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         if (!dir->i_sb) {
  64                 printk(KERN_WARNING "qnx4: no superblock on dir.\n");
  65                 return NULL;
  66         }
  67         bh = NULL;
  68         block = offset = blkofs = 0;
  69         while (blkofs * QNX4_BLOCK_SIZE + offset < dir->i_size) {
  70                 if (!bh) {
  71                         block = qnx4_block_map(dir, blkofs);
  72                         if (block)
  73                                 bh = sb_bread(dir->i_sb, block);
  74                         if (!bh) {
  75                                 blkofs++;
  76                                 continue;
  77                         }
  78                 }
  79                 *res_dir = (struct qnx4_inode_entry *) (bh->b_data + offset);
  80                 if (qnx4_match(len, name, bh, &offset)) {
  81                         *ino = block * QNX4_INODES_PER_BLOCK +
  82                             (offset / QNX4_DIR_ENTRY_SIZE) - 1;
  83                         return bh;
  84                 }
  85                 if (offset < bh->b_size) {
  86                         continue;
  87                 }
  88                 brelse(bh);
  89                 bh = NULL;
  90                 offset = 0;
  91                 blkofs++;
  92         }
  93         brelse(bh);
  94         *res_dir = NULL;
  95         return NULL;
  96 }
  97
  98 struct dentry * qnx4_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags)
  99 {
 100         int ino;
 101         struct qnx4_inode_entry *de;
 102         struct qnx4_link_info *lnk;
 103         struct buffer_head *bh;
 104         const char *name = dentry->d_name.name;
 105         int len = dentry->d_name.len;
 106         struct inode *foundinode = NULL;
 107
 108         if (!(bh = qnx4_find_entry(len, dir, name, &de, &ino)))
 109                 goto out;
 110         /* The entry is linked, let's get the real info */
 111         if ((de->di_status & QNX4_FILE_LINK) == QNX4_FILE_LINK) {
 112                 lnk = (struct qnx4_link_info *) de;
 113                 ino = (le32_to_cpu(lnk->dl_inode_blk) - 1) *
 114                     QNX4_INODES_PER_BLOCK +
 115                     lnk->dl_inode_ndx;
 116         }
 117         brelse(bh);
 118
 119         foundinode = qnx4_iget(dir->i_sb, ino);
 120         if (IS_ERR(foundinode)) {
 121                 QNX4DEBUG((KERN_ERR "qnx4: lookup->iget -> error %ld\n",
 122                            PTR_ERR(foundinode)));
 123                 return ERR_CAST(foundinode);
 124         }
 125 out:
 126         d_add(dentry, foundinode);
 127
 128         return NULL;
 129 }