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/*

 *  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 ----- */