1/*
2 * symlink.c
3 *
4 * PURPOSE
5 *	Symlink handling routines for the OSTA-UDF(tm) filesystem.
6 *
7 * COPYRIGHT
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.
12 *
13 *  (C) 1998-2001 Ben Fennema
14 *  (C) 1999 Stelias Computing Inc
15 *
16 * HISTORY
17 *
18 *  04/16/99 blf  Created.
19 *
20 */
21
22#include "udfdecl.h"
23#include <linux/uaccess.h>
24#include <linux/errno.h>
25#include <linux/fs.h>
26#include <linux/time.h>
27#include <linux/mm.h>
28#include <linux/stat.h>
29#include <linux/pagemap.h>
30#include "udf_i.h"
31
32static int udf_pc_to_char(struct super_block *sb, unsigned char *from,
33			  int fromlen, unsigned char *to, int tolen)
34{
35	struct pathComponent *pc;
36	int elen = 0;
37	int comp_len;
38	unsigned char *p = to;
39
40	/* Reserve one byte for terminating \0 */
41	tolen--;
42	while (elen < fromlen) {
43		pc = (struct pathComponent *)(from + elen);
44		elen += sizeof(struct pathComponent);
45		switch (pc->componentType) {
46		case 1:
47			/*
48			 * Symlink points to some place which should be agreed
49 			 * upon between originator and receiver of the media. Ignore.
50			 */
51			if (pc->lengthComponentIdent > 0) {
52				elen += pc->lengthComponentIdent;
53				break;
54			}
55			/* Fall through */
56		case 2:
57			if (tolen == 0)
58				return -ENAMETOOLONG;
59			p = to;
60			*p++ = '/';
61			tolen--;
62			break;
63		case 3:
64			if (tolen < 3)
65				return -ENAMETOOLONG;
66			memcpy(p, "../", 3);
67			p += 3;
68			tolen -= 3;
69			break;
70		case 4:
71			if (tolen < 2)
72				return -ENAMETOOLONG;
73			memcpy(p, "./", 2);
74			p += 2;
75			tolen -= 2;
76			/* that would be . - just ignore */
77			break;
78		case 5:
79			elen += pc->lengthComponentIdent;
80			if (elen > fromlen)
81				return -EIO;
82			comp_len = udf_get_filename(sb, pc->componentIdent,
83						    pc->lengthComponentIdent,
84						    p, tolen);
85			p += comp_len;
86			tolen -= comp_len;
87			if (tolen == 0)
88				return -ENAMETOOLONG;
89			*p++ = '/';
90			tolen--;
91			break;
92		}
93	}
94	if (p > to + 1)
95		p[-1] = '\0';
96	else
97		p[0] = '\0';
98	return 0;
99}
100
101static int udf_symlink_filler(struct file *file, struct page *page)
102{
103	struct inode *inode = page->mapping->host;
104	struct buffer_head *bh = NULL;
105	unsigned char *symlink;
106	int err;
107	unsigned char *p = kmap(page);
108	struct udf_inode_info *iinfo;
109	uint32_t pos;
110
111	/* We don't support symlinks longer than one block */
112	if (inode->i_size > inode->i_sb->s_blocksize) {
113		err = -ENAMETOOLONG;
114		goto out_unmap;
115	}
116
117	iinfo = UDF_I(inode);
118	pos = udf_block_map(inode, 0);
119
120	down_read(&iinfo->i_data_sem);
121	if (iinfo->i_alloc_type == ICBTAG_FLAG_AD_IN_ICB) {
122		symlink = iinfo->i_ext.i_data + iinfo->i_lenEAttr;
123	} else {
124		bh = sb_bread(inode->i_sb, pos);
125
126		if (!bh) {
127			err = -EIO;
128			goto out_unlock_inode;
129		}
130
131		symlink = bh->b_data;
132	}
133
134	err = udf_pc_to_char(inode->i_sb, symlink, inode->i_size, p, PAGE_SIZE);
135	brelse(bh);
136	if (err)
137		goto out_unlock_inode;
138
139	up_read(&iinfo->i_data_sem);
140	SetPageUptodate(page);
141	kunmap(page);
142	unlock_page(page);
143	return 0;
144
145out_unlock_inode:
146	up_read(&iinfo->i_data_sem);
147	SetPageError(page);
148out_unmap:
149	kunmap(page);
150	unlock_page(page);
151	return err;
152}
153
154/*
155 * symlinks can't do much...
156 */
157const struct address_space_operations udf_symlink_aops = {
158	.readpage		= udf_symlink_filler,
159};
160