/*
   * Copyright (c) 2008, Christoph Hellwig
   * All Rights Reserved.
   *
   * 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.
   *
   * This program is distributed in the hope that it would 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 the Free Software Foundation,
   * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
   */
  #include "xfs.h"
  #include "xfs_format.h"
  #include "xfs_log_format.h"
  #include "xfs_trans_resv.h"
  #include "xfs_mount.h"
  #include "xfs_inode.h"
  #include "xfs_acl.h"
  #include "xfs_attr.h"
  #include "xfs_trace.h"
  #include <linux/slab.h>
  #include <linux/xattr.h>
  #include <linux/posix_acl_xattr.h>
  
  
  /*
   * Locking scheme:
   *  - all ACL updates are protected by inode->i_mutex, which is taken before
   *    calling into this file.
   */
  
  STATIC struct posix_acl *
  xfs_acl_from_disk(
  	const struct xfs_acl	*aclp,
  	int			len,
  	int			max_entries)
  {
  	struct posix_acl_entry *acl_e;
  	struct posix_acl *acl;
  	const struct xfs_acl_entry *ace;
  	unsigned int count, i;
  
  	if (len < sizeof(*aclp))
  		return ERR_PTR(-EFSCORRUPTED);
  	count = be32_to_cpu(aclp->acl_cnt);
  	if (count > max_entries || XFS_ACL_SIZE(count) != len)
  		return ERR_PTR(-EFSCORRUPTED);
  
  	acl = posix_acl_alloc(count, GFP_KERNEL);
  	if (!acl)
  		return ERR_PTR(-ENOMEM);
  
  	for (i = 0; i < count; i++) {
  		acl_e = &acl->a_entries[i];
  		ace = &aclp->acl_entry[i];
  
  		/*
  		 * The tag is 32 bits on disk and 16 bits in core.
  		 *
  		 * Because every access to it goes through the core
  		 * format first this is not a problem.
  		 */
  		acl_e->e_tag = be32_to_cpu(ace->ae_tag);
  		acl_e->e_perm = be16_to_cpu(ace->ae_perm);
  
  		switch (acl_e->e_tag) {
  		case ACL_USER:
  			acl_e->e_uid = xfs_uid_to_kuid(be32_to_cpu(ace->ae_id));
  			break;
  		case ACL_GROUP:
  			acl_e->e_gid = xfs_gid_to_kgid(be32_to_cpu(ace->ae_id));
  			break;
  		case ACL_USER_OBJ:
  		case ACL_GROUP_OBJ:
  		case ACL_MASK:
  		case ACL_OTHER:
  			break;
  		default:
  			goto fail;
  		}
  	}
  	return acl;
  
  fail:
  	posix_acl_release(acl);
  	return ERR_PTR(-EINVAL);
  }
  
  STATIC void
  xfs_acl_to_disk(struct xfs_acl *aclp, const struct posix_acl *acl)
  {
  	const struct posix_acl_entry *acl_e;
  	struct xfs_acl_entry *ace;
  	int i;
  
  	aclp->acl_cnt = cpu_to_be32(acl->a_count);
  	for (i = 0; i < acl->a_count; i++) {
  		ace = &aclp->acl_entry[i];
  		acl_e = &acl->a_entries[i];
  
  		ace->ae_tag = cpu_to_be32(acl_e->e_tag);
  		switch (acl_e->e_tag) {
  		case ACL_USER:
  			ace->ae_id = cpu_to_be32(xfs_kuid_to_uid(acl_e->e_uid));
  			break;
  		case ACL_GROUP:
  			ace->ae_id = cpu_to_be32(xfs_kgid_to_gid(acl_e->e_gid));
  			break;
  		default:
  			ace->ae_id = cpu_to_be32(ACL_UNDEFINED_ID);
  			break;
  		}
  
  		ace->ae_perm = cpu_to_be16(acl_e->e_perm);
  	}
  }
  
  struct posix_acl *
  xfs_get_acl(struct inode *inode, int type)
  {
  	struct xfs_inode *ip = XFS_I(inode);
  	struct posix_acl *acl = NULL;
  	struct xfs_acl *xfs_acl;
  	unsigned char *ea_name;
  	int error;
  	int len;
  
  	trace_xfs_get_acl(ip);
  
  	switch (type) {
  	case ACL_TYPE_ACCESS:
  		ea_name = SGI_ACL_FILE;
  		break;
  	case ACL_TYPE_DEFAULT:
  		ea_name = SGI_ACL_DEFAULT;
  		break;
  	default:
  		BUG();
  	}
  
  	/*
  	 * If we have a cached ACLs value just return it, not need to
  	 * go out to the disk.
  	 */
  	len = XFS_ACL_MAX_SIZE(ip->i_mount);
  	xfs_acl = kmem_zalloc_large(len, KM_SLEEP);
  	if (!xfs_acl)
  		return ERR_PTR(-ENOMEM);
  
  	error = xfs_attr_get(ip, ea_name, (unsigned char *)xfs_acl,
  							&len, ATTR_ROOT);
  	if (error) {
  		/*
  		 * If the attribute doesn't exist make sure we have a negative
  		 * cache entry, for any other error assume it is transient and
  		 * leave the cache entry as ACL_NOT_CACHED.
  		 */
  		if (error == -ENOATTR)
  			goto out_update_cache;
  		acl = ERR_PTR(error);
  		goto out;
  	}
  
  	acl = xfs_acl_from_disk(xfs_acl, len, XFS_ACL_MAX_ENTRIES(ip->i_mount));
  	if (IS_ERR(acl))
  		goto out;
  
  out_update_cache:
  	set_cached_acl(inode, type, acl);
  out:
  	kmem_free(xfs_acl);
  	return acl;
  }
  
  STATIC int
  __xfs_set_acl(struct inode *inode, int type, struct posix_acl *acl)
  {
  	struct xfs_inode *ip = XFS_I(inode);
  	unsigned char *ea_name;
  	int error;
  
  	switch (type) {
  	case ACL_TYPE_ACCESS:
  		ea_name = SGI_ACL_FILE;
  		break;
  	case ACL_TYPE_DEFAULT:
  		if (!S_ISDIR(inode->i_mode))
  			return acl ? -EACCES : 0;
  		ea_name = SGI_ACL_DEFAULT;
  		break;
  	default:
  		return -EINVAL;
  	}
  
  	if (acl) {
  		struct xfs_acl *xfs_acl;
  		int len = XFS_ACL_MAX_SIZE(ip->i_mount);
  
  		xfs_acl = kmem_zalloc_large(len, KM_SLEEP);
  		if (!xfs_acl)
  			return -ENOMEM;
  
  		xfs_acl_to_disk(xfs_acl, acl);
  
  		/* subtract away the unused acl entries */
  		len -= sizeof(struct xfs_acl_entry) *
  			 (XFS_ACL_MAX_ENTRIES(ip->i_mount) - acl->a_count);
  
  		error = xfs_attr_set(ip, ea_name, (unsigned char *)xfs_acl,
  				len, ATTR_ROOT);
  
  		kmem_free(xfs_acl);
  	} else {
  		/*
  		 * A NULL ACL argument means we want to remove the ACL.
  		 */
  		error = xfs_attr_remove(ip, ea_name, ATTR_ROOT);
  
  		/*
  		 * If the attribute didn't exist to start with that's fine.
  		 */
  		if (error == -ENOATTR)
  			error = 0;
  	}
  
  	if (!error)
  		set_cached_acl(inode, type, acl);
  	return error;
  }
  
  static int
  xfs_set_mode(struct inode *inode, umode_t mode)
  {
  	int error = 0;
  
  	if (mode != inode->i_mode) {
  		struct iattr iattr;
  
  		iattr.ia_valid = ATTR_MODE | ATTR_CTIME;
  		iattr.ia_mode = mode;
  		iattr.ia_ctime = current_fs_time(inode->i_sb);
  
  		error = xfs_setattr_nonsize(XFS_I(inode), &iattr, XFS_ATTR_NOACL);
  	}
  
  	return error;
  }
  
  static int
  xfs_acl_exists(struct inode *inode, unsigned char *name)
  {
  	int len = XFS_ACL_MAX_SIZE(XFS_M(inode->i_sb));
  
  	return (xfs_attr_get(XFS_I(inode), name, NULL, &len,
  			    ATTR_ROOT|ATTR_KERNOVAL) == 0);
  }
  
  int
  posix_acl_access_exists(struct inode *inode)
  {
  	return xfs_acl_exists(inode, SGI_ACL_FILE);
  }
  
  int
  posix_acl_default_exists(struct inode *inode)
  {
  	if (!S_ISDIR(inode->i_mode))
  		return 0;
  	return xfs_acl_exists(inode, SGI_ACL_DEFAULT);
  }
  
  int
  xfs_set_acl(struct inode *inode, struct posix_acl *acl, int type)
  {
  	int error = 0;
  
  	if (!acl)
  		goto set_acl;
  
  	error = -E2BIG;
  	if (acl->a_count > XFS_ACL_MAX_ENTRIES(XFS_M(inode->i_sb)))
  		return error;
  
  	if (type == ACL_TYPE_ACCESS) {
  		umode_t mode;
  
  		error = posix_acl_update_mode(inode, &mode, &acl);
  		if (error)
  			return error;
  		error = xfs_set_mode(inode, mode);
  		if (error)
  			return error;
  	}
  
   set_acl:
  	return __xfs_set_acl(inode, type, acl);
  }