// SPDX-License-Identifier: GPL-2.0

  /*

   *  linux/fs/ext4/symlink.c

   *
   * Only fast symlinks left here - the rest is done by generic code. AV, 1999
   *
   * Copyright (C) 1992, 1993, 1994, 1995
   * Remy Card (card@masi.ibp.fr)
   * Laboratoire MASI - Institut Blaise Pascal
   * Universite Pierre et Marie Curie (Paris VI)
   *
   *  from
   *
   *  linux/fs/minix/symlink.c
   *
   *  Copyright (C) 1991, 1992  Linus Torvalds
   *

   *  ext4 symlink handling code

   */
  
  #include <linux/fs.h>

  #include <linux/namei.h>

  #include "ext4.h"

  #include "xattr.h"

  static const char *ext4_encrypted_get_link(struct dentry *dentry,

  					   struct inode *inode,
  					   struct delayed_call *done)

  {

  	struct page *cpage = NULL;
  	char *caddr, *paddr = NULL;

  	struct fscrypt_str cstr, pstr;
  	struct fscrypt_symlink_data *sd;

  	int res;

  	u32 max_size = inode->i_sb->s_blocksize;

  	if (!dentry)
  		return ERR_PTR(-ECHILD);

  	res = fscrypt_get_encryption_info(inode);

  	if (res)
  		return ERR_PTR(res);

  
  	if (ext4_inode_is_fast_symlink(inode)) {

  		caddr = (char *) EXT4_I(inode)->i_data;
  		max_size = sizeof(EXT4_I(inode)->i_data);

  	} else {
  		cpage = read_mapping_page(inode->i_mapping, 0, NULL);

  		if (IS_ERR(cpage))

  			return ERR_CAST(cpage);

  		caddr = page_address(cpage);

  	}
  
  	/* Symlink is encrypted */

  	sd = (struct fscrypt_symlink_data *)caddr;

  	cstr.name = sd->encrypted_path;

  	cstr.len  = le16_to_cpu(sd->len);

  	if ((cstr.len + sizeof(struct fscrypt_symlink_data) - 1) > max_size) {

  		/* Symlink data on the disk is corrupted */

  		res = -EFSCORRUPTED;

  		goto errout;
  	}

  
  	res = fscrypt_fname_alloc_buffer(inode, cstr.len, &pstr);
  	if (res)

  		goto errout;

  	paddr = pstr.name;

  
  	res = fscrypt_fname_disk_to_usr(inode, 0, 0, &cstr, &pstr);

  	if (res)

  		goto errout;

  	/* Null-terminate the name */

  	paddr[pstr.len] = '\0';

  	if (cpage)

  		put_page(cpage);

  	set_delayed_call(done, kfree_link, paddr);
  	return paddr;

  errout:

  	if (cpage)

  		put_page(cpage);

  	kfree(paddr);
  	return ERR_PTR(res);
  }

  const struct inode_operations ext4_encrypted_symlink_inode_operations = {

  	.get_link	= ext4_encrypted_get_link,

  	.setattr	= ext4_setattr,

  	.getattr	= ext4_getattr,

  	.listxattr	= ext4_listxattr,

  };

  const struct inode_operations ext4_symlink_inode_operations = {

  	.get_link	= page_get_link,

  	.setattr	= ext4_setattr,

  	.getattr	= ext4_getattr,

  	.listxattr	= ext4_listxattr,

  };

  const struct inode_operations ext4_fast_symlink_inode_operations = {

  	.get_link	= simple_get_link,

  	.setattr	= ext4_setattr,

  	.getattr	= ext4_getattr,

  	.listxattr	= ext4_listxattr,

  };