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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 */
/** */
/** File */
/** */
/**************************************************************************/
/**************************************************************************/
#define FX_SOURCE_CODE
/* Include necessary system files. */
#include "fx_api.h"
#include "fx_system.h"
#include "fx_file.h"
#include "fx_utility.h"
/**************************************************************************/
/* */
/* FUNCTION RELEASE */
/* */
/* _fx_file_read PORTABLE C */
/* 6.1 */
/* AUTHOR */
/* */
/* William E. Lamie, Microsoft Corporation */
/* */
/* DESCRIPTION */
/* */
/* This function reads the specified number of bytes (or as many as */
/* possible into the buffer supplied by the caller. The actual number */
/* of bytes and the status of the read operation is returned to the */
/* caller. In addition, various internal file pointers in the file */
/* control block are also updated. */
/* */
/* INPUT */
/* */
/* file_ptr File control block pointer */
/* buffer_ptr Buffer pointer */
/* request_size Number of bytes requested */
/* actual_size Pointer to variable for the */
/* number of bytes read */
/* */
/* OUTPUT */
/* */
/* return status */
/* */
/* CALLS */
/* */
/* _fx_utility_FAT_entry_read Read a FAT entry */
/* _fx_utility_logical_sector_read Read a logical sector */
/* _fx_utility_memory_copy Fast memory copy routine */
/* */
/* CALLED BY */
/* */
/* Application Code */
/* */
/* RELEASE HISTORY */
/* */
/* DATE NAME DESCRIPTION */
/* */
/* 05-19-2020 William E. Lamie Initial Version 6.0 */
/* 09-30-2020 William E. Lamie Modified comment(s), verified */
/* memcpy usage, */
/* resulting in version 6.1 */
/* */
/**************************************************************************/
UINT _fx_file_read(FX_FILE *file_ptr, VOID *buffer_ptr, ULONG request_size, ULONG *actual_size)
{
UINT status;
ULONG bytes_remaining, i;
ULONG copy_bytes;
UCHAR *destination_ptr;
ULONG cluster, next_cluster;
UINT sectors;
FX_MEDIA *media_ptr;
#ifdef TX_ENABLE_EVENT_TRACE
TX_TRACE_BUFFER_ENTRY *trace_event;
ULONG trace_timestamp;
#endif
/* First, determine if the file is still open. */
if (file_ptr -> fx_file_id != FX_FILE_ID)
{
/* Return the file not open error status. */
return(FX_NOT_OPEN);
}
#ifndef FX_MEDIA_STATISTICS_DISABLE
/* Setup pointer to media structure. */
media_ptr = file_ptr -> fx_file_media_ptr;
/* Increment the number of times this service has been called. */
media_ptr -> fx_media_file_reads++;
#endif
/* Setup pointer to associated media control block. */
media_ptr = file_ptr -> fx_file_media_ptr;
/* If trace is enabled, insert this event into the trace buffer. */
FX_TRACE_IN_LINE_INSERT(FX_TRACE_FILE_READ, file_ptr, buffer_ptr, request_size, 0, FX_TRACE_FILE_EVENTS, &trace_event, &trace_timestamp)
/* Protect against other threads accessing the media. */
FX_PROTECT
/* Next, determine if there is any more bytes to read in the file. */
if (file_ptr -> fx_file_current_file_offset >=
file_ptr -> fx_file_current_file_size)
{
/* Release media protection. */
FX_UNPROTECT
/* The file is at the end, return the proper status and set the
actual size to 0. */
*actual_size = 0;
return(FX_END_OF_FILE);
}
/* At this point there is something to read. */
/* Setup local buffer pointer. */
destination_ptr = (UCHAR *)buffer_ptr;
/* Determine if there are less bytes left in the file than that specified
by the request. If so, adjust the requested size. */
if ((ULONG64)request_size >
(file_ptr -> fx_file_current_file_size - file_ptr -> fx_file_current_file_offset))
{
/* Adjust the bytes remaining to what's available. */
request_size = (ULONG)(file_ptr -> fx_file_current_file_size - file_ptr -> fx_file_current_file_offset);
}
/* Setup the remaining number of bytes to read. */
bytes_remaining = request_size;
/* Loop to read all of the bytes. */
while (bytes_remaining)
{
/* Determine if a beginning or ending partial read is required. */
if ((file_ptr -> fx_file_current_logical_offset) ||
(bytes_remaining < media_ptr -> fx_media_bytes_per_sector))
{
/* A partial sector read is required. */
/* Read the current logical sector. */
status = _fx_utility_logical_sector_read(media_ptr,
file_ptr -> fx_file_current_logical_sector,
media_ptr -> fx_media_memory_buffer, ((ULONG) 1), FX_DATA_SECTOR);
/* Check for good completion status. */
if (status != FX_SUCCESS)
{
/* Release media protection. */
FX_UNPROTECT
/* Return the error status. */
return(status);
}
/* Copy the appropriate number of bytes into the destination buffer. */
copy_bytes = media_ptr -> fx_media_bytes_per_sector -
file_ptr -> fx_file_current_logical_offset;
/* Check to see if only a portion of the read sector needs to be
copied. */
if (copy_bytes > bytes_remaining)
{
/* Adjust the number of bytes to copy. */
copy_bytes = bytes_remaining;
}
/* Actually perform the memory copy. */
_fx_utility_memory_copy(((UCHAR *)media_ptr -> fx_media_memory_buffer) + /* Use case of memcpy is verified. */
file_ptr -> fx_file_current_logical_offset,
destination_ptr, copy_bytes);
/* Increment the logical sector byte offset. */
file_ptr -> fx_file_current_logical_offset =
file_ptr -> fx_file_current_logical_offset + copy_bytes;
/* Adjust the remaining bytes to read. */
bytes_remaining = bytes_remaining - copy_bytes;
/* Adjust the pointer to the destination buffer. */
destination_ptr = destination_ptr + copy_bytes;
}
else
{
/* Attempt to read multiple sectors directly into the destination
buffer. */
/* Calculate the number of whole sectors to read directly into
the destination buffer. */
sectors = (UINT)(bytes_remaining / media_ptr -> fx_media_bytes_per_sector);
next_cluster = cluster = file_ptr -> fx_file_current_physical_cluster;
for (i = (media_ptr -> fx_media_sectors_per_cluster -
file_ptr -> fx_file_current_relative_sector); i < sectors; i += media_ptr -> fx_media_sectors_per_cluster)
{
#ifdef FX_ENABLE_EXFAT
if (file_ptr -> fx_file_dir_entry.fx_dir_entry_dont_use_fat & 1)
{
cluster++;
}
else
{
#endif /* FX_ENABLE_EXFAT */
status = _fx_utility_FAT_entry_read(media_ptr, cluster, &next_cluster);
/* Determine if an error is present. */
if ((status != FX_SUCCESS) || (next_cluster < FX_FAT_ENTRY_START) ||
(next_cluster > media_ptr -> fx_media_fat_reserved))
{
/* Release media protection. */
FX_UNPROTECT
/* Send error message back to caller. */
if (status != FX_SUCCESS)
{
return(status);
}
else
{
return(FX_FILE_CORRUPT);
}
}
if (next_cluster != cluster + 1)
{
break;
}
else
{
cluster = next_cluster;
}
#ifdef FX_ENABLE_EXFAT
}
#endif /* FX_ENABLE_EXFAT */
}
if (i < sectors)
{
sectors = i;
}
/* Determine if this is a single sector read request. If so, read the sector so it will
come from the internal cache. */
if (sectors == 1)
{
/* Read the current logical sector. */
status = _fx_utility_logical_sector_read(media_ptr,
file_ptr -> fx_file_current_logical_sector,
media_ptr -> fx_media_memory_buffer, ((ULONG) 1), FX_DATA_SECTOR);
/* Check for good completion status. */
if (status != FX_SUCCESS)
{
/* Release media protection. */
FX_UNPROTECT
/* Return the error status. */
return(status);
}
/* Actually perform the memory copy. */
_fx_utility_memory_copy((UCHAR *)media_ptr -> fx_media_memory_buffer, destination_ptr, media_ptr -> fx_media_bytes_per_sector); /* Use case of memcpy is verified. */
}
else
{
/* Multiple sector read request. Read all the sectors at once. */
/* Perform the data read directly into the user's buffer of
the appropriate number of sectors. */
media_ptr -> fx_media_disable_burst_cache = file_ptr -> fx_file_disable_burst_cache;
status = _fx_utility_logical_sector_read(media_ptr, file_ptr -> fx_file_current_logical_sector,
destination_ptr, (ULONG) sectors, FX_DATA_SECTOR);
media_ptr -> fx_media_disable_burst_cache = FX_FALSE;
/* Check for good completion status. */
if (status != FX_SUCCESS)
{
/* Release media protection. */
FX_UNPROTECT
/* Return the error status. */
return(status);
}
}
/* Now adjust the various file pointers. */
/* Increment the current logical sector. Subtract one from
the sector count because we are going to use the logical
offset to do additional sector/cluster arithmetic below. */
file_ptr -> fx_file_current_logical_sector =
file_ptr -> fx_file_current_logical_sector +
(sectors - 1);
/* Move the relative sector and cluster as well. */
file_ptr -> fx_file_current_relative_cluster = file_ptr -> fx_file_current_relative_cluster +
(file_ptr -> fx_file_current_relative_sector + (sectors - 1)) /
media_ptr -> fx_media_sectors_per_cluster;
file_ptr -> fx_file_current_relative_sector =
(file_ptr -> fx_file_current_relative_sector +
(sectors - 1)) % media_ptr -> fx_media_sectors_per_cluster;
/* Increment the logical sector byte offset. */
file_ptr -> fx_file_current_logical_offset =
media_ptr -> fx_media_bytes_per_sector;
file_ptr -> fx_file_current_physical_cluster = cluster;
/* Adjust the remaining bytes. */
bytes_remaining = bytes_remaining -
(((ULONG)media_ptr -> fx_media_bytes_per_sector) * sectors);
/* Adjust the pointer to the destination buffer. */
destination_ptr = destination_ptr +
(((ULONG)media_ptr -> fx_media_bytes_per_sector) * sectors);
}
/* At this point, we have either read a partial sector or have successfully
read one or more whole sectors. Determine if we are at the end of
the current logical sector. */
if (file_ptr -> fx_file_current_logical_offset >=
media_ptr -> fx_media_bytes_per_sector)
{
/* Determine if we are at the exact physical end of the file at the end of reading. */
if ((bytes_remaining == 0) && ((file_ptr -> fx_file_current_file_offset + (ULONG64)request_size) >=
file_ptr -> fx_file_current_available_size))
{
/* Skip the following file parameter adjustments. The next write will
detect the logical offset out of the range of the sector and reset
all of the pertinent information. */
break;
}
/* We need to move to the next logical sector, but first
determine if the next logical sector is within the same
cluster. */
/* Increment the current relative sector in the cluster. */
file_ptr -> fx_file_current_relative_sector++;
/* Determine if this is in a new cluster. */
if (file_ptr -> fx_file_current_relative_sector >=
media_ptr -> fx_media_sectors_per_cluster)
{
#ifdef FX_ENABLE_EXFAT
if (file_ptr -> fx_file_dir_entry.fx_dir_entry_dont_use_fat & 1)
{
next_cluster = file_ptr -> fx_file_current_physical_cluster + 1;
}
else
{
#endif /* FX_ENABLE_EXFAT */
/* Read the FAT entry of the current cluster to find
the next cluster. */
status = _fx_utility_FAT_entry_read(media_ptr,
file_ptr -> fx_file_current_physical_cluster, &next_cluster);
/* Determine if an error is present. */
if ((status != FX_SUCCESS) || (next_cluster < FX_FAT_ENTRY_START) ||
(next_cluster > media_ptr -> fx_media_fat_reserved))
{
/* Release media protection. */
FX_UNPROTECT
/* Send error message back to caller. */
if (status != FX_SUCCESS)
{
return(status);
}
else
{
return(FX_FILE_CORRUPT);
}
}
#ifdef FX_ENABLE_EXFAT
}
#endif /* FX_ENABLE_EXFAT */
/* Otherwise, we have a new cluster. Save it in the file
control block and calculate a new logical sector value. */
file_ptr -> fx_file_current_physical_cluster = next_cluster;
file_ptr -> fx_file_current_relative_cluster++;
file_ptr -> fx_file_current_logical_sector = ((ULONG)media_ptr -> fx_media_data_sector_start) +
((((ULONG64)next_cluster) - FX_FAT_ENTRY_START) *
((ULONG)media_ptr -> fx_media_sectors_per_cluster));
file_ptr -> fx_file_current_relative_sector = 0;
}
else
{
/* Still within the same cluster so just increment the
logical sector. */
file_ptr -> fx_file_current_logical_sector++;
}
/* In either case, we are now positioned at a new sector so
clear the logical sector offset. */
file_ptr -> fx_file_current_logical_offset = 0;
}
}
/* Adjust the current file offset accordingly. */
file_ptr -> fx_file_current_file_offset =
file_ptr -> fx_file_current_file_offset + (ULONG64)request_size;
/* Store the number of bytes actually read. */
*actual_size = request_size;
/* Update the trace event with the bytes read. */
FX_TRACE_EVENT_UPDATE(trace_event, trace_timestamp, FX_TRACE_FILE_READ, 0, 0, 0, request_size)
/* Update the last accessed date. */
file_ptr -> fx_file_dir_entry.fx_dir_entry_last_accessed_date = _fx_system_date;
/* Release media protection. */
FX_UNPROTECT
/* Return a successful status to the caller. */
return(FX_SUCCESS);
}