xref: /openbmc/linux/fs/udf/symlink.c (revision 9d56dd3b083a3bec56e9da35ce07baca81030b03)
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/time.h>
27 #include <linux/mm.h>
28 #include <linux/stat.h>
29 #include <linux/slab.h>
30 #include <linux/pagemap.h>
31 #include <linux/smp_lock.h>
32 #include <linux/buffer_head.h>
33 #include "udf_i.h"
34 
35 static void udf_pc_to_char(struct super_block *sb, char *from, int fromlen,
36 			   char *to)
37 {
38 	struct pathComponent *pc;
39 	int elen = 0;
40 	char *p = to;
41 
42 	while (elen < fromlen) {
43 		pc = (struct pathComponent *)(from + elen);
44 		switch (pc->componentType) {
45 		case 1:
46 			if (pc->lengthComponentIdent == 0) {
47 				p = to;
48 				*p++ = '/';
49 			}
50 			break;
51 		case 3:
52 			memcpy(p, "../", 3);
53 			p += 3;
54 			break;
55 		case 4:
56 			memcpy(p, "./", 2);
57 			p += 2;
58 			/* that would be . - just ignore */
59 			break;
60 		case 5:
61 			p += udf_get_filename(sb, pc->componentIdent, p,
62 					      pc->lengthComponentIdent);
63 			*p++ = '/';
64 			break;
65 		}
66 		elen += sizeof(struct pathComponent) + pc->lengthComponentIdent;
67 	}
68 	if (p > to + 1)
69 		p[-1] = '\0';
70 	else
71 		p[0] = '\0';
72 }
73 
74 static int udf_symlink_filler(struct file *file, struct page *page)
75 {
76 	struct inode *inode = page->mapping->host;
77 	struct buffer_head *bh = NULL;
78 	char *symlink;
79 	int err = -EIO;
80 	char *p = kmap(page);
81 	struct udf_inode_info *iinfo;
82 
83 	lock_kernel();
84 	iinfo = UDF_I(inode);
85 	if (iinfo->i_alloc_type == ICBTAG_FLAG_AD_IN_ICB) {
86 		symlink = iinfo->i_ext.i_data + iinfo->i_lenEAttr;
87 	} else {
88 		bh = sb_bread(inode->i_sb, udf_block_map(inode, 0));
89 
90 		if (!bh)
91 			goto out;
92 
93 		symlink = bh->b_data;
94 	}
95 
96 	udf_pc_to_char(inode->i_sb, symlink, inode->i_size, p);
97 	brelse(bh);
98 
99 	unlock_kernel();
100 	SetPageUptodate(page);
101 	kunmap(page);
102 	unlock_page(page);
103 	return 0;
104 
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