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windows-server-2003/base/boot/lib/fatboot.c

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/*++
Copyright (c) 1991 Microsoft Corporation
Module Name:
fatboot.c
Abstract:
This module implements the FAT boot file system used by the operating
system loader.
Author:
Gary Kimura (garyki) 29-Aug-1989
Revision History:
--*/
#include "bootlib.h"
#include "stdio.h"
#include "blcache.h"
BOOTFS_INFO FatBootFsInfo={L"fastfat"};
//
// Conditional debug print routine
//
#ifdef FATBOOTDBG
#define FatDebugOutput(X,Y,Z) { \
if (BlConsoleOutDeviceId) { \
CHAR _b[128]; \
ULONG _c; \
sprintf(&_b[0], X, Y, Z); \
ArcWrite(BlConsoleOutDeviceId, &_b[0], strlen(&_b[0]), &_c); \
} \
}
#define CharOrSpace(C) ((C) < 0x20 ? 0x20: (C))
#define FatDebugOutput83(X,N,Y,Z) { \
if (BlConsoleOutDeviceId) { \
CHAR _b[128]; \
CHAR _n[13]; \
ULONG _c; \
sprintf(&_n[0], "> %c%c%c%c%c%c%c%c.%c%c%c <", \
CharOrSpace(*((PCHAR)N +0)), \
CharOrSpace(*((PCHAR)N +1)), \
CharOrSpace(*((PCHAR)N +2)), \
CharOrSpace(*((PCHAR)N +3)), \
CharOrSpace(*((PCHAR)N +4)), \
CharOrSpace(*((PCHAR)N +5)), \
CharOrSpace(*((PCHAR)N +6)), \
CharOrSpace(*((PCHAR)N +7)), \
CharOrSpace(*((PCHAR)N +8)), \
CharOrSpace(*((PCHAR)N +9)), \
CharOrSpace(*((PCHAR)N +10))); \
sprintf(&_b[0], X, _n, Y, Z); \
ArcWrite(BlConsoleOutDeviceId, &_b[0], strlen(&_b[0]), &_c); \
} \
}
#else
#define FatDebugOutput(X,Y,Z) {NOTHING;}
#define FatDebugOutput83(X,N,Y,Z) {NOTHING;}
#endif // FATBOOTDBG
//
// Low level disk I/O procedure prototypes
//
ARC_STATUS
FatDiskRead (
IN ULONG DeviceId,
IN LBO Lbo,
IN ULONG ByteCount,
IN PVOID Buffer,
IN BOOLEAN CacheNewData
);
ARC_STATUS
FatDiskWrite (
IN ULONG DeviceId,
IN LBO Lbo,
IN ULONG ByteCount,
IN PVOID Buffer
);
//
// VOID
// DiskRead (
// IN ULONG DeviceId,
// IN LBO Lbo,
// IN ULONG ByteCount,
// IN PVOID Buffer,
// IN BOOLEAN CacheNewData,
// IN BOOLEAN IsDoubleSpace
// );
//
#define DiskRead(A,B,C,D,E,ignored) { ARC_STATUS _s; \
if ((_s = FatDiskRead(A,B,C,D,E)) != ESUCCESS) { return _s; } \
}
#define DiskWrite(A,B,C,D) { ARC_STATUS _s; \
if ((_s = FatDiskWrite(A,B,C,D)) != ESUCCESS) { return _s; } \
}
//
// Cluster/Index routines
//
typedef enum _CLUSTER_TYPE {
FatClusterAvailable,
FatClusterReserved,
FatClusterBad,
FatClusterLast,
FatClusterNext
} CLUSTER_TYPE;
CLUSTER_TYPE
FatInterpretClusterType (
IN PFAT_STRUCTURE_CONTEXT FatStructureContext,
IN FAT_ENTRY Entry
);
ARC_STATUS
FatLookupFatEntry (
IN PFAT_STRUCTURE_CONTEXT FatStructureContext,
IN ULONG DeviceId,
IN ULONG FatIndex,
OUT PULONG FatEntry,
IN BOOLEAN IsDoubleSpace
);
ARC_STATUS
FatSetFatEntry (
IN PFAT_STRUCTURE_CONTEXT FatStructureContext,
IN ULONG DeviceId,
IN FAT_ENTRY FatIndex,
IN FAT_ENTRY FatEntry
);
ARC_STATUS
FatFlushFatEntries (
IN PFAT_STRUCTURE_CONTEXT FatStructureContext,
IN ULONG DeviceId
);
LBO
FatIndexToLbo (
IN PFAT_STRUCTURE_CONTEXT FatStructureContext,
IN FAT_ENTRY FatIndex
);
#define LookupFatEntry(A,B,C,D,E) { ARC_STATUS _s; \
if ((_s = FatLookupFatEntry(A,B,C,D,E)) != ESUCCESS) { return _s; } \
}
#define SetFatEntry(A,B,C,D) { ARC_STATUS _s; \
if ((_s = FatSetFatEntry(A,B,C,D)) != ESUCCESS) { return _s; } \
}
#define FlushFatEntries(A,B) { ARC_STATUS _s; \
if ((_s = FatFlushFatEntries(A,B)) != ESUCCESS) { return _s; } \
}
//
// Directory routines
//
ARC_STATUS
FatSearchForDirent (
IN PFAT_STRUCTURE_CONTEXT FatStructureContext,
IN ULONG DeviceId,
IN FAT_ENTRY DirectoriesStartingIndex,
IN PFAT8DOT3 FileName,
OUT PDIRENT Dirent,
OUT PLBO Lbo,
IN BOOLEAN IsDoubleSpace
);
ARC_STATUS
FatCreateDirent (
IN PFAT_STRUCTURE_CONTEXT FatStructureContext,
IN ULONG DeviceId,
IN FAT_ENTRY DirectoriesStartingIndex,
IN PDIRENT Dirent,
OUT PLBO Lbo
);
VOID
FatSetDirent (
IN PFAT8DOT3 FileName,
IN OUT PDIRENT Dirent,
IN UCHAR Attributes
);
#define SearchForDirent(A,B,C,D,E,F,G) { ARC_STATUS _s; \
if ((_s = FatSearchForDirent(A,B,C,D,E,F,G)) != ESUCCESS) { return _s; } \
}
#define CreateDirent(A,B,C,D,E) { ARC_STATUS _s; \
if ((_s = FatCreateDirent(A,B,C,D,E)) != ESUCCESS) { return _s; } \
}
//
// Allocation and mcb routines
//
ARC_STATUS
FatLoadMcb (
IN ULONG FileId,
IN VBO StartingVbo,
IN BOOLEAN IsDoubleSpace
);
ARC_STATUS
FatVboToLbo (
IN ULONG FileId,
IN VBO Vbo,
OUT PLBO Lbo,
OUT PULONG ByteCount,
IN BOOLEAN IsDoubleSpace
);
ARC_STATUS
FatIncreaseFileAllocation (
IN ULONG FileId,
IN ULONG ByteSize
);
ARC_STATUS
FatTruncateFileAllocation (
IN ULONG FileId,
IN ULONG ByteSize
);
ARC_STATUS
FatAllocateClusters (
IN PFAT_STRUCTURE_CONTEXT FatStructureContext,
IN ULONG DeviceId,
IN ULONG ClusterCount,
IN ULONG Hint,
OUT PULONG AllocatedEntry
);
#define LoadMcb(A,B,C) { ARC_STATUS _s; \
if ((_s = FatLoadMcb(A,B,C)) != ESUCCESS) { return _s; } \
}
#define VboToLbo(A,B,C,D) { ARC_STATUS _s; \
if ((_s = FatVboToLbo(A,B,C,D,FALSE)) != ESUCCESS) { return _s; } \
}
#define IncreaseFileAllocation(A,B) { ARC_STATUS _s; \
if ((_s = FatIncreaseFileAllocation(A,B)) != ESUCCESS) { return _s; } \
}
#define TruncateFileAllocation(A,B) { ARC_STATUS _s; \
if ((_s = FatTruncateFileAllocation(A,B)) != ESUCCESS) { return _s; } \
}
#define AllocateClusters(A,B,C,D,E) { ARC_STATUS _s; \
if ((_s = FatAllocateClusters(A,B,C,D,E)) != ESUCCESS) { return _s; } \
}
//
// Miscellaneous routines
//
VOID
FatFirstComponent (
IN OUT PSTRING String,
OUT PFAT8DOT3 FirstComponent
);
#define AreNamesEqual(X,Y) ( \
((*(X))[0]==(*(Y))[0]) && ((*(X))[1]==(*(Y))[1]) && ((*(X))[2]==(*(Y))[2]) && \
((*(X))[3]==(*(Y))[3]) && ((*(X))[4]==(*(Y))[4]) && ((*(X))[5]==(*(Y))[5]) && \
((*(X))[6]==(*(Y))[6]) && ((*(X))[7]==(*(Y))[7]) && ((*(X))[8]==(*(Y))[8]) && \
((*(X))[9]==(*(Y))[9]) && ((*(X))[10]==(*(Y))[10]) \
)
#define ToUpper(C) ((((C) >= 'a') && ((C) <= 'z')) ? (C) - 'a' + 'A' : (C))
#define FlagOn(Flags,SingleFlag) ((Flags) & (SingleFlag))
#define BooleanFlagOn(Flags,SingleFlag) ((BOOLEAN)(((Flags) & (SingleFlag)) != 0))
#define SetFlag(Flags,SingleFlag) { (Flags) |= (SingleFlag); }
#define ClearFlag(Flags,SingleFlag) { (Flags) &= ~(SingleFlag); }
#define FatFirstFatAreaLbo(B) ( (B)->ReservedSectors * (B)->BytesPerSector )
#define Minimum(X,Y) ((X) < (Y) ? (X) : (Y))
#define Maximum(X,Y) ((X) < (Y) ? (Y) : (X))
//
// The following types and macros are used to help unpack the packed and
// misaligned fields found in the Bios parameter block
//
typedef union _UCHAR1 { UCHAR Uchar[1]; UCHAR ForceAlignment; } UCHAR1, *PUCHAR1;
typedef union _UCHAR2 { UCHAR Uchar[2]; USHORT ForceAlignment; } UCHAR2, *PUCHAR2;
typedef union _UCHAR4 { UCHAR Uchar[4]; ULONG ForceAlignment; } UCHAR4, *PUCHAR4;
//
// This macro copies an unaligned src byte to an aligned dst byte
//
#define CopyUchar1(Dst,Src) { \
*((UCHAR1 *)(Dst)) = *((UNALIGNED UCHAR1 *)(Src)); \
}
//
// This macro copies an unaligned src word to an aligned dst word
//
#define CopyUchar2(Dst,Src) { \
*((UCHAR2 *)(Dst)) = *((UNALIGNED UCHAR2 *)(Src)); \
}
//
// This macro copies an unaligned src longword to an aligned dsr longword
//
#define CopyUchar4(Dst,Src) { \
*((UCHAR4 *)(Dst)) = *((UNALIGNED UCHAR4 *)(Src)); \
}
//
// DirectoryEntry routines
//
VOID
FatDirToArcDir (
IN PDIRENT FatDirent,
OUT PDIRECTORY_ENTRY ArcDirent
);
//
// Define global data.
//
//
// File entry table - This is a structure that provides entry to the FAT
// file system procedures. It is exported when a FAT file structure
// is recognized.
//
BL_DEVICE_ENTRY_TABLE FatDeviceEntryTable;
PBL_DEVICE_ENTRY_TABLE
IsFatFileStructure (
IN ULONG DeviceId,
IN PVOID StructureContext
)
/*++
Routine Description:
This routine determines if the partition on the specified channel
contains a FAT file system volume.
Arguments:
DeviceId - Supplies the file table index for the device on which
read operations are to be performed.
StructureContext - Supplies a pointer to a FAT file structure context.
Return Value:
A pointer to the FAT entry table is returned if the partition is
recognized as containing a FAT volume. Otherwise, NULL is returned.
--*/
{
PPACKED_BOOT_SECTOR BootSector;
UCHAR Buffer[sizeof(PACKED_BOOT_SECTOR)+256];
PFAT_STRUCTURE_CONTEXT FatStructureContext;
FatDebugOutput("IsFatFileStructure\r\n", 0, 0);
//
// Clear the file system context block for the specified channel and
// establish a pointer to the context structure that can be used by other
// routines
//
FatStructureContext = (PFAT_STRUCTURE_CONTEXT)StructureContext;
RtlZeroMemory(FatStructureContext, sizeof(FAT_STRUCTURE_CONTEXT));
//
// Setup and read in the boot sector for the potential fat partition
//
BootSector = (PPACKED_BOOT_SECTOR)ALIGN_BUFFER( &Buffer[0] );
if (FatDiskRead(DeviceId, 0, sizeof(PACKED_BOOT_SECTOR), BootSector, CACHE_NEW_DATA) != ESUCCESS) {
return NULL;
}
//
// Unpack the Bios parameter block
//
FatUnpackBios(&FatStructureContext->Bpb, &BootSector->PackedBpb);
//
// Check if it is fat
//
if ((BootSector->Jump[0] != 0xeb) &&
(BootSector->Jump[0] != 0xe9)) {
return NULL;
} else if ((FatStructureContext->Bpb.BytesPerSector != 128) &&
(FatStructureContext->Bpb.BytesPerSector != 256) &&
(FatStructureContext->Bpb.BytesPerSector != 512) &&
(FatStructureContext->Bpb.BytesPerSector != 1024)) {
return NULL;
} else if ((FatStructureContext->Bpb.SectorsPerCluster != 1) &&
(FatStructureContext->Bpb.SectorsPerCluster != 2) &&
(FatStructureContext->Bpb.SectorsPerCluster != 4) &&
(FatStructureContext->Bpb.SectorsPerCluster != 8) &&
(FatStructureContext->Bpb.SectorsPerCluster != 16) &&
(FatStructureContext->Bpb.SectorsPerCluster != 32) &&
(FatStructureContext->Bpb.SectorsPerCluster != 64) &&
(FatStructureContext->Bpb.SectorsPerCluster != 128)) {
return NULL;
} else if (FatStructureContext->Bpb.ReservedSectors == 0) {
return NULL;
} else if (((FatStructureContext->Bpb.Sectors == 0) && (FatStructureContext->Bpb.LargeSectors == 0)) ||
((FatStructureContext->Bpb.Sectors != 0) && (FatStructureContext->Bpb.LargeSectors != 0))) {
return NULL;
} else if (FatStructureContext->Bpb.Fats == 0) {
return NULL;
} else if ((FatStructureContext->Bpb.Media != 0xf0) &&
(FatStructureContext->Bpb.Media != 0xf8) &&
(FatStructureContext->Bpb.Media != 0xf9) &&
(FatStructureContext->Bpb.Media != 0xfc) &&
(FatStructureContext->Bpb.Media != 0xfd) &&
(FatStructureContext->Bpb.Media != 0xfe) &&
(FatStructureContext->Bpb.Media != 0xff)) {
return NULL;
} else if (FatStructureContext->Bpb.SectorsPerFat == 0) {
if (!IsBpbFat32(&BootSector->PackedBpb)) {
return NULL;
}
} else if (FatStructureContext->Bpb.RootEntries == 0) {
return NULL;
}
//
// Initialize the file entry table and return the address of the table.
//
FatDeviceEntryTable.Open = FatOpen;
FatDeviceEntryTable.Close = FatClose;
FatDeviceEntryTable.Read = FatRead;
FatDeviceEntryTable.Seek = FatSeek;
FatDeviceEntryTable.Write = FatWrite;
FatDeviceEntryTable.GetFileInformation = FatGetFileInformation;
FatDeviceEntryTable.SetFileInformation = FatSetFileInformation;
FatDeviceEntryTable.Rename = FatRename;
FatDeviceEntryTable.GetDirectoryEntry = FatGetDirectoryEntry;
FatDeviceEntryTable.BootFsInfo = &FatBootFsInfo;
return &FatDeviceEntryTable;
}
ARC_STATUS
FatClose (
IN ULONG FileId
)
/*++
Routine Description:
This routine closes the file specified by the file id.
Arguments:
FileId - Supplies the file table index.
Return Value:
ESUCCESS if returned as the function value.
--*/
{
PBL_FILE_TABLE FileTableEntry;
PFAT_STRUCTURE_CONTEXT FatStructureContext;
ULONG DeviceId;
FatDebugOutput("FatClose\r\n", 0, 0);
//
// Load our local variables
//
FileTableEntry = &BlFileTable[FileId];
FatStructureContext = (PFAT_STRUCTURE_CONTEXT)FileTableEntry->StructureContext;
DeviceId = FileTableEntry->DeviceId;
//
// Mark the file closed
//
BlFileTable[FileId].Flags.Open = 0;
//
// Check if the fat is dirty and flush it out if it is.
//
if (FatStructureContext->CachedFatDirty) {
FlushFatEntries( FatStructureContext, DeviceId );
}
//
// Check if the current mcb is for this file and if it is then zero it out.
// By setting the file id for the mcb to be the table size we guarantee that
// we've just set it to an invalid file id.
//
if (FatStructureContext->FileId == FileId) {
FatStructureContext->FileId = BL_FILE_TABLE_SIZE;
FatStructureContext->Mcb.InUse = 0;
}
return ESUCCESS;
}
ARC_STATUS
FatGetDirectoryEntry (
IN ULONG FileId,
IN DIRECTORY_ENTRY * FIRMWARE_PTR DirEntry,
IN ULONG NumberDir,
OUT ULONG * FIRMWARE_PTR CountDir
)
/*++
Routine Description:
This routine implements the GetDirectoryEntry operation for the
FAT file system.
Arguments:
FileId - Supplies the file table index.
DirEntry - Supplies a pointer to a directory entry structure.
NumberDir - Supplies the number of directory entries to read.
Count - Supplies a pointer to a variable to receive the number
of entries read.
Return Value:
ESUCCESS is returned if the read was successful, otherwise
an error code is returned.
--*/
{
//
// define local variables
//
ARC_STATUS Status; // ARC status
ULONG Position; // file position
PFAT_FILE_CONTEXT pContext; // FAT file context
ULONG RunByteCount = 0; // max sequential bytes
ULONG RunDirCount; // max dir entries to read per time
ULONG i; // general index
PDIRENT FatDirEnt; // directory entry pointer
UCHAR Buffer[ 16 * sizeof(DIRENT) + 32 ];
LBO Lbo = 0;
BOOLEAN EofDir = FALSE; // not end of file
//
// initialize local variables
//
pContext = &BlFileTable[ FileId ].u.FatFileContext;
FatDirEnt = (PDIRENT)ALIGN_BUFFER( &Buffer[0] );
//
// if not directory entry, exit with error
//
if ( !FlagOn(pContext->Dirent.Attributes, FAT_DIRENT_ATTR_DIRECTORY) ) {
return EBADF;
}
//
// Initialize the output count to zero
//
*CountDir = 0;
//
// if NumberDir is zero, return ESUCCESS.
//
if ( !NumberDir ) {
return ESUCCESS;
}
//
// read one directory at a time.
//
do {
//
// save position
//
Position = BlFileTable[ FileId ].Position.LowPart;
//
// Lookup the corresponding Lbo and run length for the current position
//
if ( !RunByteCount ) {
if ((Status = FatVboToLbo( FileId, Position, &Lbo, &RunByteCount, FALSE )) != 0) {
if ( Status == EINVAL ) {
break; // eof has been reached
} else {
return Status; // I/O error
}
}
}
//
// validate the # of bytes readable in sequance (exit loop if eof)
// the block is always multiple of a directory entry size.
//
if ( (RunDirCount = Minimum( RunByteCount/sizeof(DIRENT), 16)) == 0 ) {
break;
}
//
// issue the read
//
if ( (Status = FatDiskRead( BlFileTable[ FileId ].DeviceId,
Lbo,
RunDirCount * sizeof(DIRENT),
(PVOID)FatDirEnt,
CACHE_NEW_DATA)) != 0 ) {
BlFileTable[ FileId ].Position.LowPart = Position;
return Status;
}
for ( i=0; i<RunDirCount; i++ ) {
//
// exit from loop if logical end of directory
//
if ( FatDirEnt[i].FileName[0] == FAT_DIRENT_NEVER_USED ) {
EofDir = TRUE;
break;
}
//
// update the current position and the number of bytes transfered
//
BlFileTable[ FileId ].Position.LowPart += sizeof(DIRENT);
Lbo += sizeof(DIRENT);
RunByteCount -= sizeof(DIRENT);
//
// skip this entry if the file or directory has been erased
//
if ( FatDirEnt[i].FileName[0] == FAT_DIRENT_DELETED ) {
continue;
}
//
// skip this entry if this is a valume label
//
if (FlagOn( FatDirEnt[i].Attributes, FAT_DIRENT_ATTR_VOLUME_ID )) {
continue;
}
//
// convert FAT directory entry in ARC directory entry
//
FatDirToArcDir( &FatDirEnt[i], DirEntry++ );
//
// update pointers
//
if ( ++*CountDir >= NumberDir ) {
break;
}
}
} while ( !EofDir && *CountDir < NumberDir );
//
// all done
//
return *CountDir ? ESUCCESS : ENOTDIR;
}
ARC_STATUS
FatGetFileInformation (
IN ULONG FileId,
OUT PFILE_INFORMATION Buffer
)
/*++
Routine Description:
This procedure returns to the user a buffer filled with file information
Arguments:
FileId - Supplies the File id for the operation
Buffer - Supplies the buffer to receive the file information. Note that
it must be large enough to hold the full file name
Return Value:
ESUCCESS is returned if the open operation is successful. Otherwise,
an unsuccessful status is returned that describes the reason for failure.
--*/
{
PBL_FILE_TABLE FileTableEntry;
UCHAR Attributes;
ULONG i;
FatDebugOutput("FatGetFileInformation\r\n", 0, 0);
//
// Load our local variables
//
FileTableEntry = &BlFileTable[FileId];
Attributes = FileTableEntry->u.FatFileContext.Dirent.Attributes;
//
// Zero out the buffer, and fill in its non-zero values.
//
RtlZeroMemory(Buffer, sizeof(FILE_INFORMATION));
Buffer->EndingAddress.LowPart = FileTableEntry->u.FatFileContext.Dirent.FileSize;
Buffer->CurrentPosition.LowPart = FileTableEntry->Position.LowPart;
Buffer->CurrentPosition.HighPart = 0;
if (FlagOn(Attributes, FAT_DIRENT_ATTR_READ_ONLY)) { SetFlag(Buffer->Attributes, ArcReadOnlyFile) };
if (FlagOn(Attributes, FAT_DIRENT_ATTR_HIDDEN)) { SetFlag(Buffer->Attributes, ArcHiddenFile) };
if (FlagOn(Attributes, FAT_DIRENT_ATTR_SYSTEM)) { SetFlag(Buffer->Attributes, ArcSystemFile) };
if (FlagOn(Attributes, FAT_DIRENT_ATTR_ARCHIVE)) { SetFlag(Buffer->Attributes, ArcArchiveFile) };
if (FlagOn(Attributes, FAT_DIRENT_ATTR_DIRECTORY)) { SetFlag(Buffer->Attributes, ArcDirectoryFile) };
Buffer->FileNameLength = FileTableEntry->FileNameLength;
for (i = 0; i < FileTableEntry->FileNameLength; i += 1) {
Buffer->FileName[i] = FileTableEntry->FileName[i];
}
return ESUCCESS;
}
ARC_STATUS
FatOpen (
IN CHAR * FIRMWARE_PTR FileName,
IN OPEN_MODE OpenMode,
IN ULONG * FIRMWARE_PTR FileId
)
/*++
Routine Description:
This routine searches the device for a file matching FileName.
If a match is found the dirent for the file is saved and the file is
opened.
Arguments:
FileName - Supplies a pointer to a zero terminated file name.
OpenMode - Supplies the mode of the open.
FileId - Supplies a pointer to a variable that specifies the file
table entry that is to be filled in if the open is successful.
Return Value:
ESUCCESS is returned if the open operation is successful. Otherwise,
an unsuccessful status is returned that describes the reason for failure.
--*/
{
PBL_FILE_TABLE FileTableEntry;
PFAT_STRUCTURE_CONTEXT FatStructureContext;
ULONG DeviceId;
FAT_ENTRY CurrentDirectoryIndex;
BOOLEAN SearchSucceeded;
BOOLEAN IsDirectory;
BOOLEAN IsReadOnly;
STRING PathName;
FAT8DOT3 Name;
FatDebugOutput("FatOpen: %s\r\n", FileName, 0);
//
// Load our local variables
//
FileTableEntry = &BlFileTable[*FileId];
FatStructureContext = (PFAT_STRUCTURE_CONTEXT)FileTableEntry->StructureContext;
DeviceId = FileTableEntry->DeviceId;
//
// Construct a file name descriptor from the input file name
//
RtlInitString( &PathName, FileName );
//
// While the path name has some characters in it we'll go through our loop
// which extracts the first part of the path name and searches the current
// directory for an entry. If what we find is a directory then we have to
// continue looping until we're done with the path name.
//
FileTableEntry->u.FatFileContext.DirentLbo = 0;
FileTableEntry->Position.LowPart = 0;
FileTableEntry->Position.HighPart = 0;
CurrentDirectoryIndex = 0;
SearchSucceeded = TRUE;
IsDirectory = TRUE;
IsReadOnly = TRUE;
if ((PathName.Buffer[0] == '\\') && (PathName.Length == 1)) {
//
// We are opening the root directory.
//
// N.B.: IsDirectory and SearchSucceeded are already TRUE.
//
PathName.Length = 0;
FileTableEntry->FileNameLength = 1;
FileTableEntry->FileName[0] = PathName.Buffer[0];
//
// Root dirent is all zeroes with a directory attribute.
//
RtlZeroMemory(&FileTableEntry->u.FatFileContext.Dirent, sizeof(DIRENT));
FileTableEntry->u.FatFileContext.Dirent.Attributes = FAT_DIRENT_ATTR_DIRECTORY;
FileTableEntry->u.FatFileContext.DirentLbo = 0;
IsReadOnly = FALSE;
CurrentDirectoryIndex = FileTableEntry->u.FatFileContext.Dirent.FirstClusterOfFile;
} else {
//
// We are not opening the root directory.
//
//
// If the search begins in a FAT32 root, set up the starting point
// for the search.
//
if (IsBpbFat32(&FatStructureContext->Bpb)) {
CurrentDirectoryIndex = FatStructureContext->Bpb.RootDirFirstCluster;
}
while ((PathName.Length > 0) && IsDirectory) {
ARC_STATUS Status;
//
// Extract the first component and search the directory for a match, but
// first copy the first part to the file name buffer in the file table entry
//
if (PathName.Buffer[0] == '\\') {
PathName.Buffer +=1;
PathName.Length -=1;
}
for (FileTableEntry->FileNameLength = 0;
(((USHORT)FileTableEntry->FileNameLength < PathName.Length) &&
(PathName.Buffer[FileTableEntry->FileNameLength] != '\\'));
FileTableEntry->FileNameLength += 1) {
FileTableEntry->FileName[FileTableEntry->FileNameLength] =
PathName.Buffer[FileTableEntry->FileNameLength];
}
FatFirstComponent( &PathName, (PFAT8DOT3) Name );
Status = FatSearchForDirent( FatStructureContext,
DeviceId,
CurrentDirectoryIndex,
(PFAT8DOT3) Name,
&FileTableEntry->u.FatFileContext.Dirent,
&FileTableEntry->u.FatFileContext.DirentLbo,
FALSE );
if (Status == ENOENT) {
SearchSucceeded = FALSE;
break;
}
if (Status != ESUCCESS) {
return Status;
}
//
// We have a match now check to see if it is a directory, and also
// if it is readonly
//
IsDirectory = BooleanFlagOn( FileTableEntry->u.FatFileContext.Dirent.Attributes,
FAT_DIRENT_ATTR_DIRECTORY );
IsReadOnly = BooleanFlagOn( FileTableEntry->u.FatFileContext.Dirent.Attributes,
FAT_DIRENT_ATTR_READ_ONLY );
if (IsDirectory) {
CurrentDirectoryIndex = FileTableEntry->u.FatFileContext.Dirent.FirstClusterOfFile;
if (IsBpbFat32(&FatStructureContext->Bpb)) {
CurrentDirectoryIndex += 0x10000 *
FileTableEntry->u.FatFileContext.Dirent.FirstClusterOfFileHi;
}
}
}
}
//
// If the path name length is not zero then we were trying to crack a path
// with an nonexistent (or non directory) name in it. For example, we tried
// to crack a\b\c\d and b is not a directory or does not exist (then the path
// name will still contain c\d).
//
if (PathName.Length != 0) {
return ENOTDIR;
}
//
// At this point we've cracked the name up to (an maybe including the last
// component). We located the last component if the SearchSucceeded flag is
// true, otherwise the last component does not exist. If we located the last
// component then this is like an open or a supersede, but not a create.
//
if (SearchSucceeded) {
//
// Check if the last component is a directory
//
if (IsDirectory) {
//
// For an existing directory the only valid open mode is OpenDirectory
// all other modes return an error
//
switch (OpenMode) {
case ArcOpenReadOnly:
case ArcOpenWriteOnly:
case ArcOpenReadWrite:
case ArcCreateWriteOnly:
case ArcCreateReadWrite:
case ArcSupersedeWriteOnly:
case ArcSupersedeReadWrite:
//
// If we reach here then the caller got a directory but didn't
// want to open a directory
//
return EISDIR;
case ArcOpenDirectory:
//
// If we reach here then the caller got a directory and wanted
// to open a directory.
//
FileTableEntry->Flags.Open = 1;
FileTableEntry->Flags.Read = 1;
return ESUCCESS;
case ArcCreateDirectory:
//
// If we reach here then the caller got a directory and wanted
// to create a new directory
//
return EACCES;
}
}
//
// If we get there then we have an existing file that is being opened.
// We can open existing files through a lot of different open modes in
// some cases we need to check the read only part of file and/or truncate
// the file.
//
switch (OpenMode) {
case ArcOpenReadOnly:
//
// If we reach here then the user got a file and wanted to open the
// file read only
//
FileTableEntry->Flags.Open = 1;
FileTableEntry->Flags.Read = 1;
return ESUCCESS;
case ArcOpenWriteOnly:
//
// If we reach here then the user got a file and wanted to open the
// file write only
//
if (IsReadOnly) { return EROFS; }
FileTableEntry->Flags.Open = 1;
FileTableEntry->Flags.Write = 1;
return ESUCCESS;
case ArcOpenReadWrite:
//
// If we reach here then the user got a file and wanted to open the
// file read/write
//
if (IsReadOnly) { return EROFS; }
FileTableEntry->Flags.Open = 1;
FileTableEntry->Flags.Read = 1;
FileTableEntry->Flags.Write = 1;
return ESUCCESS;
case ArcCreateWriteOnly:
case ArcCreateReadWrite:
//
// If we reach here then the user got a file and wanted to create a new
// file
//
return EACCES;
case ArcSupersedeWriteOnly:
//
// If we reach here then the user got a file and wanted to supersede a
// file
//
if (IsReadOnly) { return EROFS; }
TruncateFileAllocation( *FileId, 0 );
FileTableEntry->Flags.Open = 1;
FileTableEntry->Flags.Read = 1;
FileTableEntry->Flags.Write = 1;
return ESUCCESS;
case ArcSupersedeReadWrite:
//
// If we reach here then the user got a file and wanted to supersede a
// file
//
if (IsReadOnly) { return EROFS; }
TruncateFileAllocation( *FileId, 0 );
FileTableEntry->Flags.Open = 1;
FileTableEntry->Flags.Read = 1;
FileTableEntry->Flags.Write = 1;
return ESUCCESS;
case ArcOpenDirectory:
case ArcCreateDirectory:
//
// If we reach here then the user got a file and wanted a directory
//
return ENOTDIR;
}
}
//
// If we get here the last component does not exist so we are trying to create
// either a new file or a directory.
//
switch (OpenMode) {
case ArcOpenReadOnly:
case ArcOpenWriteOnly:
case ArcOpenReadWrite:
//
// If we reach here then the user did not get a file but wanted a file
//
return ENOENT;
case ArcCreateWriteOnly:
case ArcSupersedeWriteOnly:
//
// If we reach here then the user did not get a file and wanted to create
// or supersede a file write only
//
RtlZeroMemory( &FileTableEntry->u.FatFileContext.Dirent, sizeof(DIRENT));
FatSetDirent( (PFAT8DOT3) Name, &FileTableEntry->u.FatFileContext.Dirent, 0 );
CreateDirent( FatStructureContext,
DeviceId,
CurrentDirectoryIndex,
&FileTableEntry->u.FatFileContext.Dirent,
&FileTableEntry->u.FatFileContext.DirentLbo );
FileTableEntry->Flags.Open = 1;
FileTableEntry->Flags.Write = 1;
return ESUCCESS;
case ArcCreateReadWrite:
case ArcSupersedeReadWrite:
//
// If we reach here then the user did not get a file and wanted to create
// or supersede a file read/write
//
RtlZeroMemory( &FileTableEntry->u.FatFileContext.Dirent, sizeof(DIRENT));
FatSetDirent( (PFAT8DOT3) Name, &FileTableEntry->u.FatFileContext.Dirent, 0 );
CreateDirent( FatStructureContext,
DeviceId,
CurrentDirectoryIndex,
&FileTableEntry->u.FatFileContext.Dirent,
&FileTableEntry->u.FatFileContext.DirentLbo );
FileTableEntry->Flags.Open = 1;
FileTableEntry->Flags.Read = 1;
FileTableEntry->Flags.Write = 1;
return ESUCCESS;
case ArcOpenDirectory:
//
// If we reach here then the user did not get a file and wanted to open
// an existing directory
//
return ENOENT;
case ArcCreateDirectory:
//
// If we reach here then the user did not get a file and wanted to create
// a new directory.
//
RtlZeroMemory( &FileTableEntry->u.FatFileContext.Dirent, sizeof(DIRENT));
FatSetDirent( (PFAT8DOT3) Name,
&FileTableEntry->u.FatFileContext.Dirent,
FAT_DIRENT_ATTR_DIRECTORY );
CreateDirent( FatStructureContext,
DeviceId,
CurrentDirectoryIndex,
&FileTableEntry->u.FatFileContext.Dirent,
&FileTableEntry->u.FatFileContext.DirentLbo );
IncreaseFileAllocation( *FileId, sizeof(DIRENT) * 2 );
{
DIRENT Buffer;
LBO Lbo;
ULONG Count;
ULONG i;
RtlZeroMemory((PVOID)&Buffer.FileName[0], sizeof(DIRENT) );
for (i = 0; i < 11; i += 1) {
Buffer.FileName[i] = ' ';
}
Buffer.Attributes = FAT_DIRENT_ATTR_DIRECTORY;
VboToLbo( *FileId, 0, &Lbo, &Count );
Buffer.FileName[0] = FAT_DIRENT_DIRECTORY_ALIAS;
Buffer.FirstClusterOfFile =
FileTableEntry->u.FatFileContext.Dirent.FirstClusterOfFile;
Buffer.FirstClusterOfFileHi =
FileTableEntry->u.FatFileContext.Dirent.FirstClusterOfFileHi;
DiskWrite( DeviceId, Lbo, sizeof(DIRENT), (PVOID)&Buffer.FileName[0] );
VboToLbo( *FileId, sizeof(DIRENT), &Lbo, &Count );
Buffer.FileName[1] = FAT_DIRENT_DIRECTORY_ALIAS;
Buffer.FirstClusterOfFile = (USHORT)CurrentDirectoryIndex;
Buffer.FirstClusterOfFileHi = (USHORT)(CurrentDirectoryIndex >> 16);
DiskWrite( DeviceId, Lbo, sizeof(DIRENT), (PVOID)&Buffer.FileName[0] );
}
FileTableEntry->Flags.Open = 1;
FileTableEntry->Flags.Read = 1;
return ESUCCESS;
}
return( EINVAL );
}
ARC_STATUS
FatRead (
IN ULONG FileId,
OUT VOID * FIRMWARE_PTR Buffer,
IN ULONG Length,
OUT ULONG * FIRMWARE_PTR Transfer
)
/*++
Routine Description:
This routine reads data from the specified file.
Arguments:
FileId - Supplies the file table index.
Buffer - Supplies a pointer to the buffer that receives the data
read.
Length - Supplies the number of bytes that are to be read.
Transfer - Supplies a pointer to a variable that receives the number
of bytes actually transfered.
Return Value:
ESUCCESS is returned if the read operation is successful. Otherwise,
an unsuccessful status is returned that describes the reason for failure.
--*/
{
PBL_FILE_TABLE FileTableEntry;
PFAT_STRUCTURE_CONTEXT FatStructureContext;
ULONG DeviceId;
FatDebugOutput("FatRead\r\n", 0, 0);
//
// Load out local variables
//
FileTableEntry = &BlFileTable[FileId];
FatStructureContext = (PFAT_STRUCTURE_CONTEXT)FileTableEntry->StructureContext;
DeviceId = FileTableEntry->DeviceId;
//
// Clear the transfer count
//
*Transfer = 0;
//
// Read in runs (i.e., bytes) until the byte count goes to zero
//
while (Length > 0) {
LBO Lbo;
ULONG CurrentRunByteCount;
//
// Lookup the corresponding Lbo and run length for the current position
// (i.e., Vbo).
//
if (FatVboToLbo( FileId, FileTableEntry->Position.LowPart, &Lbo, &CurrentRunByteCount, FALSE ) != ESUCCESS) {
return ESUCCESS;
}
//
// while there are bytes to be read in from the current run
// length and we haven't exhausted the request we loop reading
// in bytes. The biggest request we'll handle is only 32KB
// contiguous bytes per physical read. So we might need to loop
// through the run.
//
while ((Length > 0) && (CurrentRunByteCount > 0)) {
LONG SingleReadSize;
//
// Compute the size of the next physical read
//
SingleReadSize = Minimum(Length, 32 * 1024);
SingleReadSize = Minimum((ULONG)SingleReadSize, CurrentRunByteCount);
//
// Don't read beyond the eof
//
if (((ULONG)SingleReadSize + FileTableEntry->Position.LowPart) >
FileTableEntry->u.FatFileContext.Dirent.FileSize) {
SingleReadSize = FileTableEntry->u.FatFileContext.Dirent.FileSize -
FileTableEntry->Position.LowPart;
//
// If the readjusted read length is now zero then we're done.
//
if (SingleReadSize <= 0) {
return ESUCCESS;
}
//
// By also setting length here we'll make sure that this is our last
// read
//
Length = SingleReadSize;
}
//
// Issue the read
//
DiskRead( DeviceId, Lbo, SingleReadSize, Buffer, DONT_CACHE_NEW_DATA, FALSE );
//
// Update the remaining length, Current run byte count
// and new Lbo offset
//
Length -= SingleReadSize;
CurrentRunByteCount -= SingleReadSize;
Lbo += SingleReadSize;
//
// Update the current position and the number of bytes transfered
//
FileTableEntry->Position.LowPart += SingleReadSize;
*Transfer += SingleReadSize;
//
// Update buffer to point to the next byte location to fill in
//
Buffer = (PCHAR)Buffer + SingleReadSize;
}
}
//
// If we get here then remaining sector count is zero so we can
// return success to our caller
//
return ESUCCESS;
}
ARC_STATUS
FatRename(
IN ULONG FileId,
IN CHAR * FIRMWARE_PTR NewFileName
)
/*++
Routine Description:
This routine renames an open file. It does no checking to
see if the target filename already exists. It is intended for use
only when dual-booting DOS on x86 machines, where it is used to
replace the NT MVDM CONFIG.SYS and AUTOEXEC.BAT with the native DOS
CONFIG.SYS and AUTOEXEC.BAT files.
Arguments:
FileId - Supplies the file id of the file to be renamed
NewFileName - Supplies the new name for the file.
Return Value:
ARC_STATUS
--*/
{
PBL_FILE_TABLE FileTableEntry;
PFAT_STRUCTURE_CONTEXT FatStructureContext;
ULONG DeviceId;
FAT8DOT3 FatName;
STRING String;
//
// Initialize our local variables
//
RtlInitString( &String, NewFileName );
FileTableEntry = &BlFileTable[FileId];
FatStructureContext = (PFAT_STRUCTURE_CONTEXT)FileTableEntry->StructureContext;
DeviceId = FileTableEntry->DeviceId;
//
// Modify a in-memory copy of the dirent with the new name
//
FatFirstComponent( &String, (PFAT8DOT3) FatName );
FatSetDirent( (PFAT8DOT3) FatName,
&FileTableEntry->u.FatFileContext.Dirent,
FileTableEntry->u.FatFileContext.Dirent.Attributes );
//
// Write the modified dirent to disk
//
DiskWrite( DeviceId,
FileTableEntry->u.FatFileContext.DirentLbo,
sizeof(DIRENT),
&FileTableEntry->u.FatFileContext.Dirent );
//
// And return to our caller
//
return ESUCCESS;
}
ARC_STATUS
FatSeek (
IN ULONG FileId,
IN LARGE_INTEGER * FIRMWARE_PTR Offset,
IN SEEK_MODE SeekMode
)
/*++
Routine Description:
This routine seeks to the specified position for the file specified
by the file id.
Arguments:
FileId - Supplies the file table index.
Offset - Supplies the offset in the file to position to.
SeekMode - Supplies the mode of the seek operation.
Return Value:
ESUCCESS is returned if the seek operation is successful. Otherwise,
EINVAL is returned.
--*/
{
PBL_FILE_TABLE FileTableEntry;
ULONG NewPosition;
FatDebugOutput("FatSeek\r\n", 0, 0);
//
// Load our local variables
//
FileTableEntry = &BlFileTable[FileId];
//
// Compute the new position
//
if (SeekMode == SeekAbsolute) {
NewPosition = Offset->LowPart;
} else {
NewPosition = FileTableEntry->Position.LowPart + Offset->LowPart;
}
//
// If the new position is greater than the file size then return
// an error
//
if (NewPosition > FileTableEntry->u.FatFileContext.Dirent.FileSize) {
return EINVAL;
}
//
// Otherwise set the new position and return to our caller
//
FileTableEntry->Position.LowPart = NewPosition;
return ESUCCESS;
}
ARC_STATUS
FatSetFileInformation (
IN ULONG FileId,
IN ULONG AttributeFlags,
IN ULONG AttributeMask
)
/*++
Routine Description:
This routine sets the file attributes of the indicated file
Arguments:
FileId - Supplies the File Id for the operation
AttributeFlags - Supplies the value (on or off) for each attribute being modified
AttributeMask - Supplies a mask of the attributes being altered. All other
file attributes are left alone.
Return Value:
EROFS is always returned
--*/
{
UNREFERENCED_PARAMETER( FileId );
UNREFERENCED_PARAMETER( AttributeFlags );
UNREFERENCED_PARAMETER( AttributeMask );
FatDebugOutput("FatSetFileInformation\r\n", 0, 0);
return EROFS;
}
ARC_STATUS
FatWrite (
IN ULONG FileId,
IN VOID * FIRMWARE_PTR Buffer,
IN ULONG Length,
OUT ULONG * FIRMWARE_PTR Transfer
)
/*++
Routine Description:
This routine writes data to the specified file.
Arguments:
FileId - Supplies the file table index.
Buffer - Supplies a pointer to the buffer that contains the data
written.
Length - Supplies the number of bytes that are to be written.
Transfer - Supplies a pointer to a variable that receives the number
of bytes actually transfered.
Return Value:
ESUCCESS is returned if the write operation is successful. Otherwise,
an unsuccessful status is returned that describes the reason for failure.
--*/
{
PBL_FILE_TABLE FileTableEntry;
PFAT_STRUCTURE_CONTEXT FatStructureContext;
ULONG DeviceId;
ULONG OffsetBeyondWrite;
FatDebugOutput("FatWrite\r\n", 0, 0);
//
// Load our local variables
//
FileTableEntry = &BlFileTable[FileId];
FatStructureContext = (PFAT_STRUCTURE_CONTEXT)FileTableEntry->StructureContext;
DeviceId = FileTableEntry->DeviceId;
//
// Reset the file size to be the maximum of what is it now and the end of
// our write. We will assume that there is always enough allocation to support
// the file size, so we only need to increase allocation if we are increasing
// the file size.
//
OffsetBeyondWrite = FileTableEntry->Position.LowPart + Length;
if (OffsetBeyondWrite > FileTableEntry->u.FatFileContext.Dirent.FileSize) {
IncreaseFileAllocation( FileId, OffsetBeyondWrite );
FileTableEntry->u.FatFileContext.Dirent.FileSize = OffsetBeyondWrite;
DiskWrite( DeviceId,
FileTableEntry->u.FatFileContext.DirentLbo,
sizeof(DIRENT),
&FileTableEntry->u.FatFileContext.Dirent );
}
//
// Clear the transfer count
//
*Transfer = 0;
//
// Write out runs (i.e., bytes) until the byte count goes to zero
//
while (Length > 0) {
LBO Lbo;
ULONG CurrentRunByteCount;
//
// Lookup the corresponding Lbo and run length for the current position
// (i.e., Vbo).
//
VboToLbo( FileId, FileTableEntry->Position.LowPart, &Lbo, &CurrentRunByteCount );
//
// While there are bytes to be written out to the current run
// length and we haven't exhausted the request we loop reading
// in bytes. The biggest request we'll handle is only 32KB
// contiguous bytes per physical read. So we might need to loop
// through the run.
//
while ((Length > 0) && (CurrentRunByteCount > 0)) {
LONG SingleWriteSize;
//
// Compute the size of the next physical read
//
SingleWriteSize = Minimum(Length, 32 * 1024);
SingleWriteSize = Minimum((ULONG)SingleWriteSize, CurrentRunByteCount);
//
// Issue the Write
//
DiskWrite( DeviceId, Lbo, SingleWriteSize, Buffer);
//
// Update the remaining length, Current run byte count
// and new Lbo offset
//
Length -= SingleWriteSize;
CurrentRunByteCount -= SingleWriteSize;
Lbo += SingleWriteSize;
//
// Update the current position and the number of bytes transfered
//
FileTableEntry->Position.LowPart += SingleWriteSize;
*Transfer += SingleWriteSize;
//
// Update buffer to point to the next byte location to fill in
//
Buffer = (PCHAR)Buffer + SingleWriteSize;
}
}
//
// Check if the fat is dirty and flush it out if it is.
//
if (FatStructureContext->CachedFatDirty) {
FlushFatEntries( FatStructureContext, DeviceId );
}
//
// If we get here then remaining sector count is zero so we can
// return success to our caller
//
return ESUCCESS;
}
ARC_STATUS
FatInitialize (
VOID
)
/*++
Routine Description:
This routine initializes the fat boot filesystem.
Currently this is a no-op.
Arguments:
None.
Return Value:
ESUCCESS.
--*/
{
return ESUCCESS;
}
//
// Internal support routine
//
ARC_STATUS
FatDiskRead (
IN ULONG DeviceId,
IN LBO Lbo,
IN ULONG ByteCount,
IN PVOID Buffer,
IN BOOLEAN CacheNewData
)
/*++
Routine Description:
This routine reads in zero or more bytes from the specified device.
Arguments:
DeviceId - Supplies the device id to use in the arc calls.
Lbo - Supplies the LBO to start reading from.
ByteCount - Supplies the number of bytes to read.
Buffer - Supplies a pointer to the buffer to read the bytes into.
Return Value:
ESUCCESS is returned if the read operation is successful. Otherwise,
an unsuccessful status is returned that describes the reason for failure.
--*/
{
LARGE_INTEGER LargeLbo;
ARC_STATUS Status;
ULONG i;
//
// Special case the zero byte read request
//
if (ByteCount == 0) {
return ESUCCESS;
}
//
// Issue the read through the cache.
//
LargeLbo.QuadPart = Lbo;
Status = BlDiskCacheRead(DeviceId,
&LargeLbo,
Buffer,
ByteCount,
&i,
CacheNewData);
if (Status != ESUCCESS) {
return Status;
}
//
// Make sure we got back the amount requested
//
if (ByteCount != i) {
return EIO;
}
//
// Everything is fine so return success to our caller
//
return ESUCCESS;
}
//
// Internal support routine
//
ARC_STATUS
FatDiskWrite (
IN ULONG DeviceId,
IN LBO Lbo,
IN ULONG ByteCount,
IN PVOID Buffer
)
/*++
Routine Description:
This routine writes in zero or more bytes to the specified device.
Arguments:
DeviceId - Supplies the device id to use in the arc calls.
Lbo - Supplies the LBO to start writing from.
ByteCount - Supplies the number of bytes to write.
Buffer - Supplies a pointer to the buffer of bytes to write out.
Return Value:
ESUCCESS is returned if the write operation is successful. Otherwise,
an unsuccessful status is returned that describes the reason for failure.
--*/
{
LARGE_INTEGER LargeLbo;
ARC_STATUS Status;
ULONG i;
//
// Special case the zero byte write request
//
if (ByteCount == 0) {
return ESUCCESS;
}
//
// Issue the write through the cache.
//
LargeLbo.QuadPart = Lbo;
Status = BlDiskCacheWrite (DeviceId,
&LargeLbo,
Buffer,
ByteCount,
&i);
if (Status != ESUCCESS) {
return Status;
}
//
// Make sure we wrote out the amount requested
//
if (ByteCount != i) {
return EIO;
}
//
// Everything is fine so return success to our caller
//
return ESUCCESS;
}
//
// Internal support routine
//
CLUSTER_TYPE
FatInterpretClusterType (
IN PFAT_STRUCTURE_CONTEXT FatStructureContext,
IN FAT_ENTRY Entry
)
/*++
Routine Description:
This procedure tells the caller how to interpret a fat table entry. It will
indicate if the fat cluster is available, reserved, bad, the last one, or another
fat index.
Arguments:
FatStructureContext - Supplies the volume structure for the operation
DeviceId - Supplies the DeviceId for the volume being used.
Entry - Supplies the fat entry to examine.
Return Value:
The type of the input fat entry is returned
--*/
{
//
// Check for 12 or 16 bit fat.
//
if (FatIndexBitSize(&FatStructureContext->Bpb) == 12) {
//
// For 12 bit fat check for one of the cluster types, but first
// make sure we only looking at 12 bits of the entry
//
Entry &= 0x00000fff;
if (Entry == 0x000) { return FatClusterAvailable; }
else if ((Entry >= 0xff0) && (Entry <= 0xff6)) { return FatClusterReserved; }
else if (Entry == 0xff7) { return FatClusterBad; }
else if ((Entry >= 0xff8) && (Entry <= 0xfff)) { return FatClusterLast; }
else { return FatClusterNext; }
} else if (FatIndexBitSize(&FatStructureContext->Bpb) == 32) {
Entry &= 0x0fffffff;
if (Entry == 0x0000) { return FatClusterAvailable; }
else if (Entry == 0x0ffffff7) { return FatClusterBad; }
else if ((Entry >= 0x0ffffff8)) { return FatClusterLast; }
else { return FatClusterNext; }
} else {
//
// For 16 bit fat check for one of the cluster types, but first
// make sure we are only looking at 16 bits of the entry
//
Entry &= 0x0000ffff;
if (Entry == 0x0000) { return FatClusterAvailable; }
else if ((Entry >= 0xfff0) && (Entry <= 0xfff6)) { return FatClusterReserved; }
else if (Entry == 0xfff7) { return FatClusterBad; }
else if ((Entry >= 0xfff8) && (Entry <= 0xffff)) { return FatClusterLast; }
else { return FatClusterNext; }
}
}
//
// Internal support routine
//
ARC_STATUS
FatLookupFatEntry (
IN PFAT_STRUCTURE_CONTEXT FatStructureContext,
IN ULONG DeviceId,
IN ULONG FatIndex,
OUT PULONG FatEntry,
IN BOOLEAN IsDoubleSpace
)
/*++
Routine Description:
This routine returns the value stored within the fat table and the specified
fat index. It is semantically equivalent to doing
x = Fat[FatIndex]
Arguments:
FatStrutureContext - Supplies the volume struture being used
DeviceId - Supplies the device being used
FatIndex - Supplies the index being looked up.
FatEntry - Receives the value stored at the specified fat index
IsDoubleSpace - Indicates if the search is being done on a double space volume
Return Value:
ESUCCESS is returned if the operation is successful. Otherwise,
an unsuccessful status is returned that describes the reason for failure.
--*/
{
BOOLEAN TwelveBitFat;
VBO Vbo;
//****if (IsDoubleSpace) { DbgPrint("FatLookupFatEntry(%0x,%0x,%0x,%0x,%0x)\n",FatStructureContext, DeviceId, FatIndex, FatEntry, IsDoubleSpace); }
//
// Calculate the Vbo of the word in the fat we need and
// also figure out if this is a 12 or 16 bit fat
//
if (FatIndexBitSize( &FatStructureContext->Bpb ) == 12) {
TwelveBitFat = TRUE;
Vbo = (FatIndex * 3) / 2;
} else if (FatIndexBitSize( &FatStructureContext->Bpb ) == 32) {
TwelveBitFat = FALSE;
Vbo = FatIndex * 4;
} else {
TwelveBitFat = FALSE;
Vbo = FatIndex * 2;
}
//
// Check if the Vbo we need is already in the cached fat
//
if ((FatStructureContext->CachedFat == NULL) ||
(Vbo < FatStructureContext->CachedFatVbo) ||
((Vbo+1) > (FatStructureContext->CachedFatVbo + FAT_CACHE_SIZE))) {
//
// Set the aligned cached fat buffer in the structure context
//
FatStructureContext->CachedFat = ALIGN_BUFFER( &FatStructureContext->CachedFatBuffer[0] );
//
// As a safety net we'll flush any dirty fats that we might have cached before
// we turn the window
//
if (!IsDoubleSpace && FatStructureContext->CachedFatDirty) {
FlushFatEntries( FatStructureContext, DeviceId );
}
//
// Now set the new cached Vbo to be the Vbo of the cache sized section that
// we're trying to map. Each time we read in the cache we only read in
// cache sized and cached aligned pieces of the fat. So first compute an
// aligned cached fat vbo and then do the read.
//
FatStructureContext->CachedFatVbo = (Vbo / FAT_CACHE_SIZE) * FAT_CACHE_SIZE;
DiskRead( DeviceId,
FatStructureContext->CachedFatVbo + FatFirstFatAreaLbo(&FatStructureContext->Bpb),
FAT_CACHE_SIZE,
FatStructureContext->CachedFat,
CACHE_NEW_DATA,
IsDoubleSpace );
}
//
// At this point the cached fat contains the vbo we're after so simply
// extract the word
//
if (IsBpbFat32(&FatStructureContext->Bpb)) {
CopyUchar4( FatEntry,
&FatStructureContext->CachedFat[Vbo - FatStructureContext->CachedFatVbo] );
} else {
CopyUchar2( FatEntry,
&FatStructureContext->CachedFat[Vbo - FatStructureContext->CachedFatVbo] );
}
//
// Now if this is a 12 bit fat then check if the index is odd or even
// If it is odd then we need to shift it over 4 bits, and in all
// cases we need to mask out the high 4 bits.
//
if (TwelveBitFat) {
if ((FatIndex % 2) == 1) { *FatEntry >>= 4; }
*FatEntry &= 0x0fff;
}
return ESUCCESS;
}
//
// Internal support routine
//
ARC_STATUS
FatSetFatEntry(
IN PFAT_STRUCTURE_CONTEXT FatStructureContext,
IN ULONG DeviceId,
IN FAT_ENTRY FatIndex,
IN FAT_ENTRY FatEntry
)
/*++
Routine Description:
This procedure sets the data within the fat table at the specified index to
to the specified value. It is semantically equivalent to doing
Fat[FatIndex] = FatEntry;
Arguments:
FatStructureContext - Supplies the structure context for the operation
DeviceId - Supplies the device for the operation
FatIndex - Supplies the index within the fat table to set
FatEntry - Supplies the value to store within the fat table
Return Value:
ESUCCESS is returned if the operation is successful. Otherwise,
an unsuccessful status is returned that describes the reason for failure.
--*/
{
BOOLEAN TwelveBitFat;
VBO Vbo;
//
// Calculate the Vbo of the word in the fat we are modifying and
// also figure out if this is a 12 or 16 bit fat
//
if (FatIndexBitSize( &FatStructureContext->Bpb ) == 12) {
TwelveBitFat = TRUE;
Vbo = (FatIndex * 3) / 2;
} else if (FatIndexBitSize( &FatStructureContext->Bpb ) == 32) {
TwelveBitFat = FALSE;
Vbo = FatIndex * 4;
} else {
TwelveBitFat = FALSE;
Vbo = FatIndex * 2;
}
//
// Check if the Vbo we need is already in the cached fat
//
if ((FatStructureContext->CachedFat == NULL) ||
(Vbo < FatStructureContext->CachedFatVbo) ||
((Vbo+1) > (FatStructureContext->CachedFatVbo + FAT_CACHE_SIZE))) {
//
// Set the aligned cached fat buffer in the structure context
//
FatStructureContext->CachedFat = ALIGN_BUFFER( &FatStructureContext->CachedFatBuffer[0] );
//
// As a safety net we'll flush any dirty fats that we might have cached before
// we turn the window
//
if (FatStructureContext->CachedFatDirty) {
FlushFatEntries( FatStructureContext, DeviceId );
}
//
// Now set the new cached Vbo to be the Vbo of the cache sized section that
// we're trying to map. Each time we read in the cache we only read in
// cache sized and cached aligned pieces of the fat. So first compute an
// aligned cached fat vbo and then do the read.
//
FatStructureContext->CachedFatVbo = (Vbo / FAT_CACHE_SIZE) * FAT_CACHE_SIZE;
DiskRead( DeviceId,
FatStructureContext->CachedFatVbo + FatFirstFatAreaLbo(&FatStructureContext->Bpb),
FAT_CACHE_SIZE,
FatStructureContext->CachedFat,
CACHE_NEW_DATA,
FALSE );
}
//
// At this point the cached fat contains the vbo we're after. For a 16 bit
// fat we simply put in the fat entry. For the 12 bit fat we first need to extract
// the word containing the entry, modify the word, and then put it back.
//
if (TwelveBitFat) {
FAT_ENTRY Temp;
CopyUchar2( &Temp,
&FatStructureContext->CachedFat[Vbo - FatStructureContext->CachedFatVbo] );
if ((FatIndex % 2) == 0) {
FatEntry = (FAT_ENTRY)((Temp & 0xf000) | (FatEntry & 0x0fff));
} else {
FatEntry = (FAT_ENTRY)((Temp & 0x000f) | ((FatEntry << 4) & 0xfff0));
}
}
if (IsBpbFat32(&FatStructureContext->Bpb)) {
CopyUchar4( &FatStructureContext->CachedFat[Vbo - FatStructureContext->CachedFatVbo],
&FatEntry );
} else {
CopyUchar2( &FatStructureContext->CachedFat[Vbo - FatStructureContext->CachedFatVbo],
&FatEntry );
}
//
// Now that we're done we can set the fat dirty
//
FatStructureContext->CachedFatDirty = TRUE;
return ESUCCESS;
}
//
// Internal support routine
//
ARC_STATUS
FatFlushFatEntries (
IN PFAT_STRUCTURE_CONTEXT FatStructureContext,
IN ULONG DeviceId
)
/*++
Routine Description:
This routine flushes out any dirty cached fat entries to the volume.
Arguments:
FatStructureContext - Supplies the structure context for the operation
DeviceId - Supplies the Device for the operation
Return Value:
ESUCCESS is returned if the operation is successful. Otherwise,
an unsuccessful status is returned that describes the reason for failure.
--*/
{
ULONG BytesPerFat;
ULONG AmountToWrite;
ULONG i;
//
// Compute the actual number of bytes that we need to write. We do this
// because we don't want to overwrite beyond the fat.
//
BytesPerFat = FatBytesPerFat(&FatStructureContext->Bpb);
if (FatStructureContext->CachedFatVbo + FAT_CACHE_SIZE <= BytesPerFat) {
AmountToWrite = FAT_CACHE_SIZE;
} else {
AmountToWrite = BytesPerFat - FatStructureContext->CachedFatVbo;
}
//
// For each fat table on the volume we will calculate the lbo for the operation
// and then write out the cached fat
//
for (i = 0; i < FatStructureContext->Bpb.Fats; i += 1) {
LBO Lbo;
Lbo = FatStructureContext->CachedFatVbo +
FatFirstFatAreaLbo(&FatStructureContext->Bpb) +
(i * BytesPerFat);
DiskWrite( DeviceId,
Lbo,
AmountToWrite,
FatStructureContext->CachedFat );
}
//
// we are all done so now mark the fat clean
//
FatStructureContext->CachedFatDirty = FALSE;
return ESUCCESS;
}
//
// Internal support routine
//
LBO
FatIndexToLbo (
IN PFAT_STRUCTURE_CONTEXT FatStructureContext,
IN FAT_ENTRY FatIndex
)
/*++
Routine Description:
This procedure translates a fat index into its corresponding lbo.
Arguments:
FatStructureContext - Supplies the volume structure for the operation
Entry - Supplies the fat entry to examine.
Return Value:
The LBO for the input fat index is returned
--*/
{
//
// The formula for translating an index into an lbo is to take the index subtract
// 2 (because index values 0 and 1 are reserved) multiply that by the bytes per
// cluster and add the results to the first file area lbo.
//
return ((FatIndex-2) * (LBO) FatBytesPerCluster(&FatStructureContext->Bpb))
+ FatFileAreaLbo(&FatStructureContext->Bpb);
}
//
// Internal support routine
//
ARC_STATUS
FatSearchForDirent (
IN PFAT_STRUCTURE_CONTEXT FatStructureContext,
IN ULONG DeviceId,
IN FAT_ENTRY DirectoriesStartingIndex,
IN PFAT8DOT3 FileName,
OUT PDIRENT Dirent,
OUT PLBO Lbo,
IN BOOLEAN IsDoubleSpace
)
/*++
Routine Description:
The procedure searches the indicated directory for a dirent that matches
the input file name.
Arguments:
FatStructureContext - Supplies the structure context for the operation
DeviceId - Supplies the Device id for the operation
DirectoriesStartingIndex - Supplies the fat index of the directory we are
to search. A value of zero indicates that we are searching the root directory
of a non-FAT32 volume. FAT32 volumes will have a non-zero index.
FileName - Supplies the file name to look for. The name must have already been
biased by the 0xe5 transmogrification
Dirent - The caller supplies the memory for a dirent and this procedure will
fill in the dirent if one is located
Lbo - Receives the Lbo of the dirent if one is located
IsDoubleSpace - Indicates if the search is being done on a double space volume
Return Value:
ESUCCESS is returned if the operation is successful. Otherwise,
an unsuccessful status is returned that describes the reason for failure.
--*/
{
PDIRENT DirentBuffer;
UCHAR Buffer[ 16 * sizeof(DIRENT) + 256 ];
ULONG i;
ULONG j;
ULONG BytesPerCluster;
FAT_ENTRY FatEntry;
CLUSTER_TYPE ClusterType;
DirentBuffer = (PDIRENT)ALIGN_BUFFER( &Buffer[0] );
FatDebugOutput83("FatSearchForDirent: %s\r\n", FileName, 0, 0);
//****if (IsDoubleSpace) { (*FileName)[11] = 0; DbgPrint("FatSearchForDirent(%0x,%0x,%0x,\"%11s\",%0x,%0x,%0x)\n", FatStructureContext, DeviceId, DirectoriesStartingIndex, FileName, Dirent, Lbo, IsDoubleSpace); }
//
// Check if this is the root directory that is being searched
//
if (DirectoriesStartingIndex == FAT_CLUSTER_AVAILABLE) {
VBO Vbo;
ULONG RootLbo = FatRootDirectoryLbo(&FatStructureContext->Bpb);
ULONG RootSize = FatRootDirectorySize(&FatStructureContext->Bpb);
//
// For the root directory we'll zoom down the dirents until we find
// a match, or run out of dirents or hit the never used dirent.
// The outer loop reads in 512 bytes of the directory at a time into
// dirent buffer.
//
for (Vbo = 0; Vbo < RootSize; Vbo += 16 * sizeof(DIRENT)) {
*Lbo = Vbo + RootLbo;
DiskRead( DeviceId, *Lbo, 16 * sizeof(DIRENT), DirentBuffer, CACHE_NEW_DATA, IsDoubleSpace );
//
// The inner loop cycles through the 16 dirents that we've just read in
//
for (i = 0; i < 16; i += 1) {
//
// Check if we've found a non label match for file name, and if so
// then copy the buffer into the dirent and set the real lbo
// of the dirent and return
//
if (!FlagOn(DirentBuffer[i].Attributes, FAT_DIRENT_ATTR_VOLUME_ID ) &&
AreNamesEqual(&DirentBuffer[i].FileName, FileName)) {
for (j = 0; j < sizeof(DIRENT); j += 1) {
((PCHAR)Dirent)[j] = ((PCHAR)DirentBuffer)[(i * sizeof(DIRENT)) + j];
}
*Lbo = Vbo + RootLbo + (i * sizeof(DIRENT));
return ESUCCESS;
}
if (DirentBuffer[i].FileName[0] == FAT_DIRENT_NEVER_USED) {
return ENOENT;
}
}
}
return ENOENT;
}
//
// If we get here we need to search a non-root directory. The alrogithm
// for doing the search is that for each cluster we read in each dirent
// until we find a match, or run out of clusters, or hit the never used
// dirent. First set some local variables and then get the cluster type
// of the first cluster
//
BytesPerCluster = FatBytesPerCluster( &FatStructureContext->Bpb );
FatEntry = DirectoriesStartingIndex;
ClusterType = FatInterpretClusterType( FatStructureContext, FatEntry );
//
// Now loop through each cluster, and compute the starting Lbo for each cluster
// that we encounter
//
while (ClusterType == FatClusterNext) {
LBO ClusterLbo;
ULONG Offset;
ClusterLbo = FatIndexToLbo( FatStructureContext, FatEntry );
//
// Now for each dirent in the cluster compute the lbo, read in the dirent
// and check for a match, the outer loop reads in 512 bytes of dirents at
// a time.
//
for (Offset = 0; Offset < BytesPerCluster; Offset += 16 * sizeof(DIRENT)) {
*Lbo = Offset + ClusterLbo;
DiskRead( DeviceId, *Lbo, 16 * sizeof(DIRENT), DirentBuffer, CACHE_NEW_DATA, IsDoubleSpace );
//
// The inner loop cycles through the 16 dirents that we've just read in
//
for (i = 0; i < 16; i += 1) {
//
// Check if we've found a for file name, and if so
// then copy the buffer into the dirent and set the real lbo
// of the dirent and return
//
if (!FlagOn(DirentBuffer[i].Attributes, FAT_DIRENT_ATTR_VOLUME_ID ) &&
AreNamesEqual(&DirentBuffer[i].FileName, FileName)) {
for (j = 0; j < sizeof(DIRENT); j += 1) {
((PCHAR)Dirent)[j] = ((PCHAR)DirentBuffer)[(i * sizeof(DIRENT)) + j];
}
*Lbo = Offset + ClusterLbo + (i * sizeof(DIRENT));
return ESUCCESS;
}
if (DirentBuffer[i].FileName[0] == FAT_DIRENT_NEVER_USED) {
return ENOENT;
}
}
}
//
// Now that we've exhausted the current cluster we need to read
// in the next cluster. So locate the next fat entry in the chain
// and go back to the top of the while loop.
//
LookupFatEntry( FatStructureContext, DeviceId, FatEntry, (PULONG) &FatEntry, IsDoubleSpace );
ClusterType = FatInterpretClusterType(FatStructureContext, FatEntry);
}
return ENOENT;
}
//
// Internal support routine
//
ARC_STATUS
FatCreateDirent (
IN PFAT_STRUCTURE_CONTEXT FatStructureContext,
IN ULONG DeviceId,
IN FAT_ENTRY DirectoriesStartingIndex,
IN PDIRENT Dirent,
OUT PLBO Lbo
)
/*++
Routine Description:
This procedure allocates and write out a new dirent for a data file in the
specified directory. It assumes that the file name does not already exist.
Arguments:
FatStructureContext - Supplies the structure context for the operation
DeviceId - Supplies the device id for the operation
DirectoriesStartingIndex - Supplies the fat index of the directory we are
to use. A value of zero indicates that we are using the root directory
Dirent - Supplies a copy of the dirent to put out on the disk
Lbo - Recieves the Lbo of where the dirent is placed
Return Value:
ESUCCESS is returned if the operation is successful. Otherwise,
an unsuccessful status is returned that describes the reason for failure.
--*/
{
DIRENT TemporaryDirent;
ULONG BytesPerCluster;
FAT_ENTRY FatEntry;
FAT_ENTRY PreviousEntry;
//
// Check if this is the root directory that is being used
//
if (DirectoriesStartingIndex == FAT_CLUSTER_AVAILABLE) {
VBO Vbo;
ULONG RootLbo = FatRootDirectoryLbo(&FatStructureContext->Bpb);
ULONG RootSize = FatRootDirectorySize(&FatStructureContext->Bpb);
//
// For the root directory we'll zoom down the dirents until we find
// a the never used (or deleted) dirent, if we never find one then the
// directory is full.
//
for (Vbo = 0; Vbo < RootSize; Vbo += sizeof(DIRENT)) {
*Lbo = Vbo + RootLbo;
DiskRead( DeviceId, *Lbo, sizeof(DIRENT), &TemporaryDirent, CACHE_NEW_DATA, FALSE );
if ((TemporaryDirent.FileName[0] == FAT_DIRENT_DELETED) ||
(TemporaryDirent.FileName[0] == FAT_DIRENT_NEVER_USED)) {
//
// This dirent is free so write out the dirent, and we're done.
//
DiskWrite( DeviceId, *Lbo, sizeof(DIRENT), Dirent );
return ESUCCESS;
}
}
return ENOSPC;
}
//
// If we get here we need to use a non-root directory. The alrogithm
// for doing the work is that for each cluster we read in each dirent
// until we hit a never used dirent or run out of clusters. First set
// some local variables and then get the cluster type of the first
// cluster
//
BytesPerCluster = FatBytesPerCluster( &FatStructureContext->Bpb );
FatEntry = DirectoriesStartingIndex;
//
// Now loop through each cluster, and compute the starting Lbo for each cluster
// that we encounter
//
while (TRUE) {
LBO ClusterLbo;
ULONG Offset;
ClusterLbo = FatIndexToLbo( FatStructureContext, FatEntry );
//
// Now for each dirent in the cluster compute the lbo, read in the dirent
// and check if it is available.
//
for (Offset = 0; Offset < BytesPerCluster; Offset += sizeof(DIRENT)) {
*Lbo = Offset + ClusterLbo;
DiskRead( DeviceId, *Lbo, sizeof(DIRENT), &TemporaryDirent, CACHE_NEW_DATA, FALSE );
if ((TemporaryDirent.FileName[0] == FAT_DIRENT_DELETED) ||
(TemporaryDirent.FileName[0] == FAT_DIRENT_NEVER_USED)) {
//
// This dirent is free so write out the dirent, and we're done.
//
DiskWrite( DeviceId, *Lbo, sizeof(DIRENT), Dirent );
return ESUCCESS;
}
}
//
// Now that we've exhausted the current cluster we need to read
// in the next cluster. So locate the next fat entry in the chain.
// Set previous entry to be the saved entry just in case we run off
// the chain and need to allocate another cluster.
//
PreviousEntry = FatEntry;
LookupFatEntry( FatStructureContext, DeviceId, FatEntry, (PULONG) &FatEntry, FALSE );
//
// If there isn't another cluster in the chain then we need to allocate a
// new cluster, and set previous entry to point to it.
//
if (FatInterpretClusterType(FatStructureContext, FatEntry) != FatClusterNext) {
AllocateClusters( FatStructureContext, DeviceId, 1, PreviousEntry, (PULONG) &FatEntry );
SetFatEntry( FatStructureContext, DeviceId, PreviousEntry, FatEntry );
}
}
return ENOSPC;
}
//
// Internal support routine
//
VOID
FatSetDirent (
IN PFAT8DOT3 FileName,
IN OUT PDIRENT Dirent,
IN UCHAR Attributes
)
/*++
Routine Description:
This routine sets up the dirent
Arguments:
FileName - Supplies the name to store in the dirent
Dirent - Receives the current date and time
Attributes - Supplies the attributes to initialize the dirent with
Return Value:
None.
--*/
{
PTIME_FIELDS Time;
ULONG i;
for (i = 0; i < sizeof(FAT8DOT3); i+= 1) {
Dirent->FileName[i] = (*FileName)[i];
}
Dirent->Attributes = (UCHAR)(Attributes | FAT_DIRENT_ATTR_ARCHIVE);
Time = ArcGetTime();
Dirent->LastWriteTime.Time.DoubleSeconds = (USHORT)(Time->Second/2);
Dirent->LastWriteTime.Time.Minute = Time->Minute;
Dirent->LastWriteTime.Time.Hour = Time->Hour;
Dirent->LastWriteTime.Date.Day = Time->Day;
Dirent->LastWriteTime.Date.Month = Time->Month;
Dirent->LastWriteTime.Date.Year = (USHORT)(Time->Year - 1980);
return;
}
//
// Internal support routine
//
ARC_STATUS
FatLoadMcb (
IN ULONG FileId,
IN VBO StartingVbo,
IN BOOLEAN IsDoubleSpace
)
/*++
Routine Description:
This routine loads into the cached mcb table the the retrival information for
the starting vbo.
Arguments:
FileId - Supplies the FileId for the operation
StartingVbo - Supplies the starting vbo to use when loading the mcb
IsDoubleSpace - Indicates if the operation is being done on a double space volume
Return Value:
ESUCCESS is returned if the operation is successful. Otherwise,
an unsuccessful status is returned that describes the reason for failure.
--*/
{
PBL_FILE_TABLE FileTableEntry;
PFAT_STRUCTURE_CONTEXT FatStructureContext;
PFAT_MCB Mcb;
ULONG DeviceId;
ULONG BytesPerCluster;
FAT_ENTRY FatEntry;
CLUSTER_TYPE ClusterType;
VBO Vbo;
//****if (IsDoubleSpace) { DbgPrint("FatLoadMcb(%0x,%0x,%0x)\n", FileId, StartingVbo, IsDoubleSpace); }
//
// Preload some of the local variables
//
FileTableEntry = &BlFileTable[FileId];
FatStructureContext = (PFAT_STRUCTURE_CONTEXT)FileTableEntry->StructureContext;
Mcb = &FatStructureContext->Mcb;
DeviceId = FileTableEntry->DeviceId;
BytesPerCluster = FatBytesPerCluster(&FatStructureContext->Bpb);
if (IsDoubleSpace) { DeviceId = FileId; }
//
// Set the file id in the structure context, and also set the mcb to be initially
// empty
//
FatStructureContext->FileId = FileId;
Mcb->InUse = 0;
Mcb->Vbo[0] = 0;
if (!IsBpbFat32(&FatStructureContext->Bpb)) {
//
// Check if this is the root directory. If it is then we build the single
// run mcb entry for the root directory.
//
if (FileTableEntry->u.FatFileContext.DirentLbo == 0) {
Mcb->InUse = 1;
Mcb->Lbo[0] = FatRootDirectoryLbo(&FatStructureContext->Bpb);
Mcb->Vbo[1] = FatRootDirectorySize(&FatStructureContext->Bpb);
return ESUCCESS;
}
//
// For all other files/directories we need to do some work. First get the fat
// entry and cluster type of the fat entry stored in the dirent
//
FatEntry = FileTableEntry->u.FatFileContext.Dirent.FirstClusterOfFile;
} else {
//
// Check if this is the root directory. If it is then we use
// the BPB values to start the run.
//
if (FileTableEntry->u.FatFileContext.DirentLbo == 0) {
FatEntry = FatStructureContext->Bpb.RootDirFirstCluster;
} else {
//
// For all other files/directories we use the dirent values
//
if (IsBpbFat32(&FatStructureContext->Bpb)) {
FatEntry = FileTableEntry->u.FatFileContext.Dirent.FirstClusterOfFile |
(FileTableEntry->u.FatFileContext.Dirent.FirstClusterOfFileHi << 16);
} else {
FatEntry = FileTableEntry->u.FatFileContext.Dirent.FirstClusterOfFile;
}
}
}
ClusterType = FatInterpretClusterType(FatStructureContext, FatEntry);
//
// Scan through the fat until we reach the vbo we're after and then build the
// mcb for the file
//
for (Vbo = BytesPerCluster; Vbo < StartingVbo; Vbo += BytesPerCluster) {
//
// Check if the file does not have any allocation beyond this point in which
// case the mcb we return is empty
//
if (ClusterType != FatClusterNext) {
return ESUCCESS;
}
LookupFatEntry( FatStructureContext, DeviceId, FatEntry, (PULONG) &FatEntry, IsDoubleSpace );
ClusterType = FatInterpretClusterType(FatStructureContext, FatEntry);
}
//
// We need to check again if the file does not have any allocation beyond this
// point in which case the mcb we return is empty
//
if (ClusterType != FatClusterNext) {
return ESUCCESS;
}
//
// At this point FatEntry denotes another cluster, and it happens to be the
// cluster we want to start loading into the mcb. So set up the first run in
// the mcb to be this cluster, with a size of a single cluster.
//
Mcb->InUse = 1;
Mcb->Vbo[0] = Vbo - BytesPerCluster;
Mcb->Lbo[0] = FatIndexToLbo( FatStructureContext, FatEntry );
Mcb->Vbo[1] = Vbo;
//
// Now we'll scan through the fat chain until we either exhaust the fat chain
// or we fill up the mcb
//
while (TRUE) {
LBO Lbo;
//
// Get the next fat entry and interpret its cluster type
//
LookupFatEntry( FatStructureContext, DeviceId, FatEntry, (PULONG) &FatEntry, IsDoubleSpace );
ClusterType = FatInterpretClusterType(FatStructureContext, FatEntry);
if (ClusterType != FatClusterNext) {
return ESUCCESS;
}
//
// Now calculate the lbo for this cluster and determine if it
// is a continuation of the previous run or a start of a new run
//
Lbo = FatIndexToLbo(FatStructureContext, FatEntry);
//
// It is a continuation if the lbo of the last run plus the current
// size of the run is equal to the lbo for the next cluster. If it
// is a contination then we only need to add a cluster amount to the
// last vbo to increase the run size. If it is a new run then
// we need to check if the run will fit, and if so then add in the
// new run.
//
if ((Mcb->Lbo[Mcb->InUse-1] + (Mcb->Vbo[Mcb->InUse] - Mcb->Vbo[Mcb->InUse-1])) == Lbo) {
Mcb->Vbo[Mcb->InUse] += BytesPerCluster;
} else {
if ((Mcb->InUse + 1) >= FAT_MAXIMUM_MCB) {
return ESUCCESS;
}
Mcb->InUse += 1;
Mcb->Lbo[Mcb->InUse-1] = Lbo;
Mcb->Vbo[Mcb->InUse] = Mcb->Vbo[Mcb->InUse-1] + BytesPerCluster;
}
}
return ESUCCESS;
}
//
// Internal support routine
//
ARC_STATUS
FatVboToLbo (
IN ULONG FileId,
IN VBO Vbo,
OUT PLBO Lbo,
OUT PULONG ByteCount,
IN BOOLEAN IsDoubleSpace
)
/*++
Routine Description:
This routine computes the run denoted by the input vbo to into its
corresponding lbo and also returns the number of bytes remaining in
the run.
Arguments:
Vbo - Supplies the Vbo to match
Lbo - Recieves the corresponding Lbo
ByteCount - Receives the number of bytes remaining in the run
IsDoubleSpace - Indicates if the operation is being done on a double space volume
Return Value:
ESUCCESS is returned if the operation is successful. Otherwise,
an unsuccessful status is returned that describes the reason for failure.
--*/
{
PFAT_STRUCTURE_CONTEXT FatStructureContext;
PFAT_MCB Mcb;
ULONG i;
//****if (IsDoubleSpace) { DbgPrint("FatVboToLbo(%0x,%0x,%0x,%0x,%0x)\n", FileId, Vbo, Lbo, ByteCount, IsDoubleSpace); }
FatStructureContext = (PFAT_STRUCTURE_CONTEXT)BlFileTable[FileId].StructureContext;
Mcb = &FatStructureContext->Mcb;
//
// Check if the mcb is for the correct file id and has the range we're asking for.
// If it doesn't then call load mcb to load in the right range.
//
if ((FileId != FatStructureContext->FileId) ||
(Vbo < Mcb->Vbo[0]) || (Vbo >= Mcb->Vbo[Mcb->InUse])) {
LoadMcb(FileId, Vbo, IsDoubleSpace);
}
//
// Now search for the slot where the Vbo fits in the mcb. Note that
// we could also do a binary search here but because the run count
// is probably small the extra overhead of a binary search doesn't
// buy us anything
//
for (i = 0; i < Mcb->InUse; i += 1) {
//
// We found our slot if the vbo we're after is less then the
// next mcb's vbo
//
if (Vbo < Mcb->Vbo[i+1]) {
//
// Compute the corresponding lbo which is the stored lbo plus
// the difference between the stored vbo and the vbo we're
// looking up. Also compute the byte count which is the
// difference between the current vbo we're looking up and
// the vbo for the next run.
//
*Lbo = Mcb->Lbo[i] + (Vbo - Mcb->Vbo[i]);
*ByteCount = Mcb->Vbo[i+1] - Vbo;
//
// and return success to our caller
//
return ESUCCESS;
}
}
//
// If we really reach here we have an error, most likely because the file is
// not large enough for the requested Vbo.
//
return EINVAL;
}
//
// Internal support routine
//
ARC_STATUS
FatIncreaseFileAllocation (
IN ULONG FileId,
IN ULONG ByteSize
)
/*++
Routine Description:
This procedure increases the file allocation to be at minimum the indicated
size.
Arguments:
FileId - Supplies the file id being processed
ByteSize - Supplies the minimum byte size for file allocation
Return Value:
ESUCCESS is returned if the operation is successful. Otherwise,
an unsuccessful status is returned that describes the reason for failure.
--*/
{
PBL_FILE_TABLE FileTableEntry;
PFAT_STRUCTURE_CONTEXT FatStructureContext;
ULONG DeviceId;
ULONG BytesPerCluster;
ULONG NumberOfClustersNeeded;
FAT_ENTRY FatEntry;
CLUSTER_TYPE ClusterType;
FAT_ENTRY PreviousEntry;
ULONG i;
//
// Preload some of the local variables
//
FileTableEntry = &BlFileTable[FileId];
FatStructureContext = (PFAT_STRUCTURE_CONTEXT)FileTableEntry->StructureContext;
DeviceId = FileTableEntry->DeviceId;
BytesPerCluster = FatBytesPerCluster(&FatStructureContext->Bpb);
//
// Check if this is the root directory. If it is then check if the allocation
// increase is already accommodated in the volume
//
if (FileTableEntry->u.FatFileContext.DirentLbo == 0) {
if (FatRootDirectorySize(&FatStructureContext->Bpb) >= ByteSize) {
return ESUCCESS;
} else {
return ENOSPC;
}
}
//
// Compute the actual number of clusters needed to satisfy the request
// Also get the first fat entry and its cluster type from the dirent.
//
NumberOfClustersNeeded = (ByteSize + BytesPerCluster - 1) / BytesPerCluster;
if (IsBpbFat32(&FatStructureContext->Bpb)) {
FatEntry = FileTableEntry->u.FatFileContext.Dirent.FirstClusterOfFile |
(FileTableEntry->u.FatFileContext.Dirent.FirstClusterOfFileHi << 16);
} else {
FatEntry = FileTableEntry->u.FatFileContext.Dirent.FirstClusterOfFile;
}
ClusterType = FatInterpretClusterType(FatStructureContext, FatEntry);
//
// Previous Entry is as a hint to allocate new space and to show us where
// the end of the current fat chain is located
//
PreviousEntry = 2;
//
// We loop for the number of clusters we need trying to go down the fat chain.
// When we exit i is either number of clusters in the file (if less then
// the number of clusters we need) or it is set equal to the number of clusters
// we need
//
for (i = 0; i < NumberOfClustersNeeded; i += 1) {
if (ClusterType != FatClusterNext) { break; }
PreviousEntry = FatEntry;
LookupFatEntry( FatStructureContext, DeviceId, PreviousEntry, (PULONG) &FatEntry, FALSE );
ClusterType = FatInterpretClusterType(FatStructureContext, FatEntry);
}
if (i >= NumberOfClustersNeeded) {
return ESUCCESS;
}
//
// At this point previous entry points to the last entry and i contains the
// number of clusters in the file. We now need to build up the allocation
//
AllocateClusters( FatStructureContext,
DeviceId,
NumberOfClustersNeeded - i,
PreviousEntry,
(PULONG) &FatEntry );
//
// We have our additional allocation, so now figure out if we need to chain off of
// the dirent or it we already have a few clusters in the chain and we
// need to munge the fat.
//
if (FileTableEntry->u.FatFileContext.Dirent.FirstClusterOfFile == FAT_CLUSTER_AVAILABLE) {
FileTableEntry->u.FatFileContext.Dirent.FirstClusterOfFile = (USHORT)FatEntry;
FileTableEntry->u.FatFileContext.Dirent.FirstClusterOfFileHi =
(USHORT)(FatEntry >> 16);
DiskWrite( DeviceId,
FileTableEntry->u.FatFileContext.DirentLbo,
sizeof(DIRENT),
&FileTableEntry->u.FatFileContext.Dirent );
} else {
SetFatEntry( FatStructureContext, DeviceId, PreviousEntry, FatEntry );
}
return ESUCCESS;
}
//
// Internal support routine
//
ARC_STATUS
FatTruncateFileAllocation (
IN ULONG FileId,
IN ULONG ByteSize
)
/*++
Routine Description:
This procedure decreases the file allocation to be at maximum the indicated
size.
Arguments:
FileId - Supplies the file id being processed
ByteSize - Supplies the maximum byte size for file allocation
Return Value:
ESUCCESS is returned if the operation is successful. Otherwise,
an unsuccessful status is returned that describes the reason for failure.
--*/
{
PBL_FILE_TABLE FileTableEntry;
PFAT_STRUCTURE_CONTEXT FatStructureContext;
ULONG DeviceId;
ULONG BytesPerCluster;
ULONG NumberOfClustersNeeded;
FAT_ENTRY FatEntry;
CLUSTER_TYPE ClusterType;
FAT_ENTRY CurrentIndex;
ULONG i;
//
// Preload some of the local variables
//
FileTableEntry = &BlFileTable[FileId];
FatStructureContext = (PFAT_STRUCTURE_CONTEXT)FileTableEntry->StructureContext;
DeviceId = FileTableEntry->DeviceId;
BytesPerCluster = FatBytesPerCluster(&FatStructureContext->Bpb);
//
// Check if this is the root directory. If it is then noop this request
//
if (FileTableEntry->u.FatFileContext.DirentLbo == 0) {
return ESUCCESS;
}
//
// Compute the actual number of clusters needed to satisfy the request
// Also get the first fat entry and its cluster type from the dirent
//
NumberOfClustersNeeded = (ByteSize + BytesPerCluster - 1) / BytesPerCluster;
if (IsBpbFat32(&FatStructureContext->Bpb)) {
FatEntry = FileTableEntry->u.FatFileContext.Dirent.FirstClusterOfFile |
(FileTableEntry->u.FatFileContext.Dirent.FirstClusterOfFileHi << 16);
} else {
FatEntry = FileTableEntry->u.FatFileContext.Dirent.FirstClusterOfFile;
}
ClusterType = FatInterpretClusterType(FatStructureContext, FatEntry);
//
// The current index variable is used to indicate where we extracted the current
// fat entry value from. It has a value of 0 we got the fat entry from the
// dirent.
//
CurrentIndex = FAT_CLUSTER_AVAILABLE;
//
// Now loop through the fat chain for the number of clusters needed.
// If we run out of the chain before we run out of clusters needed then the
// current allocation is already smaller than necessary.
//
for (i = 0; i < NumberOfClustersNeeded; i += 1) {
//
// If we run out of the chain before we run out of clusters needed then the
// current allocation is already smaller than necessary.
//
if (ClusterType != FatClusterNext) { return ESUCCESS; }
//
// Update the current index, and read in a new fat entry and interpret its
// type
//
CurrentIndex = FatEntry;
LookupFatEntry( FatStructureContext, DeviceId, CurrentIndex, (PULONG) &FatEntry, FALSE );
ClusterType = FatInterpretClusterType(FatStructureContext, FatEntry);
}
//
// If we get here then we've found that the current allocation is equal to or
// larger than what we want. It is equal if the current cluster type does not
// point to another cluster. The first thing we have to do is terminate the
// fat chain correctly. If the current index is zero then we zero out the
// dirent, otherwise we need to set the value to be last cluster.
//
if (CurrentIndex == FAT_CLUSTER_AVAILABLE) {
FatEntry = FileTableEntry->u.FatFileContext.Dirent.FirstClusterOfFile;
if (IsBpbFat32(&FatStructureContext->Bpb)) {
FatEntry |= FileTableEntry->u.FatFileContext.Dirent.FirstClusterOfFileHi << 16;
}
if (FatEntry != FAT_CLUSTER_AVAILABLE) {
//
// By setting the dirent we set in a new date.
//
FatSetDirent( &FileTableEntry->u.FatFileContext.Dirent.FileName,
&FileTableEntry->u.FatFileContext.Dirent,
0 );
FatEntry = FAT_CLUSTER_AVAILABLE;
FileTableEntry->u.FatFileContext.Dirent.FirstClusterOfFile = (USHORT)FatEntry;
if (IsBpbFat32(&FatStructureContext->Bpb)) {
FileTableEntry->u.FatFileContext.Dirent.FirstClusterOfFileHi =
(USHORT)(FatEntry >> 16);
}
FileTableEntry->u.FatFileContext.Dirent.FileSize = 0;
DiskWrite( DeviceId,
FileTableEntry->u.FatFileContext.DirentLbo,
sizeof(DIRENT),
&FileTableEntry->u.FatFileContext.Dirent );
}
} else {
if (ClusterType != FatClusterLast) {
SetFatEntry( FatStructureContext, DeviceId, CurrentIndex, FAT_CLUSTER_LAST );
}
}
//
// Now while there are clusters left to deallocate then we need to go down the
// chain freeing up the clusters
//
while (ClusterType == FatClusterNext) {
//
// Read in the value at the next fat entry and interpret its cluster type
//
CurrentIndex = FatEntry;
LookupFatEntry( FatStructureContext, DeviceId, CurrentIndex, (PULONG) &FatEntry, FALSE );
ClusterType = FatInterpretClusterType(FatStructureContext, FatEntry);
//
// Now deallocate the cluster at the current index
//
SetFatEntry( FatStructureContext, DeviceId, CurrentIndex, FAT_CLUSTER_AVAILABLE );
}
return ESUCCESS;
}
//
// Internal support routine
//
ARC_STATUS
FatAllocateClusters (
IN PFAT_STRUCTURE_CONTEXT FatStructureContext,
IN ULONG DeviceId,
IN ULONG ClusterCount,
IN ULONG Hint,
OUT PULONG AllocatedEntry
)
/*++
Routine Description:
This procedure allocates a new cluster, set its entry to be the last one,
and zeros out the cluster.
Arguments:
FatStructureContext - Supplies the structure context for the operation
DeviceId - Supplies the device id for the operation
ClusterCount - Supplies the number of clusters we need to allocate
Hint - Supplies a hint to start from when looking for a free cluster
AllocatedEntry - Receives the first fat index for the new allocated cluster chain
Return Value:
ESUCCESS is returned if the operation is successful. Otherwise,
an unsuccessful status is returned that describes the reason for failure.
--*/
{
ULONG TotalClustersInVolume;
ULONG BytesPerCluster;
UCHAR BlankBuffer[512];
FAT_ENTRY PreviousEntry;
ULONG CurrentClusterCount;
ULONG j;
LBO ClusterLbo;
ULONG i;
//
// Load some local variables
//
TotalClustersInVolume = FatNumberOfClusters(&FatStructureContext->Bpb);
BytesPerCluster = FatBytesPerCluster(&FatStructureContext->Bpb);
RtlZeroMemory((PVOID)&BlankBuffer[0], 512);
PreviousEntry = 0;
CurrentClusterCount = 0;
//
// For each cluster on the disk we'll do the following loop
//
for (j = 0; j < TotalClustersInVolume; j += 1) {
FAT_ENTRY EntryToExamine;
FAT_ENTRY FatEntry;
//
// Check if the current allocation is enough.
//
if (CurrentClusterCount >= ClusterCount) {
return ESUCCESS;
}
//
// Compute an entry to examine based on the loop iteration and our hint
//
EntryToExamine = (FAT_ENTRY)(((j + Hint - 2) % TotalClustersInVolume) + 2);
//
// Read in the prospective fat entry and check if it is available. If it
// is not available then continue looping.
//
LookupFatEntry( FatStructureContext, DeviceId, EntryToExamine, (PULONG) &FatEntry, FALSE );
if (FatInterpretClusterType(FatStructureContext, FatEntry) != FatClusterAvailable) {
continue;
}
//
// We have a free cluster, so put it at the end of the chain.
//
if (PreviousEntry == 0) {
*AllocatedEntry = EntryToExamine;
} else {
SetFatEntry( FatStructureContext, DeviceId, PreviousEntry, EntryToExamine );
}
SetFatEntry( FatStructureContext, DeviceId, EntryToExamine, FAT_CLUSTER_LAST );
//
// Now we need to go through and zero out the data in the cluster that we've
// just allocated. Because all clusters must be a multiple of dirents we'll
// do it a dirent at a time.
//
ClusterLbo = FatIndexToLbo( FatStructureContext, EntryToExamine );
for (i = 0; i < BytesPerCluster; i += 512) {
DiskWrite( DeviceId, ClusterLbo + i, 512, BlankBuffer );
}
//
// Before we go back to the top of the loop we need to update the
// previous entry so that it points to the end of the current chain and
// also i because we've just added another cluster.
//
PreviousEntry = EntryToExamine;
CurrentClusterCount += 1;
}
return ENOSPC;
}
//
// Internal support routine
//
VOID
FatFirstComponent (
IN OUT PSTRING String,
OUT PFAT8DOT3 FirstComponent
)
/*++
Routine Description:
Convert a string into fat 8.3 format and advance the input string
descriptor to point to the next file name component.
Arguments:
InputString - Supplies a pointer to the input string descriptor.
Output8dot3 - Supplies a pointer to the converted string.
Return Value:
None.
--*/
{
ULONG Extension;
ULONG Index;
//
// Fill the output name with blanks.
//
for (Index = 0; Index < 11; Index += 1) { (*FirstComponent)[Index] = ' '; }
//
// Copy the first part of the file name up to eight characters and
// skip to the end of the name or the input string as appropriate.
//
for (Index = 0; Index < String->Length; Index += 1) {
if ((String->Buffer[Index] == '\\') || (String->Buffer[Index] == '.')) {
break;
}
if (Index < 8) {
(*FirstComponent)[Index] = (CHAR)ToUpper(String->Buffer[Index]);
}
}
//
// Check if the end of the string was reached, an extension was specified,
// or a subdirectory was specified..
//
if (Index < String->Length) {
if (String->Buffer[Index] == '.') {
//
// Skip over the extension separator and add the extension to
// the file name.
//
Index += 1;
Extension = 8;
while (Index < String->Length) {
if (String->Buffer[Index] == '\\') {
break;
}
if (Extension < 11) {
(*FirstComponent)[Extension] = (CHAR)ToUpper(String->Buffer[Index]);
Extension += 1;
}
Index += 1;
}
}
}
//
// Now we'll bias the first component by the 0xe5 factor so that all our tests
// to names on the disk will be ready for a straight 11 byte comparison
//
if ((*FirstComponent)[0] == 0xe5) {
(*FirstComponent)[0] = FAT_DIRENT_REALLY_0E5;
}
//
// Update string descriptor.
//
String->Buffer += Index;
String->Length = String->Length - (USHORT)Index;
return;
}
//
// Internal support routine
//
VOID
FatDirToArcDir (
IN PDIRENT FatDirent,
OUT PDIRECTORY_ENTRY ArcDirent
)
/*++
Routine Description:
This routine converts a FAT directory entry into an ARC
directory entry.
Arguments:
FatDirent - supplies a pointer to a FAT directory entry.
ArcDirent - supplies a pointer to an ARC directory entry.
Return Value:
None.
--*/
{
ULONG i, e;
//
// clear info area
//
RtlZeroMemory( ArcDirent, sizeof(DIRECTORY_ENTRY) );
//
// check the directory flag
//
if (FlagOn( FatDirent->Attributes, FAT_DIRENT_ATTR_DIRECTORY )) {
SetFlag( ArcDirent->FileAttribute, ArcDirectoryFile );
}
//
// check the read-only flag
//
if (FlagOn( FatDirent->Attributes, FAT_DIRENT_ATTR_READ_ONLY )) {
SetFlag( ArcDirent->FileAttribute, ArcReadOnlyFile );
}
//
// clear name string
//
RtlZeroMemory( ArcDirent->FileName, 32 );
//
// copy first portion of file name
//
for (i = 0; (i < 8) && (FatDirent->FileName[i] != ' '); i += 1) {
ArcDirent->FileName[i] = FatDirent->FileName[i];
}
//
// check for an extension
//
if ( FatDirent->FileName[8] != ' ' ) {
//
// store the dot char
//
ArcDirent->FileName[i++] = '.';
//
// add the extension
//
for (e = 8; (e < 11) && (FatDirent->FileName[e] != ' '); e += 1) {
ArcDirent->FileName[i++] = FatDirent->FileName[e];
}
}
//
// set file name length before returning
//
ArcDirent->FileNameLength = i;
return;
}