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Linux/fs/ncpfs/symlink.c

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  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 
 42 static 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 
 87 failEIO:
 88         error = -EIO;
 89         kfree(rawlink);
 90 fail:
 91         SetPageError(page);
 92         kunmap(page);
 93         unlock_page(page);
 94         return error;
 95 }
 96 
 97 /*
 98  * symlinks can't do much...
 99  */
100 const struct address_space_operations ncp_symlink_aops = {
101         .readpage       = ncp_symlink_readpage,
102 };
103         
104 /* ----- create a new symbolic link -------------------------------------- */
105  
106 int 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         ncp_dbg(1, "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=d_inode(dentry);
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;
173 fail:;
174         ncp_inode_close(inode);
175         ncp_make_closed(inode);
176 failfree:;
177         kfree(rawlink);
178         return err;
179 }
180 
181 /* ----- EOF ----- */
182 

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