1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Copyright (C) 2020 Bootlin
4  *
5  * Author: Joao Marcos Costa <joaomarcos.costa@bootlin.com>
6  */
7 
8 #include <errno.h>
9 #include <linux/types.h>
10 #include <linux/byteorder/little_endian.h>
11 #include <linux/byteorder/generic.h>
12 #include <stdint.h>
13 #include <stdio.h>
14 #include <stdlib.h>
15 
16 #include "sqfs_filesystem.h"
17 #include "sqfs_utils.h"
18 
sqfs_is_dir(u16 type)19 bool sqfs_is_dir(u16 type)
20 {
21 	return type == SQFS_DIR_TYPE || type == SQFS_LDIR_TYPE;
22 }
23 
24 /*
25  * Receives a pointer (void *) to a position in the inode table containing the
26  * directory's inode. Returns directory inode offset into the directory table.
27  * m_list contains each metadata block's position, and m_count is the number of
28  * elements of m_list. Those metadata blocks come from the compressed directory
29  * table.
30  */
sqfs_dir_offset(void * dir_i,u32 * m_list,int m_count)31 int sqfs_dir_offset(void *dir_i, u32 *m_list, int m_count)
32 {
33 	struct squashfs_base_inode *base = dir_i;
34 	struct squashfs_ldir_inode *ldir;
35 	struct squashfs_dir_inode *dir;
36 	u32 start_block;
37 	int j, offset;
38 
39 	switch (get_unaligned_le16(&base->inode_type)) {
40 	case SQFS_DIR_TYPE:
41 		dir = (struct squashfs_dir_inode *)base;
42 		start_block = get_unaligned_le32(&dir->start_block);
43 		offset = get_unaligned_le16(&dir->offset);
44 		break;
45 	case SQFS_LDIR_TYPE:
46 		ldir = (struct squashfs_ldir_inode *)base;
47 		start_block = get_unaligned_le32(&ldir->start_block);
48 		offset = get_unaligned_le16(&ldir->offset);
49 		break;
50 	default:
51 		printf("Error: this is not a directory.\n");
52 		return -EINVAL;
53 	}
54 
55 	if (offset < 0)
56 		return -EINVAL;
57 
58 	for (j = 0; j < m_count; j++) {
59 		if (m_list[j] == start_block)
60 			return (++j * SQFS_METADATA_BLOCK_SIZE) + offset;
61 	}
62 
63 	if (start_block == 0)
64 		return offset;
65 
66 	printf("Error: invalid inode reference to directory table.\n");
67 
68 	return -EINVAL;
69 }
70 
sqfs_is_empty_dir(void * dir_i)71 bool sqfs_is_empty_dir(void *dir_i)
72 {
73 	struct squashfs_base_inode *base = dir_i;
74 	struct squashfs_ldir_inode *ldir;
75 	struct squashfs_dir_inode *dir;
76 	u32 file_size;
77 
78 	switch (get_unaligned_le16(&base->inode_type)) {
79 	case SQFS_DIR_TYPE:
80 		dir = (struct squashfs_dir_inode *)base;
81 		file_size = get_unaligned_le16(&dir->file_size);
82 		break;
83 	case SQFS_LDIR_TYPE:
84 		ldir = (struct squashfs_ldir_inode *)base;
85 		file_size = get_unaligned_le16(&ldir->file_size);
86 		break;
87 	default:
88 		printf("Error: this is not a directory.\n");
89 		return false;
90 	}
91 
92 	return file_size == SQFS_EMPTY_FILE_SIZE;
93 }
94