/*
Get starting sector# of specified partition on drive #unit
NOTE: This code ASSUMES an MBR on the disk.
scratchsector should point to a SECTOR_SIZE scratch area
Returns 0xffffffff for any error.
If pactive is non-NULL, this function also returns the partition active flag.
If pptype is non-NULL, this function also returns the partition type.
If psize is non-NULL, this function also returns the partition size.
*/
uint32_t DFS_GetPtnStart(uint8_t unit, uint8_t *scratchsector, uint8_t pnum, uint8_t *pactive, uint8_t *pptype, uint32_t *psize)
{
uint32_t result;
PMBR mbr = (PMBR) scratchsector;
// DOS ptable supports maximum 4 partitions
if (pnum > 3)
return DFS_ERRMISC;
// Read MBR from target media
if (DFS_ReadSector(unit,scratchsector,0,1)) {
return DFS_ERRMISC;
}
result = (uint32_t) mbr->ptable[pnum].start_0 |
(((uint32_t) mbr->ptable[pnum].start_1) << 8) |
(((uint32_t) mbr->ptable[pnum].start_2) << 16) |
(((uint32_t) mbr->ptable[pnum].start_3) << 24);
if (pactive)
*pactive = mbr->ptable[pnum].active;
if (pptype)
*pptype = mbr->ptable[pnum].type;
if (psize)
*psize = (uint32_t) mbr->ptable[pnum].size_0 |
(((uint32_t) mbr->ptable[pnum].size_1) << 8) |
(((uint32_t) mbr->ptable[pnum].size_2) << 16) |
(((uint32_t) mbr->ptable[pnum].size_3) << 24);
return result;
}
uint32_t mount_complete(void)
{
int retval, sector;
strcpy(dfs_currdir, "/");
// Start up the low-level file I/O driver
if ((retval = DFS_InitFileIO()) != DFS_OK)
return retval;
// Find the first sector of the volume
if ((retval = DFS_ReadSector(0, dfs_scratch, 0, 1)) != DFS_OK)
return retval;
if (!strncmp((char *)dfs_scratch+0x36, "FAT16", 5) ||
!strncmp((char *)dfs_scratch+0x52, "FAT32", 5))
sector = 0;
else
memcpy(§or, &dfs_scratch[0x1c6], 4);
// Get the volume information
retval = DFS_GetVolInfo(0, dfs_scratch, sector, &dfs_volinfo);
dfs_mountflag = (retval == DFS_OK);
return retval;
}
void telnet_sddump( file_handle_t handle, char** argv, unsigned int argc )
{
unsigned long sector = 0;
char tmp[8];
char* parseend;
if( argc != 2)
{
file_puts("sddump [sector]\r\n", telnet_handle);
return;
}
sector = strtoul( argv[1], &parseend, 0);
unsigned char* data = malloc( SECTOR_SIZE );
unsigned char result = DFS_ReadSector(0, data, sector, 1);
if( result == 0 )
{
memdump( handle, data, data + SECTOR_SIZE);
}
else
{
file_puts("Error reading sector. Response code:", handle );
sprintf(tmp,"%02hhx", result );
file_puts(tmp, handle);
file_puts(CRLF, handle);
}
free(data);
return;
}
/*
Fetch FAT entry for specified cluster number
You must provide a scratch buffer for one sector (SECTOR_SIZE) and a populated VOLINFO
Returns a FAT32 BAD_CLUSTER value for any error, otherwise the contents of the desired
FAT entry.
scratchcache should point to a UINT32. This variable caches the physical sector number
last read into the scratch buffer for performance enhancement reasons.
*/
uint32_t DFS_GetFAT(PVOLINFO volinfo, uint8_t *scratch, uint32_t *scratchcache, uint32_t cluster)
{
uint32_t offset, sector, result;
if (volinfo->filesystem == FAT12) {
offset = cluster + (cluster / 2);
}
else if (volinfo->filesystem == FAT16) {
offset = cluster * 2;
}
else if (volinfo->filesystem == FAT32) {
offset = cluster * 4;
}
else
return 0x0ffffff7; // FAT32 bad cluster
// at this point, offset is the BYTE offset of the desired sector from the start
// of the FAT. Calculate the physical sector containing this FAT entry.
sector = ldiv(offset, SECTOR_SIZE).quot + volinfo->fat1;
// If this is not the same sector we last read, then read it into RAM
if (sector != *scratchcache) {
if(DFS_ReadSector(volinfo->unit, scratch, sector, 1)) {
// avoid anyone assuming that this cache value is still valid, which
// might cause disk corruption
*scratchcache = 0;
return 0x0ffffff7; // FAT32 bad cluster
}
*scratchcache = sector;
}
// At this point, we "merely" need to extract the relevant entry.
// This is easy for FAT16 and FAT32, but a royal PITA for FAT12 as a single entry
// may span a sector boundary. The normal way around this is always to read two
// FAT sectors, but that luxury is (by design intent) unavailable to DOSFS.
offset = ldiv(offset, SECTOR_SIZE).rem;
if (volinfo->filesystem == FAT12) {
// Special case for sector boundary - Store last byte of current sector.
// Then read in the next sector and put the first byte of that sector into
// the high byte of result.
if (offset == SECTOR_SIZE - 1) {
result = (uint32_t) scratch[offset];
sector++;
if(DFS_ReadSector(volinfo->unit, scratch, sector, 1)) {
// avoid anyone assuming that this cache value is still valid, which
// might cause disk corruption
*scratchcache = 0;
return 0x0ffffff7; // FAT32 bad cluster
}
*scratchcache = sector;
// Thanks to Claudio Leonel for pointing out this missing line.
result |= ((uint32_t) scratch[0]) << 8;
}
else {
result = (uint32_t) scratch[offset] |
((uint32_t) scratch[offset+1]) << 8;
}
if (cluster & 1)
result = result >> 4;
else
result = result & 0xfff;
}
/*
Retrieve volume info from BPB and store it in a VOLINFO structure
You must provide the unit and starting sector of the filesystem, and
a pointer to a sector buffer for scratch
Attempts to read BPB and glean information about the FS from that.
Returns 0 OK, nonzero for any error.
*/
uint32_t DFS_GetVolInfo(uint8_t unit, uint8_t *scratchsector, uint32_t startsector, PVOLINFO volinfo)
{
PLBR lbr = (PLBR) scratchsector;
volinfo->unit = unit;
volinfo->startsector = startsector;
if(DFS_ReadSector(unit,scratchsector,startsector,1))
return DFS_ERRMISC;
// tag: OEMID, refer dosfs.h
// strncpy(volinfo->oemid, lbr->oemid, 8);
// volinfo->oemid[8] = 0;
volinfo->secperclus = lbr->bpb.secperclus;
volinfo->reservedsecs = (uint16_t) lbr->bpb.reserved_l |
(((uint16_t) lbr->bpb.reserved_h) << 8);
volinfo->numsecs = (uint16_t) lbr->bpb.sectors_s_l |
(((uint16_t) lbr->bpb.sectors_s_h) << 8);
if (!volinfo->numsecs)
volinfo->numsecs = (uint32_t) lbr->bpb.sectors_l_0 |
(((uint32_t) lbr->bpb.sectors_l_1) << 8) |
(((uint32_t) lbr->bpb.sectors_l_2) << 16) |
(((uint32_t) lbr->bpb.sectors_l_3) << 24);
// If secperfat is 0, we must be in a FAT32 volume; get secperfat
// from the FAT32 EBPB. The volume label and system ID string are also
// in different locations for FAT12/16 vs FAT32.
volinfo->secperfat = (uint16_t) lbr->bpb.secperfat_l |
(((uint16_t) lbr->bpb.secperfat_h) << 8);
if (!volinfo->secperfat) {
volinfo->secperfat = (uint32_t) lbr->ebpb.ebpb32.fatsize_0 |
(((uint32_t) lbr->ebpb.ebpb32.fatsize_1) << 8) |
(((uint32_t) lbr->ebpb.ebpb32.fatsize_2) << 16) |
(((uint32_t) lbr->ebpb.ebpb32.fatsize_3) << 24);
memcpy(volinfo->label, lbr->ebpb.ebpb32.label, 11);
volinfo->label[11] = 0;
// tag: OEMID, refer dosfs.h
// memcpy(volinfo->system, lbr->ebpb.ebpb32.system, 8);
// volinfo->system[8] = 0;
}
else {
memcpy(volinfo->label, lbr->ebpb.ebpb.label, 11);
volinfo->label[11] = 0;
// tag: OEMID, refer dosfs.h
// memcpy(volinfo->system, lbr->ebpb.ebpb.system, 8);
// volinfo->system[8] = 0;
}
// note: if rootentries is 0, we must be in a FAT32 volume.
volinfo->rootentries = (uint16_t) lbr->bpb.rootentries_l |
(((uint16_t) lbr->bpb.rootentries_h) << 8);
// after extracting raw info we perform some useful precalculations
volinfo->fat1 = startsector + volinfo->reservedsecs;
// The calculation below is designed to round up the root directory size for FAT12/16
// and to simply ignore the root directory for FAT32, since it's a normal, expandable
// file in that situation.
if (volinfo->rootentries) {
volinfo->rootdir = volinfo->fat1 + (volinfo->secperfat * 2);
volinfo->dataarea = volinfo->rootdir + (((volinfo->rootentries * 32) + (SECTOR_SIZE - 1)) / SECTOR_SIZE);
}
else {
volinfo->dataarea = volinfo->fat1 + (volinfo->secperfat * 2);
volinfo->rootdir = (uint32_t) lbr->ebpb.ebpb32.root_0 |
(((uint32_t) lbr->ebpb.ebpb32.root_1) << 8) |
(((uint32_t) lbr->ebpb.ebpb32.root_2) << 16) |
(((uint32_t) lbr->ebpb.ebpb32.root_3) << 24);
}
// Calculate number of clusters in data area and infer FAT type from this information.
volinfo->numclusters = (volinfo->numsecs - volinfo->dataarea) / volinfo->secperclus;
if (volinfo->numclusters < 4085)
volinfo->filesystem = FAT12;
else if (volinfo->numclusters < 65525)
volinfo->filesystem = FAT16;
else
volinfo->filesystem = FAT32;
return DFS_OK;
}
