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
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
|
/* -*- linux-c -*- --------------------------------------------------------- *
*
* linux/fs/devpts/root.c
*
* Copyright 1998 H. Peter Anvin -- All Rights Reserved
*
* This file is part of the Linux kernel and is made available under
* the terms of the GNU General Public License, version 2, or at your
* option, any later version, incorporated herein by reference.
*
* ------------------------------------------------------------------------- */
#include <linux/errno.h>
#include <linux/stat.h>
#include <linux/param.h>
#include <linux/string.h>
#include "devpts_i.h"
static int devpts_root_readdir(struct file *,void *,filldir_t);
static struct dentry *devpts_root_lookup(struct inode *,struct dentry *);
static int devpts_revalidate(struct dentry *, int);
static struct file_operations devpts_root_operations = {
NULL, /* llseek */
NULL, /* read */
NULL, /* write */
devpts_root_readdir, /* readdir */
NULL, /* poll */
NULL, /* ioctl */
NULL, /* mmap */
NULL, /* open */
NULL, /* flush */
NULL, /* release */
NULL, /* fsync */
NULL, /* fasync */
NULL, /* check_media_change */
NULL, /* revalidate */
NULL /* lock */
};
struct inode_operations devpts_root_inode_operations = {
&devpts_root_operations, /* file operations */
NULL, /* create */
devpts_root_lookup, /* lookup */
NULL, /* link */
NULL, /* unlink */
NULL, /* symlink */
NULL, /* mkdir */
NULL, /* rmdir */
NULL, /* mknod */
NULL, /* rename */
NULL, /* readlink */
NULL, /* follow_link */
NULL, /* readpage */
NULL, /* writepage */
NULL, /* bmap */
NULL, /* truncate */
NULL, /* permission */
NULL, /* smap */
NULL, /* updatepage */
NULL /* revalidate */
};
static struct dentry_operations devpts_dentry_operations = {
devpts_revalidate, /* d_revalidate */
NULL, /* d_hash */
NULL, /* d_compare */
};
/*
* The normal naming convention is simply /dev/pts/<number>; this conforms
* to the System V naming convention
*/
#define genptsname(buf,num) sprintf(buf, "%d", num)
static int devpts_root_readdir(struct file *filp, void *dirent, filldir_t filldir)
{
struct inode * inode = filp->f_dentry->d_inode;
struct devpts_sb_info * sbi = SBI(filp->f_dentry->d_inode->i_sb);
off_t nr;
char numbuf[16];
nr = filp->f_pos;
switch(nr)
{
case 0:
if (filldir(dirent, ".", 1, nr, inode->i_ino) < 0)
return 0;
filp->f_pos = ++nr;
/* fall through */
case 1:
if (filldir(dirent, "..", 2, nr, inode->i_ino) < 0)
return 0;
filp->f_pos = ++nr;
/* fall through */
default:
while ( nr < sbi->max_ptys ) {
int ptynr = nr - 2;
if ( sbi->inodes[ptynr] ) {
genptsname(numbuf, ptynr);
if ( filldir(dirent, numbuf, strlen(numbuf), nr, nr) < 0 )
return 0;
}
filp->f_pos = ++nr;
}
break;
}
return 0;
}
/*
* Revalidate is called on every cache lookup. We use it to check that
* the pty really does still exist. Never revalidate negative dentries;
* for simplicity (fix later?)
*/
static int devpts_revalidate(struct dentry * dentry, int flags)
{
struct devpts_sb_info *sbi;
if ( !dentry->d_inode )
return 0;
sbi = SBI(dentry->d_inode->i_sb);
return ( sbi->inodes[dentry->d_inode->i_ino - 2] == dentry->d_inode );
}
static struct dentry *devpts_root_lookup(struct inode * dir, struct dentry * dentry)
{
struct devpts_sb_info *sbi = SBI(dir->i_sb);
unsigned int entry;
int i;
const char *p;
dentry->d_inode = NULL; /* Assume failure */
dentry->d_op = &devpts_dentry_operations;
if ( dentry->d_name.len == 1 && dentry->d_name.name[0] == '0' ) {
entry = 0;
} else if ( dentry->d_name.len < 1 ) {
return NULL;
} else {
p = dentry->d_name.name;
if ( *p < '1' || *p > '9' )
return NULL;
entry = *p++ - '0';
for ( i = dentry->d_name.len-1 ; i ; i-- ) {
unsigned int nentry = *p++ - '0';
if ( nentry > 9 )
return NULL;
nentry += entry * 10;
if (nentry < entry)
return NULL;
entry = nentry;
}
}
if ( entry >= sbi->max_ptys )
return NULL;
dentry->d_inode = sbi->inodes[entry];
if ( dentry->d_inode )
dentry->d_inode->i_count++;
d_add(dentry, dentry->d_inode);
return NULL;
}
|
