *out_bfree, u_int *out_bavail);


static char *
do_readlink(am_node *mp, int *error_return)
{
  char *ln;

  /*
   * If there is a readlink method then use it,
   * otherwise if a link exists use that,
   * otherwise use the mount point.
   */
  if (mp->am_al->al_mnt->mf_ops->readlink) {
    int retry = 0;
    mp = (*mp->am_al->al_mnt->mf_ops->readlink) (mp, &retry);
    if (mp == NULL) {
      *error_return = retry;
      return 0;
    }
    /* reschedule_timeout_mp(); */
  }

  if (mp->am_link) {
    ln = mp->am_link;
  } else {
    ln = mp->am_al->al_mnt->mf_mount;
  }

  return ln;
}


voidp
nfsproc_null_2_svc(voidp argp, struct svc_req *rqstp)
{
  static char res;

  return (voidp) &res;
}


nfsattrstat *
nfsproc_getattr_2_svc(am_nfs_fh *argp, struct svc_req *rqstp)
{
  static nfsattrstat res;
  am_node *mp;
  int retry = 0;
  time_t now = clocktime(NULL);

  if (amuDebug(D_TRACE))
    plog(XLOG_DEBUG, "getattr:");

  mp = fh_to_mp3(argp, &retry, VLOOK_CREATE);
  if (mp == NULL) {
    if (amuDebug(D_TRACE))
      plog(XLOG_DEBUG, "\tretry=%d", retry);

    if (retry < 0) {
      amd_stats.d_drops++;
      return 0;
    }
    res.ns_status = nfs_error(retry);
    return &res;
  }

  res = mp->am_attr;
  if (amuDebug(D_TRACE))
    plog(XLOG_DEBUG, "\tstat(%s), size = %d, mtime=%ld.%ld",
	 mp->am_path,
	 (int) res.ns_u.ns_attr_u.na_size,
	 (long) res.ns_u.ns_attr_u.na_mtime.nt_seconds,
	 (long) res.ns_u.ns_attr_u.na_mtime.nt_useconds);

  /* Delay unmount of what was looked up */
  if (mp->am_timeo_w < 4 * gopt.am_timeo_w)
    mp->am_timeo_w += gopt.am_timeo_w;
  mp->am_ttl = now + mp->am_timeo_w;

  mp->am_stats.s_getattr++;
  return &res;
}


nfsattrstat *
nfsproc_setattr_2_svc(nfssattrargs *argp, struct svc_req *rqstp)
{
  static nfsattrstat res;

  if (!fh_to_mp(&argp->sag_fhandle))
    res.ns_status = nfs_error(ESTALE);
  else
    res.ns_status = nfs_error(EROFS);

  return &res;
}


voidp
nfsproc_root_2_svc(voidp argp, struct svc_req *rqstp)
{
  static char res;

  return (voidp) &res;
}


nfsdiropres *
nfsproc_lookup_2_svc(nfsdiropargs *argp, struct svc_req *rqstp)
{
  static nfsdiropres res;
  am_node *mp;
  int retry;
  uid_t uid;
  gid_t gid;

  if (amuDebug(D_TRACE))
    plog(XLOG_DEBUG, "lookup:");

  /* finally, find the effective uid/gid from RPC request */
  if (getcreds(rqstp, &uid, &gid, nfsxprt) < 0)
    plog(XLOG_ERROR, "cannot get uid/gid from RPC credentials");
  xsnprintf(opt_uid, sizeof(uid_str), "%d", (int) uid);
  xsnprintf(opt_gid, sizeof(gid_str), "%d", (int) gid);

  mp = fh_to_mp3(&argp->da_fhandle, &retry, VLOOK_CREATE);
  if (mp == NULL) {
    if (retry < 0) {
      amd_stats.d_drops++;
      return 0;
    }
    res.dr_status = nfs_error(retry);
  } else {
    int error;
    am_node *ap;
    if (amuDebug(D_TRACE))
      plog(XLOG_DEBUG, "\tlookup(%s, %s)", mp->am_path, argp->da_name);
    ap = mp->am_al->al_mnt->mf_ops->lookup_child(mp, argp->da_name, &error, VLOOK_CREATE);
    if (ap && error < 0)
      ap = mp->am_al->al_mnt->mf_ops->mount_child(ap, &error);
    if (ap == 0) {
      if (error < 0) {
	amd_stats.d_drops++;
	return 0;
      }
      res.dr_status = nfs_error(error);
    } else {
      /*
       * XXX: EXPERIMENTAL! Delay unmount of what was looked up.  This
       * should reduce the chance for race condition between unmounting an
       * entry synchronously, and re-mounting it asynchronously.
       */
      if (ap->am_ttl < mp->am_ttl)
 	ap->am_ttl = mp->am_ttl;
      mp_to_fh(ap, &res.dr_u.dr_drok_u.drok_fhandle);
      res.dr_u.dr_drok_u.drok_attributes = ap->am_fattr;
      res.dr_status = NFS_OK;
    }
    mp->am_stats.s_lookup++;
    /* reschedule_timeout_mp(); */
  }

  return &res;
}


void
nfs_quick_reply(am_node *mp, int error)
{
  SVCXPRT *transp = mp->am_transp;
  nfsdiropres res;
  xdrproc_t xdr_result = (xdrproc_t) xdr_diropres;

  /*
   * If there's a transp structure then we can reply to the client's
   * nfs lookup request.
   */
  if (transp) {
    if (error == 0) {
      /*
       * Construct a valid reply to a lookup request.  Same
       * code as in nfsproc_lookup_2_svc() above.
       */
      mp_to_fh(mp, &res.dr_u.dr_drok_u.drok_fhandle);
      res.dr_u.dr_drok_u.drok_attributes = mp->am_fattr;
      res.dr_status = NFS_OK;
    } else
      /*
       * Return the error that was passed to us.
       */
      res.dr_status = nfs_error(error);

    /*
     * Send off our reply
     */
    if (!svc_sendreply(transp, (XDRPROC_T_TYPE) xdr_result, (SVC_IN_ARG_TYPE) & res))
      svcerr_systemerr(transp);

    /*
     * Free up transp.  It's only used for one reply.
     */
    XFREE(mp->am_transp);
    dlog("Quick reply sent for %s", mp->am_al->al_mnt->mf_mount);
  }
}


nfsreadlinkres *
nfsproc_readlink_2_svc(am_nfs_fh *argp, struct svc_req *rqstp)
{
  static nfsreadlinkres res;
  am_node *mp;
  int retry;

  if (amuDebug(D_TRACE))
    plog(XLOG_DEBUG, "readlink:");

  mp = fh_to_mp3(argp, &retry, VLOOK_CREATE);
  if (mp == NULL) {
  readlink_retry:
    if (retry < 0) {
      amd_stats.d_drops++;
      return 0;
    }
    res.rlr_status = nfs_error(retry);
  } else {
    char *ln = do_readlink(mp, &retry);
    if (ln == 0)
      goto readlink_retry;
    res.rlr_status = NFS_OK;
    if (amuDebug(D_TRACE) && ln)
      plog(XLOG_DEBUG, "\treadlink(%s) = %s", mp->am_path, ln);
    res.rlr_u.rlr_data_u = ln;
    mp->am_stats.s_readlink++;
  }

  return &res;
}


nfsreadres *
nfsproc_read_2_svc(nfsreadargs *argp, struct svc_req *rqstp)
{
  static nfsreadres res;

  memset((char *) &res, 0, sizeof(res));
  res.rr_status = nfs_error(EACCES);

  return &res;
}


voidp
nfsproc_writecache_2_svc(voidp argp, struct svc_req *rqstp)
{
  static char res;

  return (voidp) &res;
}


nfsattrstat *
nfsproc_write_2_svc(nfswriteargs *argp, struct svc_req *rqstp)
{
  static nfsattrstat res;

  if (!fh_to_mp(&argp->wra_fhandle))
    res.ns_status = nfs_error(ESTALE);
  else
    res.ns_status = nfs_error(EROFS);

  return &res;
}


nfsdiropres *
nfsproc_create_2_svc(nfscreateargs *argp, struct svc_req *rqstp)
{
  static nfsdiropres res;

  if (!fh_to_mp(&argp->ca_where.da_fhandle))
    res.dr_status = nfs_error(ESTALE);
  else
    res.dr_status = nfs_error(EROFS);

  return &res;
}


static nfsstat *
unlink_or_rmdir(nfsdiropargs *argp, struct svc_req *rqstp, int unlinkp)
{
  static nfsstat res;
  int retry;

  am_node *mp = fh_to_mp3(&argp->da_fhandle, &retry, VLOOK_DELETE);
  if (mp == NULL) {
    if (retry < 0) {
      amd_stats.d_drops++;
      return 0;
    }
    res = nfs_error(retry);
    goto out;
  }

  if (mp->am_fattr.na_type != NFDIR) {
    res = nfs_error(ENOTDIR);
    goto out;
  }

  if (amuDebug(D_TRACE))
    plog(XLOG_DEBUG, "\tremove(%s, %s)", mp->am_path, argp->da_name);

  mp = mp->am_al->al_mnt->mf_ops->lookup_child(mp, argp->da_name, &retry, VLOOK_DELETE);
  if (mp == NULL) {
    /*
     * Ignore retries...
     */
    if (retry < 0)
      retry = 0;
    /*
     * Usual NFS workaround...
     */
    else if (retry == ENOENT)
      retry = 0;
    res = nfs_error(retry);
  } else {
    forcibly_timeout_mp(mp);
    res = NFS_OK;
  }

out:
  return &res;
}


nfsstat *
nfsproc_remove_2_svc(nfsdiropargs *argp, struct svc_req *rqstp)
{
  return unlink_or_rmdir(argp, rqstp, TRUE);
}


nfsstat *
nfsproc_rename_2_svc(nfsrenameargs *argp, struct svc_req *rqstp)
{
  static nfsstat res;

  if (!fh_to_mp(&argp->rna_from.da_fhandle) || !fh_to_mp(&argp->rna_to.da_fhandle))
    res = nfs_error(ESTALE);
  /*
   * If the kernel is doing clever things with referenced files
   * then let it pretend...
   */
  else if (NSTREQ(argp->rna_to.da_name, ".nfs", 4))
    res = NFS_OK;
  /*
   * otherwise a failure
   */
  else
    res = nfs_error(EROFS);

  return &res;
}


nfsstat *
nfsproc_link_2_svc(nfslinkargs *argp, struct svc_req *rqstp)
{
  static nfsstat res;

  if (!fh_to_mp(&argp->la_fhandle) || !fh_to_mp(&argp->la_to.da_fhandle))
    res = nfs_error(ESTALE);
  else
    res = nfs_error(EROFS);

  return &res;
}


nfsstat *
nfsproc_symlink_2_svc(nfssymlinkargs *argp, struct svc_req *rqstp)
{
  static nfsstat res;

  if (!fh_to_mp(&argp->sla_from.da_fhandle))
    res = nfs_error(ESTALE);
  else
    res = nfs_error(EROFS);

  return &res;
}


nfsdiropres *
nfsproc_mkdir_2_svc(nfscreateargs *argp, struct svc_req *rqstp)
{
  static nfsdiropres res;

  if (!fh_to_mp(&argp->ca_where.da_fhandle))
    res.dr_status = nfs_error(ESTALE);
  else
    res.dr_status = nfs_error(EROFS);

  return &res;
}


nfsstat *
nfsproc_rmdir_2_svc(nfsdiropargs *argp, struct svc_req *rqstp)
{
  return unlink_or_rmdir(argp, rqstp, FALSE);
}


nfsreaddirres *
nfsproc_readdir_2_svc(nfsreaddirargs *argp, struct svc_req *rqstp)
{
  static nfsreaddirres res;
  static nfsentry e_res[MAX_READDIR_ENTRIES];
  am_node *mp;
  int retry;

  if (amuDebug(D_TRACE))
    plog(XLOG_DEBUG, "readdir:");

  mp = fh_to_mp3(&argp->rda_fhandle, &retry, VLOOK_CREATE);
  if (mp == NULL) {
    if (retry < 0) {
      amd_stats.d_drops++;
      return 0;
    }
    res.rdr_status = nfs_error(retry);
  } else {
    if (amuDebug(D_TRACE))
      plog(XLOG_DEBUG, "\treaddir(%s)", mp->am_path);
    res.rdr_status = nfs_error((*mp->am_al->al_mnt->mf_ops->readdir)
			   (mp, argp->rda_cookie,
			    &res.rdr_u.rdr_reply_u, e_res, argp->rda_count));
    mp->am_stats.s_readdir++;
  }

  return &res;
}


nfsstatfsres *
nfsproc_statfs_2_svc(am_nfs_fh *argp, struct svc_req *rqstp)
{
  static nfsstatfsres res;
  am_node *mp;
  int retry;
  mntent_t mnt;

  if (amuDebug(D_TRACE))
    plog(XLOG_DEBUG, "statfs:");

  mp = fh_to_mp3(argp, &retry, VLOOK_CREATE);
  if (mp == NULL) {
    if (retry < 0) {
      amd_stats.d_drops++;
      return 0;
    }
    res.sfr_status = nfs_error(retry);
  } else {
    nfsstatfsokres *fp;
    if (amuDebug(D_TRACE))
      plog(XLOG_DEBUG, "\tstat_fs(%s)", mp->am_path);

    /*
     * just return faked up file system information
     */
    fp = &res.sfr_u.sfr_reply_u;

    fp->sfrok_tsize = 1024;
    fp->sfrok_bsize = 1024;

    /* check if map is browsable and show_statfs_entries=yes  */
    if ((gopt.flags & CFM_SHOW_STATFS_ENTRIES) &&
	mp->am_al->al_mnt && mp->am_al->al_mnt->mf_mopts) {
      mnt.mnt_opts = mp->am_al->al_mnt->mf_mopts;
      if (amu_hasmntopt(&mnt, "browsable")) {
	count_map_entries(mp,
			  &fp->sfrok_blocks,
			  &fp->sfrok_bfree,
			  &fp->sfrok_bavail);
      }
    } else {
      fp->sfrok_blocks = 0; /* set to 1 if you don't want empty automounts */
      fp->sfrok_bfree = 0;
      fp->sfrok_bavail = 0;
    }

    res.sfr_status = NFS_OK;
    mp->am_stats.s_statfs++;
  }

  return &res;
}


/*
 * count how many total entries there are in a map, and how many
 * of them are in use.
 */
static void
count_map_entries(const am_node *mp, u_int *out_blocks, u_int *out_bfree, u_int *out_bavail)
{
  u_int blocks, bfree, bavail, i;
  mntfs *mf;
  mnt_map *mmp;
  kv *k;

  blocks = bfree = bavail = 0;
  if (!mp)
    goto out;
  mf = mp->am_al->al_mnt;
  if (!mf)
    goto out;
  mmp = (mnt_map *) mf->mf_private;
  if (!mmp)
    goto out;

  /* iterate over keys */
  for (i = 0; i < NKVHASH; i++) {
    for (k = mmp->kvhash[i]; k ; k = k->next) {
      if (!k->key)
	continue;
      blocks++;
      /*
       * XXX: Need to count how many are actively in use and recompute
       * bfree and bavail based on it.
       */
    }
  }

out:
  *out_blocks = blocks;
  *out_bfree = bfree;
  *out_bavail = bavail;
}


/*
 * Convert from file handle to automount node.
 */
static am_node *
fh_to_mp3(am_nfs_fh *fhp, int *rp, int vop)
{
  struct am_fh *fp = (struct am_fh *) fhp;
  am_node *ap = NULL;

  if (fp->u.s.fhh_type != 0) {
    /* New filehandle type */
    int len = sizeof(*fhp) - sizeof(fp->fhh_gen);
    char *path = xmalloc(len+1);
    /*
     * Because fhp is treated as a filehandle we use memcpy
     * instead of xstrlcpy.
     */
    memcpy(path, (char *) fp->u.fhh_path, len);
    path[len] = '\0';
    /* dlog("fh_to_mp3: new filehandle: %s", path); */

    ap = path_to_exported_ap(path);
    XFREE(path);
  } else {
    /* dlog("fh_to_mp3: old filehandle: %d", fp->u.s.fhh_id); */
    /*
     * Check process id matches
     * If it doesn't then it is probably
     * from an old kernel-cached filehandle
     * which is now out of date.
     */
    if (fp->u.s.fhh_pid != get_server_pid()) {
      dlog("fh_to_mp3: wrong pid %ld != my pid %ld",
	   (long) fp->u.s.fhh_pid, get_server_pid());
      goto drop;
    }

    /*
     * Get hold of the supposed mount node
     */
    ap = get_exported_ap(fp->u.s.fhh_id);
  }

  /*
   * Check the generation number in the node
   * matches the one from the kernel.  If not
   * then the old node has been timed out and
   * a new one allocated.
   */
  if (ap != NULL && ap->am_gen != fp->fhh_gen)
    ap = NULL;

  /*
   * If it doesn't exists then drop the request
   */
  if (!ap)
    goto drop;

#if 0
  /*
   * If the node is hung then locate a new node
   * for it.  This implements the replicated filesystem
   * retries.
   */
  if (ap->am_al->al_mnt && FSRV_ISDOWN(ap->am_al->al_mnt->mf_server) && ap->am_parent) {
    int error;
    am_node *orig_ap = ap;

    dlog("fh_to_mp3: %s (%s) is hung: lookup alternative file server",
	 orig_ap->am_path, orig_ap->am_al->al_mnt->mf_info);

    /*
     * Update modify time of parent node.
     * With any luck the kernel will re-stat
     * the child node and get new information.
     */
    clocktime(&orig_ap->am_fattr.na_mtime);

    /*
     * Call the parent's lookup routine for an object
     * with the same name.  This may return -1 in error
     * if a mount is in progress.  In any case, if no
     * mount node is returned the error code is propagated
     * to the caller.
     */
    if (vop == VLOOK_CREATE) {
      ap = orig_ap->am_parent->am_al->al_mnt->mf_ops->lookup_child(orig_ap->am_parent, orig_ap->am_name, &error, vop);
      if (ap && error < 0)
	ap = orig_ap->am_parent->am_al->al_mnt->mf_ops->mount_child(ap, &error);
    } else {
      ap = NULL;
      error = ESTALE;
    }
    if (ap == 0) {
      if (error < 0 && amd_state == Finishing)
	error = ENOENT;
      *rp = error;
      return 0;
    }

    /*
     * Update last access to original node.  This
     * avoids timing it out and so sending ESTALE
     * back to the kernel.
     * XXX - Not sure we need this anymore (jsp, 90/10/6).
     */
    new_ttl(orig_ap);

  }
#endif /* 0 */

  /*
   * Disallow references to objects being unmounted, unless
   * they are automount points.
   */
  if (ap->am_al->al_mnt && (ap->am_al->al_mnt->mf_flags & MFF_UNMOUNTING) &&
      !(ap->am_flags & AMF_ROOT)) {
    if (amd_state == Finishing)
      *rp = ENOENT;
    else
      *rp = -1;
    return 0;
  }
  new_ttl(ap);

drop:
  if (!ap || !ap->am_al->al_mnt) {
    /*
     * If we are shutting down then it is likely
     * that this node has disappeared because of
     * a fast timeout.  To avoid things thrashing
     * just pretend it doesn't exist at all.  If
     * ESTALE is returned, some NFS clients just
     * keep retrying (stupid or what - if it's
     * stale now, what's it going to be in 5 minutes?)
     */
    if (amd_state == Finishing)
      *rp = ENOENT;
    else {
      *rp = ESTALE;
      amd_stats.d_stale++;
    }
  }

  return ap;
}


static am_node *
fh_to_mp(am_nfs_fh *fhp)
{
  int dummy;

  return fh_to_mp3(fhp, &dummy, VLOOK_CREATE);
}


/*
 * Convert from automount node to file handle.
 */
void
mp_to_fh(am_node *mp, am_nfs_fh *fhp)
{
  u_int pathlen;
  struct am_fh *fp = (struct am_fh *) fhp;

  memset((char *) fhp, 0, sizeof(am_nfs_fh));

  /* Store the generation number */
  fp->fhh_gen = mp->am_gen;

  pathlen = strlen(mp->am_path);
  if (pathlen <= sizeof(*fhp) - sizeof(fp->fhh_gen)) {
    /* dlog("mp_to_fh: new filehandle: %s", mp->am_path); */

    /*
     * Because fhp is treated as a filehandle we use memcpy instead of
     * xstrlcpy.
     */
    memcpy(fp->u.fhh_path, mp->am_path, pathlen); /* making a filehandle */
  } else {
    /*
     * Take the process id
     */
    fp->u.s.fhh_pid = get_server_pid();

    /*
     * ... the map number
     */
    fp->u.s.fhh_id = mp->am_mapno;

    /*
     * ... and the generation number (previously stored)
     * to make a "unique" triple that will never
     * be reallocated except across reboots (which doesn't matter)
     * or if we are unlucky enough to be given the same
     * pid as a previous amd (very unlikely).
     */
    /* dlog("mp_to_fh: old filehandle: %d", fp->u.s.fhh_id); */
  }
}
