usbloadergx/source/libfat/partition.c

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/*
partition.c
Functions for mounting and dismounting partitions
on various block devices.
Copyright (c) 2006 Michael "Chishm" Chisholm
Redistribution and use in source and binary forms, with or without modification,
are permitted provided that the following conditions are met:
1. Redistributions of source code must retain the above copyright notice,
this list of conditions and the following disclaimer.
2. Redistributions in binary form must reproduce the above copyright notice,
this list of conditions and the following disclaimer in the documentation and/or
other materials provided with the distribution.
3. The name of the author may not be used to endorse or promote products derived
from this software without specific prior written permission.
THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE
LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include "partition.h"
#include "bit_ops.h"
#include "file_allocation_table.h"
#include "directory.h"
#include "mem_allocate.h"
#include "fatfile.h"
#include <string.h>
#include <ctype.h>
#include <sys/iosupport.h>
sec_t _FAT_startSector;
/*
This device name, as known by devkitPro toolchains
*/
const char* DEVICE_NAME = "fat";
/*
Data offsets
*/
// BIOS Parameter Block offsets
enum BPB {
BPB_jmpBoot = 0x00,
BPB_OEMName = 0x03,
// BIOS Parameter Block
BPB_bytesPerSector = 0x0B,
BPB_sectorsPerCluster = 0x0D,
BPB_reservedSectors = 0x0E,
BPB_numFATs = 0x10,
BPB_rootEntries = 0x11,
BPB_numSectorsSmall = 0x13,
BPB_mediaDesc = 0x15,
BPB_sectorsPerFAT = 0x16,
BPB_sectorsPerTrk = 0x18,
BPB_numHeads = 0x1A,
BPB_numHiddenSectors = 0x1C,
BPB_numSectors = 0x20,
// Ext BIOS Parameter Block for FAT16
BPB_FAT16_driveNumber = 0x24,
BPB_FAT16_reserved1 = 0x25,
BPB_FAT16_extBootSig = 0x26,
BPB_FAT16_volumeID = 0x27,
BPB_FAT16_volumeLabel = 0x2B,
BPB_FAT16_fileSysType = 0x36,
// Bootcode
BPB_FAT16_bootCode = 0x3E,
// FAT32 extended block
BPB_FAT32_sectorsPerFAT32 = 0x24,
BPB_FAT32_extFlags = 0x28,
BPB_FAT32_fsVer = 0x2A,
BPB_FAT32_rootClus = 0x2C,
BPB_FAT32_fsInfo = 0x30,
BPB_FAT32_bkBootSec = 0x32,
// Ext BIOS Parameter Block for FAT32
BPB_FAT32_driveNumber = 0x40,
BPB_FAT32_reserved1 = 0x41,
BPB_FAT32_extBootSig = 0x42,
BPB_FAT32_volumeID = 0x43,
BPB_FAT32_volumeLabel = 0x47,
BPB_FAT32_fileSysType = 0x52,
// Bootcode
BPB_FAT32_bootCode = 0x5A,
BPB_bootSig_55 = 0x1FE,
BPB_bootSig_AA = 0x1FF
};
static const char FAT_SIG[3] = {'F', 'A', 'T'};
sec_t FindFirstValidPartition(const DISC_INTERFACE* disc)
{
uint8_t part_table[16*4];
uint8_t *ptr;
int i;
uint8_t sectorBuffer[BYTES_PER_READ] = {0};
// Read first sector of disc
if (!_FAT_disc_readSectors (disc, 0, 1, sectorBuffer)) {
return 0;
}
memcpy(part_table,sectorBuffer+0x1BE,16*4);
ptr = part_table;
for(i=0;i<4;i++,ptr+=16) {
sec_t part_lba = u8array_to_u32(ptr, 0x8);
if (!memcmp(sectorBuffer + BPB_FAT16_fileSysType, FAT_SIG, sizeof(FAT_SIG)) ||
!memcmp(sectorBuffer + BPB_FAT32_fileSysType, FAT_SIG, sizeof(FAT_SIG))) {
return part_lba;
}
if(ptr[4]==0) continue;
if(ptr[4]==0x0F) {
sec_t part_lba2=part_lba;
sec_t next_lba2=0;
int n;
for(n=0;n<8;n++) // max 8 logic partitions
{
if(!_FAT_disc_readSectors (disc, part_lba+next_lba2, 1, sectorBuffer)) return 0;
part_lba2 = part_lba + next_lba2 + u8array_to_u32(sectorBuffer, 0x1C6) ;
next_lba2 = u8array_to_u32(sectorBuffer, 0x1D6);
if(!_FAT_disc_readSectors (disc, part_lba2, 1, sectorBuffer)) return 0;
if (!memcmp(sectorBuffer + BPB_FAT16_fileSysType, FAT_SIG, sizeof(FAT_SIG)) ||
!memcmp(sectorBuffer + BPB_FAT32_fileSysType, FAT_SIG, sizeof(FAT_SIG)))
{
return part_lba2;
}
if(next_lba2==0) break;
}
} else {
if(!_FAT_disc_readSectors (disc, part_lba, 1, sectorBuffer)) return 0;
if (!memcmp(sectorBuffer + BPB_FAT16_fileSysType, FAT_SIG, sizeof(FAT_SIG)) ||
!memcmp(sectorBuffer + BPB_FAT32_fileSysType, FAT_SIG, sizeof(FAT_SIG))) {
return part_lba;
}
}
}
return 0;
}
PARTITION* _FAT_partition_constructor (const DISC_INTERFACE* disc, uint32_t cacheSize, uint32_t sectorsPerPage, sec_t startSector) {
PARTITION* partition;
uint8_t sectorBuffer[BYTES_PER_READ] = {0};
// Read first sector of disc
if (!_FAT_disc_readSectors (disc, startSector, 1, sectorBuffer)) {
return NULL;
}
// Make sure it is a valid MBR or boot sector
if ( (sectorBuffer[BPB_bootSig_55] != 0x55) || (sectorBuffer[BPB_bootSig_AA] != 0xAA)) {
return NULL;
}
if (startSector != 0) {
// We're told where to start the partition, so just accept it
} else if (!memcmp(sectorBuffer + BPB_FAT16_fileSysType, FAT_SIG, sizeof(FAT_SIG))) {
// Check if there is a FAT string, which indicates this is a boot sector
startSector = 0;
} else if (!memcmp(sectorBuffer + BPB_FAT32_fileSysType, FAT_SIG, sizeof(FAT_SIG))) {
// Check for FAT32
startSector = 0;
} else {
startSector = FindFirstValidPartition(disc);
if (!_FAT_disc_readSectors (disc, startSector, 1, sectorBuffer)) {
return NULL;
}
}
// Now verify that this is indeed a FAT partition
if (memcmp(sectorBuffer + BPB_FAT16_fileSysType, FAT_SIG, sizeof(FAT_SIG)) &&
memcmp(sectorBuffer + BPB_FAT32_fileSysType, FAT_SIG, sizeof(FAT_SIG)))
{
return NULL;
}
// check again for the last two cases to make sure that we really have a FAT filesystem here
// and won't corrupt any data
if(memcmp(sectorBuffer + BPB_FAT16_fileSysType, "FAT", 3) != 0 && memcmp(sectorBuffer + BPB_FAT32_fileSysType, "FAT32", 5) != 0)
{
return NULL;
}
partition = (PARTITION*) _FAT_mem_allocate (sizeof(PARTITION));
if (partition == NULL) {
return NULL;
}
// Init the partition lock
_FAT_lock_init(&partition->lock);
_FAT_startSector = startSector;
if (!memcmp(sectorBuffer + BPB_FAT16_fileSysType, FAT_SIG, sizeof(FAT_SIG)))
strncpy(partition->label, (char*)(sectorBuffer + BPB_FAT16_volumeLabel), 11);
else
strncpy(partition->label, (char*)(sectorBuffer + BPB_FAT32_volumeLabel), 11);
partition->label[11] = '\0';
// Set partition's disc interface
partition->disc = disc;
// Store required information about the file system
partition->fat.sectorsPerFat = u8array_to_u16(sectorBuffer, BPB_sectorsPerFAT);
if (partition->fat.sectorsPerFat == 0) {
partition->fat.sectorsPerFat = u8array_to_u32( sectorBuffer, BPB_FAT32_sectorsPerFAT32);
}
partition->numberOfSectors = u8array_to_u16( sectorBuffer, BPB_numSectorsSmall);
if (partition->numberOfSectors == 0) {
partition->numberOfSectors = u8array_to_u32( sectorBuffer, BPB_numSectors);
}
partition->bytesPerSector = BYTES_PER_READ; // Sector size is redefined to be 512 bytes
partition->sectorsPerCluster = sectorBuffer[BPB_sectorsPerCluster] * u8array_to_u16(sectorBuffer, BPB_bytesPerSector) / BYTES_PER_READ;
partition->bytesPerCluster = partition->bytesPerSector * partition->sectorsPerCluster;
partition->fat.fatStart = startSector + u8array_to_u16(sectorBuffer, BPB_reservedSectors);
partition->rootDirStart = partition->fat.fatStart + (sectorBuffer[BPB_numFATs] * partition->fat.sectorsPerFat);
partition->dataStart = partition->rootDirStart +
(( u8array_to_u16(sectorBuffer, BPB_rootEntries) * DIR_ENTRY_DATA_SIZE) / partition->bytesPerSector);
partition->totalSize = ((uint64_t)partition->numberOfSectors - (partition->dataStart - startSector)) * (uint64_t)partition->bytesPerSector;
// Store info about FAT
uint32_t clusterCount = (partition->numberOfSectors - (uint32_t)(partition->dataStart - startSector)) / partition->sectorsPerCluster;
partition->fat.lastCluster = clusterCount + CLUSTER_FIRST - 1;
partition->fat.firstFree = CLUSTER_FIRST;
if (clusterCount < CLUSTERS_PER_FAT12) {
partition->filesysType = FS_FAT12; // FAT12 volume
} else if (clusterCount < CLUSTERS_PER_FAT16) {
partition->filesysType = FS_FAT16; // FAT16 volume
} else {
partition->filesysType = FS_FAT32; // FAT32 volume
}
if (partition->filesysType != FS_FAT32) {
partition->rootDirCluster = FAT16_ROOT_DIR_CLUSTER;
} else {
// Set up for the FAT32 way
partition->rootDirCluster = u8array_to_u32(sectorBuffer, BPB_FAT32_rootClus);
// Check if FAT mirroring is enabled
if (!(sectorBuffer[BPB_FAT32_extFlags] & 0x80)) {
// Use the active FAT
partition->fat.fatStart = partition->fat.fatStart + ( partition->fat.sectorsPerFat * (sectorBuffer[BPB_FAT32_extFlags] & 0x0F));
}
}
// Create a cache to use
partition->cache = _FAT_cache_constructor (cacheSize, sectorsPerPage, partition->disc, startSector+partition->numberOfSectors);
// Set current directory to the root
partition->cwdCluster = partition->rootDirCluster;
// Check if this disc is writable, and set the readOnly property appropriately
partition->readOnly = !(_FAT_disc_features(disc) & FEATURE_MEDIUM_CANWRITE);
// There are currently no open files on this partition
partition->openFileCount = 0;
partition->firstOpenFile = NULL;
return partition;
}
void _FAT_partition_destructor (PARTITION* partition) {
FILE_STRUCT* nextFile;
_FAT_lock(&partition->lock);
// Synchronize open files
nextFile = partition->firstOpenFile;
while (nextFile) {
_FAT_syncToDisc (nextFile);
nextFile = nextFile->nextOpenFile;
}
// Free memory used by the cache, writing it to disc at the same time
_FAT_cache_destructor (partition->cache);
// Unlock the partition and destroy the lock
_FAT_unlock(&partition->lock);
_FAT_lock_deinit(&partition->lock);
// Free memory used by the partition
_FAT_mem_free (partition);
}
PARTITION* _FAT_partition_getPartitionFromPath (const char* path) {
const devoptab_t *devops;
devops = GetDeviceOpTab (path);
if (!devops) {
return NULL;
}
return (PARTITION*)devops->deviceData;
}