1 // SPDX-License-Identifier: GPL-2.0-only
6 * Symlink handling routines for the OSTA-UDF(tm) filesystem.
9 * (C) 1998-2001 Ben Fennema
10 * (C) 1999 Stelias Computing Inc
14 * 04/16/99 blf Created.
19 #include <linux/uaccess.h>
20 #include <linux/errno.h>
22 #include <linux/time.h>
24 #include <linux/stat.h>
25 #include <linux/pagemap.h>
28 static int udf_pc_to_char(struct super_block *sb, unsigned char *from,
29 int fromlen, unsigned char *to, int tolen)
31 struct pathComponent *pc;
34 unsigned char *p = to;
36 /* Reserve one byte for terminating \0 */
38 while (elen < fromlen) {
39 pc = (struct pathComponent *)(from + elen);
40 elen += sizeof(struct pathComponent);
41 switch (pc->componentType) {
44 * Symlink points to some place which should be agreed
45 * upon between originator and receiver of the media. Ignore.
47 if (pc->lengthComponentIdent > 0) {
48 elen += pc->lengthComponentIdent;
72 /* that would be . - just ignore */
75 elen += pc->lengthComponentIdent;
78 comp_len = udf_get_filename(sb, pc->componentIdent,
79 pc->lengthComponentIdent,
100 static int udf_symlink_filler(struct file *file, struct folio *folio)
102 struct page *page = &folio->page;
103 struct inode *inode = page->mapping->host;
104 struct buffer_head *bh = NULL;
105 unsigned char *symlink;
107 unsigned char *p = page_address(page);
108 struct udf_inode_info *iinfo = UDF_I(inode);
110 /* We don't support symlinks longer than one block */
111 if (inode->i_size > inode->i_sb->s_blocksize) {
116 if (iinfo->i_alloc_type == ICBTAG_FLAG_AD_IN_ICB) {
117 symlink = iinfo->i_data + iinfo->i_lenEAttr;
119 bh = udf_bread(inode, 0, 0, &err);
125 symlink = bh->b_data;
128 err = udf_pc_to_char(inode->i_sb, symlink, inode->i_size, p, PAGE_SIZE);
133 SetPageUptodate(page);
144 static int udf_symlink_getattr(struct mnt_idmap *idmap,
145 const struct path *path, struct kstat *stat,
146 u32 request_mask, unsigned int flags)
148 struct dentry *dentry = path->dentry;
149 struct inode *inode = d_backing_inode(dentry);
152 generic_fillattr(&nop_mnt_idmap, request_mask, inode, stat);
153 page = read_mapping_page(inode->i_mapping, 0, NULL);
155 return PTR_ERR(page);
157 * UDF uses non-trivial encoding of symlinks so i_size does not match
158 * number of characters reported by readlink(2) which apparently some
159 * applications expect. Also POSIX says that "The value returned in the
160 * st_size field shall be the length of the contents of the symbolic
161 * link, and shall not count a trailing null if one is present." So
162 * let's report the length of string returned by readlink(2) for
165 stat->size = strlen(page_address(page));
172 * symlinks can't do much...
174 const struct address_space_operations udf_symlink_aops = {
175 .read_folio = udf_symlink_filler,
178 const struct inode_operations udf_symlink_inode_operations = {
179 .get_link = page_get_link,
180 .getattr = udf_symlink_getattr,