128 lines
3.8 KiB
C
128 lines
3.8 KiB
C
/*
|
|
* Squashfs - a compressed read only filesystem for Linux
|
|
*
|
|
* Copyright (c) 2002, 2003, 2004, 2005, 2006, 2007, 2008
|
|
* Phillip Lougher <phillip@squashfs.org.uk>
|
|
*
|
|
* This program is free software; you can redistribute it and/or
|
|
* modify it under the terms of the GNU General Public License
|
|
* as published by the Free Software Foundation; either version 2,
|
|
* or (at your option) any later version.
|
|
*
|
|
* This program is distributed in the hope that it will be useful,
|
|
* but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
* GNU General Public License for more details.
|
|
*
|
|
* You should have received a copy of the GNU General Public License
|
|
* along with this program; if not, write to the Free Software
|
|
* Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
|
|
*
|
|
* symlink.c
|
|
*/
|
|
|
|
/*
|
|
* This file implements code to handle symbolic links.
|
|
*
|
|
* The data contents of symbolic links are stored inside the symbolic
|
|
* link inode within the inode table. This allows the normally small symbolic
|
|
* link to be compressed as part of the inode table, achieving much greater
|
|
* compression than if the symbolic link was compressed individually.
|
|
*/
|
|
|
|
#include <linux/fs.h>
|
|
#include <linux/vfs.h>
|
|
#include <linux/kernel.h>
|
|
#include <linux/string.h>
|
|
#include <linux/pagemap.h>
|
|
#include <linux/xattr.h>
|
|
|
|
#include "squashfs_fs.h"
|
|
#include "squashfs_fs_sb.h"
|
|
#include "squashfs_fs_i.h"
|
|
#include "squashfs.h"
|
|
#include "xattr.h"
|
|
|
|
static int squashfs_symlink_readpage(struct file *file, struct page *page)
|
|
{
|
|
struct inode *inode = page->mapping->host;
|
|
struct super_block *sb = inode->i_sb;
|
|
struct squashfs_sb_info *msblk = sb->s_fs_info;
|
|
int index = page->index << PAGE_CACHE_SHIFT;
|
|
u64 block = squashfs_i(inode)->start;
|
|
int offset = squashfs_i(inode)->offset;
|
|
int length = min_t(int, i_size_read(inode) - index, PAGE_CACHE_SIZE);
|
|
int bytes, copied;
|
|
void *pageaddr;
|
|
struct squashfs_cache_entry *entry;
|
|
|
|
TRACE("Entered squashfs_symlink_readpage, page index %ld, start block "
|
|
"%llx, offset %x\n", page->index, block, offset);
|
|
|
|
/*
|
|
* Skip index bytes into symlink metadata.
|
|
*/
|
|
if (index) {
|
|
bytes = squashfs_read_metadata(sb, NULL, &block, &offset,
|
|
index);
|
|
if (bytes < 0) {
|
|
ERROR("Unable to read symlink [%llx:%x]\n",
|
|
squashfs_i(inode)->start,
|
|
squashfs_i(inode)->offset);
|
|
goto error_out;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Read length bytes from symlink metadata. Squashfs_read_metadata
|
|
* is not used here because it can sleep and we want to use
|
|
* kmap_atomic to map the page. Instead call the underlying
|
|
* squashfs_cache_get routine. As length bytes may overlap metadata
|
|
* blocks, we may need to call squashfs_cache_get multiple times.
|
|
*/
|
|
for (bytes = 0; bytes < length; offset = 0, bytes += copied) {
|
|
entry = squashfs_cache_get(sb, msblk->block_cache, block, 0);
|
|
if (entry->error) {
|
|
ERROR("Unable to read symlink [%llx:%x]\n",
|
|
squashfs_i(inode)->start,
|
|
squashfs_i(inode)->offset);
|
|
squashfs_cache_put(entry);
|
|
goto error_out;
|
|
}
|
|
|
|
pageaddr = kmap_atomic(page);
|
|
copied = squashfs_copy_data(pageaddr + bytes, entry, offset,
|
|
length - bytes);
|
|
if (copied == length - bytes)
|
|
memset(pageaddr + length, 0, PAGE_CACHE_SIZE - length);
|
|
else
|
|
block = entry->next_index;
|
|
kunmap_atomic(pageaddr);
|
|
squashfs_cache_put(entry);
|
|
}
|
|
|
|
flush_dcache_page(page);
|
|
SetPageUptodate(page);
|
|
unlock_page(page);
|
|
return 0;
|
|
|
|
error_out:
|
|
SetPageError(page);
|
|
unlock_page(page);
|
|
return 0;
|
|
}
|
|
|
|
|
|
const struct address_space_operations squashfs_symlink_aops = {
|
|
.readpage = squashfs_symlink_readpage
|
|
};
|
|
|
|
const struct inode_operations squashfs_symlink_inode_ops = {
|
|
.readlink = generic_readlink,
|
|
.follow_link = page_follow_link_light,
|
|
.put_link = page_put_link,
|
|
.getxattr = generic_getxattr,
|
|
.listxattr = squashfs_listxattr
|
|
};
|
|
|