/*
 * Copyright IBM Corporation, 2010
 * Author Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of version 2.1 of the GNU Lesser 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.
 *
 */

#include <linux/module.h>
#include <linux/fs.h>
#include <linux/sched.h>
#include <net/9p/9p.h>
#include <net/9p/client.h>

#include "fid.h"
#include "xattr.h"

ssize_t v9fs_fid_xattr_get(struct p9_fid *fid, const char *name,
                           void *buffer, size_t buffer_size)
{
        ssize_t retval;
        int msize, read_count;
        u64 offset = 0, attr_size;
        struct p9_fid *attr_fid;

        attr_fid = p9_client_xattrwalk(fid, name, &attr_size);
        if (IS_ERR(attr_fid)) {
                retval = PTR_ERR(attr_fid);
                p9_debug(P9_DEBUG_VFS, "p9_client_attrwalk failed %zd\n",
                         retval);
                attr_fid = NULL;
                goto error;
        }
        if (!buffer_size) {
                /* request to get the attr_size */
                retval = attr_size;
                goto error;
        }
        if (attr_size > buffer_size) {
                retval = -ERANGE;
                goto error;
        }
        msize = attr_fid->clnt->msize;
        while (attr_size) {
                if (attr_size > (msize - P9_IOHDRSZ))
                        read_count = msize - P9_IOHDRSZ;
                else
                        read_count = attr_size;
                read_count = p9_client_read(attr_fid, ((char *)buffer)+offset,
                                        NULL, offset, read_count);
                if (read_count < 0) {
                        /* error in xattr read */
                        retval = read_count;
                        goto error;
                }
                offset += read_count;
                attr_size -= read_count;
        }
        /* Total read xattr bytes */
        retval = offset;
error:
        if (attr_fid)
                p9_client_clunk(attr_fid);
        return retval;

}


/*
 * v9fs_xattr_get()
 *
 * Copy an extended attribute into the buffer
 * provided, or compute the buffer size required.
 * Buffer is NULL to compute the size of the buffer required.
 *
 * Returns a negative error number on failure, or the number of bytes
 * used / required on success.
 */
ssize_t v9fs_xattr_get(struct dentry *dentry, const char *name,
                       void *buffer, size_t buffer_size)
{
        struct p9_fid *fid;

        p9_debug(P9_DEBUG_VFS, "name = %s value_len = %zu\n",
                 name, buffer_size);
        fid = v9fs_fid_lookup(dentry);
        if (IS_ERR(fid))
                return PTR_ERR(fid);

        return v9fs_fid_xattr_get(fid, name, buffer, buffer_size);
}

/*
 * v9fs_xattr_set()
 *
 * Create, replace or remove an extended attribute for this inode. Buffer
 * is NULL to remove an existing extended attribute, and non-NULL to
 * either replace an existing extended attribute, or create a new extended
 * attribute. The flags XATTR_REPLACE and XATTR_CREATE
 * specify that an extended attribute must exist and must not exist
 * previous to the call, respectively.
 *
 * Returns 0, or a negative error number on failure.
 */
int v9fs_xattr_set(struct dentry *dentry, const char *name,
                   const void *value, size_t value_len, int flags)
{
        u64 offset = 0;
        int retval, msize, write_count;
        struct p9_fid *fid = NULL;

        p9_debug(P9_DEBUG_VFS, "name = %s value_len = %zu flags = %d\n",
                 name, value_len, flags);

        fid = v9fs_fid_clone(dentry);
        if (IS_ERR(fid)) {
                retval = PTR_ERR(fid);
                fid = NULL;
                goto error;
        }
        /*
         * On success fid points to xattr
         */
        retval = p9_client_xattrcreate(fid, name, value_len, flags);
        if (retval < 0) {
                p9_debug(P9_DEBUG_VFS, "p9_client_xattrcreate failed %d\n",
                         retval);
                goto error;
        }
        msize = fid->clnt->msize;
        while (value_len) {
                if (value_len > (msize - P9_IOHDRSZ))
                        write_count = msize - P9_IOHDRSZ;
                else
                        write_count = value_len;
                write_count = p9_client_write(fid, ((char *)value)+offset,
                                        NULL, offset, write_count);
                if (write_count < 0) {
                        /* error in xattr write */
                        retval = write_count;
                        goto error;
                }
                offset += write_count;
                value_len -= write_count;
        }
        /* Total read xattr bytes */
        retval = offset;
error:
        if (fid)
                retval = p9_client_clunk(fid);
        return retval;
}

ssize_t v9fs_listxattr(struct dentry *dentry, char *buffer, size_t buffer_size)
{
        return v9fs_xattr_get(dentry, NULL, buffer, buffer_size);
}

const struct xattr_handler *v9fs_xattr_handlers[] = {
        &v9fs_xattr_user_handler,
#ifdef CONFIG_9P_FS_POSIX_ACL
        &v9fs_xattr_acl_access_handler,
        &v9fs_xattr_acl_default_handler,
#endif
        NULL
};