1 // SPDX-License-Identifier: GPL-2.0-or-later
3  * Squashfs - a compressed read only filesystem for Linux
16  * the metablock containing the directory and the offset into the
17  * decompressed block (<block, offset>).
22  * compressed metadata block, and therefore, can share the start block.
24  * header containing the shared start block value, and a sequence of directory
25  * entries, each of which share the shared start block.  A new directory header
26  * is written once/if the inode start block changes.  The directory
32  * in each metadata block.  Directories are sorted in alphabetical order,
35  * location of the metadata block the filename is in has been found.
36  * The general idea of the index is ensure only one metadata block needs to be
57  * block containing it, and the directory index this represents.
60  * (if any) we have managed to read - the index isn't essential, just
67 	struct squashfs_sb_info *msblk = sb->s_fs_info;  in get_dir_index_using_name()
87 		size = le32_to_cpu(index->size) + 1;  in get_dir_index_using_name()
91 		err = squashfs_read_metadata(sb, index->name, &index_start,  in get_dir_index_using_name()
96 		index->name[size] = '\0';  in get_dir_index_using_name()
98 		if (strcmp(index->name, name) > 0)  in get_dir_index_using_name()
101 		length = le32_to_cpu(index->index);  in get_dir_index_using_name()
102 		*next_block = le32_to_cpu(index->start_block) +  in get_dir_index_using_name()
103 					msblk->directory_table;  in get_dir_index_using_name()
111 	 * Return index (f_pos) of the looked up metadata block.  Translate  in get_dir_index_using_name()
112 	 * from internal f_pos to external f_pos which is offset by 3 because  in get_dir_index_using_name()
123 	const unsigned char *name = dentry->d_name.name;  in squashfs_lookup()
124 	int len = dentry->d_name.len;  in squashfs_lookup()
126 	struct squashfs_sb_info *msblk = dir->i_sb->s_fs_info;  in squashfs_lookup()
129 	u64 block = squashfs_i(dir)->start + msblk->directory_table;  in squashfs_lookup()  local
130 	int offset = squashfs_i(dir)->offset;  in squashfs_lookup()  local
134 	TRACE("Entered squashfs_lookup [%llx:%x]\n", block, offset);  in squashfs_lookup()
139 		return ERR_PTR(-ENOMEM);  in squashfs_lookup()
143 		err = -ENAMETOOLONG;  in squashfs_lookup()
147 	length = get_dir_index_using_name(dir->i_sb, &block, &offset,  in squashfs_lookup()
148 				squashfs_i(dir)->dir_idx_start,  in squashfs_lookup()
149 				squashfs_i(dir)->dir_idx_offset,  in squashfs_lookup()
150 				squashfs_i(dir)->dir_idx_cnt, name);  in squashfs_lookup()
156 		err = squashfs_read_metadata(dir->i_sb, &dirh, &block,  in squashfs_lookup()
157 				&offset, sizeof(dirh));  in squashfs_lookup()
168 		while (dir_count--) {  in squashfs_lookup()
172 			err = squashfs_read_metadata(dir->i_sb, dire, &block,  in squashfs_lookup()
173 					&offset, sizeof(*dire));  in squashfs_lookup()
177 			size = le16_to_cpu(dire->size) + 1;  in squashfs_lookup()
183 			err = squashfs_read_metadata(dir->i_sb, dire->name,  in squashfs_lookup()
184 					&block, &offset, size);  in squashfs_lookup()
190 			if (name[0] < dire->name[0])  in squashfs_lookup()
193 			if (len == size && !strncmp(name, dire->name, len)) {  in squashfs_lookup()
197 				off = le16_to_cpu(dire->offset);  in squashfs_lookup()
199 					(short) le16_to_cpu(dire->inode_number);  in squashfs_lookup()
206 				inode = squashfs_iget(dir->i_sb, ino, ino_num);  in squashfs_lookup()
217 	err = -EIO;  in squashfs_lookup()
220 	ERROR("Unable to read directory block [%llx:%x]\n",  in squashfs_lookup()
221 		squashfs_i(dir)->start + msblk->directory_table,  in squashfs_lookup()
222 		squashfs_i(dir)->offset);  in squashfs_lookup()