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