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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 | // SPDX-License-Identifier: GPL-2.0-only /* * symlink.c * * PURPOSE * Symlink handling routines for the OSTA-UDF(tm) filesystem. * * COPYRIGHT * (C) 1998-2001 Ben Fennema * (C) 1999 Stelias Computing Inc * * HISTORY * * 04/16/99 blf Created. * */ #include "udfdecl.h" #include <linux/uaccess.h> #include <linux/errno.h> #include <linux/fs.h> #include <linux/time.h> #include <linux/mm.h> #include <linux/stat.h> #include <linux/pagemap.h> #include "udf_i.h" static int udf_pc_to_char(struct super_block *sb, unsigned char *from, int fromlen, unsigned char *to, int tolen) { struct pathComponent *pc; int elen = 0; int comp_len; unsigned char *p = to; /* Reserve one byte for terminating \0 */ tolen--; while (elen < fromlen) { pc = (struct pathComponent *)(from + elen); elen += sizeof(struct pathComponent); switch (pc->componentType) { case 1: /* * Symlink points to some place which should be agreed * upon between originator and receiver of the media. Ignore. */ if (pc->lengthComponentIdent > 0) { elen += pc->lengthComponentIdent; break; } fallthrough; case 2: if (tolen == 0) return -ENAMETOOLONG; p = to; *p++ = '/'; tolen--; break; case 3: if (tolen < 3) return -ENAMETOOLONG; memcpy(p, "../", 3); p += 3; tolen -= 3; break; case 4: if (tolen < 2) return -ENAMETOOLONG; memcpy(p, "./", 2); p += 2; tolen -= 2; /* that would be . - just ignore */ break; case 5: elen += pc->lengthComponentIdent; if (elen > fromlen) return -EIO; comp_len = udf_get_filename(sb, pc->componentIdent, pc->lengthComponentIdent, p, tolen); if (comp_len < 0) return comp_len; p += comp_len; tolen -= comp_len; if (tolen == 0) return -ENAMETOOLONG; *p++ = '/'; tolen--; break; } } if (p > to + 1) p[-1] = '\0'; else p[0] = '\0'; return 0; } static int udf_symlink_filler(struct file *file, struct folio *folio) { struct page *page = &folio->page; struct inode *inode = page->mapping->host; struct buffer_head *bh = NULL; unsigned char *symlink; int err = 0; unsigned char *p = page_address(page); struct udf_inode_info *iinfo = UDF_I(inode); /* We don't support symlinks longer than one block */ if (inode->i_size > inode->i_sb->s_blocksize) { err = -ENAMETOOLONG; goto out_unlock; } if (iinfo->i_alloc_type == ICBTAG_FLAG_AD_IN_ICB) { symlink = iinfo->i_data + iinfo->i_lenEAttr; } else { bh = udf_bread(inode, 0, 0, &err); if (!bh) { if (!err) err = -EFSCORRUPTED; goto out_err; } symlink = bh->b_data; } err = udf_pc_to_char(inode->i_sb, symlink, inode->i_size, p, PAGE_SIZE); brelse(bh); if (err) goto out_err; SetPageUptodate(page); unlock_page(page); return 0; out_err: SetPageError(page); out_unlock: unlock_page(page); return err; } static int udf_symlink_getattr(struct mnt_idmap *idmap, const struct path *path, struct kstat *stat, u32 request_mask, unsigned int flags) { struct dentry *dentry = path->dentry; struct inode *inode = d_backing_inode(dentry); struct page *page; generic_fillattr(&nop_mnt_idmap, inode, stat); page = read_mapping_page(inode->i_mapping, 0, NULL); if (IS_ERR(page)) return PTR_ERR(page); /* * UDF uses non-trivial encoding of symlinks so i_size does not match * number of characters reported by readlink(2) which apparently some * applications expect. Also POSIX says that "The value returned in the * st_size field shall be the length of the contents of the symbolic * link, and shall not count a trailing null if one is present." So * let's report the length of string returned by readlink(2) for * st_size. */ stat->size = strlen(page_address(page)); put_page(page); return 0; } /* * symlinks can't do much... */ const struct address_space_operations udf_symlink_aops = { .read_folio = udf_symlink_filler, }; const struct inode_operations udf_symlink_inode_operations = { .get_link = page_get_link, .getattr = udf_symlink_getattr, }; |