symlink.c
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/*
* symlink.c
*
* PURPOSE
* Symlink handling routines for the OSTA-UDF(tm) filesystem.
*
* COPYRIGHT
* This file is distributed under the terms of the GNU General Public
* License (GPL). Copies of the GPL can be obtained from:
* ftp://prep.ai.mit.edu/pub/gnu/GPL
* Each contributing author retains all rights to their own work.
*
* (C) 1998-2001 Ben Fennema
* (C) 1999 Stelias Computing Inc
*
* HISTORY
*
* 04/16/99 blf Created.
*
*/
#include "udfdecl.h"
#include <asm/uaccess.h>
#include <linux/errno.h>
#include <linux/fs.h>
#include <linux/time.h>
#include <linux/mm.h>
#include <linux/stat.h>
#include <linux/pagemap.h>
#include <linux/buffer_head.h>
#include "udf_i.h"
static void udf_pc_to_char(struct super_block *sb, unsigned char *from,
int fromlen, unsigned char *to)
{
struct pathComponent *pc;
int elen = 0;
unsigned char *p = to;
while (elen < fromlen) {
pc = (struct pathComponent *)(from + elen);
switch (pc->componentType) {
case 1:
/*
* Symlink points to some place which should be agreed
* upon between originator and receiver of the media. Ignore.
*/
if (pc->lengthComponentIdent > 0)
break;
/* Fall through */
case 2:
p = to;
*p++ = '/';
break;
case 3:
memcpy(p, "../", 3);
p += 3;
break;
case 4:
memcpy(p, "./", 2);
p += 2;
/* that would be . - just ignore */
break;
case 5:
p += udf_get_filename(sb, pc->componentIdent, p,
pc->lengthComponentIdent);
*p++ = '/';
break;
}
elen += sizeof(struct pathComponent) + pc->lengthComponentIdent;
}
if (p > to + 1)
p[-1] = '\0';
else
p[0] = '\0';
}
static int udf_symlink_filler(struct file *file, struct page *page)
{
struct inode *inode = page->mapping->host;
struct buffer_head *bh = NULL;
unsigned char *symlink;
int err;
unsigned char *p = kmap(page);
struct udf_inode_info *iinfo;
uint32_t pos;
/* We don't support symlinks longer than one block */
if (inode->i_size > inode->i_sb->s_blocksize) {
err = -ENAMETOOLONG;
goto out_unmap;
}
iinfo = UDF_I(inode);
pos = udf_block_map(inode, 0);
down_read(&iinfo->i_data_sem);
if (iinfo->i_alloc_type == ICBTAG_FLAG_AD_IN_ICB) {
symlink = iinfo->i_ext.i_data + iinfo->i_lenEAttr;
} else {
bh = sb_bread(inode->i_sb, pos);
if (!bh) {
err = -EIO;
goto out_unlock_inode;
}
symlink = bh->b_data;
}
udf_pc_to_char(inode->i_sb, symlink, inode->i_size, p);
brelse(bh);
up_read(&iinfo->i_data_sem);
SetPageUptodate(page);
kunmap(page);
unlock_page(page);
return 0;
out_unlock_inode:
up_read(&iinfo->i_data_sem);
SetPageError(page);
out_unmap:
kunmap(page);
unlock_page(page);
return err;
}
/*
* symlinks can't do much...
*/
const struct address_space_operations udf_symlink_aops = {
.readpage = udf_symlink_filler,
};