1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
|
/*
* linux/fs/umsdos/file.c
*
* Written 1992 by Jacques Gelinas
* inspired from linux/fs/msdos/file.c Werner Almesberger
*
* Extended MS-DOS regular file handling primitives
*/
#include <linux/sched.h>
#include <linux/fs.h>
#include <linux/msdos_fs.h>
#include <linux/errno.h>
#include <linux/fcntl.h>
#include <linux/stat.h>
#include <linux/umsdos_fs.h>
#include <linux/malloc.h>
#include <asm/uaccess.h>
#include <asm/system.h>
static struct file_operations umsdos_symlink_operations;
/*
* Read the data associate with the symlink.
* Return length read in buffer or a negative error code.
*
*/
int umsdos_readlink_x ( struct dentry *dentry,
char *buffer,
int bufsiz)
{
size_t size = dentry->d_inode->i_size;
loff_t loffs = 0;
ssize_t ret;
struct file filp;
Printk((KERN_DEBUG "UMSDOS_read: %s/%s, size=%u\n",
dentry->d_parent->d_name.name, dentry->d_name.name, size));
fill_new_filp (&filp, dentry);
filp.f_reada = 0;
filp.f_flags = O_RDONLY;
filp.f_op = &umsdos_symlink_operations;
if (size > bufsiz)
size = bufsiz;
ret = fat_file_read (&filp, buffer, size, &loffs);
if (ret != size) {
ret = -EIO;
}
return ret;
}
static int UMSDOS_readlink (struct dentry *dentry, char *buffer, int buflen)
{
return umsdos_readlink_x (dentry, buffer, buflen);
}
/* this one mostly stolen from romfs :) */
static struct dentry *UMSDOS_followlink (struct dentry *dentry,
struct dentry *base,
unsigned int follow)
{
struct inode *inode = dentry->d_inode;
char *symname;
int len, cnt;
mm_segment_t old_fs = get_fs ();
Printk((KERN_DEBUG "UMSDOS_followlink /mn/: (%s/%s)\n",
dentry->d_parent->d_name.name, dentry->d_name.name));
len = inode->i_size;
if (!(symname = kmalloc (len + 1, GFP_KERNEL))) {
dentry = ERR_PTR (-ENOMEM);
goto outnobuf;
}
set_fs (KERNEL_DS); /* we read into kernel space this time */
cnt = umsdos_readlink_x (dentry, symname, len);
set_fs (old_fs);
if (len != cnt) {
dentry = ERR_PTR (-EIO);
goto out;
}
symname[len] = 0;
dentry = lookup_dentry (symname, base, follow);
kfree (symname);
if (0) {
out:
kfree (symname);
outnobuf:
dput (base);
}
return dentry;
}
/* needed to patch the file structure */
static struct file_operations umsdos_symlink_operations =
{
NULL, /* lseek - default */
NULL, /* read */
NULL, /* write */
NULL, /* readdir - bad */
NULL, /* poll - default */
NULL, /* ioctl - default */
NULL, /* mmap */
NULL, /* no special open is needed */
NULL, /* no flush code */
NULL, /* release */
NULL /* fsync */
};
struct inode_operations umsdos_symlink_inode_operations =
{
NULL, /* default file operations (none) */
NULL, /* create */
NULL, /* lookup */
NULL, /* link */
NULL, /* unlink */
NULL, /* symlink */
NULL, /* mkdir */
NULL, /* rmdir */
NULL, /* mknod */
NULL, /* rename */
UMSDOS_readlink, /* readlink */
UMSDOS_followlink, /* followlink */
generic_readpage, /* readpage */
NULL, /* writepage */
fat_bmap, /* bmap */
NULL, /* truncate */
NULL, /* permission */
NULL, /* smap */
NULL /* revalidate */
};
|
