backup.c

ST5518机顶盒系统文件系统源代码！绝对超值！

/******************************************************************************

    File Name   : backup.c

    Description : This API implements the backup on write policy for file
                  system data. The backup on write policy is intended to
                  ensure that is any file system write becomes corrupted then
                  it can be recovered.

******************************************************************************/

/* Includes ---------------------------------------------------------------- */

#include <stdlib.h>
#include <stdio.h>
#include <ctype.h>
#include <assert.h>
#include <string.h>
#include "backup.h"
#include "root.h"
#include "hal.h"
#include "sttbx.h"

/* Private Types ----------------------------------------------------------- */

/* Private Constants ------------------------------------------------------- */

/* Private Variables ------------------------------------------------------- */

/* Private Macros ---------------------------------------------------------- */

/* Private Function Prototypes --------------------------------------------- */

/* Functions --------------------------------------------------------------- */



/******************************************************************************
Function Name : stavfs_BOWRead
  Description : Do a BOW Read. Read the specified file system data automaticaly
                recovering on error.
   Parameters :
******************************************************************************/
ST_ErrorCode_t stavfs_BOWRead(stavfs_Device_t *Device, U64 *LBA, U16 Sectors, U8 *Data)
{
    ST_ErrorCode_t Error = ST_NO_ERROR;
    
#ifndef STAVFS_NO_BACKUP_ON_WRITE
    U32 CRC;
#endif
    
    assert (NULL != Data);
    assert (NULL != LBA);
    assert (NULL != Device);

    /* Read the partition's first sector (root sector) */
    if (ST_NO_ERROR != stavfs_HalRead(Device->HALData, LBA, Sectors, (char*)Data, FALSE))
    {
	 STTBX_Print(("Unable to read the root sector\n"));
         Error = STAVFS_ERROR_UNREADABLE_DISK;
    }
#ifndef STAVFS_NO_BACKUP_ON_WRITE
    else
    {
        /* If the CRC is wrong then read the back up */
        CRC = 0XFFFFFFFF;
        stavfs_DoBufferCRC((char*)Data +sizeof(U64),
                           Sectors*DISK_SECTOR_SIZE -sizeof(U64),
                           &CRC);

        if (CRC != 0)
        {
            U64 BackupLBA;
            
            stavfs_GetBackupLBA(Device, LBA, &BackupLBA);
 
            if (ST_NO_ERROR != stavfs_HalRead(Device->HALData, &BackupLBA, Sectors, (char*)Data, FALSE))
            {
                 STTBX_Print(("Unable to read the root sector\n"));
                 Error = STAVFS_ERROR_UNREADABLE_DISK;
            }
            
            /* Check the LBA addess for the backup data */
            
            else if (INT_I64_AreNotEqual(*LBA, *((U64*)Data)))
            {
                 STTBX_Print(("Backup invalid for this read\n"));
                 Error = STAVFS_ERROR_CORRUPT_DISK;
            }
            else
            {
                /* Check for corrupt backup data */
                
                CRC = 0XFFFFFFFF;
                stavfs_DoBufferCRC((char*)Data +sizeof(U64),
                                   Sectors*DISK_SECTOR_SIZE -sizeof(U64),
                                   &CRC);
 
                if (CRC != 0)
                {
                     STTBX_Print(("Root sector corrupt\n"));
                     Error = STAVFS_ERROR_CORRUPT_DISK;
                }
                else
                {
                    /* Write back the restored data */
                    
                    if (ST_NO_ERROR != stavfs_HalWrite(Device->HALData, LBA, Sectors, (char*)Data, FALSE))
                    {
                         STTBX_Print(("Unable to read the root sector\n"));
                         Error = STAVFS_ERROR_CORRUPT_DISK;
                    }
                }
            }
        }
    }
#endif
      
    return (Error);
}




/******************************************************************************
Function Name : stavfs_BOWWrite
  Description : Do a BOW Write. Write the specified file system data automaticaly
                making a backup.
   Parameters :
******************************************************************************/
ST_ErrorCode_t stavfs_BOWWrite(stavfs_Device_t *Device, U64 *LBA, U16 Sectors, U8 *Data)
{
    ST_ErrorCode_t Error = ST_NO_ERROR;
    
#ifndef STAVFS_NO_BACKUP_ON_WRITE
    U64 BackupLBA;
    U32 CRC;
#endif
    
    assert (NULL != Data);
    assert (NULL != LBA);
    assert (NULL != Device);
            
#ifndef STAVFS_NO_BACKUP_ON_WRITE
    stavfs_GetBackupLBA(Device, LBA, &BackupLBA);
    
    /* Set the LBA feild */
    
    *((U64*)Data) = *LBA;
    
    /* Set the CRC */
    CRC = 0XFFFFFFFF;
    stavfs_DoBufferCRC((char*)Data +sizeof(U64),
                       Sectors*DISK_SECTOR_SIZE-sizeof(CRC)-sizeof(U64),
                       &CRC);
    
    /* The CRC goes in the last four bytes of the Data */
    /* Copy the CRC with byte swap for big-endian to little-endian */
    *((U32*)(Data +Sectors*DISK_SECTOR_SIZE-sizeof(CRC))) =
            (CRC >> 24) | (CRC << 24) | ((CRC >> 8) & 0X0000FF00) | ((CRC << 8) & 0X00FF0000);
    
    /* Write the backup data to the second sector of the partition (root sector) */
    
    if (ST_NO_ERROR != stavfs_HalWrite(Device->HALData, &BackupLBA, Sectors, (char*)Data, FALSE))
    {
	 STTBX_Print(("Unable to write the back up sector\n"));
         Error = STAVFS_ERROR_UNWRITABLE_DISK;
    }
#endif
      
    /* Write the data to the first sector of the partition (root sector) */
   
    if (ST_NO_ERROR != stavfs_HalWrite(Device->HALData, LBA, Sectors, (char*)Data, FALSE))
    {
	 STTBX_Print(("Unable to write the root sector\n"));
         Error = STAVFS_ERROR_UNWRITABLE_DISK;
    }

    return (Error);
}