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