path: root/fs/exfat/dir.c

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Copyright (C) 2012-2013 Samsung Electronics Co., Ltd.
 */

#include <linux/slab.h>
#include <linux/compat.h>
#include <linux/bio.h>
#include <linux/buffer_head.h>

#include "exfat_raw.h"
#include "exfat_fs.h"

static int exfat_extract_uni_name(struct exfat_dentry *ep,
		unsigned short *uniname)
{
	int i, len = 0;

	for (i = 0; i < EXFAT_FILE_NAME_LEN; i++) {
		*uniname = le16_to_cpu(ep->dentry.name.unicode_0_14[i]);
		if (*uniname == 0x0)
			return len;
		uniname++;
		len++;
	}

	*uniname = 0x0;
	return len;

}

static void exfat_get_uniname_from_ext_entry(struct super_block *sb,
		struct exfat_chain *p_dir, int entry, unsigned short *uniname)
{
	int i;
	struct exfat_entry_set_cache *es;

	es = exfat_get_dentry_set(sb, p_dir, entry, ES_ALL_ENTRIES);
	if (!es)
		return;

	/*
	 * First entry  : file entry
	 * Second entry : stream-extension entry
	 * Third entry  : first file-name entry
	 * So, the index of first file-name dentry should start from 2.
	 */
	for (i = 2; i < es->num_entries; i++) {
		struct exfat_dentry *ep = exfat_get_dentry_cached(es, i);

		/* end of name entry */
		if (exfat_get_entry_type(ep) != TYPE_EXTEND)
			break;

		exfat_extract_uni_name(ep, uniname);
		uniname += EXFAT_FILE_NAME_LEN;
	}

	exfat_free_dentry_set(es, false);
}

/* read a directory entry from the opened directory */
static int exfat_readdir(struct inode *inode, loff_t *cpos, struct exfat_dir_entry *dir_entry)
{
	int i, dentries_per_clu, dentries_per_clu_bits = 0, num_ext;
	unsigned int type, clu_offset, max_dentries;
	sector_t sector;
	struct exfat_chain dir, clu;
	struct exfat_uni_name uni_name;
	struct exfat_dentry *ep;
	struct super_block *sb = inode->i_sb;
	struct exfat_sb_info *sbi = EXFAT_SB(sb);
	struct exfat_inode_info *ei = EXFAT_I(inode);
	unsigned int dentry = EXFAT_B_TO_DEN(*cpos) & 0xFFFFFFFF;
	struct buffer_head *bh;

	/* check if the given file ID is opened */
	if (ei->type != TYPE_DIR)
		return -EPERM;

	if (ei->entry == -1)
		exfat_chain_set(&dir, sbi->root_dir, 0, ALLOC_FAT_CHAIN);
	else
		exfat_chain_set(&dir, ei->start_clu,
			EXFAT_B_TO_CLU(i_size_read(inode), sbi), ei->flags);

	dentries_per_clu = sbi->dentries_per_clu;
	dentries_per_clu_bits = ilog2(dentries_per_clu);
	max_dentries = (unsigned int)min_t(u64, MAX_EXFAT_DENTRIES,
					   (u64)sbi->num_clusters << dentries_per_clu_bits);

	clu_offset = dentry >> dentries_per_clu_bits;
	exfat_chain_dup(&clu, &dir);

	if (clu.flags == ALLOC_NO_FAT_CHAIN) {
		clu.dir += clu_offset;
		clu.size -= clu_offset;
	} else {
		/* hint_information */
		if (clu_offset > 0 && ei->hint_bmap.off != EXFAT_EOF_CLUSTER &&
		    ei->hint_bmap.off > 0 && clu_offset >= ei->hint_bmap.off) {
			clu_offset -= ei->hint_bmap.off;
			clu.dir = ei->hint_bmap.clu;
		}

		while (clu_offset > 0) {
			if (exfat_get_next_cluster(sb, &(clu.dir)))
				return -EIO;

			clu_offset--;
		}
	}

	while (clu.dir