xref: /openbmc/linux/fs/udf/symlink.c (revision e868d61272caa648214046a096e5a6bfc068dc8c)
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 <asm/uaccess.h>
24 #include <linux/errno.h>
25 #include <linux/fs.h>
26 #include <linux/udf_fs.h>
27 #include <linux/time.h>
28 #include <linux/mm.h>
29 #include <linux/stat.h>
30 #include <linux/slab.h>
31 #include <linux/pagemap.h>
32 #include <linux/smp_lock.h>
33 #include <linux/buffer_head.h>
34 #include "udf_i.h"
35 
36 static void udf_pc_to_char(struct super_block *sb, char *from, int fromlen, char *to)
37 {
38 	struct pathComponent *pc;
39 	int elen = 0;
40 	char *p = to;
41 
42 	while (elen < fromlen)
43 	{
44 		pc = (struct pathComponent *)(from + elen);
45 		switch (pc->componentType)
46 		{
47 			case 1:
48 				if (pc->lengthComponentIdent == 0)
49 				{
50 					p = to;
51 					*p++ = '/';
52 				}
53 				break;
54 			case 3:
55 				memcpy(p, "../", 3);
56 				p += 3;
57 				break;
58 			case 4:
59 				memcpy(p, "./", 2);
60 				p += 2;
61 				/* that would be . - just ignore */
62 				break;
63 			case 5:
64 				p += udf_get_filename(sb, pc->componentIdent, p, pc->lengthComponentIdent);
65 				*p++ = '/';
66 				break;
67 		}
68 		elen += sizeof(struct pathComponent) + pc->lengthComponentIdent;
69 	}
70 	if (p > to+1)
71 		p[-1] = '\0';
72 	else
73 		p[0] = '\0';
74 }
75 
76 static int udf_symlink_filler(struct file *file, struct page *page)
77 {
78 	struct inode *inode = page->mapping->host;
79 	struct buffer_head *bh = NULL;
80 	char *symlink;
81 	int err = -EIO;
82 	char *p = kmap(page);
83 
84 	lock_kernel();
85 	if (UDF_I_ALLOCTYPE(inode) == ICBTAG_FLAG_AD_IN_ICB)
86 		symlink = UDF_I_DATA(inode) + UDF_I_LENEATTR(inode);
87 	else
88 	{
89 		bh = sb_bread(inode->i_sb, udf_block_map(inode, 0));
90 
91 		if (!bh)
92 			goto out;
93 
94 		symlink = bh->b_data;
95 	}
96 
97 	udf_pc_to_char(inode->i_sb, symlink, inode->i_size, p);
98 	brelse(bh);
99 
100 	unlock_kernel();
101 	SetPageUptodate(page);
102 	kunmap(page);
103 	unlock_page(page);
104 	return 0;
105 out:
106 	unlock_kernel();
107 	SetPageError(page);
108 	kunmap(page);
109 	unlock_page(page);
110 	return err;
111 }
112 
113 /*
114  * symlinks can't do much...
115  */
116 const struct address_space_operations udf_symlink_aops = {
117 	.readpage		= udf_symlink_filler,
118 };
119