| // 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, |
| }; |
| |