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/smp_lock.h>
  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("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         /* "" means "." ---> so paths like "/usr/lib//libc.a" work */
  44         if (!len && (de->di_fname[0] == '.') && (de->di_fname[1] == '\0')) {
  45                 return 1;
  46         }
  47         thislen = strlen( de->di_fname );
  48         if ( thislen > namelen )
  49                 thislen = namelen;
  50         if (len != thislen) {
  51                 return 0;
  52         }
  53         if (strncmp(name, de->di_fname, len) == 0) {
  54                 if ((de->di_status & (QNX4_FILE_USED|QNX4_FILE_LINK)) != 0) {
  55                         return 1;
  56                 }
  57         }
  58         return 0;
  59 }
  60
  61 static struct buffer_head *qnx4_find_entry(int len, struct inode *dir,
  62            const char *name, struct qnx4_inode_entry **res_dir, int *ino)
  63 {
  64         unsigned long block, offset, blkofs;
  65         struct buffer_head *bh;
  66
  67         *res_dir = NULL;
  68         if (!dir->i_sb) {
  69                 printk("qnx4: no superblock on dir.\n");
  70                 return NULL;
  71         }
  72         bh = NULL;
  73         block = offset = blkofs = 0;
  74         while (blkofs * QNX4_BLOCK_SIZE + offset < dir->i_size) {
  75                 if (!bh) {
  76                         bh = qnx4_bread(dir, blkofs, 0);
  77                         if (!bh) {
  78                                 blkofs++;
  79                                 continue;
  80                         }
  81                 }
  82                 *res_dir = (struct qnx4_inode_entry *) (bh->b_data + offset);
  83                 if (qnx4_match(len, name, bh, &offset)) {
  84                         block = qnx4_block_map( dir, blkofs );
  85                         *ino = block * QNX4_INODES_PER_BLOCK +
  86                             (offset / QNX4_DIR_ENTRY_SIZE) - 1;
  87                         return bh;
  88                 }
  89                 if (offset < bh->b_size) {
  90                         continue;
  91                 }
  92                 brelse(bh);
  93                 bh = NULL;
  94                 offset = 0;
  95                 blkofs++;
  96         }
  97         brelse(bh);
  98         *res_dir = NULL;
  99         return NULL;
 100 }
 101
 102 struct dentry * qnx4_lookup(struct inode *dir, struct dentry *dentry, struct nameidata *nd)
 103 {
 104         int ino;
 105         struct qnx4_inode_entry *de;
 106         struct qnx4_link_info *lnk;
 107         struct buffer_head *bh;
 108         const char *name = dentry->d_name.name;
 109         int len = dentry->d_name.len;
 110         struct inode *foundinode = NULL;
 111
 112         lock_kernel();
 113         if (!(bh = qnx4_find_entry(len, dir, name, &de, &ino)))
 114                 goto out;
 115         /* The entry is linked, let's get the real info */
 116         if ((de->di_status & QNX4_FILE_LINK) == QNX4_FILE_LINK) {
 117                 lnk = (struct qnx4_link_info *) de;
 118                 ino = (le32_to_cpu(lnk->dl_inode_blk) - 1) *
 119                     QNX4_INODES_PER_BLOCK +
 120                     lnk->dl_inode_ndx;
 121         }
 122         brelse(bh);
 123
 124         foundinode = qnx4_iget(dir->i_sb, ino);
 125         if (IS_ERR(foundinode)) {
 126                 unlock_kernel();
 127                 QNX4DEBUG(("qnx4: lookup->iget -> error %ld\n",
 128                            PTR_ERR(foundinode)));
 129                 return ERR_CAST(foundinode);
 130         }
 131 out:
 132         unlock_kernel();
 133         d_add(dentry, foundinode);
 134
 135         return NULL;
 136 }