LXR linux/fs/isofs/namei.c

   1// SPDX-License-Identifier: GPL-2.0
   2/*
   3 *  linux/fs/isofs/namei.c
   4 *
   5 *  (C) 1992  Eric Youngdale Modified for ISO 9660 filesystem.
   6 *
   7 *  (C) 1991  Linus Torvalds - minix filesystem
   8 */
   9
  10#include <linux/gfp.h>
  11#include "isofs.h"
  12
  13/*
  14 * ok, we cannot use strncmp, as the name is not in our data space.
  15 * Thus we'll have to use isofs_match. No big problem. Match also makes
  16 * some sanity tests.
  17 */
  18static int
  19isofs_cmp(struct dentry *dentry, const char *compare, int dlen)
  20{
  21        struct qstr qstr;
  22        qstr.name = compare;
  23        qstr.len = dlen;
  24        if (likely(!dentry->d_op))
  25                return dentry->d_name.len != dlen || memcmp(dentry->d_name.name, compare, dlen);
  26        return dentry->d_op->d_compare(NULL, dentry->d_name.len, dentry->d_name.name, &qstr);
  27}
  28
  29/*
  30 *      isofs_find_entry()
  31 *
  32 * finds an entry in the specified directory with the wanted name. It
  33 * returns the inode number of the found entry, or 0 on error.
  34 */
  35static unsigned long
  36isofs_find_entry(struct inode *dir, struct dentry *dentry,
  37        unsigned long *block_rv, unsigned long *offset_rv,
  38        char *tmpname, struct iso_directory_record *tmpde)
  39{
  40        unsigned long bufsize = ISOFS_BUFFER_SIZE(dir);
  41        unsigned char bufbits = ISOFS_BUFFER_BITS(dir);
  42        unsigned long block, f_pos, offset, block_saved, offset_saved;
  43        struct buffer_head *bh = NULL;
  44        struct isofs_sb_info *sbi = ISOFS_SB(dir->i_sb);
  45
  46        if (!ISOFS_I(dir)->i_first_extent)
  47                return 0;
  48
  49        f_pos = 0;
  50        offset = 0;
  51        block = 0;
  52
  53        while (f_pos < dir->i_size) {
  54                struct iso_directory_record *de;
  55                int de_len, match, i, dlen;
  56                char *dpnt;
  57
  58                if (!bh) {
  59                        bh = isofs_bread(dir, block);
  60                        if (!bh)
  61                                return 0;
  62                }
  63
  64                de = (struct iso_directory_record *) (bh->b_data + offset);
  65
  66                de_len = *(unsigned char *) de;
  67                if (!de_len) {
  68                        brelse(bh);
  69                        bh = NULL;
  70                        f_pos = (f_pos + ISOFS_BLOCK_SIZE) & ~(ISOFS_BLOCK_SIZE - 1);
  71                        block = f_pos >> bufbits;
  72                        offset = 0;
  73                        continue;
  74                }
  75
  76                block_saved = bh->b_blocknr;
  77                offset_saved = offset;
  78                offset += de_len;
  79                f_pos += de_len;
  80
  81                /* Make sure we have a full directory entry */
  82                if (offset >= bufsize) {
  83                        int slop = bufsize - offset + de_len;
  84                        memcpy(tmpde, de, slop);
  85                        offset &= bufsize - 1;
  86                        block++;
  87                        brelse(bh);
  88                        bh = NULL;
  89                        if (offset) {
  90                                bh = isofs_bread(dir, block);
  91                                if (!bh)
  92                                        return 0;
  93                                memcpy((void *) tmpde + slop, bh->b_data, offset);
  94                        }
  95                        de = tmpde;
  96                }
  97
  98                dlen = de->name_len[0];
  99                dpnt = de->name;
 100                /* Basic sanity check, whether name doesn't exceed dir entry */
 101                if (de_len < dlen + sizeof(struct iso_directory_record)) {
 102                        printk(KERN_NOTICE "iso9660: Corrupted directory entry"
 103                               " in block %lu of inode %lu\n", block,
 104                               dir->i_ino);
 105                        brelse(bh);
 106                        return 0;
 107                }
 108
 109                if (sbi->s_rock &&
 110                    ((i = get_rock_ridge_filename(de, tmpname, dir)))) {
 111                        dlen = i;       /* possibly -1 */
 112                        dpnt = tmpname;
 113#ifdef CONFIG_JOLIET
 114                } else if (sbi->s_joliet_level) {
 115                        dlen = get_joliet_filename(de, tmpname, dir);
 116                        dpnt = tmpname;
 117#endif
 118                } else if (sbi->s_mapping == 'a') {
 119                        dlen = get_acorn_filename(de, tmpname, dir);
 120                        dpnt = tmpname;
 121                } else if (sbi->s_mapping == 'n') {
 122                        dlen = isofs_name_translate(de, tmpname, dir);
 123                        dpnt = tmpname;
 124                }
 125
 126                /*
 127                 * Skip hidden or associated files unless hide or showassoc,
 128                 * respectively, is set
 129                 */
 130                match = 0;
 131                if (dlen > 0 &&
 132                        (!sbi->s_hide ||
 133                                (!(de->flags[-sbi->s_high_sierra] & 1))) &&
 134                        (sbi->s_showassoc ||
 135                                (!(de->flags[-sbi->s_high_sierra] & 4)))) {
 136                        if (dpnt && (dlen > 1 || dpnt[0] > 1))
 137                                match = (isofs_cmp(dentry, dpnt, dlen) == 0);
 138                }
 139                if (match) {
 140                        isofs_normalize_block_and_offset(de,
 141                                                         &block_saved,
 142                                                         &offset_saved);
 143                        *block_rv = block_saved;
 144                        *offset_rv = offset_saved;
 145                        brelse(bh);
 146                        return 1;
 147                }
 148        }
 149        brelse(bh);
 150        return 0;
 151}
 152
 153struct dentry *isofs_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags)
 154{
 155        int found;
 156        unsigned long block;
 157        unsigned long offset;
 158        struct inode *inode;
 159        struct page *page;
 160
 161        page = alloc_page(GFP_USER);
 162        if (!page)
 163                return ERR_PTR(-ENOMEM);
 164
 165        found = isofs_find_entry(dir, dentry,
 166                                &block, &offset,
 167                                page_address(page),
 168                                1024 + page_address(page));
 169        __free_page(page);
 170
 171        inode = found ? isofs_iget(dir->i_sb, block, offset) : NULL;
 172
 173        return d_splice_alias(inode, dentry);
 174}
 175