reactos/boot/freeldr/freeldr/disk/ramdisk.c

   1 /*
   2  * PROJECT:         ReactOS Boot Loader
   3  * LICENSE:         BSD - See COPYING.ARM in the top level directory
   4  * FILE:            boot/freeldr/arch/i386/ramdisk.c
   5  * PURPOSE:         Implements routines to support booting from a RAM Disk
   6  * PROGRAMMERS:     ReactOS Portable Systems Group
   7  */
   8
   9 /* INCLUDES *******************************************************************/
  10
  11 #include <freeldr.h>
  12 #define NDEBUG
  13 #include <debug.h>
  14
  15 /* GLOBALS ********************************************************************/
  16
  17 PVOID gRamDiskBase;
  18 ULONG gRamDiskSize;
  19 extern BOOLEAN gCacheEnabled;
  20
  21 /* FUNCTIONS ******************************************************************/
  22
  23 FORCEINLINE
  24 PVOID
  25 RamDiskGetDataAtOffset(IN PVOID Offset)
  26 {
  27     //
  28     // Return data from our RAM Disk
  29     //
  30     ASSERT(((ULONG_PTR)gRamDiskBase + (ULONG_PTR)Offset) <
  31            ((ULONG_PTR)gRamDiskBase + (ULONG_PTR)gRamDiskSize));
  32     return (PVOID)((ULONG_PTR)gRamDiskBase + (ULONG_PTR)(Offset));
  33 }
  34
  35 ULONG
  36 RamDiskGetCacheableBlockCount(IN ULONG Reserved)
  37 {
  38     //
  39     // Allow 32KB transfers (64 sectors), emulating BIOS LBA
  40     //
  41     ASSERT(Reserved == 0x49);
  42     return 64;
  43 }
  44
  45 BOOLEAN
  46 RamDiskGetDriveGeometry(IN ULONG Reserved,
  47                         OUT PGEOMETRY Geometry)
  48 {
  49     //
  50     // Should never be called when the caller expects valid Geometry!
  51     //
  52     ASSERT(Reserved == 0x49);
  53     return TRUE;
  54 }
  55
  56 BOOLEAN
  57 RamDiskReadLogicalSectors(IN ULONG Reserved,
  58                           IN ULONGLONG SectorNumber,
  59                           IN ULONG SectorCount,
  60                           IN PVOID Buffer)
  61 {
  62     PVOID StartAddress;
  63     ULONG Length;
  64     ASSERT(Reserved == 0x49);
  65
  66     //
  67     // Get actual pointers and lengths
  68     //
  69     StartAddress = (PVOID)((ULONG_PTR)SectorNumber * 512);
  70     Length = SectorCount * 512;
  71
  72     //
  73     // Don't allow reads past our image
  74     //
  75     if (((ULONG_PTR)StartAddress + Length) > gRamDiskSize) return FALSE;
  76
  77     //
  78     // Do the read
  79     //
  80     RtlCopyMemory(Buffer, RamDiskGetDataAtOffset(StartAddress), Length);
  81     return TRUE;
  82 }
  83
  84 VOID
  85 NTAPI
  86 RamDiskLoadVirtualFile(IN PCHAR FileName)
  87 {
  88     PFILE RamFile;
  89     ULONG TotalRead, ChunkSize;
  90         PCHAR MsgBuffer = "Loading ramdisk...";
  91     ULONG PercentPerChunk, Percent;
  92
  93     //
  94     // Display progress
  95     //
  96     UiDrawProgressBarCenter(1, 100, MsgBuffer);
  97
  98     //
  99     // Try opening the ramdisk file (this assumes the boot volume was opened)
 100     //
 101     RamFile = FsOpenFile(FileName);
 102     if (RamFile)
 103     {
 104         //
 105         // Get the file size
 106         //
 107         gRamDiskSize = FsGetFileSize(RamFile);
 108         if (!gRamDiskSize) return;
 109
 110         //
 111         // Allocate memory for it
 112         //
 113         ChunkSize = 8 * 1024 * 1024;
 114         Percent = PercentPerChunk = 100 / (gRamDiskSize / ChunkSize);
 115         gRamDiskBase = MmAllocateMemory(gRamDiskSize);
 116         if (!gRamDiskBase) return;
 117
 118         //
 119         // Read it in chunks
 120         //
 121         for (TotalRead = 0; TotalRead < gRamDiskSize; TotalRead += ChunkSize)
 122         {
 123             //
 124             // Check if we're at the last chunk
 125             //
 126             if ((gRamDiskSize - TotalRead) < ChunkSize)
 127             {
 128                 //
 129                 // Only need the actual data required
 130                 //
 131                 ChunkSize = gRamDiskSize - TotalRead;
 132             }
 133
 134             //
 135             // Draw progress
 136             //
 137             UiDrawProgressBarCenter(Percent, 100, MsgBuffer);
 138             Percent += PercentPerChunk;
 139
 140             //
 141             // Copy the contents
 142             //
 143
 144             if (!FsReadFile(RamFile,
 145                             ChunkSize,
 146                             NULL,
 147                             (PVOID)((ULONG_PTR)gRamDiskBase + TotalRead)))
 148             {
 149                 //
 150                 // Fail
 151                 //
 152                 UiMessageBox("Failed to read ramdisk\n");
 153             }
 154         }
 155     }
 156 }
 157
 158 VOID
 159 NTAPI
 160 RamDiskSwitchFromBios(VOID)
 161 {
 162     extern ULONG BootDrive, BootPartition;
 163
 164     //
 165     // Check if we have a ramdisk, in which case we need to switch routines
 166     //
 167     if (gRamDiskBase)
 168     {
 169         //
 170         // Don't use the BIOS for reads anymore
 171         //
 172         MachVtbl.DiskReadLogicalSectors = RamDiskReadLogicalSectors;
 173         MachVtbl.DiskGetDriveGeometry = RamDiskGetDriveGeometry;
 174         MachVtbl.DiskGetCacheableBlockCount = RamDiskGetCacheableBlockCount;
 175
 176         //
 177         // Also disable cached FAT reads
 178         //
 179         gCacheEnabled = FALSE;
 180
 181         //
 182         // Switch to ramdisk boot partition
 183         //
 184         BootDrive = 0x49;
 185         BootPartition = 0;
 186     }
 187 }