Root/fs/udf/symlink.c

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/pagemap.h>
30#include <linux/buffer_head.h>
31#include "udf_i.h"
32
33static void udf_pc_to_char(struct super_block *sb, unsigned char *from,
34               int fromlen, unsigned char *to)
35{
36    struct pathComponent *pc;
37    int elen = 0;
38    unsigned char *p = to;
39
40    while (elen < fromlen) {
41        pc = (struct pathComponent *)(from + elen);
42        switch (pc->componentType) {
43        case 1:
44            if (pc->lengthComponentIdent == 0) {
45                p = to;
46                *p++ = '/';
47            }
48            break;
49        case 3:
50            memcpy(p, "../", 3);
51            p += 3;
52            break;
53        case 4:
54            memcpy(p, "./", 2);
55            p += 2;
56            /* that would be . - just ignore */
57            break;
58        case 5:
59            p += udf_get_filename(sb, pc->componentIdent, p,
60                          pc->lengthComponentIdent);
61            *p++ = '/';
62            break;
63        }
64        elen += sizeof(struct pathComponent) + pc->lengthComponentIdent;
65    }
66    if (p > to + 1)
67        p[-1] = '\0';
68    else
69        p[0] = '\0';
70}
71
72static int udf_symlink_filler(struct file *file, struct page *page)
73{
74    struct inode *inode = page->mapping->host;
75    struct buffer_head *bh = NULL;
76    unsigned char *symlink;
77    int err = -EIO;
78    unsigned char *p = kmap(page);
79    struct udf_inode_info *iinfo;
80    uint32_t pos;
81
82    iinfo = UDF_I(inode);
83    pos = udf_block_map(inode, 0);
84
85    down_read(&iinfo->i_data_sem);
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, pos);
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    up_read(&iinfo->i_data_sem);
101    SetPageUptodate(page);
102    kunmap(page);
103    unlock_page(page);
104    return 0;
105
106out:
107    up_read(&iinfo->i_data_sem);
108    SetPageError(page);
109    kunmap(page);
110    unlock_page(page);
111    return err;
112}
113
114/*
115 * symlinks can't do much...
116 */
117const struct address_space_operations udf_symlink_aops = {
118    .readpage = udf_symlink_filler,
119};
120

Archive Download this file



interactive