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
43static 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
88failEIO:
89	error = -EIO;
90	kfree(rawlink);
91fail:
92	SetPageError(page);
93	kunmap(page);
94	unlock_page(page);
95	return error;
96}
97
98/*
99 * symlinks can't do much...
100 */
101const struct address_space_operations ncp_symlink_aops = {
102	.readpage	= ncp_symlink_readpage,
103};
104
105/* ----- create a new symbolic link -------------------------------------- */
106
107int 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;
174fail:;
175	ncp_inode_close(inode);
176	ncp_make_closed(inode);
177failfree:;
178	kfree(rawlink);
179	return err;
180}
181
182/* ----- EOF ----- */
183