freeldr/freeldr/disk/partition.c

   1 /*
   2  *  FreeLoader
   3  *  Copyright (C) 1998-2002  Brian Palmer  <brianp@sginet.com>
   4  *
   5  *  This program is free software; you can redistribute it and/or modify
   6  *  it under the terms of the GNU General Public License as published by
   7  *  the Free Software Foundation; either version 2 of the License, or
   8  *  (at your option) any later version.
   9  *
  10  *  This program is distributed in the hope that it will be useful,
  11  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  *  GNU General Public License for more details.
  14  *
  15  *  You should have received a copy of the GNU General Public License
  16  *  along with this program; if not, write to the Free Software
  17  *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  18  */
  19
  20 #include <freeldr.h>
  21 #include <disk.h>
  22 #include <rtl.h>
  23 #include <mm.h>
  24 #include <debug.h>
  25 #include <arch.h>
  26
  27
  28
  29 BOOL DiskIsDriveRemovable(ULONG DriveNumber)
  30 {
  31         // Hard disks use drive numbers >= 0x80
  32         // So if the drive number indicates a hard disk
  33         // then return FALSE
  34         if (DriveNumber >= 0x80)
  35         {
  36                 return FALSE;
  37         }
  38
  39         // Drive is a floppy diskette so return TRUE
  40         return TRUE;
  41 }
  42
  43
  44 BOOL DiskIsDriveCdRom(ULONG DriveNumber)
  45 {
  46         PUCHAR Sector;
  47         BOOL Result;
  48
  49         // Hard disks use drive numbers >= 0x80
  50         // So if the drive number indicates a hard disk
  51         // then return FALSE
  52         if ((DriveNumber >= 0x80) && (BiosInt13ExtensionsSupported(DriveNumber)))
  53         {
  54                 Sector = AllocateMemory(2048);
  55
  56                 if (!BiosInt13ReadExtended(DriveNumber, 16, 1, Sector))
  57                 {
  58                         DiskError("Disk read error.");
  59                         FreeMemory(Sector);
  60                         return FALSE;
  61                 }
  62
  63                 Result = (Sector[0] == 1 &&
  64                           Sector[1] == 'C' &&
  65                           Sector[2] == 'D' &&
  66                           Sector[3] == '0' &&
  67                           Sector[4] == '0' &&
  68                           Sector[5] == '1');
  69
  70                 FreeMemory(Sector);
  71
  72                 return Result;
  73         }
  74
  75         // Drive is not CdRom so return FALSE
  76         return FALSE;
  77 }
  78
  79
  80 BOOL DiskGetActivePartitionEntry(ULONG DriveNumber, PPARTITION_TABLE_ENTRY PartitionTableEntry)
  81 {
  82         ULONG                           BootablePartitionCount = 0;
  83         MASTER_BOOT_RECORD      MasterBootRecord;
  84
  85         // Read master boot record
  86         if (!DiskReadBootRecord(DriveNumber, 0, &MasterBootRecord))
  87         {
  88                 return FALSE;
  89         }
  90
  91         // Count the bootable partitions
  92         if (MasterBootRecord.PartitionTable[0].BootIndicator == 0x80)
  93         {
  94                 BootablePartitionCount++;
  95                 BootPartition = 0;
  96         }
  97         if (MasterBootRecord.PartitionTable[1].BootIndicator == 0x80)
  98         {
  99                 BootablePartitionCount++;
 100                 BootPartition = 1;
 101         }
 102         if (MasterBootRecord.PartitionTable[2].BootIndicator == 0x80)
 103         {
 104                 BootablePartitionCount++;
 105                 BootPartition = 2;
 106         }
 107         if (MasterBootRecord.PartitionTable[3].BootIndicator == 0x80)
 108         {
 109                 BootablePartitionCount++;
 110                 BootPartition = 3;
 111         }
 112
 113         // Make sure there was only one bootable partition
 114         if (BootablePartitionCount != 1)
 115         {
 116                 DiskError("Too many bootable partitions or none found.");
 117                 return FALSE;
 118         }
 119
 120         // Copy the partition table entry
 121         RtlCopyMemory(PartitionTableEntry, &MasterBootRecord.PartitionTable[BootPartition], sizeof(PARTITION_TABLE_ENTRY));
 122
 123         return TRUE;
 124 }
 125
 126 BOOL DiskGetPartitionEntry(ULONG DriveNumber, ULONG PartitionNumber, PPARTITION_TABLE_ENTRY PartitionTableEntry)
 127 {
 128         MASTER_BOOT_RECORD              MasterBootRecord;
 129         PARTITION_TABLE_ENTRY   ExtendedPartitionTableEntry;
 130         ULONG                                   ExtendedPartitionNumber;
 131         ULONG                                   Index;
 132
 133         // Read master boot record
 134         if (!DiskReadBootRecord(DriveNumber, 0, &MasterBootRecord))
 135         {
 136                 return FALSE;
 137         }
 138
 139         // If they are asking for a primary
 140         // partition then things are easy
 141         if (PartitionNumber < 5)
 142         {
 143                 // PartitionNumber is one-based and we need it zero-based
 144                 PartitionNumber--;
 145
 146                 // Copy the partition table entry
 147                 RtlCopyMemory(PartitionTableEntry, &MasterBootRecord.PartitionTable[PartitionNumber], sizeof(PARTITION_TABLE_ENTRY));
 148
 149                 return TRUE;
 150         }
 151         else
 152         {
 153                 // They want an extended partition entry so we will need
 154                 // to loop through all the extended partitions on the disk
 155                 // and return the one they want.
 156
 157                 ExtendedPartitionNumber = PartitionNumber - 5;
 158
 159                 for (Index=0; Index<=ExtendedPartitionNumber; Index++)
 160                 {
 161                         // Get the extended partition table entry
 162                         if (!DiskGetFirstExtendedPartitionEntry(&MasterBootRecord, &ExtendedPartitionTableEntry))
 163                         {
 164                                 return FALSE;
 165                         }
 166
 167                         // Read the partition boot record
 168                         if (!DiskReadBootRecord(DriveNumber, ExtendedPartitionTableEntry.SectorCountBeforePartition, &MasterBootRecord))
 169                         {
 170                                 return FALSE;
 171                         }
 172
 173                         // Get the first real partition table entry
 174                         if (!DiskGetFirstPartitionEntry(&MasterBootRecord, PartitionTableEntry))
 175                         {
 176                                 return FALSE;
 177                         }
 178                 }
 179
 180                 // When we get here we should have the correct entry
 181                 // already stored in PartitionTableEntry
 182                 // so just return TRUE
 183                 return TRUE;
 184         }
 185
 186 }
 187
 188 BOOL DiskGetFirstPartitionEntry(PMASTER_BOOT_RECORD MasterBootRecord, PPARTITION_TABLE_ENTRY PartitionTableEntry)
 189 {
 190         ULONG   Index;
 191
 192         for (Index=0; Index<4; Index++)
 193         {
 194                 // Check the system indicator
 195                 // If it's not an extended or unused partition
 196                 // then we're done
 197                 if ((MasterBootRecord->PartitionTable[Index].SystemIndicator != PARTITION_ENTRY_UNUSED) &&
 198                         (MasterBootRecord->PartitionTable[Index].SystemIndicator != PARTITION_EXTENDED) &&
 199                         (MasterBootRecord->PartitionTable[Index].SystemIndicator != PARTITION_XINT13_EXTENDED))
 200                 {
 201                         RtlCopyMemory(PartitionTableEntry, &MasterBootRecord->PartitionTable[Index], sizeof(PARTITION_TABLE_ENTRY));
 202                         return TRUE;
 203                 }
 204         }
 205
 206         return FALSE;
 207 }
 208
 209 BOOL DiskGetFirstExtendedPartitionEntry(PMASTER_BOOT_RECORD MasterBootRecord, PPARTITION_TABLE_ENTRY PartitionTableEntry)
 210 {
 211         ULONG   Index;
 212
 213         for (Index=0; Index<4; Index++)
 214         {
 215                 // Check the system indicator
 216                 // If it an extended partition then we're done
 217                 if ((MasterBootRecord->PartitionTable[Index].SystemIndicator == PARTITION_EXTENDED) ||
 218                         (MasterBootRecord->PartitionTable[Index].SystemIndicator == PARTITION_XINT13_EXTENDED))
 219                 {
 220                         RtlCopyMemory(PartitionTableEntry, &MasterBootRecord->PartitionTable[Index], sizeof(PARTITION_TABLE_ENTRY));
 221                         return TRUE;
 222                 }
 223         }
 224
 225         return FALSE;
 226 }
 227
 228 BOOL DiskReadBootRecord(ULONG DriveNumber, ULONG LogicalSectorNumber, PMASTER_BOOT_RECORD BootRecord)
 229 {
 230         ULONG   Index;
 231
 232         // Read master boot record
 233         if (!DiskReadLogicalSectors(DriveNumber, LogicalSectorNumber, 1, (PVOID)DISKREADBUFFER))
 234         {
 235                 return FALSE;
 236         }
 237         RtlCopyMemory(BootRecord, (PVOID)DISKREADBUFFER, sizeof(MASTER_BOOT_RECORD));
 238
 239
 240 #ifdef DEBUG
 241
 242         DbgPrint((DPRINT_DISK, "Dumping partition table for drive 0x%x:\n", DriveNumber));
 243         DbgPrint((DPRINT_DISK, "Boot record logical start sector = %d\n", LogicalSectorNumber));
 244         DbgPrint((DPRINT_DISK, "sizeof(MASTER_BOOT_RECORD) = 0x%x.\n", sizeof(MASTER_BOOT_RECORD)));
 245
 246         for (Index=0; Index<4; Index++)
 247         {
 248                 DbgPrint((DPRINT_DISK, "-------------------------------------------\n"));
 249                 DbgPrint((DPRINT_DISK, "Partition %d\n", (Index + 1)));
 250                 DbgPrint((DPRINT_DISK, "BootIndicator: 0x%x\n", BootRecord->PartitionTable[Index].BootIndicator));
 251                 DbgPrint((DPRINT_DISK, "StartHead: 0x%x\n", BootRecord->PartitionTable[Index].StartHead));
 252                 DbgPrint((DPRINT_DISK, "StartSector (Plus 2 cylinder bits): 0x%x\n", BootRecord->PartitionTable[Index].StartSector));
 253                 DbgPrint((DPRINT_DISK, "StartCylinder: 0x%x\n", BootRecord->PartitionTable[Index].StartCylinder));
 254                 DbgPrint((DPRINT_DISK, "SystemIndicator: 0x%x\n", BootRecord->PartitionTable[Index].SystemIndicator));
 255                 DbgPrint((DPRINT_DISK, "EndHead: 0x%x\n", BootRecord->PartitionTable[Index].EndHead));
 256                 DbgPrint((DPRINT_DISK, "EndSector (Plus 2 cylinder bits): 0x%x\n", BootRecord->PartitionTable[Index].EndSector));
 257                 DbgPrint((DPRINT_DISK, "EndCylinder: 0x%x\n", BootRecord->PartitionTable[Index].EndCylinder));
 258                 DbgPrint((DPRINT_DISK, "SectorCountBeforePartition: 0x%x\n", BootRecord->PartitionTable[Index].SectorCountBeforePartition));
 259                 DbgPrint((DPRINT_DISK, "PartitionSectorCount: 0x%x\n", BootRecord->PartitionTable[Index].PartitionSectorCount));
 260         }
 261
 262 #endif // defined DEBUG
 263
 264         // Check the partition table magic value
 265         if (BootRecord->MasterBootRecordMagic != 0xaa55)
 266         {
 267                 DiskError("Invalid partition table magic (0xaa55)");
 268                 return FALSE;
 269         }
 270
 271         return TRUE;
 272 }