| lh | 9ed821d | 2023-04-07 01:36:19 -0700 | [diff] [blame] | 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 | |
| 33 | static int udf_pc_to_char(struct super_block *sb, unsigned char *from, |
| 34 | int fromlen, unsigned char *to, int tolen) |
| 35 | { |
| 36 | struct pathComponent *pc; |
| 37 | int elen = 0; |
| 38 | int comp_len; |
| 39 | unsigned char *p = to; |
| 40 | |
| 41 | /* Reserve one byte for terminating \0 */ |
| 42 | tolen--; |
| 43 | while (elen < fromlen) { |
| 44 | pc = (struct pathComponent *)(from + elen); |
| 45 | elen += sizeof(struct pathComponent); |
| 46 | switch (pc->componentType) { |
| 47 | case 1: |
| 48 | /* |
| 49 | * Symlink points to some place which should be agreed |
| 50 | * upon between originator and receiver of the media. Ignore. |
| 51 | */ |
| 52 | if (pc->lengthComponentIdent > 0) { |
| 53 | elen += pc->lengthComponentIdent; |
| 54 | break; |
| 55 | } |
| 56 | /* Fall through */ |
| 57 | case 2: |
| 58 | if (tolen == 0) |
| 59 | return -ENAMETOOLONG; |
| 60 | p = to; |
| 61 | *p++ = '/'; |
| 62 | tolen--; |
| 63 | break; |
| 64 | case 3: |
| 65 | if (tolen < 3) |
| 66 | return -ENAMETOOLONG; |
| 67 | memcpy(p, "../", 3); |
| 68 | p += 3; |
| 69 | tolen -= 3; |
| 70 | break; |
| 71 | case 4: |
| 72 | if (tolen < 2) |
| 73 | return -ENAMETOOLONG; |
| 74 | memcpy(p, "./", 2); |
| 75 | p += 2; |
| 76 | tolen -= 2; |
| 77 | /* that would be . - just ignore */ |
| 78 | break; |
| 79 | case 5: |
| 80 | elen += pc->lengthComponentIdent; |
| 81 | if (elen > fromlen) |
| 82 | return -EIO; |
| 83 | comp_len = udf_get_filename(sb, pc->componentIdent, |
| 84 | pc->lengthComponentIdent, |
| 85 | p, tolen); |
| 86 | p += comp_len; |
| 87 | tolen -= comp_len; |
| 88 | if (tolen == 0) |
| 89 | return -ENAMETOOLONG; |
| 90 | *p++ = '/'; |
| 91 | tolen--; |
| 92 | break; |
| 93 | } |
| 94 | } |
| 95 | if (p > to + 1) |
| 96 | p[-1] = '\0'; |
| 97 | else |
| 98 | p[0] = '\0'; |
| 99 | return 0; |
| 100 | } |
| 101 | |
| 102 | static int udf_symlink_filler(struct file *file, struct page *page) |
| 103 | { |
| 104 | struct inode *inode = page->mapping->host; |
| 105 | struct buffer_head *bh = NULL; |
| 106 | unsigned char *symlink; |
| 107 | int err; |
| 108 | unsigned char *p = kmap(page); |
| 109 | struct udf_inode_info *iinfo; |
| 110 | uint32_t pos; |
| 111 | |
| 112 | /* We don't support symlinks longer than one block */ |
| 113 | if (inode->i_size > inode->i_sb->s_blocksize) { |
| 114 | err = -ENAMETOOLONG; |
| 115 | goto out_unmap; |
| 116 | } |
| 117 | |
| 118 | iinfo = UDF_I(inode); |
| 119 | pos = udf_block_map(inode, 0); |
| 120 | |
| 121 | down_read(&iinfo->i_data_sem); |
| 122 | if (iinfo->i_alloc_type == ICBTAG_FLAG_AD_IN_ICB) { |
| 123 | symlink = iinfo->i_ext.i_data + iinfo->i_lenEAttr; |
| 124 | } else { |
| 125 | bh = sb_bread(inode->i_sb, pos); |
| 126 | |
| 127 | if (!bh) { |
| 128 | err = -EIO; |
| 129 | goto out_unlock_inode; |
| 130 | } |
| 131 | |
| 132 | symlink = bh->b_data; |
| 133 | } |
| 134 | |
| 135 | err = udf_pc_to_char(inode->i_sb, symlink, inode->i_size, p, PAGE_SIZE); |
| 136 | brelse(bh); |
| 137 | if (err) |
| 138 | goto out_unlock_inode; |
| 139 | |
| 140 | up_read(&iinfo->i_data_sem); |
| 141 | SetPageUptodate(page); |
| 142 | kunmap(page); |
| 143 | unlock_page(page); |
| 144 | return 0; |
| 145 | |
| 146 | out_unlock_inode: |
| 147 | up_read(&iinfo->i_data_sem); |
| 148 | SetPageError(page); |
| 149 | out_unmap: |
| 150 | kunmap(page); |
| 151 | unlock_page(page); |
| 152 | return err; |
| 153 | } |
| 154 | |
| 155 | /* |
| 156 | * symlinks can't do much... |
| 157 | */ |
| 158 | const struct address_space_operations udf_symlink_aops = { |
| 159 | .readpage = udf_symlink_filler, |
| 160 | }; |