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 void debug_one_dentry(unsigned char d_type, const char *de_name, 10 unsigned int de_namelen) 11 { 12 #ifdef CONFIG_EROFS_FS_DEBUG 13 /* since the on-disk name could not have the trailing '\0' */ 14 unsigned char dbg_namebuf[EROFS_NAME_LEN + 1]; 15 16 memcpy(dbg_namebuf, de_name, de_namelen); 17 dbg_namebuf[de_namelen] = '\0'; 18 19 erofs_dbg("found dirent %s de_len %u d_type %d", dbg_namebuf, 20 de_namelen, d_type); 21 #endif 22 } 23 24 static int erofs_fill_dentries(struct inode *dir, struct dir_context *ctx, 25 void *dentry_blk, struct erofs_dirent *de, 26 unsigned int nameoff, unsigned int maxsize) 27 { 28 const struct erofs_dirent *end = dentry_blk + nameoff; 29 30 while (de < end) { 31 const char *de_name; 32 unsigned int de_namelen; 33 unsigned char d_type; 34 35 d_type = fs_ftype_to_dtype(de->file_type); 36 37 nameoff = le16_to_cpu(de->nameoff); 38 de_name = (char *)dentry_blk + nameoff; 39 40 /* the last dirent in the block? */ 41 if (de + 1 >= end) 42 de_namelen = strnlen(de_name, maxsize - nameoff); 43 else 44 de_namelen = le16_to_cpu(de[1].nameoff) - nameoff; 45 46 /* a corrupted entry is found */ 47 if (nameoff + de_namelen > maxsize || 48 de_namelen > EROFS_NAME_LEN) { 49 erofs_err(dir->i_sb, "bogus dirent @ nid %llu", 50 EROFS_I(dir)->nid); 51 DBG_BUGON(1); 52 return -EFSCORRUPTED; 53 } 54 55 debug_one_dentry(d_type, de_name, de_namelen); 56 if (!dir_emit(ctx, de_name, de_namelen, 57 le64_to_cpu(de->nid), d_type)) 58 /* stopped by some reason */ 59 return 1; 60 ++de; 61 ctx->pos += sizeof(struct erofs_dirent); 62 } 63 return 0; 64 } 65 66 static int erofs_readdir(struct file *f, struct dir_context *ctx) 67 { 68 struct inode *dir = file_inode(f); 69 struct erofs_buf buf = __EROFS_BUF_INITIALIZER; 70 const size_t dirsize = i_size_read(dir); 71 unsigned int i = ctx->pos / EROFS_BLKSIZ; 72 unsigned int ofs = ctx->pos % EROFS_BLKSIZ; 73 int err = 0; 74 bool initial = true; 75 76 while (ctx->pos < dirsize) { 77 struct erofs_dirent *de; 78 unsigned int nameoff, maxsize; 79 80 de = erofs_bread(&buf, dir, i, EROFS_KMAP); 81 if (IS_ERR(de)) { 82 erofs_err(dir->i_sb, 83 "fail to readdir of logical block %u of nid %llu", 84 i, EROFS_I(dir)->nid); 85 err = PTR_ERR(de); 86 break; 87 } 88 89 nameoff = le16_to_cpu(de->nameoff); 90 if (nameoff < sizeof(struct erofs_dirent) || 91 nameoff >= EROFS_BLKSIZ) { 92 erofs_err(dir->i_sb, 93 "invalid de[0].nameoff %u @ nid %llu", 94 nameoff, EROFS_I(dir)->nid); 95 err = -EFSCORRUPTED; 96 break; 97 } 98 99 maxsize = min_t(unsigned int, 100 dirsize - ctx->pos + ofs, EROFS_BLKSIZ); 101 102 /* search dirents at the arbitrary position */ 103 if (initial) { 104 initial = false; 105 106 ofs = roundup(ofs, sizeof(struct erofs_dirent)); 107 ctx->pos = blknr_to_addr(i) + ofs; 108 if (ofs >= nameoff) 109 goto skip_this; 110 } 111 112 err = erofs_fill_dentries(dir, ctx, de, (void *)de + ofs, 113 nameoff, maxsize); 114 if (err) 115 break; 116 skip_this: 117 ctx->pos = blknr_to_addr(i) + maxsize; 118 ++i; 119 ofs = 0; 120 } 121 erofs_put_metabuf(&buf); 122 return err < 0 ? err : 0; 123 } 124 125 const struct file_operations erofs_dir_fops = { 126 .llseek = generic_file_llseek, 127 .read = generic_read_dir, 128 .iterate_shared = erofs_readdir, 129 }; 130