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/*

 * QNX4 file system, Linux implementation.

 *

 * Version : 0.2.1

 *

 * Using parts of the xiafs filesystem.

 *

 * History :

 *

 * 01-06-1998 by Richard Frowijn : first release.

 * 21-06-1998 by Frank Denis : dcache support, fixed error codes.

 * 04-07-1998 by Frank Denis : first step for rmdir/unlink.

 */

#include <linux/time.h>

#include <linux/fs.h>

#include <linux/qnx4_fs.h>

#include <linux/kernel.h>

#include <linux/string.h>

#include <linux/stat.h>

#include <linux/fcntl.h>

#include <linux/errno.h>

#include <linux/smp_lock.h>

#include <linux/buffer_head.h>

/*

 * check if the filename is correct. For some obscure reason, qnx writes a

 * new file twice in the directory entry, first with all possible options at 0

 * and for a second time the way it is, they want us not to access the qnx

 * filesystem when whe are using linux.

 */

static int qnx4_match(int len, const char *name,

                      struct buffer_head *bh, unsigned long *offset)

{

        struct qnx4_inode_entry *de;

        int namelen, thislen;

        if (bh == NULL) {

                printk("qnx4: matching unassigned buffer !\n");

                return 0;

        }

        de = (struct qnx4_inode_entry *) (bh->b_data + *offset);

        *offset += QNX4_DIR_ENTRY_SIZE;

        if ((de->di_status & QNX4_FILE_LINK) != 0) {

                namelen = QNX4_NAME_MAX;

        } else {

                namelen = QNX4_SHORT_NAME_MAX;

        }

        /* "" means "." ---> so paths like "/usr/lib//libc.a" work */

        if (!len && (de->di_fname[0] == '.') && (de->di_fname[1] == '\0')) {

                return 1;

        }

        thislen = strlen( de->di_fname );

        if ( thislen > namelen )

                thislen = namelen;

        if (len != thislen) {

                return 0;

        }

        if (strncmp(name, de->di_fname, len) == 0) {

                if ((de->di_status & (QNX4_FILE_USED|QNX4_FILE_LINK)) != 0) {

                        return 1;

                }

        }

        return 0;

}

static struct buffer_head *qnx4_find_entry(int len, struct inode *dir,

           const char *name, struct qnx4_inode_entry **res_dir, int *ino)

{

        unsigned long block, offset, blkofs;

        struct buffer_head *bh;

        *res_dir = NULL;

        if (!dir->i_sb) {

                printk("qnx4: no superblock on dir.\n");

                return NULL;

        }

        bh = NULL;

        block = offset = blkofs = 0;

        while (blkofs * QNX4_BLOCK_SIZE + offset < dir->i_size) {

                if (!bh) {

                        bh = qnx4_bread(dir, blkofs, 0);

                        if (!bh) {

                                blkofs++;

                                continue;

                        }

                }

                *res_dir = (struct qnx4_inode_entry *) (bh->b_data + offset);

                if (qnx4_match(len, name, bh, &offset)) {

                        block = qnx4_block_map( dir, blkofs );

                        *ino = block * QNX4_INODES_PER_BLOCK +

                            (offset / QNX4_DIR_ENTRY_SIZE) - 1;

                        return bh;

                }

                if (offset < bh->b_size) {

                        continue;

                }

                brelse(bh);

                bh = NULL;

                offset = 0;

                blkofs++;

        }

        brelse(bh);

        *res_dir = NULL;

        return NULL;

}

struct dentry * qnx4_lookup(struct inode *dir, struct dentry *dentry, struct nameidata *nd)

{

        int ino;

        struct qnx4_inode_entry *de;

        struct qnx4_link_info *lnk;

        struct buffer_head *bh;

        const char *name = dentry->d_name.name;

        int len = dentry->d_name.len;

        struct inode *foundinode = NULL;

        lock_kernel();

        if (!(bh = qnx4_find_entry(len, dir, name, &de, &ino)))

                goto out;

        /* The entry is linked, let's get the real info */

        if ((de->di_status & QNX4_FILE_LINK) == QNX4_FILE_LINK) {

                lnk = (struct qnx4_link_info *) de;

                ino = (le32_to_cpu(lnk->dl_inode_blk) - 1) *

                    QNX4_INODES_PER_BLOCK +

                    lnk->dl_inode_ndx;

        }

        brelse(bh);

        if ((foundinode = iget(dir->i_sb, ino)) == NULL) {

                unlock_kernel();

                QNX4DEBUG(("qnx4: lookup->iget -> NULL\n"));

                return ERR_PTR(-EACCES);

        }

out:

        unlock_kernel();

        d_add(dentry, foundinode);

        return NULL;

}

#ifdef CONFIG_QNX4FS_RW

int qnx4_create(struct inode *dir, struct dentry *dentry, int mode,

                struct nameidata *nd)

{

        QNX4DEBUG(("qnx4: qnx4_create\n"));

        if (dir == NULL) {

                return -ENOENT;

        }

        return -ENOSPC;

}

int qnx4_rmdir(struct inode *dir, struct dentry *dentry)

{

        struct buffer_head *bh;

        struct qnx4_inode_entry *de;

        struct inode *inode;

        int retval;

        int ino;

        QNX4DEBUG(("qnx4: qnx4_rmdir [%s]\n", dentry->d_name.name));

        lock_kernel();

        bh = qnx4_find_entry(dentry->d_name.len, dir, dentry->d_name.name,

                             &de, &ino);

        if (bh == NULL) {

                unlock_kernel();

                return -ENOENT;

        }

        inode = dentry->d_inode;

        if (inode->i_ino != ino) {

                retval = -EIO;

                goto end_rmdir;

        }

#if 0

        if (!empty_dir(inode)) {

                retval = -ENOTEMPTY;

                goto end_rmdir;

        }

#endif

        if (inode->i_nlink != 2) {

                QNX4DEBUG(("empty directory has nlink!=2 (%d)\n", inode->i_nlink));

        }

        QNX4DEBUG(("qnx4: deleting directory\n"));

        de->di_status = 0;

        memset(de->di_fname, 0, sizeof de->di_fname);

        de->di_mode = 0;

        mark_buffer_dirty(bh);

        clear_nlink(inode);

        mark_inode_dirty(inode);

        inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME_SEC;

        inode_dec_link_count(dir);

        retval = 0;

      end_rmdir:

        brelse(bh);

        unlock_kernel();

        return retval;

}

int qnx4_unlink(struct inode *dir, struct dentry *dentry)

{

        struct buffer_head *bh;

        struct qnx4_inode_entry *de;

        struct inode *inode;

        int retval;

        int ino;

        QNX4DEBUG(("qnx4: qnx4_unlink [%s]\n", dentry->d_name.name));

        lock_kernel();

        bh = qnx4_find_entry(dentry->d_name.len, dir, dentry->d_name.name,

                             &de, &ino);

        if (bh == NULL) {

                unlock_kernel();

                return -ENOENT;

        }

        inode = dentry->d_inode;

        if (inode->i_ino != ino) {

                retval = -EIO;

                goto end_unlink;

        }

        retval = -EPERM;

        if (!inode->i_nlink) {

                QNX4DEBUG(("Deleting nonexistent file (%s:%lu), %d\n",

                           inode->i_sb->s_id,

                           inode->i_ino, inode->i_nlink));

                inode->i_nlink = 1;

        }

        de->di_status = 0;

        memset(de->di_fname, 0, sizeof de->di_fname);

        de->di_mode = 0;

        mark_buffer_dirty(bh);

        dir->i_ctime = dir->i_mtime = CURRENT_TIME_SEC;

        mark_inode_dirty(dir);

        inode->i_ctime = dir->i_ctime;

        inode_dec_link_count(inode);

        retval = 0;

end_unlink:

        unlock_kernel();

        brelse(bh);

        return retval;

}

#endif