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1// SPDX-License-Identifier: GPL-2.0-only2/*3 * Copyright (C) 2017-2018 HUAWEI, Inc.4 * https://www.huawei.com/5 * Copyright (C) 2022, Alibaba Cloud6 */7#include "internal.h"8 9static int erofs_fill_dentries(struct inode *dir, struct dir_context *ctx,10 void *dentry_blk, struct erofs_dirent *de,11 unsigned int nameoff0, unsigned int maxsize)12{13 const struct erofs_dirent *end = dentry_blk + nameoff0;14 15 while (de < end) {16 unsigned char d_type = fs_ftype_to_dtype(de->file_type);17 unsigned int nameoff = le16_to_cpu(de->nameoff);18 const char *de_name = (char *)dentry_blk + nameoff;19 unsigned int de_namelen;20 21 /* the last dirent in the block? */22 if (de + 1 >= end)23 de_namelen = strnlen(de_name, maxsize - nameoff);24 else25 de_namelen = le16_to_cpu(de[1].nameoff) - nameoff;26 27 /* a corrupted entry is found */28 if (nameoff + de_namelen > maxsize ||29 de_namelen > EROFS_NAME_LEN) {30 erofs_err(dir->i_sb, "bogus dirent @ nid %llu",31 EROFS_I(dir)->nid);32 DBG_BUGON(1);33 return -EFSCORRUPTED;34 }35 36 if (!dir_emit(ctx, de_name, de_namelen,37 le64_to_cpu(de->nid), d_type))38 return 1;39 ++de;40 ctx->pos += sizeof(struct erofs_dirent);41 }42 return 0;43}44 45static int erofs_readdir(struct file *f, struct dir_context *ctx)46{47 struct inode *dir = file_inode(f);48 struct erofs_buf buf = __EROFS_BUF_INITIALIZER;49 struct super_block *sb = dir->i_sb;50 unsigned long bsz = sb->s_blocksize;51 unsigned int ofs = erofs_blkoff(sb, ctx->pos);52 int err = 0;53 bool initial = true;54 55 buf.mapping = dir->i_mapping;56 while (ctx->pos < dir->i_size) {57 erofs_off_t dbstart = ctx->pos - ofs;58 struct erofs_dirent *de;59 unsigned int nameoff, maxsize;60 61 de = erofs_bread(&buf, dbstart, EROFS_KMAP);62 if (IS_ERR(de)) {63 erofs_err(sb, "fail to readdir of logical block %u of nid %llu",64 erofs_blknr(sb, dbstart), EROFS_I(dir)->nid);65 err = PTR_ERR(de);66 break;67 }68 69 nameoff = le16_to_cpu(de->nameoff);70 if (nameoff < sizeof(struct erofs_dirent) || nameoff >= bsz) {71 erofs_err(sb, "invalid de[0].nameoff %u @ nid %llu",72 nameoff, EROFS_I(dir)->nid);73 err = -EFSCORRUPTED;74 break;75 }76 77 maxsize = min_t(unsigned int, dir->i_size - dbstart, bsz);78 /* search dirents at the arbitrary position */79 if (initial) {80 initial = false;81 ofs = roundup(ofs, sizeof(struct erofs_dirent));82 ctx->pos = dbstart + ofs;83 }84 85 err = erofs_fill_dentries(dir, ctx, de, (void *)de + ofs,86 nameoff, maxsize);87 if (err)88 break;89 ctx->pos = dbstart + maxsize;90 ofs = 0;91 }92 erofs_put_metabuf(&buf);93 return err < 0 ? err : 0;94}95 96const struct file_operations erofs_dir_fops = {97 .llseek = generic_file_llseek,98 .read = generic_read_dir,99 .iterate_shared = erofs_readdir,100};101