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112 lines
3.1 KiB
112 lines
3.1 KiB
// SPDX-License-Identifier: GPL-2.0-or-later |
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/* |
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* Squashfs - a compressed read only filesystem for Linux |
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* |
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* Copyright (c) 2002, 2003, 2004, 2005, 2006, 2007, 2008 |
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* Phillip Lougher <[email protected]> |
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* |
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* symlink.c |
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*/ |
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/* |
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* This file implements code to handle symbolic links. |
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* |
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* The data contents of symbolic links are stored inside the symbolic |
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* link inode within the inode table. This allows the normally small symbolic |
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* link to be compressed as part of the inode table, achieving much greater |
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* compression than if the symbolic link was compressed individually. |
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*/ |
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#include <linux/fs.h> |
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#include <linux/vfs.h> |
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#include <linux/kernel.h> |
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#include <linux/string.h> |
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#include <linux/pagemap.h> |
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#include <linux/xattr.h> |
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#include "squashfs_fs.h" |
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#include "squashfs_fs_sb.h" |
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#include "squashfs_fs_i.h" |
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#include "squashfs.h" |
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#include "xattr.h" |
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static int squashfs_symlink_read_folio(struct file *file, struct folio *folio) |
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{ |
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struct page *page = &folio->page; |
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struct inode *inode = page->mapping->host; |
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struct super_block *sb = inode->i_sb; |
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struct squashfs_sb_info *msblk = sb->s_fs_info; |
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int index = page->index << PAGE_SHIFT; |
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u64 block = squashfs_i(inode)->start; |
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int offset = squashfs_i(inode)->offset; |
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int length = min_t(int, i_size_read(inode) - index, PAGE_SIZE); |
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int bytes, copied; |
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void *pageaddr; |
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struct squashfs_cache_entry *entry; |
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TRACE("Entered squashfs_symlink_readpage, page index %ld, start block " |
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"%llx, offset %x\n", page->index, block, offset); |
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/* |
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* Skip index bytes into symlink metadata. |
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*/ |
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if (index) { |
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bytes = squashfs_read_metadata(sb, NULL, &block, &offset, |
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index); |
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if (bytes < 0) { |
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ERROR("Unable to read symlink [%llx:%x]\n", |
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squashfs_i(inode)->start, |
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squashfs_i(inode)->offset); |
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goto error_out; |
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} |
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} |
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/* |
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* Read length bytes from symlink metadata. Squashfs_read_metadata |
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* is not used here because it can sleep and we want to use |
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* kmap_atomic to map the page. Instead call the underlying |
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* squashfs_cache_get routine. As length bytes may overlap metadata |
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* blocks, we may need to call squashfs_cache_get multiple times. |
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*/ |
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for (bytes = 0; bytes < length; offset = 0, bytes += copied) { |
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entry = squashfs_cache_get(sb, msblk->block_cache, block, 0); |
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if (entry->error) { |
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ERROR("Unable to read symlink [%llx:%x]\n", |
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squashfs_i(inode)->start, |
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squashfs_i(inode)->offset); |
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squashfs_cache_put(entry); |
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goto error_out; |
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} |
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pageaddr = kmap_atomic(page); |
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copied = squashfs_copy_data(pageaddr + bytes, entry, offset, |
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length - bytes); |
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if (copied == length - bytes) |
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memset(pageaddr + length, 0, PAGE_SIZE - length); |
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else |
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block = entry->next_index; |
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kunmap_atomic(pageaddr); |
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squashfs_cache_put(entry); |
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} |
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flush_dcache_page(page); |
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SetPageUptodate(page); |
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unlock_page(page); |
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return 0; |
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error_out: |
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SetPageError(page); |
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unlock_page(page); |
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return 0; |
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} |
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const struct address_space_operations squashfs_symlink_aops = { |
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.read_folio = squashfs_symlink_read_folio |
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}; |
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const struct inode_operations squashfs_symlink_inode_ops = { |
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.get_link = page_get_link, |
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.listxattr = squashfs_listxattr |
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}; |
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