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