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/slab.h>
31#include <linux/mm.h>
32#include <linux/stat.h>
33#include "ncplib_kernel.h"
34
35
36/* these magic numbers must appear in the symlink file -- this makes it a bit
37   more resilient against the magic attributes being set on random files. */
38
39#define NCP_SYMLINK_MAGIC0	cpu_to_le32(0x6c6d7973)     /* "symlnk->" */
40#define NCP_SYMLINK_MAGIC1	cpu_to_le32(0x3e2d6b6e)
41
42/* ----- read a symbolic link ------------------------------------------ */
43
44static int ncp_symlink_readpage(struct file *file, struct page *page)
45{
46	struct inode *inode = page->mapping->host;
47	int error, length, len;
48	char *link, *rawlink;
49	char *buf = kmap(page);
50
51	error = -ENOMEM;
52	rawlink = kmalloc(NCP_MAX_SYMLINK_SIZE, GFP_KERNEL);
53	if (!rawlink)
54		goto fail;
55
56	if (ncp_make_open(inode,O_RDONLY))
57		goto failEIO;
58
59	error=ncp_read_kernel(NCP_SERVER(inode),NCP_FINFO(inode)->file_handle,
60                         0,NCP_MAX_SYMLINK_SIZE,rawlink,&length);
61
62	ncp_inode_close(inode);
63	/* Close file handle if no other users... */
64	ncp_make_closed(inode);
65	if (error)
66		goto failEIO;
67
68	if (NCP_FINFO(inode)->flags & NCPI_KLUDGE_SYMLINK) {
69		if (length<NCP_MIN_SYMLINK_SIZE ||
70		    ((__le32 *)rawlink)[0]!=NCP_SYMLINK_MAGIC0 ||
71		    ((__le32 *)rawlink)[1]!=NCP_SYMLINK_MAGIC1)
72		    	goto failEIO;
73		link = rawlink + 8;
74		length -= 8;
75	} else {
76		link = rawlink;
77	}
78
79	len = NCP_MAX_SYMLINK_SIZE;
80	error = ncp_vol2io(NCP_SERVER(inode), buf, &len, link, length, 0);
81	kfree(rawlink);
82	if (error)
83		goto fail;
84	SetPageUptodate(page);
85	kunmap(page);
86	unlock_page(page);
87	return 0;
88
89failEIO:
90	error = -EIO;
91	kfree(rawlink);
92fail:
93	SetPageError(page);
94	kunmap(page);
95	unlock_page(page);
96	return error;
97}
98
99/*
100 * symlinks can't do much...
101 */
102const struct address_space_operations ncp_symlink_aops = {
103	.readpage	= ncp_symlink_readpage,
104};
105
106/* ----- create a new symbolic link -------------------------------------- */
107
108int ncp_symlink(struct inode *dir, struct dentry *dentry, const char *symname) {
109	struct inode *inode;
110	char *rawlink;
111	int length, err, i, outlen;
112	int kludge;
113	int mode;
114	__le32 attr;
115	unsigned int hdr;
116
117	DPRINTK("ncp_symlink(dir=%p,dentry=%p,symname=%s)\n",dir,dentry,symname);
118
119	if (ncp_is_nfs_extras(NCP_SERVER(dir), NCP_FINFO(dir)->volNumber))
120		kludge = 0;
121	else
122#ifdef CONFIG_NCPFS_EXTRAS
123	if (NCP_SERVER(dir)->m.flags & NCP_MOUNT_SYMLINKS)
124		kludge = 1;
125	else
126#endif
127	/* EPERM is returned by VFS if symlink procedure does not exist */
128		return -EPERM;
129
130	rawlink = kmalloc(NCP_MAX_SYMLINK_SIZE, GFP_KERNEL);
131	if (!rawlink)
132		return -ENOMEM;
133
134	if (kludge) {
135		mode = 0;
136		attr = aSHARED | aHIDDEN;
137		((__le32 *)rawlink)[0]=NCP_SYMLINK_MAGIC0;
138		((__le32 *)rawlink)[1]=NCP_SYMLINK_MAGIC1;
139		hdr = 8;
140	} else {
141		mode = S_IFLNK | S_IRWXUGO;
142		attr = 0;
143		hdr = 0;
144	}
145
146	length = strlen(symname);
147	/* map to/from server charset, do not touch upper/lower case as
148	   symlink can point out of ncp filesystem */
149	outlen = NCP_MAX_SYMLINK_SIZE - hdr;
150	err = ncp_io2vol(NCP_SERVER(dir), rawlink + hdr, &outlen, symname, length, 0);
151	if (err)
152		goto failfree;
153
154	outlen += hdr;
155
156	err = -EIO;
157	if (ncp_create_new(dir,dentry,mode,0,attr)) {
158		goto failfree;
159	}
160
161	inode=dentry->d_inode;
162
163	if (ncp_make_open(inode, O_WRONLY))
164		goto failfree;
165
166	if (ncp_write_kernel(NCP_SERVER(inode), NCP_FINFO(inode)->file_handle,
167			     0, outlen, rawlink, &i) || i!=outlen) {
168		goto fail;
169	}
170
171	ncp_inode_close(inode);
172	ncp_make_closed(inode);
173	kfree(rawlink);
174	return 0;
175fail:;
176	ncp_inode_close(inode);
177	ncp_make_closed(inode);
178failfree:;
179	kfree(rawlink);
180	return err;
181}
182
183/* ----- EOF ----- */
184