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         struct qnx4_inode_entry *de;
  30         int namelen, thislen;
  31
  32         if (bh == NULL) {
  33                 printk(KERN_WARNING "qnx4: matching unassigned buffer !\n");
  34                 return 0;
  35         }
  36         de = (struct qnx4_inode_entry *) (bh->b_data + *offset);
  37         *offset += QNX4_DIR_ENTRY_SIZE;
  38         if ((de->di_status & QNX4_FILE_LINK) != 0) {
  39                 namelen = QNX4_NAME_MAX;
  40         } else {
  41                 namelen = QNX4_SHORT_NAME_MAX;
  42         }
  43         thislen = strlen( de->di_fname );
  44         if ( thislen > namelen )
  45                 thislen = namelen;
  46         if (len != thislen) {
  47                 return 0;
  48         }
  49         if (strncmp(name, de->di_fname, len) == 0) {
  50                 if ((de->di_status & (QNX4_FILE_USED|QNX4_FILE_LINK)) != 0) {
  51                         return 1;
  52                 }
  53         }
  54         return 0;
  55 }
  56
  57 static struct buffer_head *qnx4_find_entry(int len, struct inode *dir,
  58            const char *name, struct qnx4_inode_entry **res_dir, int *ino)
  59 {
  60         unsigned long block, offset, blkofs;
  61         struct buffer_head *bh;
  62
  63         *res_dir = NULL;
  64         bh = NULL;
  65         block = offset = blkofs = 0;
  66         while (blkofs * QNX4_BLOCK_SIZE + offset < dir->i_size) {
  67                 if (!bh) {
  68                         block = qnx4_block_map(dir, blkofs);
  69                         if (block)
  70                                 bh = sb_bread(dir->i_sb, block);
  71                         if (!bh) {
  72                                 blkofs++;
  73                                 continue;
  74                         }
  75                 }
  76                 *res_dir = (struct qnx4_inode_entry *) (bh->b_data + offset);
  77                 if (qnx4_match(len, name, bh, &offset)) {
  78                         *ino = block * QNX4_INODES_PER_BLOCK +
  79                             (offset / QNX4_DIR_ENTRY_SIZE) - 1;
  80                         return bh;
  81                 }
  82                 if (offset < bh->b_size) {
  83                         continue;
  84                 }
  85                 brelse(bh);
  86                 bh = NULL;
  87                 offset = 0;
  88                 blkofs++;
  89         }
  90         brelse(bh);
  91         *res_dir = NULL;
  92         return NULL;
  93 }
  94
  95 struct dentry * qnx4_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags)
  96 {
  97         int ino;
  98         struct qnx4_inode_entry *de;
  99         struct qnx4_link_info *lnk;
 100         struct buffer_head *bh;
 101         const char *name = dentry->d_name.name;
 102         int len = dentry->d_name.len;
 103         struct inode *foundinode = NULL;
 104
 105         if (!(bh = qnx4_find_entry(len, dir, name, &de, &ino)))
 106                 goto out;
 107         /* The entry is linked, let's get the real info */
 108         if ((de->di_status & QNX4_FILE_LINK) == QNX4_FILE_LINK) {
 109                 lnk = (struct qnx4_link_info *) de;
 110                 ino = (le32_to_cpu(lnk->dl_inode_blk) - 1) *
 111                     QNX4_INODES_PER_BLOCK +
 112                     lnk->dl_inode_ndx;
 113         }
 114         brelse(bh);
 115
 116         foundinode = qnx4_iget(dir->i_sb, ino);
 117         if (IS_ERR(foundinode))
 118                 QNX4DEBUG((KERN_ERR "qnx4: lookup->iget -> error %ld\n",
 119                            PTR_ERR(foundinode)));
 120 out:
 121         return d_splice_alias(foundinode, dentry);
 122 }