From ace9429bb58fd418f0c81d4c2835699bddf6bde6 Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Thu, 11 Apr 2024 10:27:49 +0200 Subject: Adding upstream version 6.6.15. Signed-off-by: Daniel Baumann --- fs/squashfs/symlink.c | 112 ++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 112 insertions(+) create mode 100644 fs/squashfs/symlink.c (limited to 'fs/squashfs/symlink.c') diff --git a/fs/squashfs/symlink.c b/fs/squashfs/symlink.c new file mode 100644 index 000000000..2bf977a52 --- /dev/null +++ b/fs/squashfs/symlink.c @@ -0,0 +1,112 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Squashfs - a compressed read only filesystem for Linux + * + * Copyright (c) 2002, 2003, 2004, 2005, 2006, 2007, 2008 + * Phillip Lougher + * + * 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 +#include +#include +#include +#include +#include + +#include "squashfs_fs.h" +#include "squashfs_fs_sb.h" +#include "squashfs_fs_i.h" +#include "squashfs.h" +#include "xattr.h" + +static int squashfs_symlink_read_folio(struct file *file, struct folio *folio) +{ + struct page *page = &folio->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_SHIFT; + u64 block = squashfs_i(inode)->start; + int offset = squashfs_i(inode)->offset; + int length = min_t(int, i_size_read(inode) - index, PAGE_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_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 = { + .read_folio = squashfs_symlink_read_folio +}; + +const struct inode_operations squashfs_symlink_inode_ops = { + .get_link = page_get_link, + .listxattr = squashfs_listxattr +}; + -- cgit v1.2.3