#include <linux/posix_acl.h>
#include <linux/reiserfs_fs.h>
#include <linux/errno.h>
#include <linux/fs.h>
#include <linux/pagemap.h>
#include <linux/xattr.h>
#include <linux/xattr_acl.h>
#include <linux/reiserfs_xattr.h>
#include <linux/reiserfs_acl.h>
#include <asm/uaccess.h>

static int
xattr_set_acl(struct inode *inode, int type, const void *value, size_t size)
{
	struct posix_acl *acl;
	int error;

	if (!reiserfs_posixacl(inode->i_sb))
		return -EOPNOTSUPP;
	if ((current->fsuid != inode->i_uid) && !capable(CAP_FOWNER))
		return -EPERM;

	if (value) {
		acl = posix_acl_from_xattr(value, size);
		if (IS_ERR(acl)) {
			return PTR_ERR(acl);
		} else if (acl) {
			error = posix_acl_valid(acl);
			if (error)
				goto release_and_out;
		}
	} else
		acl = NULL;

	error = reiserfs_set_acl (inode, type, acl);

release_and_out:
	posix_acl_release(acl);
	return error;
}


static int
xattr_get_acl(struct inode *inode, int type, void *buffer, size_t size)
{
	struct posix_acl *acl;
	int error;

	if (!reiserfs_posixacl(inode->i_sb))
		return -EOPNOTSUPP;

	acl = reiserfs_get_acl (inode, type);
	if (IS_ERR(acl))
		return PTR_ERR(acl);
	if (acl == NULL)
		return -ENODATA;
	error = posix_acl_to_xattr(acl, buffer, size);
	posix_acl_release(acl);

	return error;
}


/*
 * Convert from filesystem to in-memory representation.
 */
static struct posix_acl *
posix_acl_from_disk(const void *value, size_t size)
{
	const char *end = (char *)value + size;
	int n, count;
	struct posix_acl *acl;

	if (!value)
		return NULL;
	if (size < sizeof(reiserfs_acl_header))
		 return ERR_PTR(-EINVAL);
	if (((reiserfs_acl_header *)value)->a_version !=
	    cpu_to_le32(REISERFS_ACL_VERSION))
		return ERR_PTR(-EINVAL);
	value = (char *)value + sizeof(reiserfs_acl_header);
	count = reiserfs_acl_count(size);
	if (count < 0)
		return ERR_PTR(-EINVAL);
	if (count == 0)
		return NULL;
	acl = posix_acl_alloc(count, GFP_NOFS);
	if (!acl)
		return ERR_PTR(-ENOMEM);
	for (n=0; n < count; n++) {
		reiserfs_acl_entry *entry =
			(reiserfs_acl_entry *)value;
		if ((char *)value + sizeof(reiserfs_acl_entry_short) > end)
			goto fail;
		acl->a_entries[n].e_tag  = le16_to_cpu(entry->e_tag);
		acl->a_entries[n].e_perm = le16_to_cpu(entry->e_perm);
		switch(acl->a_entries[n].e_tag) {
			case ACL_USER_OBJ:
			case ACL_GROUP_OBJ:
			case ACL_MASK:
			case ACL_OTHER:
				value = (char *)value +
					sizeof(reiserfs_acl_entry_short);
				acl->a_entries[n].e_id = ACL_UNDEFINED_ID;
				break;

			case ACL_USER:
			case ACL_GROUP:
				value = (char *)value + sizeof(reiserfs_acl_entry);
				if ((char *)value > end)
					goto fail;
				acl->a_entries[n].e_id =
					le32_to_cpu(entry->e_id);
				break;

			default:
				goto fail;
		}
	}
	if (value != end)
		goto fail;
	return acl;

fail:
	posix_acl_release(acl);
	return ERR_PTR(-EINVAL);
}

/*
 * Convert from in-memory to filesystem representation.
 */
static void *
posix_acl_to_disk(const struct posix_acl *acl, size_t *size)
{
	reiserfs_acl_header *ext_acl;
	char *e;
	int n;

	*size = reiserfs_acl_size(acl->a_count);
	ext_acl = (reiserfs_acl_header *)kmalloc(sizeof(reiserfs_acl_header) +
		acl->a_count * sizeof(reiserfs_acl_entry), GFP_NOFS);
	if (!ext_acl)
		return ERR_PTR(-ENOMEM);
	ext_acl->a_version = cpu_to_le32(REISERFS_ACL_VERSION);
	e = (char *)ext_acl + sizeof(reiserfs_acl_header);
	for (n=0; n < acl->a_count; n++) {
		reiserfs_acl_entry *entry = (reiserfs_acl_entry *)e;
		entry->e_tag  = cpu_to_le16(acl->a_entries[n].e_tag);
		entry->e_perm = cpu_to_le16(acl->a_entries[n].e_perm);
		switch(acl->a_entries[n].e_tag) {
			case ACL_USER:
			case ACL_GROUP:
				entry->e_id =
					cpu_to_le32(acl->a_entries[n].e_id);
				e += sizeof(reiserfs_acl_entry);
				break;

			case ACL_USER_OBJ:
			case ACL_GROUP_OBJ:
			case ACL_MASK:
			case ACL_OTHER:
				e += sizeof(reiserfs_acl_entry_short);
				break;

			default:
				goto fail;
		}
	}
	return (char *)ext_acl;

fail:
	kfree(ext_acl);
	return ERR_PTR(-EINVAL);
}

/*
 * Inode operation get_posix_acl().
 *
 * inode->i_sem: down
 * BKL held [before 2.5.x]
 */
struct posix_acl *
reiserfs_get_acl(struct inode *inode, int type)
{
	char *name, *value;
	struct posix_acl *acl, **p_acl;
	size_t size;
	int retval;

        switch (type) {
            case ACL_TYPE_ACCESS:
                name = XATTR_NAME_ACL_ACCESS;
                p_acl = &inode->u.reiserfs_i.i_acl_access;
                break;
            case ACL_TYPE_DEFAULT:
                name = XATTR_NAME_ACL_DEFAULT;
                p_acl = &inode->u.reiserfs_i.i_acl_default;
                break;
            default:
                return ERR_PTR (-EINVAL);
        }

        if (IS_ERR (*p_acl)) {
            if (PTR_ERR (*p_acl) == -ENODATA)
                return NULL;
        } else if (*p_acl != NULL)
            return posix_acl_dup (*p_acl);

        size = reiserfs_xattr_get (inode, name, NULL, 0);
        if ((int)size < 0) {
            if (size == -ENODATA || size == -ENOSYS) {
		*p_acl = ERR_PTR (-ENODATA);
		return NULL;
            }
            return ERR_PTR (size);
        }

        value = kmalloc (size, GFP_NOFS);
        if (!value)
            return ERR_PTR (-ENOMEM);

	retval = reiserfs_xattr_get(inode, name, value, size);
	if (retval == -ENODATA || retval == -ENOSYS) {
		/* This shouldn't actually happen as it should have
		   been caught above.. but just in case */
		acl = NULL;
		*p_acl = ERR_PTR (-ENODATA);
        } else if (retval < 0) {
		acl = ERR_PTR(retval);
	} else {
		acl = posix_acl_from_disk(value, retval);
		*p_acl = posix_acl_dup (acl);
        }

	kfree(value);
	return acl;
}

/*
 * Inode operation set_posix_acl().
 *
 * inode->i_sem: down
 * BKL held [before 2.5.x]
 */
int
reiserfs_set_acl(struct inode *inode, int type, struct posix_acl *acl)
{
        char *name;
	void *value = NULL;
	struct posix_acl **p_acl;
	size_t size;
	int error;

	if (S_ISLNK(inode->i_mode))
		return -EOPNOTSUPP;


        switch (type) {
            case ACL_TYPE_ACCESS:
                name = XATTR_NAME_ACL_ACCESS;
                p_acl = &inode->u.reiserfs_i.i_acl_access;
                if (acl) {
                    mode_t mode = inode->i_mode;
                    error = posix_acl_equiv_mode (acl, &mode);
                    if (error < 0)
                        return error;
                    else {
                        inode->i_mode = mode;
                        if (error == 0)
                            acl = NULL;
                    }
                }
                break;
            case ACL_TYPE_DEFAULT:
                name = XATTR_NAME_ACL_DEFAULT;
                p_acl = &inode->u.reiserfs_i.i_acl_default;
                if (!S_ISDIR (inode->i_mode))
                    return acl ? -EACCES : 0;
                break;
            default:
                return -EINVAL;
        }

 	if (acl) {
            value = posix_acl_to_disk(acl, &size);
            if (IS_ERR(value))
                return (int)PTR_ERR(value);
            error = reiserfs_xattr_set(inode, name, value, size, 0);
	} else {
            error = reiserfs_xattr_del (inode, name);
            if (error == -ENODATA)
                error = 0;
        }

	if (value)
		kfree(value);

        if (!error) {
            /* Release the old one */
            if (!IS_ERR (*p_acl) && *p_acl)
                posix_acl_release (*p_acl);

            if (acl == NULL)
                *p_acl = ERR_PTR (-ENODATA);
            else 
                *p_acl = posix_acl_dup (acl);
        }

	return error;
}

/* dir->i_sem: down,
 * inode is new and not released into the wild yet */
int
reiserfs_inherit_default_acl (struct inode *dir, struct dentry *dentry, struct inode *inode)
{
    struct posix_acl *acl;
    int err = 0;

    /* ACLs only get applied to files and directories */
    if (S_ISLNK (inode->i_mode))
        return 0;

    /* ACLs can only be used on "new" objects, so if it's an old object
     * there is nothing to inherit from */
    if (get_inode_sd_version (dir) == STAT_DATA_V1)
        goto apply_umask;

    /* Don't apply ACLs to objects in the .reiserfs_priv tree.. This
     * would be useless since permissions are ignored, and a pain because
     * it introduces locking cycles */
    if (is_reiserfs_priv_object (dir)) {
        inode->u.reiserfs_i.i_flags |= i_priv_object;
        goto apply_umask;
    }

    acl = reiserfs_get_acl (dir, ACL_TYPE_DEFAULT);
    if (IS_ERR (acl)) {
        if (PTR_ERR (acl) == -ENODATA)
            goto apply_umask;
        return PTR_ERR (acl);
    }

    if (acl) {
        struct posix_acl *acl_copy;
        mode_t mode = inode->i_mode;
        int need_acl;

        /* Copy the default ACL to the default ACL of a new directory */
        if (S_ISDIR (inode->i_mode)) {
            err = reiserfs_set_acl (inode, ACL_TYPE_DEFAULT, acl);
            if (err)
                goto cleanup;
        }

        /* Now we reconcile the new ACL and the mode,
           potentially modifying both */
        acl_copy = posix_acl_clone (acl, GFP_NOFS);
        if (!acl_copy) {
            err = -ENOMEM;
            goto cleanup;
        }


        need_acl = posix_acl_create_masq (acl_copy, &mode);
        if (need_acl >= 0) {
            if (mode != inode->i_mode) {
                inode->i_mode = mode;
            }

            /* If we need an ACL.. */
            if (need_acl > 0) {
                err = reiserfs_set_acl (inode, ACL_TYPE_ACCESS, acl_copy);
                if (err) 
                    goto cleanup_copy;
            }
        }
cleanup_copy:
        posix_acl_release (acl_copy);
cleanup:
        posix_acl_release (acl);
    } else {
apply_umask:
        /* no ACL, apply umask */
        inode->i_mode &= ~current->fs->umask;
    }

    return err;
}

/* Looks up and caches the result of the default ACL.
 * We do this so that we don't need to carry the xattr_sem into
 * reiserfs_new_inode if we don't need to */
int
reiserfs_cache_default_acl (struct inode *inode)
{
    int ret = 0;
    if (reiserfs_posixacl (inode->i_sb) &&
        !is_reiserfs_priv_object (inode)) {
        struct posix_acl *acl;
        reiserfs_read_lock_xattrs (inode->i_sb);
        acl = reiserfs_get_acl (inode, ACL_TYPE_DEFAULT);
        reiserfs_read_unlock_xattrs (inode->i_sb);
        ret = acl ? 1 : 0;
        posix_acl_release (acl);
    }

    return ret;
}

static int
__reiserfs_permission (struct inode *inode, int mask, int need_lock)
{
	int mode = inode->i_mode;

	/* Nobody gets write access to a read-only fs */
	if ((mask & MAY_WRITE) && IS_RDONLY(inode) &&
	    (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode)))
		return -EROFS;

	/* Nobody gets write access to an immutable file */
	if ((mask & MAY_WRITE) && IS_IMMUTABLE(inode))
	    return -EACCES;

        /* We don't do permission checks on the internal objects.
         * Permissions are determined by the "owning" object. */
        if (is_reiserfs_priv_object (inode))
            return 0;

	if (current->fsuid == inode->i_uid) {
		mode >>= 6;
	} else if (reiserfs_posixacl(inode->i_sb) &&
                   get_inode_sd_version (inode) != STAT_DATA_V1) {
                struct posix_acl *acl;

		/* ACL can't contain additional permissions if
		   the ACL_MASK entry is 0 */
		if (!(mode & S_IRWXG))
			goto check_groups;

                if (need_lock)
                    reiserfs_read_lock_xattrs (inode->i_sb);
                acl = reiserfs_get_acl (inode, ACL_TYPE_ACCESS);
                if (need_lock)
                    reiserfs_read_unlock_xattrs (inode->i_sb);
                if (IS_ERR (acl)) {
                    if (PTR_ERR (acl) == -ENODATA)
                        goto check_groups;
                    return PTR_ERR (acl);
                }

                if (acl) {
                    int err = posix_acl_permission (inode, acl, mask);
                    posix_acl_release (acl);
                    if (err == -EACCES) {
                        goto check_capabilities;
                    }
                    return err;
		} else {
			goto check_groups;
                }

	} else {
check_groups:
		if (in_group_p(inode->i_gid))
			mode >>= 3;
	}
	if ((mode & mask & S_IRWXO) == mask)
		return 0;

check_capabilities:
       /* Allowed to override Discretionary Access Control? */
        if ((mask & (MAY_READ|MAY_WRITE)) || (inode->i_mode & S_IXUGO))
                if (capable(CAP_DAC_OVERRIDE))
                        return 0;
        /* Read and search granted if capable(CAP_DAC_READ_SEARCH) */
        if (capable(CAP_DAC_READ_SEARCH) && ((mask == MAY_READ) ||
            (S_ISDIR(inode->i_mode) && !(mask & MAY_WRITE))))
                return 0;
	return -EACCES;
}

int
reiserfs_permission (struct inode *inode, int mask)
{
    return __reiserfs_permission (inode, mask, 1);
}

int
reiserfs_permission_locked (struct inode *inode, int mask)
{
    return __reiserfs_permission (inode, mask, 0);
}

int
reiserfs_acl_chmod (struct inode *inode)
{
        struct posix_acl *acl, *clone;
        int error;

        if (S_ISLNK(inode->i_mode))
                return -EOPNOTSUPP;

	if (get_inode_sd_version (inode) == STAT_DATA_V1 ||
	    !reiserfs_posixacl(inode->i_sb))
        {
	    return 0;
	}

        reiserfs_read_lock_xattrs (inode->i_sb);
        acl = reiserfs_get_acl(inode, ACL_TYPE_ACCESS);
        reiserfs_read_unlock_xattrs (inode->i_sb);
        if (!acl)
                return 0;
        if (IS_ERR(acl))
                return PTR_ERR(acl);
        clone = posix_acl_clone(acl, GFP_NOFS);
        posix_acl_release(acl);
        if (!clone)
                return -ENOMEM;
        error = posix_acl_chmod_masq(clone, inode->i_mode);
        if (!error) {
                reiserfs_write_lock_xattrs (inode->i_sb);
                error = reiserfs_set_acl(inode, ACL_TYPE_ACCESS, clone);
                reiserfs_write_unlock_xattrs (inode->i_sb);
        }
        posix_acl_release(clone);
        return error;
}

static int
posix_acl_access_get(struct inode *inode, const char *name,
			  void *buffer, size_t size)
{
	if (strlen(name) != sizeof(XATTR_NAME_ACL_ACCESS)-1)
		return -EINVAL;
	return xattr_get_acl(inode, ACL_TYPE_ACCESS, buffer, size);
}

static int
posix_acl_access_set(struct inode *inode, const char *name,
			  const void *value, size_t size, int flags)
{
	if (strlen(name) != sizeof(XATTR_NAME_ACL_ACCESS)-1)
		return -EINVAL;
	return xattr_set_acl(inode, ACL_TYPE_ACCESS, value, size);
}

static int
posix_acl_access_del (struct inode *inode, const char *name)
{
    struct posix_acl **acl = &inode->u.reiserfs_i.i_acl_access;
    if (strlen(name) != sizeof(XATTR_NAME_ACL_ACCESS)-1)
	return -EINVAL;
    if (!IS_ERR (*acl) && *acl) {
        posix_acl_release (*acl);
        *acl = ERR_PTR (-ENODATA);
    }

    return 0;
}

static int
posix_acl_access_list (struct inode *inode, const char *name, int namelen, char *out)
{
    int len = namelen;
    if (!reiserfs_posixacl (inode->i_sb))
        return 0;
    if (out)
        memcpy (out, name, len);

    return len;
}

struct reiserfs_xattr_handler posix_acl_access_handler = {
    prefix: XATTR_NAME_ACL_ACCESS,
    get: posix_acl_access_get,
    set: posix_acl_access_set,
    del: posix_acl_access_del,
    list: posix_acl_access_list,
};

static int
posix_acl_default_get (struct inode *inode, const char *name,
			   void *buffer, size_t size)
{
	if (strlen(name) != sizeof(XATTR_NAME_ACL_DEFAULT)-1)
		return -EINVAL;
	return xattr_get_acl(inode, ACL_TYPE_DEFAULT, buffer, size);
}

static int
posix_acl_default_set(struct inode *inode, const char *name,
			   const void *value, size_t size, int flags)
{
	if (strlen(name) != sizeof(XATTR_NAME_ACL_DEFAULT)-1)
		return -EINVAL;
	return xattr_set_acl(inode, ACL_TYPE_DEFAULT, value, size);
}

static int
posix_acl_default_del (struct inode *inode, const char *name)
{
    struct posix_acl **acl = &inode->u.reiserfs_i.i_acl_default;
    if (strlen(name) != sizeof(XATTR_NAME_ACL_DEFAULT)-1)
	return -EINVAL;
    if (!IS_ERR (*acl) && *acl) {
        posix_acl_release (*acl);
        *acl = ERR_PTR (-ENODATA);
    }

    return 0;
}

static int
posix_acl_default_list (struct inode *inode, const char *name, int namelen, char *out)
{
    int len = namelen;
    if (!reiserfs_posixacl (inode->i_sb))
        return 0;
    if (out)
        memcpy (out, name, len);

    return len;
}

struct reiserfs_xattr_handler posix_acl_default_handler = {
    prefix: XATTR_NAME_ACL_DEFAULT,
    get: posix_acl_default_get,
    set: posix_acl_default_set,
    del: posix_acl_default_del,
    list: posix_acl_default_list,
};

int __init
reiserfs_xattr_posix_acl_init (void)
{
    int err;
    err = reiserfs_xattr_register_handler (&posix_acl_access_handler);
    if (!err)
        err = reiserfs_xattr_register_handler (&posix_acl_default_handler);
    return err;
}

int
reiserfs_xattr_posix_acl_exit (void)
{
    int err;
    err = reiserfs_xattr_unregister_handler (&posix_acl_access_handler);
    if (!err)
        err = reiserfs_xattr_unregister_handler (&posix_acl_default_handler);
    return err;
}
