// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (C) 2024, Huawei Technologies Co, Ltd.
 *
 * Authors: Huang Xiaojia <huangxiaojia2@huawei.com>
 *          Zhihao Cheng <chengzhihao1@huawei.com>
 */

#include <stdio.h>
#include <stdlib.h>
#include <sys/stat.h>

#include "linux_err.h"
#include "kmem.h"
#include "ubifs.h"
#include "defs.h"
#include "debug.h"
#include "key.h"
#include "fsck.ubifs.h"

#define LOST_FOUND_DIR_NAME "lost+found"
#define MAX_REPEAT_NAME_RETRY_TIMES 10000000

/**
 * check_and_create_lost_found - Check and create the lost+found directory.
 * @c: UBIFS file-system description object
 *
 * This function checks whether the lost+found directory exists and creates a
 * new one if no valid lost+found existing. If there is a valid lost+found
 * directory, inode number is stored in @FSCK(c)->lost_and_found. Returns zero
 * in case of success, a negative error code in case of failure.
 */
int check_and_create_lost_found(struct ubifs_info *c)
{
	struct ubifs_inode *root_ui, *lost_found_ui;
	struct fscrypt_name nm;
	int err = 0;

	root_ui = ubifs_lookup_by_inum(c, UBIFS_ROOT_INO);
	if (IS_ERR(root_ui)) {
		err = PTR_ERR(root_ui);
		/* Previous step ensures that the root dir is valid. */
		ubifs_assert(c, err != -ENOENT);
		return err;
	}

	if (root_ui->flags & UBIFS_CRYPT_FL) {
		ubifs_msg(c, "The root dir is encrypted, skip checking lost+found");
		goto free_root;
	}

	fname_name(&nm) = LOST_FOUND_DIR_NAME;
	fname_len(&nm) = strlen(LOST_FOUND_DIR_NAME);
	lost_found_ui = ubifs_lookup(c, root_ui, &nm);
	if (IS_ERR(lost_found_ui)) {
		err = PTR_ERR(lost_found_ui);
		if (err != -ENOENT)
			goto free_root;

		/* Not found. Create a new lost+found. */
		err = ubifs_mkdir(c, root_ui, &nm, S_IRUGO | S_IWUSR | S_IXUSR);
		if (err < 0) {
			if (err == -ENOSPC) {
				ubifs_msg(c, "No free space to create lost+found");
				err = 0;
			}
			goto free_root;
		}
		lost_found_ui = ubifs_lookup(c, root_ui, &nm);
		if (IS_ERR(lost_found_ui)) {
			err = PTR_ERR(lost_found_ui);
			ubifs_assert(c, err != -ENOENT);
			goto free_root;
		}
		FSCK(c)->lost_and_found = lost_found_ui->vfs_inode.inum;
		ubifs_msg(c, "Create the lost+found");
	} else if (!(lost_found_ui->flags & UBIFS_CRYPT_FL) &&
		   S_ISDIR(lost_found_ui->vfs_inode.mode)) {
		FSCK(c)->lost_and_found = lost_found_ui->vfs_inode.inum;
	} else {
		ubifs_msg(c, "The type of lost+found is %s%s",
			  ubifs_get_type_name(ubifs_get_dent_type(lost_found_ui->vfs_inode.mode)),
			  lost_found_ui->flags & UBIFS_CRYPT_FL ? ", encrypted" : "");
	}

	kfree(lost_found_ui);
free_root:
	kfree(root_ui);
	return err;
}

static int handle_disonnected_file(struct ubifs_info *c,
				   struct scanned_file *file)
{
	int err = 0;

	if (FSCK(c)->lost_and_found) {
		unsigned int index = 0;
		char file_name[UBIFS_MAX_NLEN + 1];
		struct fscrypt_name nm;
		struct ubifs_inode *ui = NULL, *lost_found_ui = NULL;

		lost_found_ui = ubifs_lookup_by_inum(c, FSCK(c)->lost_and_found);
		if (IS_ERR(lost_found_ui)) {
			err = PTR_ERR(lost_found_ui);
			ubifs_assert(c, err != -ENOENT);
			return err;
		}
		ui = ubifs_lookup_by_inum(c, file->inum);
		if (IS_ERR(ui)) {
			err = PTR_ERR(ui);
			ubifs_assert(c, err != -ENOENT);
			goto free_lost_found_ui;
		}

		while (index < MAX_REPEAT_NAME_RETRY_TIMES) {
			struct ubifs_inode *target_ui;

			err = snprintf(file_name, sizeof(file_name),
				       "INO_%lu_%u", file->inum, index);
			if (err < 0)
				goto free_ui;
			fname_name(&nm) = file_name;
			fname_len(&nm) = strlen(file_name);
			target_ui = ubifs_lookup(c, lost_found_ui, &nm);
			if (IS_ERR(target_ui)) {
				err = PTR_ERR(target_ui);
				if (err == -ENOENT)
					break;
				goto free_ui;
			}
			kfree(target_ui);
			index++;
		}

		if (err != -ENOENT) {
			err = 0;
			kfree(ui);
			kfree(lost_found_ui);
			log_out(c, "Too many duplicated names(%u) in lost+found for inum %lu",
				index, file->inum);
			goto delete_file;
		}

		/* Try to recover disconnected file into lost+found. */
		err = ubifs_link_recovery(c, lost_found_ui, ui, &nm);
		if (err && err == -ENOSPC) {
			err = 0;
			log_out(c, "No free space to recover disconnected file");
			goto delete_file;
		}
		dbg_fsck("recover disconnected file %lu, in %s",
			 file->inum, c->dev_name);

free_ui:
		kfree(ui);
free_lost_found_ui:
		kfree(lost_found_ui);
		return err;
	}

	log_out(c, "No valid lost+found");

delete_file:
	if (fix_problem(c, DISCONNECTED_FILE_CANNOT_BE_RECOVERED, file))
		err = delete_file(c, file);
	return err;
}

/**
 * handle_disonnected_files - Handle disconnected files.
 * @c: UBIFS file-system description object
 *
 * This function tries to recover disonnected files into lost+found directory.
 * If there is no free space left to recover the disconnected files, fsck may
 * delete the files to make filesystem be consistent. Returns zero in case of
 * success, a negative error code in case of failure.
 */
int handle_disonnected_files(struct ubifs_info *c)
{
	int err, ret = 0;
	struct scanned_file *file;

	while (!list_empty(&FSCK(c)->disconnected_files)) {
		file = list_entry(FSCK(c)->disconnected_files.next,
				  struct scanned_file, list);

		list_del(&file->list);
		err = handle_disonnected_file(c, file);
		if (err)
			ret = ret ? ret : err;
		destroy_file_content(c, file);
		kfree(file);
	}

	return ret;
}