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// SPDX-License-Identifier: GPL-2.0
/*
* linux/drivers/staging/erofs/dir.c
*
* Copyright (C) 2017-2018 HUAWEI, Inc.
* http://www.huawei.com/
* Created by Gao Xiang <gaoxiang25@huawei.com>
*
* This file is subject to the terms and conditions of the GNU General Public
* License. See the file COPYING in the main directory of the Linux
* distribution for more details.
*/
#include "internal.h"
static const unsigned char erofs_filetype_table[EROFS_FT_MAX] = {
[EROFS_FT_UNKNOWN] = DT_UNKNOWN,
[EROFS_FT_REG_FILE] = DT_REG,
[EROFS_FT_DIR] = DT_DIR,
[EROFS_FT_CHRDEV] = DT_CHR,
[EROFS_FT_BLKDEV] = DT_BLK,
[EROFS_FT_FIFO] = DT_FIFO,
[EROFS_FT_SOCK] = DT_SOCK,
[EROFS_FT_SYMLINK] = DT_LNK,
};
static int erofs_fill_dentries(struct dir_context *ctx,
void *dentry_blk, unsigned *ofs,
unsigned nameoff, unsigned maxsize)
{
struct erofs_dirent *de = dentry_blk;
const struct erofs_dirent *end = dentry_blk + nameoff;
de = dentry_blk + *ofs;
while (de < end) {
const char *de_name;
int de_namelen;
unsigned char d_type;
#ifdef CONFIG_EROFS_FS_DEBUG
unsigned dbg_namelen;
unsigned char dbg_namebuf[EROFS_NAME_LEN];
#endif
if (unlikely(de->file_type < EROFS_FT_MAX))
d_type = erofs_filetype_table[de->file_type];
else
d_type = DT_UNKNOWN;
nameoff = le16_to_cpu(de->nameoff);
de_name = (char *)dentry_blk + nameoff;
de_namelen = unlikely(de + 1 >= end) ?
/* last directory entry */
strnlen(de_name, maxsize - nameoff) :
le16_to_cpu(de[1].nameoff) - nameoff;
/* the corrupted directory found */
BUG_ON(de_namelen < 0);
#ifdef CONFIG_EROFS_FS_DEBUG
dbg_namelen = min(EROFS_NAME_LEN - 1, de_namelen);
memcpy(dbg_namebuf, de_name, dbg_namelen);
dbg_namebuf[dbg_namelen] = '\0';
debugln("%s, found de_name %s de_len %d d_type %d", __func__,
dbg_namebuf, de_namelen, d_type);
#endif
if (!dir_emit(ctx, de_name, de_namelen,
le64_to_cpu(de->nid), d_type))
/* stoped by some reason */
return 1;
++de;
*ofs += sizeof(struct erofs_dirent);
}
*ofs = maxsize;
return 0;
}
static int erofs_readdir(struct file *f, struct dir_context *ctx)
{
struct inode *dir = file_inode(f);
struct address_space *mapping = dir->i_mapping;
const size_t dirsize = i_size_read(dir);
unsigned i = ctx->pos / EROFS_BLKSIZ;
unsigned ofs = ctx->pos % EROFS_BLKSIZ;
int err = 0;
bool initial = true;
while (ctx->pos < dirsize) {
struct page *dentry_page;
struct erofs_dirent *de;
unsigned nameoff, maxsize;
dentry_page = read_mapping_page(mapping, i, NULL);
if (IS_ERR(dentry_page))
continue;
lock_page(dentry_page);
de = (struct erofs_dirent *)kmap(dentry_page);
nameoff = le16_to_cpu(de->nameoff);
if (unlikely(nameoff < sizeof(struct erofs_dirent) ||
nameoff >= PAGE_SIZE)) {
errln("%s, invalid de[0].nameoff %u",
__func__, nameoff);
err = -EIO;
goto skip_this;
}
maxsize = min_t(unsigned, dirsize - ctx->pos + ofs, PAGE_SIZE);
/* search dirents at the arbitrary position */
if (unlikely(initial)) {
initial = false;
ofs = roundup(ofs, sizeof(struct erofs_dirent));
if (unlikely(ofs >= nameoff))
goto skip_this;
}
err = erofs_fill_dentries(ctx, de, &ofs, nameoff, maxsize);
skip_this:
kunmap(dentry_page);
unlock_page(dentry_page);
put_page(dentry_page);
ctx->pos = blknr_to_addr(i) + ofs;
if (unlikely(err))
break;
++i;
ofs = 0;
}
return err < 0 ? err : 0;
}
const struct file_operations erofs_dir_fops = {
.llseek = generic_file_llseek,
.read = generic_read_dir,
.iterate = erofs_readdir,
};
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