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