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1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * Squashfs - a compressed read only filesystem for Linux
4 *
5 * Copyright (c) 2002, 2003, 2004, 2005, 2006, 2007, 2008
6 * Phillip Lougher <phillip@squashfs.org.uk>
7 *
8 * symlink.c
9 */
10
11/*
12 * This file implements code to handle symbolic links.
13 *
14 * The data contents of symbolic links are stored inside the symbolic
15 * link inode within the inode table. This allows the normally small symbolic
16 * link to be compressed as part of the inode table, achieving much greater
17 * compression than if the symbolic link was compressed individually.
18 */
19
20#include <linux/fs.h>
21#include <linux/vfs.h>
22#include <linux/kernel.h>
23#include <linux/string.h>
24#include <linux/pagemap.h>
25#include <linux/xattr.h>
26
27#include "squashfs_fs.h"
28#include "squashfs_fs_sb.h"
29#include "squashfs_fs_i.h"
30#include "squashfs.h"
31#include "xattr.h"
32
33static int squashfs_symlink_read_folio(struct file *file, struct folio *folio)
34{
35 struct page *page = &folio->page;
36 struct inode *inode = page->mapping->host;
37 struct super_block *sb = inode->i_sb;
38 struct squashfs_sb_info *msblk = sb->s_fs_info;
39 int index = page->index << PAGE_SHIFT;
40 u64 block = squashfs_i(inode)->start;
41 int offset = squashfs_i(inode)->offset;
42 int length = min_t(int, i_size_read(inode) - index, PAGE_SIZE);
43 int bytes, copied;
44 void *pageaddr;
45 struct squashfs_cache_entry *entry;
46
47 TRACE("Entered squashfs_symlink_readpage, page index %ld, start block "
48 "%llx, offset %x\n", page->index, block, offset);
49
50 /*
51 * Skip index bytes into symlink metadata.
52 */
53 if (index) {
54 bytes = squashfs_read_metadata(sb, NULL, &block, &offset,
55 index);
56 if (bytes < 0) {
57 ERROR("Unable to read symlink [%llx:%x]\n",
58 squashfs_i(inode)->start,
59 squashfs_i(inode)->offset);
60 goto error_out;
61 }
62 }
63
64 /*
65 * Read length bytes from symlink metadata. Squashfs_read_metadata
66 * is not used here because it can sleep and we want to use
67 * kmap_atomic to map the page. Instead call the underlying
68 * squashfs_cache_get routine. As length bytes may overlap metadata
69 * blocks, we may need to call squashfs_cache_get multiple times.
70 */
71 for (bytes = 0; bytes < length; offset = 0, bytes += copied) {
72 entry = squashfs_cache_get(sb, msblk->block_cache, block, 0);
73 if (entry->error) {
74 ERROR("Unable to read symlink [%llx:%x]\n",
75 squashfs_i(inode)->start,
76 squashfs_i(inode)->offset);
77 squashfs_cache_put(entry);
78 goto error_out;
79 }
80
81 pageaddr = kmap_atomic(page);
82 copied = squashfs_copy_data(pageaddr + bytes, entry, offset,
83 length - bytes);
84 if (copied == length - bytes)
85 memset(pageaddr + length, 0, PAGE_SIZE - length);
86 else
87 block = entry->next_index;
88 kunmap_atomic(pageaddr);
89 squashfs_cache_put(entry);
90 }
91
92 flush_dcache_page(page);
93 SetPageUptodate(page);
94 unlock_page(page);
95 return 0;
96
97error_out:
98 SetPageError(page);
99 unlock_page(page);
100 return 0;
101}
102
103
104const struct address_space_operations squashfs_symlink_aops = {
105 .read_folio = squashfs_symlink_read_folio
106};
107
108const struct inode_operations squashfs_symlink_inode_ops = {
109 .get_link = page_get_link,
110 .listxattr = squashfs_listxattr
111};
112
1/*
2 * Squashfs - a compressed read only filesystem for Linux
3 *
4 * Copyright (c) 2002, 2003, 2004, 2005, 2006, 2007, 2008
5 * Phillip Lougher <phillip@squashfs.org.uk>
6 *
7 * This program is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU General Public License
9 * as published by the Free Software Foundation; either version 2,
10 * or (at your option) any later version.
11 *
12 * This program is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 * GNU General Public License for more details.
16 *
17 * You should have received a copy of the GNU General Public License
18 * along with this program; if not, write to the Free Software
19 * Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
20 *
21 * symlink.c
22 */
23
24/*
25 * This file implements code to handle symbolic links.
26 *
27 * The data contents of symbolic links are stored inside the symbolic
28 * link inode within the inode table. This allows the normally small symbolic
29 * link to be compressed as part of the inode table, achieving much greater
30 * compression than if the symbolic link was compressed individually.
31 */
32
33#include <linux/fs.h>
34#include <linux/vfs.h>
35#include <linux/kernel.h>
36#include <linux/string.h>
37#include <linux/pagemap.h>
38#include <linux/xattr.h>
39
40#include "squashfs_fs.h"
41#include "squashfs_fs_sb.h"
42#include "squashfs_fs_i.h"
43#include "squashfs.h"
44#include "xattr.h"
45
46static int squashfs_symlink_readpage(struct file *file, struct page *page)
47{
48 struct inode *inode = page->mapping->host;
49 struct super_block *sb = inode->i_sb;
50 struct squashfs_sb_info *msblk = sb->s_fs_info;
51 int index = page->index << PAGE_SHIFT;
52 u64 block = squashfs_i(inode)->start;
53 int offset = squashfs_i(inode)->offset;
54 int length = min_t(int, i_size_read(inode) - index, PAGE_SIZE);
55 int bytes, copied;
56 void *pageaddr;
57 struct squashfs_cache_entry *entry;
58
59 TRACE("Entered squashfs_symlink_readpage, page index %ld, start block "
60 "%llx, offset %x\n", page->index, block, offset);
61
62 /*
63 * Skip index bytes into symlink metadata.
64 */
65 if (index) {
66 bytes = squashfs_read_metadata(sb, NULL, &block, &offset,
67 index);
68 if (bytes < 0) {
69 ERROR("Unable to read symlink [%llx:%x]\n",
70 squashfs_i(inode)->start,
71 squashfs_i(inode)->offset);
72 goto error_out;
73 }
74 }
75
76 /*
77 * Read length bytes from symlink metadata. Squashfs_read_metadata
78 * is not used here because it can sleep and we want to use
79 * kmap_atomic to map the page. Instead call the underlying
80 * squashfs_cache_get routine. As length bytes may overlap metadata
81 * blocks, we may need to call squashfs_cache_get multiple times.
82 */
83 for (bytes = 0; bytes < length; offset = 0, bytes += copied) {
84 entry = squashfs_cache_get(sb, msblk->block_cache, block, 0);
85 if (entry->error) {
86 ERROR("Unable to read symlink [%llx:%x]\n",
87 squashfs_i(inode)->start,
88 squashfs_i(inode)->offset);
89 squashfs_cache_put(entry);
90 goto error_out;
91 }
92
93 pageaddr = kmap_atomic(page);
94 copied = squashfs_copy_data(pageaddr + bytes, entry, offset,
95 length - bytes);
96 if (copied == length - bytes)
97 memset(pageaddr + length, 0, PAGE_SIZE - length);
98 else
99 block = entry->next_index;
100 kunmap_atomic(pageaddr);
101 squashfs_cache_put(entry);
102 }
103
104 flush_dcache_page(page);
105 SetPageUptodate(page);
106 unlock_page(page);
107 return 0;
108
109error_out:
110 SetPageError(page);
111 unlock_page(page);
112 return 0;
113}
114
115
116const struct address_space_operations squashfs_symlink_aops = {
117 .readpage = squashfs_symlink_readpage
118};
119
120const struct inode_operations squashfs_symlink_inode_ops = {
121 .readlink = generic_readlink,
122 .get_link = page_get_link,
123 .getxattr = generic_getxattr,
124 .listxattr = squashfs_listxattr
125};
126