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/**************************************************************************/
/* */
/* Copyright (c) Microsoft Corporation. All rights reserved. */
/* */
/* This software is licensed under the Microsoft Software License */
/* Terms for Microsoft Azure RTOS. Full text of the license can be */
/* found in the LICENSE file at https://aka.ms/AzureRTOS_EULA */
/* and in the root directory of this software. */
/* */
/**************************************************************************/
/**************************************************************************/
/**************************************************************************/
/** */
/** FileX Component */
/** */
/** Media */
/** */
/**************************************************************************/
/**************************************************************************/
#define FX_SOURCE_CODE
/* Include necessary system files. */
#include "fx_api.h"
#include "fx_system.h"
#include "fx_media.h"
#include "fx_utility.h"
/**************************************************************************/
/* */
/* FUNCTION RELEASE */
/* */
/* _fx_media_boot_info_extract PORTABLE C */
/* 6.1.10 */
/* AUTHOR */
/* */
/* William E. Lamie, Microsoft Corporation */
/* */
/* DESCRIPTION */
/* */
/* This function extracts and validates the information from the boot */
/* record found in the memory buffer. If the boot record is invalid, */
/* an FX_MEDIA_INVALID status is returned to the caller. */
/* */
/* The FAT boot sector (512 bytes) that is operated on by this */
/* function must look like the following: */
/* */
/* Byte Offset Meaning Size */
/* */
/* 0x000 Jump Instructions 3 */
/* 0x003 OEM Name 8 */
/* 0x00B *Bytes per Sector 2 */
/* 0x00D *Sectors per Cluster 1 */
/* 0x00E *Reserved Sectors 2 */
/* 0x010 *Number of FATs 1 */
/* 0x011 *Max Root Dir Entries 2 */
/* 0x013 *Number of Sectors 2 */
/* 0x015 Media Type 1 */
/* 0x016 *Sectors per FAT 2 */
/* 0x018 *Sectors per Track 2 */
/* 0x01A *Number of Heads 2 */
/* 0x01C *Hidden Sectors 4 */
/* 0x020 *Huge Sectors 4 */
/* 0x024 Drive Number 1 */
/* 0x025 Reserved 1 */
/* 0x026 Boot Signature 1 */
/* 0x027 Volume ID 4 */
/* 0x02B Volume Label 11 */
/* 0x036 File System Type 8 */
/* ... ... ... */
/* 0x1FE **Signature (0x55aa) 2 */
/* */
/* * Denotes which elements of the boot record */
/* FileX uses. */
/* */
/* **Denotes the element is checked by the I/O */
/* driver. This eliminates the need for a minimum */
/* 512-byte buffer for FileX. */
/* */
/* Note: All values above are in little endian format, i.e. the LSB is */
/* in the lowest address. */
/* */
/* INPUT */
/* */
/* media_ptr Media control block pointer */
/* */
/* OUTPUT */
/* */
/* return status */
/* */
/* CALLS */
/* */
/* _fx_utility_16_unsigned_read Read a UINT from buffer */
/* _fx_utility_32_unsigned_read Read a ULONG from buffer */
/* _fx_utility_64_unsigned_read Read a ULONG64 from memory */
/* */
/* CALLED BY */
/* */
/* _fx_media_open Media open function */
/* */
/* RELEASE HISTORY */
/* */
/* DATE NAME DESCRIPTION */
/* */
/* 05-19-2020 William E. Lamie Initial Version 6.0 */
/* 09-30-2020 William E. Lamie Modified comment(s), */
/* resulting in version 6.1 */
/* 01-31-2022 Bhupendra Naphade Modified comment(s), added */
/* check for bimap cache size, */
/* resulting in version 6.1.10 */
/* */
/**************************************************************************/
UINT _fx_media_boot_info_extract(FX_MEDIA *media_ptr)
{
UCHAR *boot_sector;
/* Move the buffer pointer into a local copy. */
boot_sector = media_ptr -> fx_media_driver_buffer;
/* Extract the number of bytes per sector. */
media_ptr -> fx_media_bytes_per_sector = _fx_utility_16_unsigned_read(&boot_sector[FX_BYTES_SECTOR]);
if (media_ptr -> fx_media_bytes_per_sector == 0)
#ifdef FX_ENABLE_EXFAT
{
/* Treat as exFAT volume. */
/* Extract the number of bytes per sector. */
media_ptr -> fx_media_exfat_bytes_per_sector_shift = boot_sector[FX_EF_BYTE_PER_SECTOR_SHIFT];
/* exFAT requires minimal value 9 (512 bytes) and maximum value 12(4096 bytes) for bytes_per_sector_shift */
if((media_ptr -> fx_media_exfat_bytes_per_sector_shift < 9) || (media_ptr -> fx_media_exfat_bytes_per_sector_shift > 12))
{
return(FX_MEDIA_INVALID);
}
media_ptr -> fx_media_bytes_per_sector = (UINT)(1 << media_ptr -> fx_media_exfat_bytes_per_sector_shift);
/* Validate bytes per sector value: no more than bitmap cache size */
if (media_ptr -> fx_media_bytes_per_sector > sizeof(media_ptr -> fx_media_exfat_bitmap_cache))
{
return(FX_NOT_ENOUGH_MEMORY);
}
media_ptr -> fx_media_total_sectors = _fx_utility_64_unsigned_read(&boot_sector[FX_EF_VOLUME_LENGTH]);
if (media_ptr -> fx_media_total_sectors == 0)
{
return(FX_MEDIA_INVALID);
}
media_ptr -> fx_media_reserved_sectors = _fx_utility_32_unsigned_read(&boot_sector[FX_EF_FAT_OFFSET]);
if (media_ptr -> fx_media_reserved_sectors == 0)
{
return(FX_MEDIA_INVALID);
}
media_ptr -> fx_media_sectors_per_FAT = _fx_utility_32_unsigned_read(&boot_sector[FX_EF_FAT_LENGTH]);
if (media_ptr -> fx_media_sectors_per_FAT == 0)
{
return(FX_MEDIA_INVALID);
}
media_ptr -> fx_media_data_sector_start = _fx_utility_32_unsigned_read(&boot_sector[FX_EF_CLUSTER_HEAP_OFFSET]);
if (media_ptr -> fx_media_data_sector_start == 0)
{
return(FX_MEDIA_INVALID);
}
media_ptr -> fx_media_total_clusters = _fx_utility_32_unsigned_read(&boot_sector[FX_EF_CLUSTER_COUNT]);
if (media_ptr -> fx_media_total_clusters == 0)
{
return(FX_MEDIA_INVALID);
}
media_ptr -> fx_media_exfat_sector_per_clusters_shift = boot_sector[FX_EF_SECTOR_PER_CLUSTER_SHIFT];
if (media_ptr -> fx_media_exfat_sector_per_clusters_shift > 25 - media_ptr -> fx_media_exfat_bytes_per_sector_shift)
{
return(FX_MEDIA_INVALID);
}
media_ptr -> fx_media_sectors_per_cluster = (UINT)(1 << media_ptr -> fx_media_exfat_sector_per_clusters_shift);
media_ptr -> fx_media_number_of_FATs = boot_sector[FX_EF_NUMBER_OF_FATS];
if (media_ptr -> fx_media_number_of_FATs == 0)
{
return(FX_MEDIA_INVALID);
}
media_ptr -> fx_media_root_cluster_32 = _fx_utility_32_unsigned_read(&boot_sector[FX_EF_FIRST_CLUSTER_OF_ROOT_DIR]);
/* Root cluster starts from at least FX_FAT_ENTRY_START (2), or higher. */
if (media_ptr -> fx_media_root_cluster_32 < FX_FAT_ENTRY_START)
{
return(FX_MEDIA_INVALID);
}
/* Overflow check. */
if (((ULONG64)media_ptr -> fx_media_data_sector_start +
(ULONG64)(media_ptr -> fx_media_root_cluster_32 - FX_FAT_ENTRY_START) *
media_ptr -> fx_media_sectors_per_cluster) > 0xFFFFFFFF)
{
/* Return the invalid media error status. */
return(FX_MEDIA_INVALID);
}
/* Calculate logical number of root dir sector. */
media_ptr -> fx_media_root_sector_start = media_ptr -> fx_media_data_sector_start +
(media_ptr -> fx_media_root_cluster_32 - FX_FAT_ENTRY_START) *
media_ptr -> fx_media_sectors_per_cluster;
media_ptr -> fx_media_exfat_volume_serial_number = _fx_utility_32_unsigned_read(&boot_sector[FX_EF_VOLUME_SERIAL_NUMBER]);
media_ptr -> fx_media_exfat_file_system_revision = _fx_utility_16_unsigned_read(&boot_sector[FX_EF_FILE_SYSTEM_REVISION]);
media_ptr -> fx_media_exfat_volume_flag = _fx_utility_16_unsigned_read(&boot_sector[FX_EF_VOLUME_FLAGS]);
media_ptr -> fx_media_number_of_FATs = boot_sector[FX_EF_NUMBER_OF_FATS];
if (0 == media_ptr -> fx_media_number_of_FATs)
{
return(FX_MEDIA_INVALID);
}
/* Extract the number of hidden sectors. */
#ifdef FX_DRIVER_USE_64BIT_LBA
media_ptr -> fx_media_hidden_sectors = _fx_utility_64_unsigned_read(&boot_sector[FX_EF_PARTITION_OFFSET]);
#else
media_ptr -> fx_media_hidden_sectors = _fx_utility_32_unsigned_read(&boot_sector[FX_EF_PARTITION_OFFSET]);
#endif
media_ptr -> fx_media_exfat_drive_select = boot_sector[FX_EF_DRIVE_SELECT];
media_ptr -> fx_media_exfat_percent_in_use = boot_sector[FX_EF_PERCENT_IN_USE];
media_ptr -> fx_media_12_bit_FAT = FX_FALSE;
media_ptr -> fx_media_32_bit_FAT = FX_FALSE;
/* Legacy code support:
We will use fx_media_FAT_type for determine FAT type instead of
fx_media_12_bit_FAT and fx_media_32_bit_FAT. */
media_ptr -> fx_media_12_bit_FAT = FX_FALSE;
media_ptr -> fx_media_32_bit_FAT = FX_FALSE;
media_ptr -> fx_media_FAT_type = FX_exFAT;
return(_fx_utility_exFAT_geometry_check(media_ptr, boot_sector));
}
else
{
#else
return(FX_MEDIA_INVALID);
#endif /* FX_ENABLE_EXFAT */
/* FAT12/16/32 volume. */
/* Extract the number of sectors per track. */
media_ptr -> fx_media_sectors_per_track = _fx_utility_16_unsigned_read(&boot_sector[FX_SECTORS_PER_TRK]);
/* Extract the number of heads. */
media_ptr -> fx_media_heads = _fx_utility_16_unsigned_read(&boot_sector[FX_HEADS]);
/* Extract the total number of sectors. */
media_ptr -> fx_media_total_sectors = _fx_utility_16_unsigned_read(&boot_sector[FX_SECTORS]);
if (media_ptr -> fx_media_total_sectors == 0)
{
media_ptr -> fx_media_total_sectors = _fx_utility_32_unsigned_read(&boot_sector[FX_HUGE_SECTORS]);
}
if (media_ptr -> fx_media_total_sectors == 0)
{
return(FX_MEDIA_INVALID);
}
/* Extract the number of reserved sectors before the first FAT. */
media_ptr -> fx_media_reserved_sectors = _fx_utility_16_unsigned_read(&boot_sector[FX_RESERVED_SECTORS]);
if (media_ptr -> fx_media_reserved_sectors == 0)
{
return(FX_MEDIA_INVALID);
}
/* Extract the number of sectors per cluster. */
media_ptr -> fx_media_sectors_per_cluster = ((UINT)boot_sector[FX_SECTORS_CLUSTER] & 0xFF);
/* There should always be at least one reserved sector, representing the boot record itself. */
if (media_ptr -> fx_media_sectors_per_cluster == 0)
{
return(FX_MEDIA_INVALID);
}
/* Extract the number of sectors per FAT. */
media_ptr -> fx_media_sectors_per_FAT = _fx_utility_16_unsigned_read(&boot_sector[FX_SECTORS_PER_FAT]);
if (media_ptr -> fx_media_sectors_per_FAT == 0)
{
media_ptr -> fx_media_sectors_per_FAT = _fx_utility_32_unsigned_read(&boot_sector[FX_SECTORS_PER_FAT_32]);
}
if (media_ptr -> fx_media_sectors_per_FAT == 0)
{
return(FX_MEDIA_INVALID);
}
/* Extract the number of FATs. */
media_ptr -> fx_media_number_of_FATs = ((UINT)boot_sector[FX_NUMBER_OF_FATS] & 0xFF);
if (media_ptr -> fx_media_number_of_FATs == 0)
{
return(FX_BOOT_ERROR);
}
/* Extract the number of hidden sectors. */
#ifdef FX_DRIVER_USE_64BIT_LBA
media_ptr -> fx_media_hidden_sectors = _fx_utility_64_unsigned_read(&boot_sector[FX_HIDDEN_SECTORS]);
#else
media_ptr -> fx_media_hidden_sectors = _fx_utility_32_unsigned_read(&boot_sector[FX_HIDDEN_SECTORS]);
#endif
/* Extract the number of root directory entries. */
media_ptr -> fx_media_root_directory_entries = _fx_utility_16_unsigned_read(&boot_sector[FX_ROOT_DIR_ENTRIES]);
/* Extract root directory starting cluster (32 bit only) and compute start sector */
media_ptr -> fx_media_root_cluster_32 = _fx_utility_32_unsigned_read(&boot_sector[FX_ROOT_CLUSTER_32]);
#ifdef FX_ENABLE_EXFAT
}
#endif /* FX_ENABLE_EXFAT */
/* Return a successful status. */
return(FX_SUCCESS);
}