[FREELDR]

[reactos.git] / reactos / boot / freeldr / freeldr / fs / fat.c

diff --git a/reactos/boot/freeldr/freeldr/fs/fat.c b/reactos/boot/freeldr/freeldr/fs/fat.c
index 49fe95a..79c3dd3 100644 (file)
--- a/reactos/boot/freeldr/freeldr/fs/fat.c
+++ b/reactos/boot/freeldr/freeldr/fs/fat.c
@@ -904,9 +904,19 @@ BOOLEAN FatGetFatEntry(PFAT_VOLUME_INFO Volume, ULONG Cluster, ULONG* ClusterPoi
        UINT32          FatOffset;
        UINT32          ThisFatSecNum;
        UINT32          ThisFatEntOffset;
+       ULONG SectorCount;
+       PUCHAR ReadBuffer;
+       BOOLEAN status = TRUE;
 
        //TRACE("FatGetFatEntry() Retrieving FAT entry for cluster %d.\n", Cluster);
 
+       // We need a buffer for 2 secors
+       ReadBuffer = HeapAllocate(FrLdrTempHeap, 2 * Volume->BytesPerSector, 'xTAF');
+       if (!ReadBuffer)
+       {
+               return FALSE;
+       }
+
        switch(Volume->FatType)
        {
        case FAT12:
@@ -921,20 +931,20 @@ BOOLEAN FatGetFatEntry(PFAT_VOLUME_INFO Volume, ULONG Cluster, ULONG* ClusterPoi
 
                if (ThisFatEntOffset == (Volume->BytesPerSector - 1))
                {
-                       if (!FatReadVolumeSectors(Volume, ThisFatSecNum, 2, (PVOID)FILESYSBUFFER))
-                       {
-                               return FALSE;
-                       }
+                   SectorCount = 2;
                }
                else
                {
-                       if (!FatReadVolumeSectors(Volume, ThisFatSecNum, 1, (PVOID)FILESYSBUFFER))
-                       {
-                               return FALSE;
-                       }
+                   SectorCount = 1;
+               }
+
+               if (!FatReadVolumeSectors(Volume, ThisFatSecNum, SectorCount, ReadBuffer))
+               {
+                       status = FALSE;
+                       break;
                }
 
-               fat = *((USHORT *) ((ULONG_PTR)FILESYSBUFFER + ThisFatEntOffset));
+               fat = *((USHORT *) (ReadBuffer + ThisFatEntOffset));
                fat = SWAPW(fat);
                if (Cluster & 0x0001)
                        fat = fat >> 4; /* Cluster number is ODD */
@@ -950,12 +960,13 @@ BOOLEAN FatGetFatEntry(PFAT_VOLUME_INFO Volume, ULONG Cluster, ULONG* ClusterPoi
                ThisFatSecNum = Volume->ActiveFatSectorStart + (FatOffset / Volume->BytesPerSector);
                ThisFatEntOffset = (FatOffset % Volume->BytesPerSector);
 
-               if (!FatReadVolumeSectors(Volume, ThisFatSecNum, 1, (PVOID)FILESYSBUFFER))
+               if (!FatReadVolumeSectors(Volume, ThisFatSecNum, 1, ReadBuffer))
                {
-                       return FALSE;
+                       status = FALSE;
+                       break;
                }
 
-               fat = *((USHORT *) ((ULONG_PTR)FILESYSBUFFER + ThisFatEntOffset));
+               fat = *((USHORT *) (ReadBuffer + ThisFatEntOffset));
                fat = SWAPW(fat);
 
                break;
@@ -967,28 +978,30 @@ BOOLEAN FatGetFatEntry(PFAT_VOLUME_INFO Volume, ULONG Cluster, ULONG* ClusterPoi
                ThisFatSecNum = Volume->ActiveFatSectorStart + (FatOffset / Volume->BytesPerSector);
                ThisFatEntOffset = (FatOffset % Volume->BytesPerSector);
 
-               if (!FatReadVolumeSectors(Volume, ThisFatSecNum, 1, (PVOID)FILESYSBUFFER))
+               if (!FatReadVolumeSectors(Volume, ThisFatSecNum, 1, ReadBuffer))
                {
                        return FALSE;
                }
 
                // Get the fat entry
-               fat = (*((ULONG *) ((ULONG_PTR)FILESYSBUFFER + ThisFatEntOffset))) & 0x0FFFFFFF;
+               fat = (*((ULONG *) (ReadBuffer + ThisFatEntOffset))) & 0x0FFFFFFF;
                fat = SWAPD(fat);
 
                break;
 
        default:
-               TRACE("Unknown FAT type %d\n", Volume->FatType);
-               return FALSE;
-
+               ERR("Unknown FAT type %d\n", Volume->FatType);
+               status = FALSE;
+               break;
        }
 
        //TRACE("FAT entry is 0x%x.\n", fat);
 
+       HeapFree(FrLdrTempHeap, ReadBuffer, 'xTAF');
+
        *ClusterPointer = fat;
 
-       return TRUE;
+       return status;
 }
 
 ULONG FatCountClustersInChain(PFAT_VOLUME_INFO Volume, ULONG StartCluster)
@@ -1106,13 +1119,11 @@ BOOLEAN FatReadClusterChain(PFAT_VOLUME_INFO Volume, ULONG StartClusterNumber, U
                //
                // Read cluster into memory
                //
-               if (!FatReadVolumeSectors(Volume, ClusterStartSector, Volume->SectorsPerCluster, (PVOID)FILESYSBUFFER))
+               if (!FatReadVolumeSectors(Volume, ClusterStartSector, Volume->SectorsPerCluster, Buffer))
                {
                        return FALSE;
                }
 
-               memcpy(Buffer, (PVOID)FILESYSBUFFER, Volume->SectorsPerCluster * Volume->BytesPerSector);
-
                //
                // Decrement count of clusters left to read
                //
@@ -1152,19 +1163,39 @@ BOOLEAN FatReadClusterChain(PFAT_VOLUME_INFO Volume, ULONG StartClusterNumber, U
 BOOLEAN FatReadPartialCluster(PFAT_VOLUME_INFO Volume, ULONG ClusterNumber, ULONG StartingOffset, ULONG Length, PVOID Buffer)
 {
        ULONG           ClusterStartSector;
+       ULONG SectorOffset, ReadSize, SectorCount;
+       PUCHAR ReadBuffer;
+       BOOLEAN status = FALSE;
 
        //TRACE("FatReadPartialCluster() ClusterNumber = %d StartingOffset = %d Length = %d Buffer = 0x%x\n", ClusterNumber, StartingOffset, Length, Buffer);
 
        ClusterStartSector = ((ClusterNumber - 2) * Volume->SectorsPerCluster) + Volume->DataSectorStart;
 
-       if (!FatReadVolumeSectors(Volume, ClusterStartSector, Volume->SectorsPerCluster, (PVOID)FILESYSBUFFER))
+    // This is the offset of the data in sectors
+    SectorOffset = (StartingOffset / Volume->BytesPerSector);
+    StartingOffset %= Volume->BytesPerSector;
+
+    // Calculate how many sectors we need to read
+    SectorCount = (StartingOffset + Length + Volume->BytesPerSector - 1) / Volume->BytesPerSector;
+
+    // Calculate rounded up read size
+    ReadSize = SectorCount * Volume->BytesPerSector;
+
+    ReadBuffer = HeapAllocate(FrLdrTempHeap, ReadSize, 'xTAF');
+    if (!ReadBuffer)
+    {
+        return FALSE;
+    }
+
+       if (FatReadVolumeSectors(Volume, ClusterStartSector + SectorOffset, SectorCount, ReadBuffer))
        {
-               return FALSE;
+               memcpy(Buffer, ReadBuffer + StartingOffset, Length);
+               status = TRUE;
        }
 
-       memcpy(Buffer, (PVOID)((ULONG_PTR)FILESYSBUFFER + StartingOffset), Length);
+       HeapFree(FrLdrTempHeap, ReadBuffer, 'xTAF');
 
-       return TRUE;
+       return status;
 }
 
 /*
@@ -1338,7 +1369,7 @@ BOOLEAN FatReadVolumeSectors(PFAT_VOLUME_INFO Volume, ULONG SectorNumber, ULONG
        //
        // Seek to right position
        //
-       Position.QuadPart = SectorNumber * 512;
+       Position.QuadPart = (ULONGLONG)SectorNumber * 512;
        ret = ArcSeek(Volume->DeviceId, &Position, SeekAbsolute);
        if (ret != ESUCCESS)
        {