1/*
  2 * symlink.c
  3 *
  4 * PURPOSE
  5 *	Symlink handling routines for the OSTA-UDF(tm) filesystem.
  6 *
  7 * COPYRIGHT
  8 *	This file is distributed under the terms of the GNU General Public
  9 *	License (GPL). Copies of the GPL can be obtained from:
 10 *		ftp://prep.ai.mit.edu/pub/gnu/GPL
 11 *	Each contributing author retains all rights to their own work.
 12 *
 13 *  (C) 1998-2001 Ben Fennema
 14 *  (C) 1999 Stelias Computing Inc
 15 *
 16 * HISTORY
 17 *
 18 *  04/16/99 blf  Created.
 19 *
 20 */
 21
 22#include "udfdecl.h"
 23#include <asm/uaccess.h>
 24#include <linux/errno.h>
 25#include <linux/fs.h>
 26#include <linux/time.h>
 27#include <linux/mm.h>
 28#include <linux/stat.h>
 29#include <linux/pagemap.h>
 30#include <linux/buffer_head.h>
 31#include "udf_i.h"
 32
 33static void udf_pc_to_char(struct super_block *sb, unsigned char *from,
 34			   int fromlen, unsigned char *to)
 35{
 36	struct pathComponent *pc;
 37	int elen = 0;
 38	unsigned char *p = to;
 39
 40	while (elen < fromlen) {
 41		pc = (struct pathComponent *)(from + elen);
 42		switch (pc->componentType) {
 43		case 1:
 44			/*
 45			 * Symlink points to some place which should be agreed
 46 			 * upon between originator and receiver of the media. Ignore.
 47			 */
 48			if (pc->lengthComponentIdent > 0)
 49				break;
 50			/* Fall through */
 51		case 2:
 52			p = to;
 53			*p++ = '/';
 54			break;
 55		case 3:
 56			memcpy(p, "../", 3);
 57			p += 3;
 58			break;
 59		case 4:
 60			memcpy(p, "./", 2);
 61			p += 2;
 62			/* that would be . - just ignore */
 63			break;
 64		case 5:
 65			p += udf_get_filename(sb, pc->componentIdent, p,
 66					      pc->lengthComponentIdent);
 67			*p++ = '/';
 68			break;
 69		}
 70		elen += sizeof(struct pathComponent) + pc->lengthComponentIdent;
 71	}
 72	if (p > to + 1)
 73		p[-1] = '\0';
 74	else
 75		p[0] = '\0';
 76}
 77
 78static int udf_symlink_filler(struct file *file, struct page *page)
 79{
 80	struct inode *inode = page->mapping->host;
 81	struct buffer_head *bh = NULL;
 82	unsigned char *symlink;
 83	int err = -EIO;
 84	unsigned char *p = kmap(page);
 85	struct udf_inode_info *iinfo;
 86	uint32_t pos;
 87
 88	iinfo = UDF_I(inode);
 89	pos = udf_block_map(inode, 0);
 90
 91	down_read(&iinfo->i_data_sem);
 92	if (iinfo->i_alloc_type == ICBTAG_FLAG_AD_IN_ICB) {
 93		symlink = iinfo->i_ext.i_data + iinfo->i_lenEAttr;
 94	} else {
 95		bh = sb_bread(inode->i_sb, pos);
 96
 97		if (!bh)
 98			goto out;
 99
100		symlink = bh->b_data;
101	}
102
103	udf_pc_to_char(inode->i_sb, symlink, inode->i_size, p);
104	brelse(bh);
105
106	up_read(&iinfo->i_data_sem);
107	SetPageUptodate(page);
108	kunmap(page);
109	unlock_page(page);
110	return 0;
111
112out:
113	up_read(&iinfo->i_data_sem);
114	SetPageError(page);
115	kunmap(page);
116	unlock_page(page);
117	return err;
118}
119
120/*
121 * symlinks can't do much...
122 */
123const struct address_space_operations udf_symlink_aops = {
124	.readpage		= udf_symlink_filler,
125};