// SPDX-License-Identifier: GPL-2.0

  /*
   * linux/fs/lockd/svcshare.c
   *
   * Management of DOS shares.
   *
   * Copyright (C) 1996 Olaf Kirch <okir@monad.swb.de>
   */
  
  #include <linux/time.h>
  #include <linux/unistd.h>
  #include <linux/string.h>
  #include <linux/slab.h>
  
  #include <linux/sunrpc/clnt.h>
  #include <linux/sunrpc/svc.h>
  #include <linux/lockd/lockd.h>
  #include <linux/lockd/share.h>
  
  static inline int
  nlm_cmp_owner(struct nlm_share *share, struct xdr_netobj *oh)
  {
  	return share->s_owner.len == oh->len
  	    && !memcmp(share->s_owner.data, oh->data, oh->len);
  }

  __be32

  nlmsvc_share_file(struct nlm_host *host, struct nlm_file *file,
  			struct nlm_args *argp)
  {
  	struct nlm_share	*share;
  	struct xdr_netobj	*oh = &argp->lock.oh;
  	u8			*ohdata;
  
  	for (share = file->f_shares; share; share = share->s_next) {
  		if (share->s_host == host && nlm_cmp_owner(share, oh))
  			goto update;
  		if ((argp->fsm_access & share->s_mode)
  		 || (argp->fsm_mode   & share->s_access ))
  			return nlm_lck_denied;
  	}

  	share = kmalloc(sizeof(*share) + oh->len,

  						GFP_KERNEL);
  	if (share == NULL)
  		return nlm_lck_denied_nolocks;
  
  	/* Copy owner handle */
  	ohdata = (u8 *) (share + 1);
  	memcpy(ohdata, oh->data, oh->len);
  
  	share->s_file	    = file;
  	share->s_host       = host;
  	share->s_owner.data = ohdata;
  	share->s_owner.len  = oh->len;
  	share->s_next       = file->f_shares;
  	file->f_shares      = share;
  
  update:
  	share->s_access = argp->fsm_access;
  	share->s_mode   = argp->fsm_mode;
  	return nlm_granted;
  }
  
  /*
   * Delete a share.
   */

  __be32

  nlmsvc_unshare_file(struct nlm_host *host, struct nlm_file *file,
  			struct nlm_args *argp)
  {
  	struct nlm_share	*share, **shpp;
  	struct xdr_netobj	*oh = &argp->lock.oh;

  	for (shpp = &file->f_shares; (share = *shpp) != NULL;
  					shpp = &share->s_next) {

  		if (share->s_host == host && nlm_cmp_owner(share, oh)) {
  			*shpp = share->s_next;
  			kfree(share);
  			return nlm_granted;
  		}
  	}
  
  	/* X/Open spec says return success even if there was no
  	 * corresponding share. */
  	return nlm_granted;
  }
  
  /*

   * Traverse all shares for a given file, and delete
   * those owned by the given (type of) host

   */

  void nlmsvc_traverse_shares(struct nlm_host *host, struct nlm_file *file,
  		nlm_host_match_fn_t match)

  {
  	struct nlm_share	*share, **shpp;
  
  	shpp = &file->f_shares;
  	while ((share = *shpp) !=  NULL) {

  		if (match(share->s_host, host)) {
  			*shpp = share->s_next;
  			kfree(share);
  			continue;

  		}
  		shpp = &share->s_next;
  	}

  }