5 * Symlink handling routines for the OSTA-UDF(tm) filesystem.
8 * This file is distributed under the terms of the GNU General Public
9 * License (GPL). Copies of the GPL can be obtained from:
10 * ftp://prep.ai.mit.edu/pub/gnu/GPL
11 * Each contributing author retains all rights to their own work.
13 * (C) 1998-2001 Ben Fennema
14 * (C) 1999 Stelias Computing Inc
18 * 04/16/99 blf Created.
23 #include <linux/uaccess.h>
24 #include <linux/errno.h>
26 #include <linux/time.h>
28 #include <linux/stat.h>
29 #include <linux/pagemap.h>
32 static int udf_pc_to_char(struct super_block *sb, unsigned char *from,
33 int fromlen, unsigned char *to, int tolen)
35 struct pathComponent *pc;
38 unsigned char *p = to;
40 /* Reserve one byte for terminating \0 */
42 while (elen < fromlen) {
43 pc = (struct pathComponent *)(from + elen);
44 elen += sizeof(struct pathComponent);
45 switch (pc->componentType) {
48 * Symlink points to some place which should be agreed
49 * upon between originator and receiver of the media. Ignore.
51 if (pc->lengthComponentIdent > 0) {
52 elen += pc->lengthComponentIdent;
76 /* that would be . - just ignore */
79 elen += pc->lengthComponentIdent;
82 comp_len = udf_get_filename(sb, pc->componentIdent,
83 pc->lengthComponentIdent,
104 static int udf_symlink_filler(struct file *file, struct folio *folio)
106 struct page *page = &folio->page;
107 struct inode *inode = page->mapping->host;
108 struct buffer_head *bh = NULL;
109 unsigned char *symlink;
111 unsigned char *p = page_address(page);
112 struct udf_inode_info *iinfo;
115 /* We don't support symlinks longer than one block */
116 if (inode->i_size > inode->i_sb->s_blocksize) {
121 iinfo = UDF_I(inode);
122 pos = udf_block_map(inode, 0);
124 down_read(&iinfo->i_data_sem);
125 if (iinfo->i_alloc_type == ICBTAG_FLAG_AD_IN_ICB) {
126 symlink = iinfo->i_data + iinfo->i_lenEAttr;
128 bh = sb_bread(inode->i_sb, pos);
132 goto out_unlock_inode;
135 symlink = bh->b_data;
138 err = udf_pc_to_char(inode->i_sb, symlink, inode->i_size, p, PAGE_SIZE);
141 goto out_unlock_inode;
143 up_read(&iinfo->i_data_sem);
144 SetPageUptodate(page);
149 up_read(&iinfo->i_data_sem);
156 static int udf_symlink_getattr(struct user_namespace *mnt_userns,
157 const struct path *path, struct kstat *stat,
158 u32 request_mask, unsigned int flags)
160 struct dentry *dentry = path->dentry;
161 struct inode *inode = d_backing_inode(dentry);
164 generic_fillattr(&init_user_ns, inode, stat);
165 page = read_mapping_page(inode->i_mapping, 0, NULL);
167 return PTR_ERR(page);
169 * UDF uses non-trivial encoding of symlinks so i_size does not match
170 * number of characters reported by readlink(2) which apparently some
171 * applications expect. Also POSIX says that "The value returned in the
172 * st_size field shall be the length of the contents of the symbolic
173 * link, and shall not count a trailing null if one is present." So
174 * let's report the length of string returned by readlink(2) for
177 stat->size = strlen(page_address(page));
184 * symlinks can't do much...
186 const struct address_space_operations udf_symlink_aops = {
187 .read_folio = udf_symlink_filler,
190 const struct inode_operations udf_symlink_inode_operations = {
191 .get_link = page_get_link,
192 .getattr = udf_symlink_getattr,