1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Copyright (C) 2017-2018 HUAWEI, Inc. 4 * https://www.huawei.com/ 5 * Copyright (C) 2022, Alibaba Cloud 6 */ 7 #include "internal.h" 8 9 static 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 else 25 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 45 static 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 96 const struct file_operations erofs_dir_fops = { 97 .llseek = generic_file_llseek, 98 .read = generic_read_dir, 99 .iterate_shared = erofs_readdir, 100 }; 101