root/fs/ncpfs/symlink.c

DEFINITIONS

1. ncp_symlink_readpage
2. ncp_symlink

/*
 *  linux/fs/ncpfs/symlink.c
 *
 *  Code for allowing symbolic links on NCPFS (i.e. NetWare)
 *  Symbolic links are not supported on native NetWare, so we use an
 *  infrequently-used flag (Sh) and store a two-word magic header in
 *  the file to make sure we don't accidentally use a non-link file
 *  as a link.
 *
 *  When using the NFS namespace, we set the mode to indicate a symlink and
 *  don't bother with the magic numbers.
 *
 *  from linux/fs/ext2/symlink.c
 *
 *  Copyright (C) 1998-99, Frank A. Vorstenbosch
 *
 *  ncpfs symlink handling code
 *  NLS support (c) 1999 Petr Vandrovec
 *  Modified 2000 Ben Harris, University of Cambridge for NFS NS meta-info
 *
 */


#include <asm/uaccess.h>

#include <linux/errno.h>
#include <linux/fs.h>
#include <linux/ncp_fs.h>
#include <linux/time.h>
#include <linux/mm.h>
#include <linux/stat.h>
#include "ncplib_kernel.h"


/* these magic numbers must appear in the symlink file -- this makes it a bit
   more resilient against the magic attributes being set on random files. */

#define NCP_SYMLINK_MAGIC0      cpu_to_le32(0x6c6d7973)     /* "symlnk->" */
#define NCP_SYMLINK_MAGIC1      cpu_to_le32(0x3e2d6b6e)

/* ----- read a symbolic link ------------------------------------------ */

static int ncp_symlink_readpage(struct file *file, struct page *page)
{
        struct inode *inode = page->mapping->host;
        int error, length, len;
        char *link, *rawlink;
        char *buf = kmap(page);

        error = -ENOMEM;
        rawlink = kmalloc(NCP_MAX_SYMLINK_SIZE, GFP_KERNEL);
        if (!rawlink)
                goto fail;

        if (ncp_make_open(inode,O_RDONLY))
                goto failEIO;

        error=ncp_read_kernel(NCP_SERVER(inode),NCP_FINFO(inode)->file_handle,
                         0,NCP_MAX_SYMLINK_SIZE,rawlink,&length);

        ncp_inode_close(inode);
        /* Close file handle if no other users... */
        ncp_make_closed(inode);
        if (error)
                goto failEIO;

        if (NCP_FINFO(inode)->flags & NCPI_KLUDGE_SYMLINK) {
                if (length<NCP_MIN_SYMLINK_SIZE || 
                    ((__le32 *)rawlink)[0]!=NCP_SYMLINK_MAGIC0 ||
                    ((__le32 *)rawlink)[1]!=NCP_SYMLINK_MAGIC1)
                        goto failEIO;
                link = rawlink + 8;
                length -= 8;
        } else {
                link = rawlink;
        }

        len = NCP_MAX_SYMLINK_SIZE;
        error = ncp_vol2io(NCP_SERVER(inode), buf, &len, link, length, 0);
        kfree(rawlink);
        if (error)
                goto fail;
        SetPageUptodate(page);
        kunmap(page);
        unlock_page(page);
        return 0;

failEIO:
        error = -EIO;
        kfree(rawlink);
fail:
        SetPageError(page);
        kunmap(page);
        unlock_page(page);
        return error;
}

/*
 * symlinks can't do much...
 */
const struct address_space_operations ncp_symlink_aops = {
        .readpage       = ncp_symlink_readpage,
};
        
/* ----- create a new symbolic link -------------------------------------- */
 
int ncp_symlink(struct inode *dir, struct dentry *dentry, const char *symname) {
        struct inode *inode;
        char *rawlink;
        int length, err, i, outlen;
        int kludge;
        int mode;
        __le32 attr;
        unsigned int hdr;

        DPRINTK("ncp_symlink(dir=%p,dentry=%p,symname=%s)\n",dir,dentry,symname);

        if (ncp_is_nfs_extras(NCP_SERVER(dir), NCP_FINFO(dir)->volNumber))
                kludge = 0;
        else
#ifdef CONFIG_NCPFS_EXTRAS
        if (NCP_SERVER(dir)->m.flags & NCP_MOUNT_SYMLINKS)
                kludge = 1;
        else
#endif
        /* EPERM is returned by VFS if symlink procedure does not exist */
                return -EPERM;
  
        rawlink = kmalloc(NCP_MAX_SYMLINK_SIZE, GFP_KERNEL);
        if (!rawlink)
                return -ENOMEM;

        if (kludge) {
                mode = 0;
                attr = aSHARED | aHIDDEN;
                ((__le32 *)rawlink)[0]=NCP_SYMLINK_MAGIC0;
                ((__le32 *)rawlink)[1]=NCP_SYMLINK_MAGIC1;
                hdr = 8;
        } else {
                mode = S_IFLNK | S_IRWXUGO;
                attr = 0;
                hdr = 0;
        }                       

        length = strlen(symname);
        /* map to/from server charset, do not touch upper/lower case as
           symlink can point out of ncp filesystem */
        outlen = NCP_MAX_SYMLINK_SIZE - hdr;
        err = ncp_io2vol(NCP_SERVER(dir), rawlink + hdr, &outlen, symname, length, 0);
        if (err)
                goto failfree;

        outlen += hdr;

        err = -EIO;
        if (ncp_create_new(dir,dentry,mode,0,attr)) {
                goto failfree;
        }

        inode=dentry->d_inode;

        if (ncp_make_open(inode, O_WRONLY))
                goto failfree;

        if (ncp_write_kernel(NCP_SERVER(inode), NCP_FINFO(inode)->file_handle, 
                             0, outlen, rawlink, &i) || i!=outlen) {
                goto fail;
        }

        ncp_inode_close(inode);
        ncp_make_closed(inode);
        kfree(rawlink);
        return 0;
fail:;
        ncp_inode_close(inode);
        ncp_make_closed(inode);
failfree:;
        kfree(rawlink);
        return err;
}

/* ----- EOF ----- */