xref: /openbmc/linux/fs/udf/symlink.c (revision d5cb9783536a41df9f9cba5b0a1d78047ed787f7)
1 /*
2  * symlink.c
3  *
4  * PURPOSE
5  *	Symlink handling routines for the OSTA-UDF(tm) filesystem.
6  *
7  * CONTACTS
8  *	E-mail regarding any portion of the Linux UDF file system should be
9  *	directed to the development team mailing list (run by majordomo):
10  *		linux_udf@hpesjro.fc.hp.com
11  *
12  * COPYRIGHT
13  *	This file is distributed under the terms of the GNU General Public
14  *	License (GPL). Copies of the GPL can be obtained from:
15  *		ftp://prep.ai.mit.edu/pub/gnu/GPL
16  *	Each contributing author retains all rights to their own work.
17  *
18  *  (C) 1998-2001 Ben Fennema
19  *  (C) 1999 Stelias Computing Inc
20  *
21  * HISTORY
22  *
23  *  04/16/99 blf  Created.
24  *
25  */
26 
27 #include "udfdecl.h"
28 #include <asm/uaccess.h>
29 #include <linux/errno.h>
30 #include <linux/fs.h>
31 #include <linux/udf_fs.h>
32 #include <linux/time.h>
33 #include <linux/mm.h>
34 #include <linux/stat.h>
35 #include <linux/slab.h>
36 #include <linux/pagemap.h>
37 #include <linux/smp_lock.h>
38 #include <linux/buffer_head.h>
39 #include "udf_i.h"
40 
41 static void udf_pc_to_char(struct super_block *sb, char *from, int fromlen, char *to)
42 {
43 	struct pathComponent *pc;
44 	int elen = 0;
45 	char *p = to;
46 
47 	while (elen < fromlen)
48 	{
49 		pc = (struct pathComponent *)(from + elen);
50 		switch (pc->componentType)
51 		{
52 			case 1:
53 				if (pc->lengthComponentIdent == 0)
54 				{
55 					p = to;
56 					*p++ = '/';
57 				}
58 				break;
59 			case 3:
60 				memcpy(p, "../", 3);
61 				p += 3;
62 				break;
63 			case 4:
64 				memcpy(p, "./", 2);
65 				p += 2;
66 				/* that would be . - just ignore */
67 				break;
68 			case 5:
69 				p += udf_get_filename(sb, pc->componentIdent, p, pc->lengthComponentIdent);
70 				*p++ = '/';
71 				break;
72 		}
73 		elen += sizeof(struct pathComponent) + pc->lengthComponentIdent;
74 	}
75 	if (p > to+1)
76 		p[-1] = '\0';
77 	else
78 		p[0] = '\0';
79 }
80 
81 static int udf_symlink_filler(struct file *file, struct page *page)
82 {
83 	struct inode *inode = page->mapping->host;
84 	struct buffer_head *bh = NULL;
85 	char *symlink;
86 	int err = -EIO;
87 	char *p = kmap(page);
88 
89 	lock_kernel();
90 	if (UDF_I_ALLOCTYPE(inode) == ICBTAG_FLAG_AD_IN_ICB)
91 		symlink = UDF_I_DATA(inode) + UDF_I_LENEATTR(inode);
92 	else
93 	{
94 		bh = sb_bread(inode->i_sb, udf_block_map(inode, 0));
95 
96 		if (!bh)
97 			goto out;
98 
99 		symlink = bh->b_data;
100 	}
101 
102 	udf_pc_to_char(inode->i_sb, symlink, inode->i_size, p);
103 	udf_release_data(bh);
104 
105 	unlock_kernel();
106 	SetPageUptodate(page);
107 	kunmap(page);
108 	unlock_page(page);
109 	return 0;
110 out:
111 	unlock_kernel();
112 	SetPageError(page);
113 	kunmap(page);
114 	unlock_page(page);
115 	return err;
116 }
117 
118 /*
119  * symlinks can't do much...
120  */
121 struct address_space_operations udf_symlink_aops = {
122 	.readpage		= udf_symlink_filler,
123 };
124