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
|
/*
* support/export/xtab.c
*
* Interface to the etab/exports file.
*
* Copyright (C) 1995, 1996 Olaf Kirch <okir@monad.swb.de>
*/
#ifdef HAVE_CONFIG_H
#include <config.h>
#endif
#include <sys/fcntl.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include "nfslib.h"
#include "exportfs.h"
#include "xio.h"
#include "xlog.h"
#include "v4root.h"
int v4root_needed;
static void cond_rename(char *newfile, char *oldfile);
static int
xtab_read(char *xtab, char *lockfn, int is_export)
{
/* is_export == 0 => reading /proc/fs/nfs/exports - we know these things are exported to kernel
* is_export == 1 => reading /var/lib/nfs/etab - these things are allowed to be exported
*/
struct exportent *xp;
nfs_export *exp;
int lockid;
if ((lockid = xflock(lockfn, "r")) < 0)
return 0;
setexportent(xtab, "r");
if (is_export == 1)
v4root_needed = 1;
while ((xp = getexportent(is_export==0, 0)) != NULL) {
if (!(exp = export_lookup(xp->e_hostname, xp->e_path, is_export != 1)) &&
!(exp = export_create(xp, is_export!=1))) {
continue;
}
switch (is_export) {
case 0:
exp->m_exported = 1;
break;
case 1:
exp->m_xtabent = 1;
exp->m_mayexport = 1;
if ((xp->e_flags & NFSEXP_FSID) && xp->e_fsid == 0)
v4root_needed = 0;
break;
}
}
endexportent();
xfunlock(lockid);
return 0;
}
int
xtab_export_read(void)
{
return xtab_read(_PATH_ETAB, _PATH_ETABLCK, 1);
}
/*
* mountd now keeps an open fd for the etab at all times to make sure that the
* inode number changes when the xtab_export_write is done. If you change the
* routine below such that the files are edited in place, then you'll need to
* fix the auth_reload logic as well...
*/
static int
xtab_write(char *xtab, char *xtabtmp, char *lockfn, int is_export)
{
struct exportent xe;
nfs_export *exp;
int lockid, i;
if ((lockid = xflock(lockfn, "w")) < 0) {
xlog(L_ERROR, "can't lock %s for writing", xtab);
return 0;
}
setexportent(xtabtmp, "w");
for (i = 0; i < MCL_MAXTYPES; i++) {
for (exp = exportlist[i].p_head; exp; exp = exp->m_next) {
if (is_export && !exp->m_xtabent)
continue;
if (!is_export && ! exp->m_exported)
continue;
/* write out the export entry using the FQDN */
xe = exp->m_export;
xe.e_hostname = exp->m_client->m_hostname;
putexportent(&xe);
}
}
endexportent();
cond_rename(xtabtmp, xtab);
xfunlock(lockid);
return 1;
}
int
xtab_export_write()
{
return xtab_write(_PATH_ETAB, _PATH_ETABTMP, _PATH_ETABLCK, 1);
}
/*
* rename newfile onto oldfile unless
* they are identical
*/
static void cond_rename(char *newfile, char *oldfile)
{
int nfd, ofd;
char nbuf[4096], obuf[4096];
int ncnt, ocnt;
nfd = open(newfile, 0);
if (nfd < 0)
return;
ofd = open(oldfile, 0);
if (ofd < 0) {
close(nfd);
rename(newfile, oldfile);
return;
}
do {
ncnt = read(nfd, nbuf, sizeof(nbuf));
if (ncnt < 0)
break;
ocnt = read(ofd, obuf, sizeof(obuf));
if (ocnt < 0)
break;
if (ncnt != ocnt)
break;
if (ncnt == 0) {
close(nfd);
close(ofd);
unlink(newfile);
return;
}
} while (memcmp(obuf, nbuf, ncnt) == 0);
/* some mis-match */
close(nfd);
close(ofd);
rename(newfile, oldfile);
return;
}
|
