LXR linux/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 */
  26static 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
  57static 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
  95struct 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)));
 120out:
 121        return d_splice_alias(foundinode, dentry);
 122}
 123