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/config.h>
  16 #include <linux/sched.h>
  17 #include <linux/qnx4_fs.h>
  18 #include <linux/kernel.h>
  19 #include <linux/string.h>
  20 #include <linux/stat.h>
  21 #include <linux/fcntl.h>
  22 #include <linux/errno.h>
  23
  24 #include <asm/segment.h>
  25
  26 /*
  27  * check if the filename is correct. For some obscure reason, qnx writes a
  28  * new file twice in the directory entry, first with all possible options at 0
  29  * and for a second time the way it is, they want us not to access the qnx
  30  * filesystem when whe are using linux.
  31  */
  32 static int qnx4_match(int len, const char *name,
  33                       struct buffer_head *bh, unsigned long *offset)
  34 {
  35         struct qnx4_inode_entry *de;
  36         struct qnx4_link_info *le;
  37         int namelen, thislen;
  38
  39         if (bh == NULL) {
  40                 printk("qnx4: matching unassigned buffer !\n");
  41                 return 0;
  42         }
  43         de = (struct qnx4_inode_entry *) (bh->b_data + *offset);
  44         *offset += QNX4_DIR_ENTRY_SIZE;
  45         if ((de->di_status & QNX4_FILE_LINK) != 0) {
  46                 namelen = QNX4_NAME_MAX;
  47         } else {
  48                 namelen = QNX4_SHORT_NAME_MAX;
  49         }
  50         /* "" means "." ---> so paths like "/usr/lib//libc.a" work */
  51         if (!len && (de->di_fname[0] == '.') && (de->di_fname[1] == '\0')) {
  52                 return 1;
  53         }
  54         thislen = strlen( de->di_fname );
  55         if ( thislen > namelen )
  56                 thislen = namelen;
  57         if (len != thislen) {
  58                 return 0;
  59         }
  60         if (strncmp(name, de->di_fname, len) == 0) {
  61                 if ((de->di_status & (QNX4_FILE_USED|QNX4_FILE_LINK)) != 0) {
  62                         return 1;
  63                 }
  64         }
  65         return 0;
  66 }
  67
  68 static struct buffer_head *qnx4_find_entry(int len, struct inode *dir,
  69            const char *name, struct qnx4_inode_entry **res_dir, int *ino)
  70 {
  71         unsigned long block, offset, blkofs;
  72         struct buffer_head *bh;
  73
  74         *res_dir = NULL;
  75         if (!dir->i_sb) {
  76                 printk("qnx4: no superblock on dir.\n");
  77                 return NULL;
  78         }
  79         bh = NULL;
  80         block = offset = blkofs = 0;
  81         while (blkofs * QNX4_BLOCK_SIZE + offset < dir->i_size) {
  82                 if (!bh) {
  83                         block = qnx4_block_map( dir, blkofs );
  84                         bh = qnx4_bread(dir, block, 0);
  85                         if (!bh) {
  86                                 blkofs++;
  87                                 continue;
  88                         }
  89                 }
  90                 *res_dir = (struct qnx4_inode_entry *) (bh->b_data + offset);
  91                 if (qnx4_match(len, name, bh, &offset)) {
  92                         *ino = block * QNX4_INODES_PER_BLOCK +
  93                             (offset / QNX4_DIR_ENTRY_SIZE) - 1;
  94                         return bh;
  95                 }
  96                 if (offset < bh->b_size) {
  97                         continue;
  98                 }
  99                 brelse(bh);
 100                 bh = NULL;
 101                 offset = 0;
 102                 blkofs++;
 103         }
 104         brelse(bh);
 105         *res_dir = NULL;
 106         return NULL;
 107 }
 108
 109 struct dentry * qnx4_lookup(struct inode *dir, struct dentry *dentry)
 110 {
 111         int ino;
 112         struct qnx4_inode_entry *de;
 113         struct qnx4_link_info *lnk;
 114         struct buffer_head *bh;
 115         const char *name = dentry->d_name.name;
 116         int len = dentry->d_name.len;
 117         struct inode *foundinode = NULL;
 118
 119         if (!(bh = qnx4_find_entry(len, dir, name, &de, &ino)))
 120                 goto out;
 121         /* The entry is linked, let's get the real info */
 122         if ((de->di_status & QNX4_FILE_LINK) == QNX4_FILE_LINK) {
 123                 lnk = (struct qnx4_link_info *) de;
 124                 ino = (lnk->dl_inode_blk - 1) * QNX4_INODES_PER_BLOCK +
 125                     lnk->dl_inode_ndx;
 126         }
 127         brelse(bh);
 128
 129         if ((foundinode = iget(dir->i_sb, ino)) == NULL) {
 130                 QNX4DEBUG(("qnx4: lookup->iget -> NULL\n"));
 131                 return ERR_PTR(-EACCES);
 132         }
 133 out:
 134         d_add(dentry, foundinode);
 135
 136         return NULL;
 137 }
 138
 139 #ifdef CONFIG_QNX4FS_RW
 140 int qnx4_create(struct inode *dir, struct dentry *dentry, int mode)
 141 {
 142         QNX4DEBUG(("qnx4: qnx4_create\n"));
 143         if (dir == NULL) {
 144                 return -ENOENT;
 145         }
 146         return -ENOSPC;
 147 }
 148
 149 int qnx4_rmdir(struct inode *dir, struct dentry *dentry)
 150 {
 151         struct buffer_head *bh;
 152         struct qnx4_inode_entry *de;
 153         struct inode *inode;
 154         int retval;
 155         int ino;
 156
 157         QNX4DEBUG(("qnx4: qnx4_rmdir [%s]\n", dentry->d_name.name));
 158         bh = qnx4_find_entry(dentry->d_name.len, dir, dentry->d_name.name,
 159                              &de, &ino);
 160         if (bh == NULL) {
 161                 return -ENOENT;
 162         }
 163         inode = dentry->d_inode;
 164         if (inode->i_ino != ino) {
 165                 retval = -EIO;
 166                 goto end_rmdir;
 167         }
 168 #if 0
 169         if (!empty_dir(inode)) {
 170                 retval = -ENOTEMPTY;
 171                 goto end_rmdir;
 172         }
 173 #endif
 174         if (!list_empty(&dentry->d_hash)) {
 175                 retval = -EBUSY;
 176                 goto end_rmdir;
 177         }
 178         if (inode->i_nlink != 2) {
 179                 QNX4DEBUG(("empty directory has nlink!=2 (%d)\n", inode->i_nlink));
 180         }
 181         QNX4DEBUG(("qnx4: deleting directory\n"));
 182         de->di_status = 0;
 183         memset(de->di_fname, 0, sizeof de->di_fname);
 184         de->di_mode = 0;
 185         mark_buffer_dirty(bh, 1);
 186         inode->i_nlink = 0;
 187         mark_inode_dirty(inode);
 188         inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
 189         dir->i_nlink--;
 190         mark_inode_dirty(dir);
 191         d_delete(dentry);
 192         retval = 0;
 193
 194       end_rmdir:
 195         brelse(bh);
 196
 197         return retval;
 198 }
 199
 200 int qnx4_unlink(struct inode *dir, struct dentry *dentry)
 201 {
 202         struct buffer_head *bh;
 203         struct qnx4_inode_entry *de;
 204         struct inode *inode;
 205         int retval;
 206         int ino;
 207
 208         QNX4DEBUG(("qnx4: qnx4_unlink [%s]\n", dentry->d_name.name));
 209         bh = qnx4_find_entry(dentry->d_name.len, dir, dentry->d_name.name,
 210                              &de, &ino);
 211         if (bh == NULL) {
 212                 return -ENOENT;
 213         }
 214         inode = dentry->d_inode;
 215         if (inode->i_ino != ino) {
 216                 retval = -EIO;
 217                 goto end_unlink;
 218         }
 219         retval = -EPERM;
 220         if (!inode->i_nlink) {
 221                 QNX4DEBUG(("Deleting nonexistent file (%s:%lu), %d\n",
 222                            kdevname(inode->i_dev),
 223                            inode->i_ino, inode->i_nlink));
 224                 inode->i_nlink = 1;
 225         }
 226         de->di_status = 0;
 227         memset(de->di_fname, 0, sizeof de->di_fname);
 228         de->di_mode = 0;
 229         mark_buffer_dirty(bh, 1);
 230         dir->i_ctime = dir->i_mtime = CURRENT_TIME;
 231         mark_inode_dirty(dir);
 232         inode->i_nlink--;
 233         inode->i_ctime = dir->i_ctime;
 234         mark_inode_dirty(inode);
 235         d_delete(dentry);
 236         retval = 0;
 237
 238       end_unlink:
 239         brelse(bh);
 240
 241         return retval;
 242 }
 243 #endif