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/*************************************************************************** |
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* Copyright (c) 2024 Microsoft Corporation |
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* |
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* This program and the accompanying materials are made available under the |
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* terms of the MIT License which is available at |
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* https://opensource.org/licenses/MIT. |
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* |
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* SPDX-License-Identifier: MIT |
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**************************************************************************/ |
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/**************************************************************************/ |
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/**************************************************************************/ |
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/** */ |
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/** FileX Component */ |
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/** */ |
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/** Media */ |
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/** */ |
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/**************************************************************************/ |
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/**************************************************************************/ |
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#define FX_SOURCE_CODE |
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/* Include necessary system files. */ |
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#include "fx_api.h" |
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#include "fx_media.h" |
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#include "fx_utility.h" |
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/**************************************************************************/ |
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/* */ |
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/* FUNCTION RELEASE */ |
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/* */ |
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/* _fx_media_check_lost_cluster_check PORTABLE C */ |
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/* 6.1 */ |
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/* AUTHOR */ |
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/* */ |
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/* William E. Lamie, Microsoft Corporation */ |
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/* */ |
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/* DESCRIPTION */ |
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/* */ |
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/* This function examines all clusters to see if there are any unused */ |
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/* clusters that are also unavailable. If specified, this routine will */ |
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/* also mark the cluster as available. */ |
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/* */ |
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/* INPUT */ |
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/* */ |
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/* media_ptr Pointer to a previously */ |
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/* opened media */ |
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/* logical_fat Pointer to the logical FAT */ |
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/* bit map */ |
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/* total_clusters Total number of clusters */ |
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/* error_correction_option Option for correcting lost */ |
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/* cluster errors */ |
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/* */ |
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/* OUTPUT */ |
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/* */ |
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/* error Error code */ |
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/* */ |
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/* CALLS */ |
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/* */ |
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/* _fx_utility_FAT_entry_read Read a FAT entry */ |
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/* _fx_utility_FAT_entry_write Write a FAT entry */ |
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/* */ |
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/* CALLED BY */ |
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/* */ |
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/* _fx_check_media Check media function */ |
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/* */ |
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/* RELEASE HISTORY */ |
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/* */ |
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/* DATE NAME DESCRIPTION */ |
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/* */ |
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/* 05-19-2020 William E. Lamie Initial Version 6.0 */ |
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/* 09-30-2020 William E. Lamie Modified comment(s), */ |
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/* resulting in version 6.1 */ |
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/* */ |
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/**************************************************************************/ |
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ULONG _fx_media_check_lost_cluster_check(FX_MEDIA *media_ptr, UCHAR *logical_fat, ULONG total_clusters, ULONG error_correction_option) |
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{ |
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ULONG cluster, next_cluster = 0; |
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ULONG fat_last; |
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ULONG error; |
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UINT status; |
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/* Calculate the FAT reserved and last sector values. */ |
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✓✓ |
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if (media_ptr -> fx_media_32_bit_FAT) |
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{ |
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fat_last = FX_LAST_CLUSTER_1_32; |
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} |
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else |
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{ |
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fat_last = FX_LAST_CLUSTER_1; |
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} |
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/* Initialize the error. */ |
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error = 0; |
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/* Loop through all the clusters to see if any clusters NOT in the logical sector FAT have |
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a non zero value. */ |
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✓✓ |
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for (cluster = FX_FAT_ENTRY_START; cluster < total_clusters; cluster++) |
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{ |
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/* Determine if this cluster is in the logical FAT. */ |
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✓✓ |
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if (logical_fat[cluster >> 3] & (1 << (cluster & 7))) |
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{ |
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/* Yes, the cluster is in use by a file or sub-directory. Just continue the loop. */ |
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continue; |
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} |
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/* Otherwise, the cluster is not in use. */ |
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/* Read the contents of what should be a free cluster. */ |
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status = _fx_utility_FAT_entry_read(media_ptr, cluster, &next_cluster); |
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/* Check for a good status. */ |
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✓✓ |
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if (status) |
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{ |
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/* Set the error code. */ |
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error = error | FX_IO_ERROR; |
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/* Return error code. */ |
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return(error); |
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} |
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/* Determine if the contents of the cluster is valid. */ |
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✓✓✓✓
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if (((next_cluster > (ULONG)FX_FREE_CLUSTER) && (next_cluster < media_ptr -> fx_media_fat_reserved)) || |
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✓✓ |
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(next_cluster >= fat_last)) |
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{ |
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/* Lost cluster is present. */ |
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/* Set the error code status. */ |
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error = FX_LOST_CLUSTER_ERROR; |
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/* Determine if the lost cluster should be recovered. */ |
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✓✓ |
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if (error_correction_option & FX_LOST_CLUSTER_ERROR) |
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{ |
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/* Make the cluster available again. */ |
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status = _fx_utility_FAT_entry_write(media_ptr, cluster, FX_FREE_CLUSTER); |
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/* Check for a good status. */ |
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✓✓ |
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if (status) |
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{ |
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/* Increment the available clusters. */ |
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media_ptr -> fx_media_available_clusters++; |
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/* Set the error code. */ |
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error = error | FX_IO_ERROR; |
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/* Return error code. */ |
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return(error); |
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} |
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} |
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} |
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} |
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/* Return error code. */ |
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return(error); |
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} |
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