fs/qnx4/namei.c

   1 /*
   2  * QNX4 file system, Linux implementation.
   3  *
   4  * Version : 0.2.1
   5  *
   6  * Using parts of the xiafs filesystem.
   7  *
   8  * History :
   9  *
  10  * 01-06-1998 by Richard Frowijn : first release.
  11  * 21-06-1998 by Frank Denis : dcache support, fixed error codes.
  12  * 04-07-1998 by Frank Denis : first step for rmdir/unlink.
  13  */
  14
  15 #include <linux/buffer_head.h>
  16 #include "qnx4.h"
  17
  18
  19 /*
  20  * check if the filename is correct. For some obscure reason, qnx writes a
  21  * new file twice in the directory entry, first with all possible options at 0
  22  * and for a second time the way it is, they want us not to access the qnx
  23  * filesystem when whe are using linux.
  24  */
  25 static int qnx4_match(int len, const char *name,
  26                       struct buffer_head *bh, unsigned long *offset)
  27 {
  28         struct qnx4_inode_entry *de;
  29         int namelen, thislen;
  30
  31         if (bh == NULL) {
  32                 printk(KERN_WARNING "qnx4: matching unassigned buffer !\n");
  33                 return 0;
  34         }
  35         de = (struct qnx4_inode_entry *) (bh->b_data + *offset);
  36         *offset += QNX4_DIR_ENTRY_SIZE;
  37         if ((de->di_status & QNX4_FILE_LINK) != 0) {
  38                 namelen = QNX4_NAME_MAX;
  39         } else {
  40                 namelen = QNX4_SHORT_NAME_MAX;
  41         }
  42         thislen = strlen( de->di_fname );
  43         if ( thislen > namelen )
  44                 thislen = namelen;
  45         if (len != thislen) {
  46                 return 0;
  47         }
  48         if (strncmp(name, de->di_fname, len) == 0) {
  49                 if ((de->di_status & (QNX4_FILE_USED|QNX4_FILE_LINK)) != 0) {
  50                         return 1;
  51                 }
  52         }
  53         return 0;
  54 }
  55
  56 static struct buffer_head *qnx4_find_entry(int len, struct inode *dir,
  57            const char *name, struct qnx4_inode_entry **res_dir, int *ino)
  58 {
  59         unsigned long block, offset, blkofs;
  60         struct buffer_head *bh;
  61
  62         *res_dir = NULL;
  63         bh = NULL;
  64         block = offset = blkofs = 0;
  65         while (blkofs * QNX4_BLOCK_SIZE + offset < dir->i_size) {
  66                 if (!bh) {
  67                         block = qnx4_block_map(dir, blkofs);
  68                         if (block)
  69                                 bh = sb_bread(dir->i_sb, block);
  70                         if (!bh) {
  71                                 blkofs++;
  72                                 continue;
  73                         }
  74                 }
  75                 *res_dir = (struct qnx4_inode_entry *) (bh->b_data + offset);
  76                 if (qnx4_match(len, name, bh, &offset)) {
  77                         *ino = block * QNX4_INODES_PER_BLOCK +
  78                             (offset / QNX4_DIR_ENTRY_SIZE) - 1;
  79                         return bh;
  80                 }
  81                 if (offset < bh->b_size) {
  82                         continue;
  83                 }
  84                 brelse(bh);
  85                 bh = NULL;
  86                 offset = 0;
  87                 blkofs++;
  88         }
  89         brelse(bh);
  90         *res_dir = NULL;
  91         return NULL;
  92 }
  93
  94 struct dentry * qnx4_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags)
  95 {
  96         int ino;
  97         struct qnx4_inode_entry *de;
  98         struct qnx4_link_info *lnk;
  99         struct buffer_head *bh;
 100         const char *name = dentry->d_name.name;
 101         int len = dentry->d_name.len;
 102         struct inode *foundinode = NULL;
 103
 104         if (!(bh = qnx4_find_entry(len, dir, name, &de, &ino)))
 105                 goto out;
 106         /* The entry is linked, let's get the real info */
 107         if ((de->di_status & QNX4_FILE_LINK) == QNX4_FILE_LINK) {
 108                 lnk = (struct qnx4_link_info *) de;
 109                 ino = (le32_to_cpu(lnk->dl_inode_blk) - 1) *
 110                     QNX4_INODES_PER_BLOCK +
 111                     lnk->dl_inode_ndx;
 112         }
 113         brelse(bh);
 114
 115         foundinode = qnx4_iget(dir->i_sb, ino);
 116         if (IS_ERR(foundinode)) {
 117                 QNX4DEBUG((KERN_ERR "qnx4: lookup->iget -> error %ld\n",
 118                            PTR_ERR(foundinode)));
 119                 return ERR_CAST(foundinode);
 120         }
 121 out:
 122         d_add(dentry, foundinode);
 123
 124         return NULL;
 125 }