| xj | b04a402 | 2021-11-25 15:01:52 +0800 | [diff] [blame] | 1 | // SPDX-License-Identifier: GPL-2.0 |
| 2 | /* |
| 3 | * dir.c |
| 4 | * |
| 5 | * Copyright (c) 1999 Al Smith |
| 6 | */ |
| 7 | |
| 8 | #include <linux/buffer_head.h> |
| 9 | #include "efs.h" |
| 10 | |
| 11 | static int efs_readdir(struct file *, struct dir_context *); |
| 12 | |
| 13 | const struct file_operations efs_dir_operations = { |
| 14 | .llseek = generic_file_llseek, |
| 15 | .read = generic_read_dir, |
| 16 | .iterate_shared = efs_readdir, |
| 17 | }; |
| 18 | |
| 19 | const struct inode_operations efs_dir_inode_operations = { |
| 20 | .lookup = efs_lookup, |
| 21 | }; |
| 22 | |
| 23 | static int efs_readdir(struct file *file, struct dir_context *ctx) |
| 24 | { |
| 25 | struct inode *inode = file_inode(file); |
| 26 | efs_block_t block; |
| 27 | int slot; |
| 28 | |
| 29 | if (inode->i_size & (EFS_DIRBSIZE-1)) |
| 30 | pr_warn("%s(): directory size not a multiple of EFS_DIRBSIZE\n", |
| 31 | __func__); |
| 32 | |
| 33 | /* work out where this entry can be found */ |
| 34 | block = ctx->pos >> EFS_DIRBSIZE_BITS; |
| 35 | |
| 36 | /* each block contains at most 256 slots */ |
| 37 | slot = ctx->pos & 0xff; |
| 38 | |
| 39 | /* look at all blocks */ |
| 40 | while (block < inode->i_blocks) { |
| 41 | struct efs_dir *dirblock; |
| 42 | struct buffer_head *bh; |
| 43 | |
| 44 | /* read the dir block */ |
| 45 | bh = sb_bread(inode->i_sb, efs_bmap(inode, block)); |
| 46 | |
| 47 | if (!bh) { |
| 48 | pr_err("%s(): failed to read dir block %d\n", |
| 49 | __func__, block); |
| 50 | break; |
| 51 | } |
| 52 | |
| 53 | dirblock = (struct efs_dir *) bh->b_data; |
| 54 | |
| 55 | if (be16_to_cpu(dirblock->magic) != EFS_DIRBLK_MAGIC) { |
| 56 | pr_err("%s(): invalid directory block\n", __func__); |
| 57 | brelse(bh); |
| 58 | break; |
| 59 | } |
| 60 | |
| 61 | for (; slot < dirblock->slots; slot++) { |
| 62 | struct efs_dentry *dirslot; |
| 63 | efs_ino_t inodenum; |
| 64 | const char *nameptr; |
| 65 | int namelen; |
| 66 | |
| 67 | if (dirblock->space[slot] == 0) |
| 68 | continue; |
| 69 | |
| 70 | dirslot = (struct efs_dentry *) (((char *) bh->b_data) + EFS_SLOTAT(dirblock, slot)); |
| 71 | |
| 72 | inodenum = be32_to_cpu(dirslot->inode); |
| 73 | namelen = dirslot->namelen; |
| 74 | nameptr = dirslot->name; |
| 75 | pr_debug("%s(): block %d slot %d/%d: inode %u, name \"%s\", namelen %u\n", |
| 76 | __func__, block, slot, dirblock->slots-1, |
| 77 | inodenum, nameptr, namelen); |
| 78 | if (!namelen) |
| 79 | continue; |
| 80 | /* found the next entry */ |
| 81 | ctx->pos = (block << EFS_DIRBSIZE_BITS) | slot; |
| 82 | |
| 83 | /* sanity check */ |
| 84 | if (nameptr - (char *) dirblock + namelen > EFS_DIRBSIZE) { |
| 85 | pr_warn("directory entry %d exceeds directory block\n", |
| 86 | slot); |
| 87 | continue; |
| 88 | } |
| 89 | |
| 90 | /* copy filename and data in dirslot */ |
| 91 | if (!dir_emit(ctx, nameptr, namelen, inodenum, DT_UNKNOWN)) { |
| 92 | brelse(bh); |
| 93 | return 0; |
| 94 | } |
| 95 | } |
| 96 | brelse(bh); |
| 97 | |
| 98 | slot = 0; |
| 99 | block++; |
| 100 | } |
| 101 | ctx->pos = (block << EFS_DIRBSIZE_BITS) | slot; |
| 102 | return 0; |
| 103 | } |