void MFS_Delete_handles
(
MFS_DRIVE_STRUCT_PTR drive_ptr, /*[IN] the drive on which to operate */
char_ptr filename, /*[IN] the filename to be erased.*/
uint_32 cluster /*[IN] the first cluster of the file to be erased*/
)
{
MFS_HANDLE_PTR next_handle;
next_handle = (MFS_HANDLE_PTR) _queue_head(&(drive_ptr->HANDLE_LIST));
while ( next_handle )
{
if ( clustoh(next_handle->DIR_ENTRY.HFIRST_CLUSTER,
next_handle->DIR_ENTRY.LFIRST_CLUSTER) == cluster )
{
/*
** Although the starting clusters match (same file),
** a name comparison is needed in the case the file is 0 length
** (in which case the starting cluster is 0)
*/
if ( !memcmp (next_handle->DIR_ENTRY.NAME, filename, 11) )
{
*next_handle->DIR_ENTRY.NAME = '\0';
}
}
next_handle = (MFS_HANDLE_PTR) _queue_next(&drive_ptr->HANDLE_LIST, (QUEUE_ELEMENT_STRUCT_PTR) next_handle);
}
}
void *MFS_Create_file
(
MFS_DRIVE_STRUCT_PTR drive_ptr,
unsigned char attr, /*[IN] attribute for created file*/
char *pathname, /*[IN] directory and filename of the file to be created */
_mfs_error_ptr error_ptr /*[IN/OUT] error code is written to this address */
)
{
MFS_HANDLE_PTR handle;
MFS_HANDLE_PTR next_handle;
MFS_DIR_ENTRY_PTR dir_entry_ptr;
TIME_STRUCT time;
DATE_STRUCT clk_time;
uint32_t dir_cluster;
uint32_t dir_index;
char access;
_mfs_error error_code, saved_code = 0;
if ( (pathname == NULL) || (*pathname == '\0') )
{
*error_ptr = MFS_INVALID_PARAMETER;
return( NULL );
}
#if MFSCFG_READ_ONLY_CHECK
if (MFS_is_read_only (drive_ptr))
{
*error_ptr = MFS_DISK_IS_WRITE_PROTECTED;
return NULL;
}
#endif
error_code = MFS_lock_dos_disk( drive_ptr );
if ( error_code != MFS_NO_ERROR )
{
*error_ptr = error_code;
return( NULL );
}
handle = NULL;
attr &= (MFS_ATTR_READ_ONLY | MFS_ATTR_HIDDEN_FILE | MFS_ATTR_SYSTEM_FILE | MFS_ATTR_ARCHIVE | MFS_ATTR_VOLUME_NAME);
attr |= MFS_ATTR_ARCHIVE;
access = (attr & MFS_ATTR_READ_ONLY) ? MFS_ACCESS_READ_ONLY : MFS_ACCESS_READ_WRITE;
dir_entry_ptr = MFS_Create_entry_slave(drive_ptr, attr, pathname, &dir_cluster, &dir_index, &error_code, TRUE);
if ( (dir_entry_ptr != NULL) && !(attr & MFS_ATTR_VOLUME_NAME) )
{
handle = MFS_Get_handle(drive_ptr,dir_entry_ptr);
if ( handle != NULL )
{
handle->DIR_CLUSTER = dir_cluster;
handle->DIR_INDEX = dir_index;
handle->ACCESS = access;
handle->CURRENT_CLUSTER = 0;
handle->PREVIOUS_CLUSTER = 0;
/*
** If file exists, overwrite and set size to 0
*/
if ( error_code == MFS_FILE_EXISTS )
{
_time_get(&time);
_time_to_date(&time, &clk_time);
NORMALIZE_DATE(&clk_time);
saved_code = MFS_Release_chain(drive_ptr, clustoh(handle->DIR_ENTRY.HFIRST_CLUSTER, handle->DIR_ENTRY.LFIRST_CLUSTER));
if ( saved_code == MFS_NO_ERROR || saved_code == MFS_LOST_CHAIN )
{
clustod(handle->DIR_ENTRY.HFIRST_CLUSTER, handle->DIR_ENTRY.LFIRST_CLUSTER, 0);
mqx_htodl(handle->DIR_ENTRY.FILE_SIZE, 0L);
mqx_htodc(handle->DIR_ENTRY.ATTRIBUTE, attr);
mqx_htods(handle->DIR_ENTRY.TIME, PACK_TIME(clk_time));
mqx_htods(handle->DIR_ENTRY.DATE, PACK_DATE(clk_time));
error_code = MFS_Update_entry(drive_ptr, handle);
/*
** If the same file is already open, mark it as 'freshly
** truncated' so reads and writes don't clobber any data.
*/
if ( error_code == MFS_NO_ERROR )
{
next_handle = (MFS_HANDLE_PTR) _queue_head(&drive_ptr->HANDLE_LIST);
while ( next_handle )
{
if ( next_handle->DIR_CLUSTER == dir_cluster && next_handle->DIR_INDEX == dir_index )
{
next_handle->CURRENT_CLUSTER = 0;
next_handle->PREVIOUS_CLUSTER = 0;
}
next_handle = (MFS_HANDLE_PTR) _queue_next(&drive_ptr->HANDLE_LIST, (QUEUE_ELEMENT_STRUCT_PTR) next_handle);
}
}
}
}
/*
** No need to update the disk image if we didn't change anything.
*/
if ( (mqx_dtohc(handle->DIR_ENTRY.ATTRIBUTE) != attr) && (error_code == MFS_NO_ERROR) )
{
mqx_htodc(handle->DIR_ENTRY.ATTRIBUTE, attr);
error_code = MFS_Update_entry(drive_ptr, handle);
}
}
else
{
error_code = MFS_INSUFFICIENT_MEMORY;
}
}
MFS_unlock(drive_ptr,FALSE);
if ( error_code == MFS_NO_ERROR && saved_code == MFS_LOST_CHAIN )
{
*error_ptr = saved_code;
}
else
{
*error_ptr = error_code;
}
return((void *)handle);
}
/*FUNCTION*-------------------------------------------------------------------
*
* Function Name : MFS_Find_directory
* Returned Value : starting_cluster of the specified directory
* Comments : Search through the file structure to find the specified
* directory. Will search either from the current directory or from the
* root directory. Returns the starting cluster number of the specified
* directory. If the specified directory cannot be found, then
* CLUSTER_INVALID is returned.
*
*END*---------------------------------------------------------------------*/
uint32_t MFS_Find_directory
(
MFS_DRIVE_STRUCT_PTR drive_ptr, /*[IN] drive context */
char *path_ptr, /*[IN] specific directory to search for */
uint32_t first_cluster /*[IN] start searching in this cluster, used for a relative search*/
)
{
MFS_DIR_ENTRY_PTR dir_entry_ptr;
char *directory;
uint32_t current_cluster;
uint32_t dir_index;
_mfs_error error_code;
bool flag;
uint32_t prev_cluster = CLUSTER_INVALID;
unsigned char attribute;
if ( MFS_alloc_path(&directory)!= MFS_NO_ERROR )
{
return( CLUSTER_INVALID );
}
if ( *path_ptr == '\\' || *path_ptr == '/' )
{
current_cluster = ROOT_CLUSTER(drive_ptr);
path_ptr++;
}
else
{
current_cluster = first_cluster;
}
while ( path_ptr )
{
if ( *path_ptr )
{
path_ptr = MFS_Parse_next_filename(path_ptr, directory);
if ( !MFS_lfn_dirname_valid(directory) )
{
current_cluster = CLUSTER_INVALID;
break;
}
flag = FALSE;
if ( current_cluster == 0 ) flag = TRUE;
if ( drive_ptr->FAT_TYPE == MFS_FAT32 )
{
if ( current_cluster == drive_ptr->BPB32.ROOT_CLUSTER )
{
flag = TRUE;
}
}
if ( flag )
{
/*
** Special treatment for '.' and '..' in root directory
*/
dir_index = MFS_Is_dot_directory(directory);
if ( dir_index == 1 )
{
/* Return the value of the root cluster */
MFS_free_path(directory);
return ROOT_CLUSTER(drive_ptr);
}
else if ( dir_index == 2 )
{
MFS_free_path(directory);
return(CLUSTER_INVALID);
}
}
dir_index = 0;
dir_entry_ptr = MFS_Find_directory_entry( drive_ptr, directory,
¤t_cluster, &dir_index, &prev_cluster, (~ATTR_EXCLUSIVE),
&error_code);
if ( dir_entry_ptr == NULL )
{
current_cluster = CLUSTER_INVALID;
break;
}
else
{
attribute = mqx_dtohc(dir_entry_ptr->ATTRIBUTE);
if ( attribute & MFS_ATTR_DIR_NAME )
{
current_cluster = clustoh(dir_entry_ptr->HFIRST_CLUSTER, dir_entry_ptr->LFIRST_CLUSTER);
if ( current_cluster == 0 && drive_ptr->FAT_TYPE == MFS_FAT32 )
{
current_cluster = drive_ptr->BPB32.ROOT_CLUSTER;
}
}
else
{
// Found an entry, but it is not a directory
MFS_free_path(directory);
return(CLUSTER_INVALID);
}
}
}
else
{
break;
}
}
MFS_free_path(directory);
return(current_cluster);
}
_mfs_error MFS_Remove_subdir
(
MFS_DRIVE_STRUCT_PTR drive_ptr,
char *pathname /*[IN] pathname of the directory to be removed */
)
{
_mfs_error error_code, saved_error = 0;
uint32_t dir_cluster, parent_cluster, dir_index;
MFS_DIR_ENTRY_PTR dir_entry_ptr;
uint32_t prev_cluster= CLUSTER_INVALID;
uint32_t parent_prev_cluster= CLUSTER_INVALID;
if ( (pathname == NULL) || (*pathname == '\0') )
{
return MFS_INVALID_PARAMETER;
}
error_code = MFS_lock_dos_disk( drive_ptr );
if ( error_code != MFS_NO_ERROR )
{
return error_code;
}
dir_entry_ptr = MFS_Find_entry_on_disk (drive_ptr, pathname, &error_code, &parent_cluster, &dir_index, &parent_prev_cluster);
if ( dir_entry_ptr )
{
if ( mqx_dtohc(dir_entry_ptr->ATTRIBUTE) & MFS_ATTR_DIR_NAME )
{
dir_cluster = clustoh(dir_entry_ptr->HFIRST_CLUSTER, dir_entry_ptr->LFIRST_CLUSTER);
if ( dir_cluster != drive_ptr->CUR_DIR_CLUSTER )
{
dir_index = 2; /* Skip over '.' and '..' */
dir_entry_ptr = MFS_Find_directory_entry (drive_ptr, NULL, &dir_cluster, &dir_index, &prev_cluster, MFS_ATTR_ANY, &error_code);
if ( dir_entry_ptr == NULL && !error_code )
{
dir_index = 0;
dir_entry_ptr = MFS_Find_entry_on_disk (drive_ptr, pathname, &error_code, &parent_cluster, &dir_index, &parent_prev_cluster);
if ( dir_entry_ptr )
{
*dir_entry_ptr->NAME = MFS_DEL_FILE;
drive_ptr->DIR_SECTOR_DIRTY = TRUE;
error_code = MFS_remove_lfn_entries(drive_ptr, parent_cluster, dir_index, parent_prev_cluster);
if ( !error_code )
{
saved_error = MFS_Release_chain(drive_ptr, dir_cluster);
}
}
}
else if ( dir_entry_ptr != NULL && !error_code )
{
error_code = MFS_FILE_EXISTS;
}
}
else
{
error_code = MFS_ATTEMPT_TO_REMOVE_CURRENT_DIR;
}
}
else
{
error_code = MFS_WRITE_FAULT;
}
}
else
{
error_code = MFS_PATH_NOT_FOUND;
}
MFS_unlock(drive_ptr,TRUE);
if ( saved_error == MFS_LOST_CHAIN && error_code == MFS_NO_ERROR )
{
error_code = saved_error;
}
return(error_code);
}
uint32_t MFS_Write
(
MFS_HANDLE_PTR handle,
MFS_DRIVE_STRUCT_PTR drive_ptr,
uint32_t num_bytes, /*[IN] number of bytes to be written */
char *buffer_address, /*[IN/OUT] bytes are written from this buffer */
_mfs_error_ptr error_ptr /*[IN/OUT] error code is written to this address */
)
{
uint32_t bytes_written;
uint32_t copy_size;
uint32_t cluster_offset;
uint32_t sector_number, sector_index;
uint32_t sector_offset;
uint32_t whole_sectors;
uint32_t cont_sectors;
uint32_t proc_sectors;
_mfs_error error, temp_error;
uint32_t file_size;
uint32_t next_cluster;
bool need_hwread;
uint32_t location;
uint32_t num_zeros;
uint32_t zeros_written;
uint32_t zero_size;
#if MFSCFG_READ_ONLY_CHECK
if (MFS_is_read_only (drive_ptr))
{
MFS_set_error_and_return(error_ptr,MFS_DISK_IS_WRITE_PROTECTED,0);
}
#endif
if ( buffer_address == NULL )
{
MFS_set_error_and_return(error_ptr,MFS_INVALID_PARAMETER,0);
}
if ( num_bytes == 0 )
{
MFS_set_error_and_return(error_ptr,MFS_NO_ERROR,0);
}
error = MFS_lock_dos_disk( drive_ptr );
if ( error != MFS_NO_ERROR )
{
MFS_set_error_and_return(error_ptr,error,0);
}
if ( handle->ACCESS == MFS_ACCESS_READ_ONLY )
{
MFS_unlock(drive_ptr,FALSE);
MFS_set_error_and_return(error_ptr,MFS_ACCESS_DENIED,0);
}
/*
** Setup the current cluster. If this is the first time writing to the file, a cluster needs to be added.
*/
if ( handle->CURRENT_CLUSTER == 0 )
{
handle->PREVIOUS_CLUSTER = 0;
handle->CURRENT_CLUSTER = clustoh(handle->DIR_ENTRY.HFIRST_CLUSTER, handle->DIR_ENTRY.LFIRST_CLUSTER);
if ( handle->CURRENT_CLUSTER==0 )
{
next_cluster = MFS_Find_unused_cluster_from(drive_ptr,drive_ptr->NEXT_FREE_CLUSTER);
if ( next_cluster != CLUSTER_INVALID )
{
clustod(handle->DIR_ENTRY.HFIRST_CLUSTER, handle->DIR_ENTRY.LFIRST_CLUSTER, next_cluster);
handle->TOUCHED = 1;
error = MFS_Put_fat(drive_ptr, next_cluster, CLUSTER_EOF);
if ( error == MFS_NO_ERROR )
{
handle->CURRENT_CLUSTER = next_cluster;
}
else
{
MFS_unlock(drive_ptr,FALSE);
MFS_set_error_and_return(error_ptr,error,0);
}
}
else
{
MFS_unlock(drive_ptr,FALSE);
MFS_set_error_and_return(error_ptr,MFS_DISK_FULL,0);
}
}
}
else if ( handle->CURRENT_CLUSTER == CLUSTER_EOF )
{
error = MFS_Add_cluster_to_chain(drive_ptr, handle->PREVIOUS_CLUSTER, &handle->CURRENT_CLUSTER);
if ( MFS_NO_ERROR != error )
{
MFS_unlock(drive_ptr,FALSE);
MFS_set_error_and_return(error_ptr,error,0);
}
}
else if ( handle->CURRENT_CLUSTER > drive_ptr->LAST_CLUSTER )
{
MFS_unlock(drive_ptr,FALSE);
MFS_set_error_and_return(error_ptr,MFS_DISK_FULL,0);
}
/* Make sure location (local variable) never points behind the end of file */
file_size = mqx_dtohl(handle->DIR_ENTRY.FILE_SIZE);
location = (handle->LOCATION > file_size) ? file_size : handle->LOCATION;
/* Calculate sector number and offsets within cluster and sector */
cluster_offset = OFFSET_WITHIN_CLUSTER(location);
sector_index = CLUSTER_OFFSET_TO_SECTOR(cluster_offset);
sector_number = CLUSTER_TO_SECTOR(handle->CURRENT_CLUSTER) + sector_index;
sector_offset = OFFSET_WITHIN_SECTOR(location);
/* Calculate possible gap to fill in by zeros if writing behind the end of file */
num_zeros = handle->LOCATION - location;
zeros_written = 0;
bytes_written = 0;
/* Write zeros to fill in gap if LOCATION points behind the end of file */
while (zeros_written < num_zeros)
{
/* If offset is non-zero, then reading the data is required */
error = MFS_Read_data_sector(drive_ptr, handle, sector_number, sector_offset != 0);
if ( error != MFS_NO_ERROR )
break;
/* Zero the buffer */
zero_size = min(num_zeros-zeros_written, drive_ptr->BPB.SECTOR_SIZE-sector_offset);
_mem_zero(&drive_ptr->DATA_SECTOR_PTR[sector_offset], zero_size);
drive_ptr->DATA_SECTOR_DIRTY = TRUE;
if ( drive_ptr->WRITE_CACHE_POLICY == MFS_WRITE_THROUGH_CACHE )
{
error = MFS_Flush_data_sector_buffer(drive_ptr);
if ( error != MFS_NO_ERROR )
break;
}
zeros_written += zero_size;
sector_offset += zero_size;
/*
** Check to see if we need to advance to the next sector, which has
** the side effect of increasing the cluster number if required.
*/
if ( sector_offset >= drive_ptr->BPB.SECTOR_SIZE )
{
temp_error = MFS_next_data_sector(drive_ptr, handle, §or_index, §or_number);
if (temp_error == MFS_EOF)
{
/* Always allocate new cluster, there is something to be written for sure */
error = MFS_Add_cluster_to_chain(drive_ptr, handle->PREVIOUS_CLUSTER, &handle->CURRENT_CLUSTER);
if ( MFS_NO_ERROR == error )
{
sector_number = CLUSTER_TO_SECTOR(handle->CURRENT_CLUSTER);
sector_index = 0;
}
}
else
{
error = temp_error;
}
sector_offset = 0;
}
}
/* Write partial sector if sector_offset is non-zero */
if ((sector_offset != 0) && (error == MFS_NO_ERROR))
{
/* Offset is non-zero, reading the data is required */
error = MFS_Read_data_sector(drive_ptr, handle, sector_number, TRUE);
if (error == MFS_NO_ERROR)
{
/* The requested lenght of data may span the sector to it's end */
copy_size = min(num_bytes, drive_ptr->BPB.SECTOR_SIZE-sector_offset);
_mem_copy(buffer_address, &drive_ptr->DATA_SECTOR_PTR[sector_offset], copy_size);
drive_ptr->DATA_SECTOR_DIRTY = TRUE;
if (drive_ptr->WRITE_CACHE_POLICY == MFS_WRITE_THROUGH_CACHE)
{
error = MFS_Flush_data_sector_buffer(drive_ptr);
}
if (error == MFS_NO_ERROR)
{
bytes_written = copy_size;
/*
** Check to see if we need to advance to the next sector, which has
** the side effect of increasing the cluster number if required.
*/
if ((sector_offset + bytes_written) >= drive_ptr->BPB.SECTOR_SIZE)
{
temp_error = MFS_next_data_sector(drive_ptr, handle, §or_index, §or_number);
/* Only an error if we are not done writing and can't extend the chain */
if (bytes_written < num_bytes)
{
if (temp_error == MFS_EOF)
{
/* Allocate new cluster */
error = MFS_Add_cluster_to_chain(drive_ptr, handle->PREVIOUS_CLUSTER, &handle->CURRENT_CLUSTER);
/* Update sector_number and index unconditionally - if there was an error the value is never used anyways. */
sector_number = CLUSTER_TO_SECTOR(handle->CURRENT_CLUSTER);
sector_index = 0;
}
else
{
error = temp_error;
}
}
}
}
}
}
/* Check whether the application buffer is properly aligned */
if ((((uint32_t)buffer_address+bytes_written) & drive_ptr->ALIGNMENT_MASK) == 0)
{
/* Yes, use zero copy approach */
whole_sectors = (num_bytes - bytes_written) >> drive_ptr->SECTOR_POWER;
while ((whole_sectors > 0) && (error == MFS_NO_ERROR))
{
cont_sectors = drive_ptr->BPB.SECTORS_PER_CLUSTER - sector_index;
if (cont_sectors > whole_sectors)
cont_sectors = whole_sectors;
error = MFS_Write_device_sectors(drive_ptr, sector_number, cont_sectors, MFSCFG_MAX_WRITE_RETRIES, buffer_address+bytes_written, &proc_sectors);
if (proc_sectors > 0)
{
bytes_written += proc_sectors * drive_ptr->BPB.SECTOR_SIZE;
whole_sectors -= proc_sectors;
/* Advance to next unprocessed sector */
sector_index += proc_sectors - 1;
temp_error = MFS_next_data_sector(drive_ptr, handle, §or_index, §or_number);
/* Go on only if we are not done writing yet */
if ((error == MFS_NO_ERROR) && (bytes_written < num_bytes))
{
if (temp_error == MFS_EOF)
{
/* Allocate new cluster */
error = MFS_Add_cluster_to_chain(drive_ptr, handle->PREVIOUS_CLUSTER, &handle->CURRENT_CLUSTER);
/* Update sector_number and index unconditionally - if there was an error the value is never used anyways. */
sector_number = CLUSTER_TO_SECTOR(handle->CURRENT_CLUSTER);
sector_index = 0;
}
else
{
error = temp_error;
}
}
}
}
}
_mfs_error MFS_Delete_file
(
MQX_FILE_PTR mfs_fd_ptr, /*[IN] the MFS device on which to operate */
char_ptr pathname /*[IN] directory and file name of the file to delete */
)
{
MFS_DRIVE_STRUCT_PTR drive_ptr;
MFS_DIR_ENTRY_PTR dir_entry_ptr;
_mfs_error error_code, saved_code = 0;
uint_32 dir_cluster, dir_index;
uint_32 first_cluster;
uint_32 prev_cluster= CLUSTER_INVALID;
if ( (pathname == NULL) || (*pathname == '\0') )
{
return MFS_INVALID_PARAMETER;
}
#if MFSCFG_READ_ONLY_CHECK
if (MFS_is_read_only (mfs_fd_ptr, NULL))
{
return MFS_DISK_IS_WRITE_PROTECTED;
}
#endif
error_code = MFS_lock_dos_disk( mfs_fd_ptr, &drive_ptr );
if ( error_code != MFS_NO_ERROR )
{
return error_code;
}
dir_entry_ptr = MFS_Find_entry_on_disk(drive_ptr, pathname, &error_code, &dir_cluster, &dir_index, &prev_cluster);
if ( dir_entry_ptr != NULL )
{
if ( dtohc(dir_entry_ptr->ATTRIBUTE) & (MFS_ATTR_DIR_NAME | MFS_ATTR_VOLUME_NAME | MFS_ATTR_READ_ONLY) )
{
error_code = MFS_ACCESS_DENIED;
}
else
{
first_cluster = clustoh(dir_entry_ptr->HFIRST_CLUSTER, dir_entry_ptr->LFIRST_CLUSTER);
if ( first_cluster )
{
saved_code = MFS_Release_chain(drive_ptr, first_cluster);
if ( saved_code != MFS_LOST_CHAIN && saved_code != MFS_NO_ERROR )
{
MFS_unlock(drive_ptr,TRUE);
return(saved_code);
}
}
/*
** Mark all open files with the same name as erased
*/
MFS_Delete_handles(drive_ptr, dir_entry_ptr->NAME, first_cluster);
*dir_entry_ptr->NAME = MFS_DEL_FILE;
drive_ptr->DIR_SECTOR_DIRTY = TRUE;
error_code = MFS_remove_lfn_entries(drive_ptr,dir_cluster,dir_index, prev_cluster);
}
}
MFS_unlock(drive_ptr,TRUE);
if ( saved_code == MFS_LOST_CHAIN && error_code == MFS_NO_ERROR )
{
error_code = saved_code;
}
return(error_code);
}
uint32_t MFS_Move_file_pointer
(
MFS_HANDLE_PTR handle,
MFS_DRIVE_STRUCT_PTR drive_ptr,
_mfs_error_ptr error_ptr /*[IN/OUT] resulting error code is written to this address*/
)
{
uint32_t position_after_seek, position_before_seek;
uint32_t current_cluster,
previous_cluster,
first_cluster,
skip_clusters,
k;
_mfs_error error_code;
error_code = MFS_lock_dos_disk( drive_ptr );
if ( error_code != MFS_NO_ERROR )
{
if ( error_ptr != NULL )
{
*error_ptr = error_code;
}
return 0;
}
position_after_seek = handle->LOCATION;
MFS_LOG(printf("seek to %d\n",position_after_seek));
/*
** Cannot move ahead of the beginning of the file; force beginning.
*/
if ( error_code == MFS_NO_ERROR )
{
/*
** There are four cases
**
** 1) Seeking to beginning of file (position_after_seek=0, cluster=0)
** 2) No change in position (position_after_seek==position_before_seek)
** 2) Seeking ahead of current file pointer
** 3) Seeking behind current file pointer
*/
/*
** Cannot move beyond the end of file !
*/
if ( position_after_seek> mqx_dtohl(handle->DIR_ENTRY.FILE_SIZE) ) // + 1
{
position_after_seek = mqx_dtohl(handle->DIR_ENTRY.FILE_SIZE); // - 1
error_code = MFS_EOF;
}
current_cluster = 0;
previous_cluster = 0;
first_cluster = clustoh(handle->DIR_ENTRY.HFIRST_CLUSTER, handle->DIR_ENTRY.LFIRST_CLUSTER);
MFS_LOG(printf("first_cluster = %d\n",first_cluster));
/*
** Set the current_cluster correctly.
** If we're moving ahead, don't start from the beginning.
*/
position_before_seek = CLUSTER_BOUNDARY(handle->SAVED_POSITION);
if ( handle->CURRENT_CLUSTER==0 )
{
handle->CURRENT_CLUSTER = first_cluster;
handle->PREVIOUS_CLUSTER = 0;
position_before_seek = 0;
}
if ( position_after_seek == 0 )
{
current_cluster = first_cluster;
previous_cluster = 0;
}
else if ( position_after_seek == position_before_seek )
{
current_cluster = handle->CURRENT_CLUSTER;
previous_cluster = handle->PREVIOUS_CLUSTER;
}
else
{
if ( position_after_seek < position_before_seek )
{
position_before_seek = 0;
current_cluster = first_cluster;
previous_cluster = 0;
}
else
{
current_cluster = handle->CURRENT_CLUSTER;
previous_cluster = handle->PREVIOUS_CLUSTER;
}
MFS_LOG(printf("current cluster = %d\n",current_cluster));
if ( current_cluster && (current_cluster!=CLUSTER_EOF) )
{
/*
** How many clusters do we need to skip?
*/
skip_clusters = (position_after_seek - position_before_seek) >> drive_ptr->CLUSTER_POWER_BYTES;
for ( k = 0; k < skip_clusters; k++ )
{
previous_cluster = current_cluster;
error_code = MFS_get_cluster_from_fat(drive_ptr, previous_cluster, ¤t_cluster);
if ( error_code != MFS_NO_ERROR )
{
break;
}
if ( current_cluster==CLUSTER_EOF )
{
error_code = MFS_EOF;
break;
}
else if ( (current_cluster < CLUSTER_MIN_GOOD) || (current_cluster > drive_ptr->LAST_CLUSTER) )
{
error_code = MFS_BAD_DISK_UNIT;
break;
}
MFS_LOG(printf("skip, current cluster = %d\n",current_cluster));
}
}
else
{
error_code = MFS_EOF;
}
}
uint32_t MFS_Read
(
MFS_HANDLE_PTR handle, /*[IN] file handle upon which the action is to be taken */
MFS_DRIVE_STRUCT_PTR drive_ptr,
uint32_t num_bytes, /*[IN] number of bytes to be read */
char *buffer_address, /*[IN/OUT] bytes are read into this buffer */
_mfs_error_ptr error_ptr /*[IN/OUT] error code is written to this address */
)
{
uint32_t location;
uint32_t bytes_read;
uint32_t bytes_left_in_file;
uint32_t copy_size;
uint32_t cluster_offset;
uint32_t sector_number, sector_index;
uint32_t sector_offset;
uint32_t whole_sectors;
uint32_t cont_sectors;
uint32_t proc_sectors;
_mfs_error error, temp_error;
bool eof_reached;
uint32_t file_size;
if ( num_bytes == 0 )
{
MFS_set_error_and_return(error_ptr,MFS_NO_ERROR,0);
}
if ( buffer_address == NULL )
{
MFS_set_error_and_return(error_ptr,MFS_INVALID_PARAMETER,0);
}
error = MFS_lock_dos_disk(drive_ptr);
if ( error != MFS_NO_ERROR )
{
MFS_set_error_and_return(error_ptr,error,0);
}
if ( handle->ACCESS != MFS_ACCESS_READ_ONLY &&
handle->ACCESS != MFS_ACCESS_READ_WRITE )
{
MFS_unlock(drive_ptr,FALSE);
MFS_set_error_and_return(error_ptr,MFS_ACCESS_DENIED,0);
}
if ( handle->CURRENT_CLUSTER == 0 )
{
handle->PREVIOUS_CLUSTER = 0;
handle->CURRENT_CLUSTER = clustoh(handle->DIR_ENTRY.HFIRST_CLUSTER, handle->DIR_ENTRY.LFIRST_CLUSTER);
}
else if ( handle->CURRENT_CLUSTER == CLUSTER_EOF )
{
MFS_unlock(drive_ptr,FALSE);
MFS_set_error_and_return(error_ptr,MFS_EOF,0);
}
bytes_read = 0;
eof_reached = FALSE;
location = handle->LOCATION;
/*
** Can't read past file size
*/
file_size = mqx_dtohl(handle->DIR_ENTRY.FILE_SIZE);
if ( location > file_size )
{
location = file_size;
}
bytes_left_in_file = file_size - location;
if ( num_bytes > bytes_left_in_file )
{
eof_reached = TRUE;
num_bytes = bytes_left_in_file;
}
if ( bytes_left_in_file )
{
/*
** Read the number of bytes from the current file
** position to the end of the current cluster
*/
cluster_offset = OFFSET_WITHIN_CLUSTER(location);
sector_index = CLUSTER_OFFSET_TO_SECTOR(cluster_offset);
sector_number = CLUSTER_TO_SECTOR(handle->CURRENT_CLUSTER) + sector_index;
sector_offset = OFFSET_WITHIN_SECTOR(location);
/* Read partial sector if sector_offet is non-zero */
if (sector_offset != 0)
{
error = MFS_Read_data_sector(drive_ptr, handle, sector_number, TRUE);
if ( error == MFS_NO_ERROR )
{
/* The requested lenght of data may span the sector to it's end */
copy_size = min(num_bytes, drive_ptr->BPB.SECTOR_SIZE-sector_offset);
_mem_copy(&drive_ptr->DATA_SECTOR_PTR[sector_offset], buffer_address, copy_size);
bytes_read=copy_size;
/*
** Check to see if we need to advance to the next sector, which has
** the side effect of increasing the cluster number if required.
*/
if ( (sector_offset+bytes_read) >= drive_ptr->BPB.SECTOR_SIZE )
{
temp_error = MFS_next_data_sector(drive_ptr, handle, §or_index, §or_number);
/* Only an error if we are not done reading */
if ( bytes_read<num_bytes )
{
error = temp_error;
}
}
}
}
/* Check whether the application buffer is properly aligned */
if ((((uint32_t)buffer_address+bytes_read) & drive_ptr->ALIGNMENT_MASK) == 0)
{
/* Yes, use zero copy approach */
whole_sectors = (num_bytes - bytes_read) >> drive_ptr->SECTOR_POWER;
while ((whole_sectors > 0) && (error == MFS_NO_ERROR))
{
cont_sectors = drive_ptr->BPB.SECTORS_PER_CLUSTER - sector_index;
if (cont_sectors > whole_sectors)
cont_sectors = whole_sectors;
error = MFS_Read_device_sectors(drive_ptr, sector_number, cont_sectors, MFSCFG_MAX_READ_RETRIES, buffer_address+bytes_read, &proc_sectors);
if (proc_sectors > 0)
{
bytes_read += proc_sectors * drive_ptr->BPB.SECTOR_SIZE;
whole_sectors -= proc_sectors;
/* Advance to next unprocessed sector */
sector_index += proc_sectors - 1;
temp_error = MFS_next_data_sector(drive_ptr, handle, §or_index, §or_number);
/* Only an error if we are not done reading */
if ((error==MFS_NO_ERROR) && (bytes_read<num_bytes))
{
error = temp_error;
}
}
}
}
else
{
