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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 void debug_one_dentry(unsigned char d_type, const char *de_name,
unsigned int de_namelen)
{
#ifdef CONFIG_EROFS_FS_DEBUG
/* since the on-disk name could not have the trailing '\0' */
unsigned char dbg_namebuf[EROFS_NAME_LEN + 1];
memcpy(dbg_namebuf, de_name, de_namelen);
dbg_namebuf[de_namelen] = '\0';
debugln("found dirent %s de_len %u d_type %d", dbg_namebuf,
de_namelen, d_type);
#endif
}
static int erofs_fill_dentries(struct dir_context *ctx,
void *dentry_blk, unsigned int *ofs,
unsigned int nameoff, unsigned int 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;
unsigned int de_namelen;
unsigned char d_type;
if (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;
/* the last dirent in the block? */
if (de + 1 >= end)
de_namelen = strnlen(de_name, maxsize - nameoff);
else
de_namelen = le16_to_cpu(de[1].nameoff) - nameoff;
/* a corrupted entry is found */
if (unlikely(nameoff + de_namelen > maxsize ||
de_namelen > EROFS_NAME_LEN)) {
DBG_BUGON(1);
return -EIO;
}
debug_one_dentry(d_type, de_name, de_namelen);
if (!dir_emit(ctx, de_name, de_namelen,
le64_to_cpu(de->nid), d_type))
/* stopped 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 int i = ctx->pos / EROFS_BLKSIZ;
unsigned int ofs = ctx->pos % EROFS_BLKSIZ;
int err = 0;
bool initial = true;
while (ctx->pos < dirsize) {
struct page *dentry_page;
struct erofs_dirent *de;
unsigned int nameoff, maxsize;
dentry_page = read_mapping_page(mapping, i, NULL);
if (IS_ERR(dentry_page))
continue;
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 int,
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);
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_shared = erofs_readdir,
};
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