xref: /openbmc/linux/fs/udf/symlink.c (revision f42b3800)
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,
37 			   char *to)
38 {
39 	struct pathComponent *pc;
40 	int elen = 0;
41 	char *p = to;
42 
43 	while (elen < fromlen) {
44 		pc = (struct pathComponent *)(from + elen);
45 		switch (pc->componentType) {
46 		case 1:
47 			if (pc->lengthComponentIdent == 0) {
48 				p = to;
49 				*p++ = '/';
50 			}
51 			break;
52 		case 3:
53 			memcpy(p, "../", 3);
54 			p += 3;
55 			break;
56 		case 4:
57 			memcpy(p, "./", 2);
58 			p += 2;
59 			/* that would be . - just ignore */
60 			break;
61 		case 5:
62 			p += udf_get_filename(sb, pc->componentIdent, p,
63 					      pc->lengthComponentIdent);
64 			*p++ = '/';
65 			break;
66 		}
67 		elen += sizeof(struct pathComponent) + pc->lengthComponentIdent;
68 	}
69 	if (p > to + 1)
70 		p[-1] = '\0';
71 	else
72 		p[0] = '\0';
73 }
74 
75 static int udf_symlink_filler(struct file *file, struct page *page)
76 {
77 	struct inode *inode = page->mapping->host;
78 	struct buffer_head *bh = NULL;
79 	char *symlink;
80 	int err = -EIO;
81 	char *p = kmap(page);
82 	struct udf_inode_info *iinfo;
83 
84 	lock_kernel();
85 	iinfo = UDF_I(inode);
86 	if (iinfo->i_alloc_type == ICBTAG_FLAG_AD_IN_ICB) {
87 		symlink = iinfo->i_ext.i_data + iinfo->i_lenEAttr;
88 	} else {
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 
106 out:
107 	unlock_kernel();
108 	SetPageError(page);
109 	kunmap(page);
110 	unlock_page(page);
111 	return err;
112 }
113 
114 /*
115  * symlinks can't do much...
116  */
117 const struct address_space_operations udf_symlink_aops = {
118 	.readpage		= udf_symlink_filler,
119 };
120