fs/qnx4/dir.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  * 28-05-1998 by Richard Frowijn : first release.
  12  * 20-06-1998 by Frank Denis : Linux 2.1.99+ & dcache support.
  13  */
  14
  15 #include <linux/buffer_head.h>
  16 #include "qnx4.h"
  17
  18 /*
  19  * A qnx4 directory entry is an inode entry or link info
  20  * depending on the status field in the last byte. The
  21  * first byte is where the name start either way, and a
  22  * zero means it's empty.
  23  */
  24 union qnx4_directory_entry {
  25         struct {
  26                 char de_name;
  27                 char de_pad[62];
  28                 char de_status;
  29         };
  30         struct qnx4_inode_entry inode;
  31         struct qnx4_link_info link;
  32 };
  33
  34 static int qnx4_readdir(struct file *file, struct dir_context *ctx)
  35 {
  36         struct inode *inode = file_inode(file);
  37         unsigned int offset;
  38         struct buffer_head *bh;
  39         unsigned long blknum;
  40         int ix, ino;
  41         int size;
  42
  43         QNX4DEBUG((KERN_INFO "qnx4_readdir:i_size = %ld\n", (long) inode->i_size));
  44         QNX4DEBUG((KERN_INFO "pos                 = %ld\n", (long) ctx->pos));
  45
  46         while (ctx->pos < inode->i_size) {
  47                 blknum = qnx4_block_map(inode, ctx->pos >> QNX4_BLOCK_SIZE_BITS);
  48                 bh = sb_bread(inode->i_sb, blknum);
  49                 if (bh == NULL) {
  50                         printk(KERN_ERR "qnx4_readdir: bread failed (%ld)\n", blknum);
  51                         return 0;
  52                 }
  53                 ix = (ctx->pos >> QNX4_DIR_ENTRY_SIZE_BITS) % QNX4_INODES_PER_BLOCK;
  54                 for (; ix < QNX4_INODES_PER_BLOCK; ix++, ctx->pos += QNX4_DIR_ENTRY_SIZE) {
  55                         union qnx4_directory_entry *de;
  56                         const char *name;
  57
  58                         offset = ix * QNX4_DIR_ENTRY_SIZE;
  59                         de = (union qnx4_directory_entry *) (bh->b_data + offset);
  60
  61                         if (!de->de_name)
  62                                 continue;
  63                         if (!(de->de_status & (QNX4_FILE_USED|QNX4_FILE_LINK)))
  64                                 continue;
  65                         if (!(de->de_status & QNX4_FILE_LINK)) {
  66                                 size = sizeof(de->inode.di_fname);
  67                                 name = de->inode.di_fname;
  68                                 ino = blknum * QNX4_INODES_PER_BLOCK + ix - 1;
  69                         } else {
  70                                 size = sizeof(de->link.dl_fname);
  71                                 name = de->link.dl_fname;
  72                                 ino = ( le32_to_cpu(de->link.dl_inode_blk) - 1 ) *
  73                                         QNX4_INODES_PER_BLOCK +
  74                                         de->link.dl_inode_ndx;
  75                         }
  76                         size = strnlen(name, size);
  77                         QNX4DEBUG((KERN_INFO "qnx4_readdir:%.*s\n", size, name));
  78                         if (!dir_emit(ctx, name, size, ino, DT_UNKNOWN)) {
  79                                 brelse(bh);
  80                                 return 0;
  81                         }
  82                 }
  83                 brelse(bh);
  84         }
  85         return 0;
  86 }
  87
  88 const struct file_operations qnx4_dir_operations =
  89 {
  90         .llseek         = generic_file_llseek,
  91         .read           = generic_read_dir,
  92         .iterate_shared = qnx4_readdir,
  93         .fsync          = generic_file_fsync,
  94 };
  95
  96 const struct inode_operations qnx4_dir_inode_operations =
  97 {
  98         .lookup         = qnx4_lookup,
  99 };