/*
   * Copyright (C) 2012 Red Hat, Inc.
   * Copyright (C) 2012 Jeremy Kerr <jeremy.kerr@canonical.com>
   *
   * This program is free software; you can redistribute it and/or modify
   * it under the terms of the GNU General Public License version 2 as
   * published by the Free Software Foundation.
   */
  
  #include <linux/ctype.h>
  #include <linux/efi.h>
  #include <linux/fs.h>
  #include <linux/module.h>
  #include <linux/pagemap.h>
  #include <linux/ucs2_string.h>
  #include <linux/slab.h>
  #include <linux/magic.h>
  
  #include "internal.h"
  
  LIST_HEAD(efivarfs_list);
  
  static void efivarfs_evict_inode(struct inode *inode)
  {
  	clear_inode(inode);
  }
  
  static const struct super_operations efivarfs_ops = {
  	.statfs = simple_statfs,
  	.drop_inode = generic_delete_inode,
  	.evict_inode = efivarfs_evict_inode,
  	.show_options = generic_show_options,
  };
  
  static struct super_block *efivarfs_sb;
  
  /*
   * Compare two efivarfs file names.
   *
   * An efivarfs filename is composed of two parts,
   *
   *	1. A case-sensitive variable name
   *	2. A case-insensitive GUID
   *
   * So we need to perform a case-sensitive match on part 1 and a
   * case-insensitive match on part 2.
   */
  static int efivarfs_d_compare(const struct dentry *parent,
  			      const struct dentry *dentry,
  			      unsigned int len, const char *str,
  			      const struct qstr *name)
  {
  	int guid = len - EFI_VARIABLE_GUID_LEN;
  
  	if (name->len != len)
  		return 1;
  
  	/* Case-sensitive compare for the variable name */
  	if (memcmp(str, name->name, guid))
  		return 1;
  
  	/* Case-insensitive compare for the GUID */
  	return strncasecmp(name->name + guid, str + guid, EFI_VARIABLE_GUID_LEN);
  }
  
  static int efivarfs_d_hash(const struct dentry *dentry, struct qstr *qstr)
  {
  	unsigned long hash = init_name_hash();
  	const unsigned char *s = qstr->name;
  	unsigned int len = qstr->len;
  
  	if (!efivarfs_valid_name(s, len))
  		return -EINVAL;
  
  	while (len-- > EFI_VARIABLE_GUID_LEN)
  		hash = partial_name_hash(*s++, hash);
  
  	/* GUID is case-insensitive. */
  	while (len--)
  		hash = partial_name_hash(tolower(*s++), hash);
  
  	qstr->hash = end_name_hash(hash);
  	return 0;
  }
  
  static struct dentry_operations efivarfs_d_ops = {
  	.d_compare = efivarfs_d_compare,
  	.d_hash = efivarfs_d_hash,
  	.d_delete = always_delete_dentry,
  };
  
  static struct dentry *efivarfs_alloc_dentry(struct dentry *parent, char *name)
  {
  	struct dentry *d;
  	struct qstr q;
  	int err;
  
  	q.name = name;
  	q.len = strlen(name);
  
  	err = efivarfs_d_hash(NULL, &q);
  	if (err)
  		return ERR_PTR(err);
  
  	d = d_alloc(parent, &q);
  	if (d)
  		return d;
  
  	return ERR_PTR(-ENOMEM);
  }
  
  static int efivarfs_callback(efi_char16_t *name16, efi_guid_t vendor,
  			     unsigned long name_size, void *data)
  {
  	struct super_block *sb = (struct super_block *)data;
  	struct efivar_entry *entry;
  	struct inode *inode = NULL;
  	struct dentry *dentry, *root = sb->s_root;
  	unsigned long size = 0;
  	char *name;
  	int len, i;
  	int err = -ENOMEM;
  
  	entry = kmalloc(sizeof(*entry), GFP_KERNEL);
  	if (!entry)
  		return err;
  
  	memcpy(entry->var.VariableName, name16, name_size);
  	memcpy(&(entry->var.VendorGuid), &vendor, sizeof(efi_guid_t));
  
  	len = ucs2_strlen(entry->var.VariableName);
  
  	/* name, plus '-', plus GUID, plus NUL*/
  	name = kmalloc(len + 1 + EFI_VARIABLE_GUID_LEN + 1, GFP_KERNEL);
  	if (!name)
  		goto fail;
  
  	for (i = 0; i < len; i++)
  		name[i] = entry->var.VariableName[i] & 0xFF;
  
  	name[len] = '-';
  
  	efi_guid_unparse(&entry->var.VendorGuid, name + len + 1);
  
  	name[len + EFI_VARIABLE_GUID_LEN+1] = '\0';
  
  	inode = efivarfs_get_inode(sb, root->d_inode, S_IFREG | 0644, 0);
  	if (!inode)
  		goto fail_name;
  
  	dentry = efivarfs_alloc_dentry(root, name);
  	if (IS_ERR(dentry)) {
  		err = PTR_ERR(dentry);
  		goto fail_inode;
  	}
  
  	/* copied by the above to local storage in the dentry. */
  	kfree(name);
  
  	efivar_entry_size(entry, &size);
  	efivar_entry_add(entry, &efivarfs_list);
  
  	mutex_lock(&inode->i_mutex);
  	inode->i_private = entry;
  	i_size_write(inode, size + sizeof(entry->var.Attributes));
  	mutex_unlock(&inode->i_mutex);
  	d_add(dentry, inode);
  
  	return 0;
  
  fail_inode:
  	iput(inode);
  fail_name:
  	kfree(name);
  fail:
  	kfree(entry);
  	return err;
  }
  
  static int efivarfs_destroy(struct efivar_entry *entry, void *data)
  {
  	efivar_entry_remove(entry);
  	kfree(entry);
  	return 0;
  }
  
  static int efivarfs_fill_super(struct super_block *sb, void *data, int silent)
  {
  	struct inode *inode = NULL;
  	struct dentry *root;
  	int err;
  
  	efivarfs_sb = sb;
  
  	sb->s_maxbytes          = MAX_LFS_FILESIZE;
  	sb->s_blocksize         = PAGE_CACHE_SIZE;
  	sb->s_blocksize_bits    = PAGE_CACHE_SHIFT;
  	sb->s_magic             = EFIVARFS_MAGIC;
  	sb->s_op                = &efivarfs_ops;
  	sb->s_d_op		= &efivarfs_d_ops;
  	sb->s_time_gran         = 1;
  
  	inode = efivarfs_get_inode(sb, NULL, S_IFDIR | 0755, 0);
  	if (!inode)
  		return -ENOMEM;
  	inode->i_op = &efivarfs_dir_inode_operations;
  
  	root = d_make_root(inode);
  	sb->s_root = root;
  	if (!root)
  		return -ENOMEM;
  
  	INIT_LIST_HEAD(&efivarfs_list);
  
  	err = efivar_init(efivarfs_callback, (void *)sb, false,
  			  true, &efivarfs_list);
  	if (err)
  		__efivar_entry_iter(efivarfs_destroy, &efivarfs_list, NULL, NULL);
  
  	return err;
  }
  
  static struct dentry *efivarfs_mount(struct file_system_type *fs_type,
  				    int flags, const char *dev_name, void *data)
  {
  	return mount_single(fs_type, flags, data, efivarfs_fill_super);
  }
  
  static void efivarfs_kill_sb(struct super_block *sb)
  {
  	kill_litter_super(sb);
  	efivarfs_sb = NULL;
  
  	/* Remove all entries and destroy */
  	__efivar_entry_iter(efivarfs_destroy, &efivarfs_list, NULL, NULL);
  }
  
  static struct file_system_type efivarfs_type = {
  	.name    = "efivarfs",
  	.mount   = efivarfs_mount,
  	.kill_sb = efivarfs_kill_sb,
  };
  
  static __init int efivarfs_init(void)
  {
  	if (!efi_enabled(EFI_RUNTIME_SERVICES))
  		return 0;
  
  	if (!efivars_kobject())
  		return 0;
  
  	return register_filesystem(&efivarfs_type);
  }
  
  MODULE_AUTHOR("Matthew Garrett, Jeremy Kerr");
  MODULE_DESCRIPTION("EFI Variable Filesystem");
  MODULE_LICENSE("GPL");
  MODULE_ALIAS_FS("efivarfs");
  
  module_init(efivarfs_init);