/*
   * 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
  ",
  			 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
  ",
  		 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)
  {
  	struct p9_fid *fid = v9fs_fid_lookup(dentry);
  	if (IS_ERR(fid))
  		return PTR_ERR(fid);
  	return v9fs_fid_xattr_set(fid, name, value, value_len, flags);
  }
  
  int v9fs_fid_xattr_set(struct p9_fid *fid, const char *name,
  		   const void *value, size_t value_len, int flags)
  {
  	u64 offset = 0;
  	int retval, msize, write_count;
  
  	p9_debug(P9_DEBUG_VFS, "name = %s value_len = %zu flags = %d
  ",
  		 name, value_len, flags);
  
  	/* Clone it */
  	fid = p9_client_walk(fid, 0, NULL, 1);
  	if (IS_ERR(fid))
  		return PTR_ERR(fid);
  
  	/*
  	 * 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
  ",
  			 retval);
  		goto err;
  	}
  	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 err;
  		}
  		offset += write_count;
  		value_len -= write_count;
  	}
  	retval = offset;
  err:
  	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,
  	&v9fs_xattr_trusted_handler,
  #ifdef CONFIG_9P_FS_POSIX_ACL
  	&v9fs_xattr_acl_access_handler,
  	&v9fs_xattr_acl_default_handler,
  #endif
  #ifdef CONFIG_9P_FS_SECURITY
  	&v9fs_xattr_security_handler,
  #endif
  	NULL
  };