fs/qnx4/namei.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * QNX4 file system, Linux implementation.
   4  *
   5  * Version : 0.2.1
   6  *
   7  * Using parts of the xiafs filesystem.
   8  *
   9  * History :
  10  *
  11  * 01-06-1998 by Richard Frowijn : first release.
  12  * 21-06-1998 by Frank Denis : dcache support, fixed error codes.
  13  * 04-07-1998 by Frank Denis : first step for rmdir/unlink.
  14  */
  15
  16 #include <linux/buffer_head.h>
  17 #include "qnx4.h"
  18
  19
  20 /*
  21  * check if the filename is correct. For some obscure reason, qnx writes a
  22  * new file twice in the directory entry, first with all possible options at 0
  23  * and for a second time the way it is, they want us not to access the qnx
  24  * filesystem when whe are using linux.
  25  */
  26 static int qnx4_match(int len, const char *name,
  27                       struct buffer_head *bh, unsigned long *offset)
  28 {
  29         union qnx4_directory_entry *de;
  30         const char *fname;
  31         int fnamelen;
  32
  33         if (bh == NULL) {
  34                 printk(KERN_WARNING "qnx4: matching unassigned buffer !\n");
  35                 return 0;
  36         }
  37         de = (union qnx4_directory_entry *) (bh->b_data + *offset);
  38         *offset += QNX4_DIR_ENTRY_SIZE;
  39
  40         fname = get_entry_fname(de, &fnamelen);
  41         if (!fname || len != fnamelen)
  42                 return 0;
  43
  44         if (strncmp(name, fname, len) == 0)
  45                 return 1;
  46
  47         return 0;
  48 }
  49
  50 static struct buffer_head *qnx4_find_entry(int len, struct inode *dir,
  51            const char *name, struct qnx4_inode_entry **res_dir, int *ino)
  52 {
  53         unsigned long block, offset, blkofs;
  54         struct buffer_head *bh;
  55
  56         *res_dir = NULL;
  57         bh = NULL;
  58         block = offset = blkofs = 0;
  59         while (blkofs * QNX4_BLOCK_SIZE + offset < dir->i_size) {
  60                 if (!bh) {
  61                         block = qnx4_block_map(dir, blkofs);
  62                         if (block)
  63                                 bh = sb_bread(dir->i_sb, block);
  64                         if (!bh) {
  65                                 blkofs++;
  66                                 continue;
  67                         }
  68                 }
  69                 *res_dir = (struct qnx4_inode_entry *) (bh->b_data + offset);
  70                 if (qnx4_match(len, name, bh, &offset)) {
  71                         *ino = block * QNX4_INODES_PER_BLOCK +
  72                             (offset / QNX4_DIR_ENTRY_SIZE) - 1;
  73                         return bh;
  74                 }
  75                 if (offset < bh->b_size) {
  76                         continue;
  77                 }
  78                 brelse(bh);
  79                 bh = NULL;
  80                 offset = 0;
  81                 blkofs++;
  82         }
  83         brelse(bh);
  84         *res_dir = NULL;
  85         return NULL;
  86 }
  87
  88 struct dentry * qnx4_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags)
  89 {
  90         int ino;
  91         struct qnx4_inode_entry *de;
  92         struct qnx4_link_info *lnk;
  93         struct buffer_head *bh;
  94         const char *name = dentry->d_name.name;
  95         int len = dentry->d_name.len;
  96         struct inode *foundinode = NULL;
  97
  98         if (!(bh = qnx4_find_entry(len, dir, name, &de, &ino)))
  99                 goto out;
 100         /* The entry is linked, let's get the real info */
 101         if ((de->di_status & QNX4_FILE_LINK) == QNX4_FILE_LINK) {
 102                 lnk = (struct qnx4_link_info *) de;
 103                 ino = (le32_to_cpu(lnk->dl_inode_blk) - 1) *
 104                     QNX4_INODES_PER_BLOCK +
 105                     lnk->dl_inode_ndx;
 106         }
 107         brelse(bh);
 108
 109         foundinode = qnx4_iget(dir->i_sb, ino);
 110         if (IS_ERR(foundinode))
 111                 QNX4DEBUG((KERN_ERR "qnx4: lookup->iget -> error %ld\n",
 112                            PTR_ERR(foundinode)));
 113 out:
 114         return d_splice_alias(foundinode, dentry);
 115 }