1 /*
2 * linux/fs/ncpfs/symlink.c
3 *
4 * Code for allowing symbolic links on NCPFS (i.e. NetWare)
5 * Symbolic links are not supported on native NetWare, so we use an
6 * infrequently-used flag (Sh) and store a two-word magic header in
7 * the file to make sure we don't accidentally use a non-link file
8 * as a link.
9 *
10 * When using the NFS namespace, we set the mode to indicate a symlink and
11 * don't bother with the magic numbers.
12 *
13 * from linux/fs/ext2/symlink.c
14 *
15 * Copyright (C) 1998-99, Frank A. Vorstenbosch
16 *
17 * ncpfs symlink handling code
18 * NLS support (c) 1999 Petr Vandrovec
19 * Modified 2000 Ben Harris, University of Cambridge for NFS NS meta-info
20 *
21 */
22
23
24 #include <asm/uaccess.h>
25
26 #include <linux/errno.h>
27 #include <linux/fs.h>
28 #include <linux/ncp_fs.h>
29 #include <linux/time.h>
30 #include <linux/mm.h>
31 #include <linux/stat.h>
32 #include "ncplib_kernel.h"
33
34
35 /* these magic numbers must appear in the symlink file -- this makes it a bit
36 more resilient against the magic attributes being set on random files. */
37
38 #define NCP_SYMLINK_MAGIC0 cpu_to_le32(0x6c6d7973) /* "symlnk->" */
39 #define NCP_SYMLINK_MAGIC1 cpu_to_le32(0x3e2d6b6e)
40
41 /* ----- read a symbolic link ------------------------------------------ */
42
ncp_symlink_readpage(struct file * file,struct page * page)43 static int ncp_symlink_readpage(struct file *file, struct page *page)
44 {
45 struct inode *inode = page->mapping->host;
46 int error, length, len;
47 char *link, *rawlink;
48 char *buf = kmap(page);
49
50 error = -ENOMEM;
51 rawlink = kmalloc(NCP_MAX_SYMLINK_SIZE, GFP_KERNEL);
52 if (!rawlink)
53 goto fail;
54
55 if (ncp_make_open(inode,O_RDONLY))
56 goto failEIO;
57
58 error=ncp_read_kernel(NCP_SERVER(inode),NCP_FINFO(inode)->file_handle,
59 0,NCP_MAX_SYMLINK_SIZE,rawlink,&length);
60
61 ncp_inode_close(inode);
62 /* Close file handle if no other users... */
63 ncp_make_closed(inode);
64 if (error)
65 goto failEIO;
66
67 if (NCP_FINFO(inode)->flags & NCPI_KLUDGE_SYMLINK) {
68 if (length<NCP_MIN_SYMLINK_SIZE ||
69 ((__le32 *)rawlink)[0]!=NCP_SYMLINK_MAGIC0 ||
70 ((__le32 *)rawlink)[1]!=NCP_SYMLINK_MAGIC1)
71 goto failEIO;
72 link = rawlink + 8;
73 length -= 8;
74 } else {
75 link = rawlink;
76 }
77
78 len = NCP_MAX_SYMLINK_SIZE;
79 error = ncp_vol2io(NCP_SERVER(inode), buf, &len, link, length, 0);
80 kfree(rawlink);
81 if (error)
82 goto fail;
83 SetPageUptodate(page);
84 kunmap(page);
85 unlock_page(page);
86 return 0;
87
88 failEIO:
89 error = -EIO;
90 kfree(rawlink);
91 fail:
92 SetPageError(page);
93 kunmap(page);
94 unlock_page(page);
95 return error;
96 }
97
98 /*
99 * symlinks can't do much...
100 */
101 const struct address_space_operations ncp_symlink_aops = {
102 .readpage = ncp_symlink_readpage,
103 };
104
105 /* ----- create a new symbolic link -------------------------------------- */
106
ncp_symlink(struct inode * dir,struct dentry * dentry,const char * symname)107 int ncp_symlink(struct inode *dir, struct dentry *dentry, const char *symname) {
108 struct inode *inode;
109 char *rawlink;
110 int length, err, i, outlen;
111 int kludge;
112 int mode;
113 __le32 attr;
114 unsigned int hdr;
115
116 DPRINTK("ncp_symlink(dir=%p,dentry=%p,symname=%s)\n",dir,dentry,symname);
117
118 if (ncp_is_nfs_extras(NCP_SERVER(dir), NCP_FINFO(dir)->volNumber))
119 kludge = 0;
120 else
121 #ifdef CONFIG_NCPFS_EXTRAS
122 if (NCP_SERVER(dir)->m.flags & NCP_MOUNT_SYMLINKS)
123 kludge = 1;
124 else
125 #endif
126 /* EPERM is returned by VFS if symlink procedure does not exist */
127 return -EPERM;
128
129 rawlink = kmalloc(NCP_MAX_SYMLINK_SIZE, GFP_KERNEL);
130 if (!rawlink)
131 return -ENOMEM;
132
133 if (kludge) {
134 mode = 0;
135 attr = aSHARED | aHIDDEN;
136 ((__le32 *)rawlink)[0]=NCP_SYMLINK_MAGIC0;
137 ((__le32 *)rawlink)[1]=NCP_SYMLINK_MAGIC1;
138 hdr = 8;
139 } else {
140 mode = S_IFLNK | S_IRWXUGO;
141 attr = 0;
142 hdr = 0;
143 }
144
145 length = strlen(symname);
146 /* map to/from server charset, do not touch upper/lower case as
147 symlink can point out of ncp filesystem */
148 outlen = NCP_MAX_SYMLINK_SIZE - hdr;
149 err = ncp_io2vol(NCP_SERVER(dir), rawlink + hdr, &outlen, symname, length, 0);
150 if (err)
151 goto failfree;
152
153 outlen += hdr;
154
155 err = -EIO;
156 if (ncp_create_new(dir,dentry,mode,0,attr)) {
157 goto failfree;
158 }
159
160 inode=dentry->d_inode;
161
162 if (ncp_make_open(inode, O_WRONLY))
163 goto failfree;
164
165 if (ncp_write_kernel(NCP_SERVER(inode), NCP_FINFO(inode)->file_handle,
166 0, outlen, rawlink, &i) || i!=outlen) {
167 goto fail;
168 }
169
170 ncp_inode_close(inode);
171 ncp_make_closed(inode);
172 kfree(rawlink);
173 return 0;
174 fail:;
175 ncp_inode_close(inode);
176 ncp_make_closed(inode);
177 failfree:;
178 kfree(rawlink);
179 return err;
180 }
181
182 /* ----- EOF ----- */
183