drivers/fs/minix/block.c

   1 /*
   2  * COPYRIGHT:        See COPYING in the top level directory
   3  * PROJECT:          ReactOS kernel
   4  * FILE:             services/fs/minix/minix.c
   5  * PURPOSE:          Minix FSD
   6  * PROGRAMMER:       David Welch (welch@mcmail.com)
   7  * UPDATE HISTORY:
   8  */
   9
  10 /* INCLUDES *****************************************************************/
  11
  12 #include <ddk/ntddk.h>
  13
  14 //#define NDEBUG
  15 #include <debug.h>
  16
  17 #include "minix.h"
  18
  19 /* FUNCTIONS ****************************************************************/
  20
  21 static unsigned int MinixGetBlock(PDEVICE_OBJECT DeviceObject,
  22                                   PMINIX_DEVICE_EXTENSION DeviceExt,
  23                                   struct minix_inode* inode,
  24                                   ULONG FileOffset)
  25 {
  26    int block;
  27    PVOID BaseAddress;
  28    ULONG blk;
  29
  30    blk = FileOffset / BLOCKSIZE;
  31
  32    DPRINT("MinixGetBlock(inode %x, blk %d)\n",inode,blk);
  33
  34    /*
  35     * The first few blocks are available in the inode
  36     */
  37    if (blk < 7)
  38      {
  39         block = inode->i_zone[blk];
  40         return(block);
  41      }
  42    blk = blk - 7;
  43
  44    /*
  45     * Retrieve a single-indirect block
  46     */
  47    if (blk < 512)
  48      {
  49         block = inode->i_zone[7];
  50
  51         BaseAddress = ExAllocatePool(NonPagedPool, 512);
  52
  53         MinixReadSector(DeviceObject,
  54                         block,
  55                         BaseAddress);
  56
  57         block = ((PUSHORT)(BaseAddress))[blk];
  58
  59         ExFreePool(BaseAddress);
  60
  61         return(block);
  62      }
  63
  64    /*
  65     * Get a double indirect block
  66     */
  67    blk = blk - 512;
  68    block = inode->i_zone[8];
  69
  70    BaseAddress = ExAllocatePool(NonPagedPool, 512);
  71
  72    MinixReadSector(DeviceObject,
  73                    block,
  74                    BaseAddress);
  75
  76    block = ((PUSHORT)BaseAddress)[(blk>>9)&511];
  77
  78    ExFreePool(BaseAddress);
  79
  80
  81    BaseAddress = ExAllocatePool(NonPagedPool, 512);
  82
  83    MinixReadSector(DeviceObject,
  84                    block,
  85                    BaseAddress);
  86
  87    block = ((PUSHORT)BaseAddress)[blk&512];
  88
  89    ExFreePool(BaseAddress);
  90
  91    return(block);
  92 }
  93
  94 NTSTATUS MinixReadBlock(PDEVICE_OBJECT DeviceObject,
  95                         PMINIX_DEVICE_EXTENSION DeviceExt,
  96                         struct minix_inode* inode,
  97                         ULONG FileOffset,
  98                         PULONG DiskOffset)
  99 {
 100    unsigned int block;
 101
 102    DPRINT("MinixReadBlock()\n");
 103
 104    block = MinixGetBlock(DeviceObject, DeviceExt,inode, FileOffset);
 105
 106    (*DiskOffset) = block * BLOCKSIZE;
 107
 108    return(STATUS_SUCCESS);
 109 }