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193 lines
4.3 KiB
193 lines
4.3 KiB
/* |
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* symlink.c |
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* |
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* PURPOSE |
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* Symlink handling routines for the OSTA-UDF(tm) filesystem. |
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* |
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* COPYRIGHT |
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* This file is distributed under the terms of the GNU General Public |
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* License (GPL). Copies of the GPL can be obtained from: |
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* ftp://prep.ai.mit.edu/pub/gnu/GPL |
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* Each contributing author retains all rights to their own work. |
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* |
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* (C) 1998-2001 Ben Fennema |
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* (C) 1999 Stelias Computing Inc |
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* |
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* HISTORY |
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* |
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* 04/16/99 blf Created. |
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* |
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*/ |
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#include "udfdecl.h" |
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#include <linux/uaccess.h> |
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#include <linux/errno.h> |
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#include <linux/fs.h> |
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#include <linux/time.h> |
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#include <linux/mm.h> |
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#include <linux/stat.h> |
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#include <linux/pagemap.h> |
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#include "udf_i.h" |
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static int udf_pc_to_char(struct super_block *sb, unsigned char *from, |
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int fromlen, unsigned char *to, int tolen) |
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{ |
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struct pathComponent *pc; |
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int elen = 0; |
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int comp_len; |
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unsigned char *p = to; |
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/* Reserve one byte for terminating \0 */ |
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tolen--; |
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while (elen < fromlen) { |
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pc = (struct pathComponent *)(from + elen); |
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elen += sizeof(struct pathComponent); |
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switch (pc->componentType) { |
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case 1: |
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/* |
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* Symlink points to some place which should be agreed |
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* upon between originator and receiver of the media. Ignore. |
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*/ |
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if (pc->lengthComponentIdent > 0) { |
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elen += pc->lengthComponentIdent; |
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break; |
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} |
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fallthrough; |
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case 2: |
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if (tolen == 0) |
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return -ENAMETOOLONG; |
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p = to; |
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*p++ = '/'; |
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tolen--; |
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break; |
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case 3: |
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if (tolen < 3) |
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return -ENAMETOOLONG; |
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memcpy(p, "../", 3); |
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p += 3; |
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tolen -= 3; |
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break; |
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case 4: |
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if (tolen < 2) |
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return -ENAMETOOLONG; |
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memcpy(p, "./", 2); |
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p += 2; |
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tolen -= 2; |
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/* that would be . - just ignore */ |
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break; |
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case 5: |
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elen += pc->lengthComponentIdent; |
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if (elen > fromlen) |
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return -EIO; |
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comp_len = udf_get_filename(sb, pc->componentIdent, |
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pc->lengthComponentIdent, |
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p, tolen); |
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if (comp_len < 0) |
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return comp_len; |
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p += comp_len; |
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tolen -= comp_len; |
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if (tolen == 0) |
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return -ENAMETOOLONG; |
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*p++ = '/'; |
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tolen--; |
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break; |
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} |
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} |
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if (p > to + 1) |
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p[-1] = '\0'; |
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else |
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p[0] = '\0'; |
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return 0; |
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} |
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static int udf_symlink_filler(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 buffer_head *bh = NULL; |
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unsigned char *symlink; |
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int err; |
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unsigned char *p = page_address(page); |
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struct udf_inode_info *iinfo; |
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uint32_t pos; |
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/* We don't support symlinks longer than one block */ |
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if (inode->i_size > inode->i_sb->s_blocksize) { |
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err = -ENAMETOOLONG; |
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goto out_unmap; |
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} |
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iinfo = UDF_I(inode); |
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pos = udf_block_map(inode, 0); |
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down_read(&iinfo->i_data_sem); |
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if (iinfo->i_alloc_type == ICBTAG_FLAG_AD_IN_ICB) { |
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symlink = iinfo->i_data + iinfo->i_lenEAttr; |
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} else { |
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bh = sb_bread(inode->i_sb, pos); |
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if (!bh) { |
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err = -EIO; |
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goto out_unlock_inode; |
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} |
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symlink = bh->b_data; |
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} |
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err = udf_pc_to_char(inode->i_sb, symlink, inode->i_size, p, PAGE_SIZE); |
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brelse(bh); |
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if (err) |
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goto out_unlock_inode; |
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up_read(&iinfo->i_data_sem); |
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SetPageUptodate(page); |
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unlock_page(page); |
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return 0; |
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out_unlock_inode: |
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up_read(&iinfo->i_data_sem); |
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SetPageError(page); |
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out_unmap: |
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unlock_page(page); |
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return err; |
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} |
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static int udf_symlink_getattr(struct user_namespace *mnt_userns, |
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const struct path *path, struct kstat *stat, |
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u32 request_mask, unsigned int flags) |
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{ |
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struct dentry *dentry = path->dentry; |
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struct inode *inode = d_backing_inode(dentry); |
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struct page *page; |
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generic_fillattr(&init_user_ns, inode, stat); |
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page = read_mapping_page(inode->i_mapping, 0, NULL); |
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if (IS_ERR(page)) |
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return PTR_ERR(page); |
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/* |
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* UDF uses non-trivial encoding of symlinks so i_size does not match |
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* number of characters reported by readlink(2) which apparently some |
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* applications expect. Also POSIX says that "The value returned in the |
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* st_size field shall be the length of the contents of the symbolic |
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* link, and shall not count a trailing null if one is present." So |
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* let's report the length of string returned by readlink(2) for |
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* st_size. |
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*/ |
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stat->size = strlen(page_address(page)); |
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put_page(page); |
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return 0; |
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} |
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/* |
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* symlinks can't do much... |
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*/ |
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const struct address_space_operations udf_symlink_aops = { |
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.read_folio = udf_symlink_filler, |
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}; |
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const struct inode_operations udf_symlink_inode_operations = { |
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.get_link = page_get_link, |
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.getattr = udf_symlink_getattr, |
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};
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