the type of device it should return must not be FILE_DEVICE_CD_ROM, but must be the actual underlying one!
This fixes recognizing *removable* USB keys as disks and not CD-ROMs.
CORE-13184
* Add an NDK header to define INIT_FUNCTION/INIT_SECTION globally
* Use _declspec(allocate(x)) and _declspec(code_seg(x)) on MSVC versions that support it
* Use INIT_FUNCTION on functions only and INIT_SECTION on data only (required by MSVC)
* Place INIT_FUNCTION before the return type (required by MSVC)
* Make sure declarations and implementations share the same modifiers (required by MSVC)
* Add a global linker option to suppress warnings about defined but unused INIT section
* Merge INIT section into .text in freeldr
- Cache the RootFcb so that its cleanup can be handled separately
during dismounting.
- Force volume dismount at cleanup if the VCB_DISMOUNT_PENDING flag
is set.
- Actually dismount a volume if its VCB has been flagged as not good,
or if we force dismounting.
NOTE: In their *CheckForDismount() function, our 3rd-party FS drivers
as well as MS' fastfat, perform a comparison check of the current VCB's
VPB ReferenceCount with some sort of "dangling"/"residual" open count.
It seems to be related to the fact that the volume root directory as
well as auxiliary data stream(s) are still opened, and only these are
allowed to be opened at that moment. After analysis it appears that for
the ReactOS' fastfat, this number is equal to "3".
- On dismounting, cleanup and destroy the RootFcb, VolumeFcb and the
FATFileObject. Then cleanup the SpareVPB or the IoVPB members, and
finish by removing the dismounted volume from the VolumeListEntry
and cleaning up the notify synchronization object and the resources.
- During dismounting, and on shutdown, flush the volume before
resetting its dirty bit.
- On shutdown, after volume flushing, try to unmount it without forcing.
- Release the VCB resources only when we actually dismount the volume
in VfatCheckForDismount().
- Initialize first the notify list and the synchronization object,
before sending the FSRTL_VOLUME_MOUNT notification.
- If we failed at mounting a volume but its VCB's FATFileObject was
already initialized, first call CcUninitializeCacheMap() on it
before dereferencing it.
- Send FSRTL_VOLUME_LOCK, FSRTL_VOLUME_LOCK_FAILED and
FSRTL_VOLUME_UNLOCK notifications during volume locking (and failure)
and volume unlocking.
- Flush the volume before locking it, and clean its dirty bit if needed.
NOTE: In addition to checking for VCB_CLEAR_DIRTY, we also check for the
presence of the VCB_IS_DIRTY flag before cleaning up the dirty bit: this
allows us to not re-clean the bit if it has been previously cleaned.
This is needed for instance in this scenario:
- The volume is locked (it gets flushed and the dirty bit is possibly cleared);
- The volume then gets formatted with a completely different FS, that
possibly clears up the first sector (e.g. BTRFS ignores 1st sector);
- The volume is then dismounted: if we didn't check whether VCB_IS_DIRTY
was set prior to resetting it, we could attempt clearing it again! But
now that the volume's filesystem has been completely changed, we would
then try to modify the dirty bit on an erroneous position on disk!
That's why it should not be touched in this case during dismounting.
- The volume is unlocked (same comment as above), and later can be
detected as being BTRFS.
This leaked at least one IRP for every write, making it the largest leak when
running with BTRFS as the system volume.
Thanks to Victor Perevertkin.
Submitted upstream thanks to Pierre:
https://github.com/maharmstone/btrfs/pull/106
Up to now, it was working by chance. Indeed, due to the invalid
ASCII check performed before calling FsRtlIsAnsiCharacterLegalHpfs(), the
macro is improperly called and overruns the FsRtlLegalAnsiCharacterArray
buffer. Fortunately, up to now, right after that buffer in kernel binary
there are strings which are more or less consistent with the flags that
are expected by the macro, causing a decent behavior of
FsRtlIsAnsiCharacterLegalHpfs() even for extended ASCII characters
(whereas FsRtlIsAnsiCharacterLegalHpfs() is only designed for ASCII
characters). But this is a totally out of control and wrong behavior.
A single change in the way the kernel was built could have caused the
CDFS driver not to work as previously.
I have made the choice to allow any extended ASCII character as done
for the unicode characters. This is a good compromise to avoid drastic
regressions for users having extended ASCII characters in their CD
file names.
This imports proposed upstream commit 1b6b625641dffb49951e60398e1a9c672318ea71
See pull request https://github.com/Microsoft/Windows-driver-samples/pull/278
CORE-14067
When we're about to close a file (ie, forget everything about it
and release any associated structure), actually delay it.
This allows keep data fresh in memory for faster reuse in case
it would be required. The effective closing will only happen after some time.
For specific operations, this will produce a real speed up in ReactOS.
For instance, with that patch, Winamp starts within seconds, instead of dozen
of minutes.
In most cases, it will bring ReactOS to performances it had before fixing
the huge leak in FastFAT (commit 94ead99) without leaking the whole FS.
For now, due to regressions, this is only activated for files and not
for directories. Once it gets fixed, it will be enabled for both.
CORE-14826
CORE-14917
For whatever (unknown) reason yet, this stream file object
seems to be deleted when still in use while installing
ReactOS on BtrFS partition, leading to use after free.
So, quick and dirty hack: leak it to prevent deletion.
CORE-13769
Multiple "error C4189: '[...]': local variable is initialized but not referenced".
Thanks to Yuntian Zhang, who hinted at this in CORE-11836.
CORE-11280
This avoids race conditions under high IOs and thus corruption on
the FS, or assertions failures in the kernel.
Easily triggered by building ReactOS on ReactOS ;-).
Until now, our support for dirty volumes was totally broken
to a point where, on FAT32 volume, the dirty couldn't even
be written nor read from the disk.
This commit totally rewrites its handling, for both FAT16 and FAT32
so that it's now fully functionnal. Furthermore, it also gets
totally compatible with our vfatlib, and thus, autochk.
Now, on mount, FastFAT will check if the volume is dirty or not, and
autochk will be able to ask for a repair if dirty. vfatlib will
repair the volume and remove the dirty bit. So that, on next
reboot, the volume will be mounted clean.
As a reminder, the dirty bit is set immediately after mounting
the volume, so that, if you crash or have a powercut, autochk
will always attempt to repair your volume (with more or less,
that's FAT!).
If you want to experience without breaking your FAT volume,
just boot, open a cmd prompt and type: fsutil dirty set c:
and reboot!
CORE-13758
CORE-13760
CORE-13759
This is a hack, and totally not the default behavior.
But it will allow autochk locking the boot volume in
order to verify it on boot, in case it would have
been improperly dismounted.
CORE-13759
This avoids initializing cache directly on directory
open/create.
The advantage is we reduce the load on cache manager
and on memory manager by avoiding creating everytime
a stream file object, and initializing cache for it.
This will avoid initializing cache for started
applications 'current directory' which is just opened
for having a valid handle but no read/write is performed
in it, by default.
This is a step forward for autochk.
CORE-14629
Before performing a read operation, FastFAT driver will
attempt to compute whether it would run out of stack
during the operation. If so, instead of attempting the
operation in the current thread, it will post the read
request to the overflow thread.
This should help with the regressions brought in by
94ead99e0c.
CORE-14601
Before any write operation that would involve caching, ask
the cache controler whether writing would make it exceed its memory
consumption. If so, queue the write operation for later execution.
In case the write operation can wait, then, the FSD operation will be
halted until the write is allowed.
I could test it successfully by copying huge files from a FAT volume to
another. The write is halted until some portions of the file is written
to the disk.
I could also properly install Qt (SDK) on ReactOS with this and less than 1GB RAM:
- https://www.heisspiter.net/~Pierre/rostests/Qt_OS.png
- https://www.heisspiter.net/~Pierre/rostests/Qt_OS2.png
CORE-12081
CORE-14582
CORE-14313
This is a PoC of what it's possible to realize thanks to an
already existing hack in ntoskrnl :-).
With this extension, on the kdb:> prompt, you're able to type
in commands that will be handled by the FastFAT driver and not
by the kernel, allowing internal debug, not possible otherwise.
So far, three commands exist:
- ?fat.vols: lists all the mounted volumes by FastFAT
- ?fat.files: lists all the files on a specific volume (with their attributes)
- ?fat.setdbgfile: allows watching on specifics files lifetime
This is obviously only the begin and could be greatly improved.
For instance, this is what allowed to debug CORE-14557
Once a directory is crossed (opened or a child is opened), associated
FCB structure is created in FastFAT, but also a stream FO for caching.
Up to now, due to an extra reference taken by the stream file object,
even when the directory was no longer used, the directory was kept in
memory: the FCB was never deleted, the file object was never dereferenced,
and the cache never released.
The immediate effect of this bug is that our FAT driver was leaking every
directory that was used affecting the whole OS situation. In case of
directories intensive operation (like extraction the ReactOS source code
in ReactOS ;-)), we were just killin the whole OS RAM without any way to
release it and recover.
The other side effects: IOs were faster as half of the FS was always
permanant in RAM.
This commit fixes the issue by forcing the FSD to release the FO,
and the cache when a directory is no longer used, leading to its
destruction in RAM.
Downside: on IO intensive operation, expect slowdowns, obviously,
there's less caching now. But more efficient!
CORE-14557
This makes the function return the error instead of continuing and
performing use-after-frees operations.
This is likely to be a forgotten return!
CID 1434254, 1434268
is set before locking is actually attempted for Cc worker thread (lazy write/read ahead).
So in case locking fails, the top level IRP is set and never unset, and latter
call will hit the assert where it expects the top level IRP to be NULL.
Should be reported upstream (tm).
CORE-14315
This is assorted with misc fixes to make this code closer to what we currently have in FastFAT.
This also allows fixing a memory leak in case of single entry return.
CORE-13367
leaves volumes in half-(dis)mounted state and thus they get remounted while not
completely dismounted.
This can lead to major breakage and data corruption.
This requires deeper fixes (let's just drop that driver!).
CORE-14124
CORE-14126
CORE-14133
This avoids issues when these partitions are formatted to FAT for setup.
For now, this commit doesn't change anything, but once IopParseDevice hack
gets removed, this will make a difference!
CORE-6305
It fixes assertion failure in vfatDestroyFCB() where we would have release parent before child.
This is still not perfect, but less bug prone...
With this commits (and ENABLE_SWAPOUT defined), ReactOS seems to unmount FAT volumes quite nice! :-)
(Tried with fsutil volume dismount X:)
AddNewMftEntry() - Zero the (larger) buffer for the bitmap prior to reading the bitmap.
BrowseIndexEntries() - Check sub-nodes before checking an index entry. Read and use the index bitmap when checking sub-nodes.
+BrowseSubNodeIndexEntries() - Called for sub-nodes of an index when browsing index entries.
+NtfsDumpData() - Diagnostic function which allows for visualizing a series of bytes.
svn path=/branches/GSoC_2016/NTFS/; revision=75817
+AddBitmap() - adds a $BITMAP attribute to a file record.
+AddIndexAllocation() - adds an $INDEX_ALLOCATION attribute to a file record.
+CountBTreeKeys() - Counts the number of linked B-Tree keys.
CreateIndexBufferFromBTreeNode() - Set INDEX_NODE_LARGE if the node has sub-nodes.
CreateIndexRootFromBTree() - Simplify the usage and math of MaxIndexSize; make it only account for the cumulative size of the index entries.
+DemoteBTreeRoot() - Replaces the contents of an index root with a dummy key, and puts those contents in a new node, which is made a child of the dummy key. This is done when an index root grows too large.
+GetIndexEntryVCN() - Retrieves the VCN from an index entry.
NtfsAddFilenameToDirectory() - Fix math for MaxIndexRootSize.
NtfsInsertKey() - Add support for splitting a B-Tree node. Don't check size of index root (that will be handled later).
+SplitBTreeNode() - Called when a B-Tree node grows too large.
UpdateIndexAllocation() - Create an $I30 index allocation attribute and bitmap attribute if needed.
UpdateIndexNode() - Update children before updating the current node. Store VCN of child nodes in the index entries of their respective keys.
svn path=/branches/GSoC_2016/NTFS/; revision=75707
IncreaseMftSize() - Add some fixes. Write blank records to newly-allocated mft entries, and update $MFTMirr when finished; these changes are needed for chkdsk. Increase size by 64 records instead of 8.
+UpdateMftMirror() - Backs up the first ~4 master file table entries to the $MFTMirr file.
svn path=/branches/GSoC_2016/NTFS/; revision=75694
+AddIndexRoot() - Creates an $INDEX_ROOT attribute and adds it to a file record.
AddNewMftEntry() - Make sure the buffer used by RtlInitializeBitmap() is ULONG-aligned, and a ULONG-multiple in size, per MSDN.
AllocateIndexNode() - Calculate BytesNeeded correctly. Read $BITMAP attribute before increasing its length, in anticipation of a future commit that will check for a free bit before assigning a new index record to the end of the allocation. Use appropriate Set*AttributeDataLength() function, as $BITMAP can be resident or non-resident.
B_TREE_FILENAME_NODE - Give two members more accurate names: change "ExistsOnDisk" member to "HasValidVCN" and rename "NodeNumber" member "VCN."
+CreateEmptyBTree() - Creates a B-Tree to represent an empty directory (for AddIndexRoot).
+NtfsCreateEmptyFileRecord() - Creates an empty file record in memory, with no attributes.
CreateIndexRootFromBTree() - Fix TotalSizeOfEntries calculation.
+NtfsCreateDirectory() - Creates a file record for an empty directory and adds it to the mft.
svn path=/branches/GSoC_2016/NTFS/; revision=75692
-Don't add a preceding backslash when creating files on root.
-Use NTFS_FILE_NAME_POSIX name type if CaseSensitive option is specified.
-Don't try to create a file when a folder is requested (folder creation is still TODO).
svn path=/branches/GSoC_2016/NTFS/; revision=75671
+AllocateIndexNode() - Allocates a new index record in an index allocation.
+CreateDummyKey() - Creates the final B_TREE_KEY for a B_TREE_FILENAME_NODE. Also creates the associated index entry.
GetSizeOfIndexEntries() - Sums the size of each index entry in every key in a B-Tree node.
+SetIndexEntryVCN() - Sets the VCN of a given IndexEntry.
NtfsInsertKey() - Handle instance when the index root grows too large. If it does, add its contents to a new sub-node, and replace contents with a dummy-key whose child is the new node.
UpdateIndexAllocation() - Update index entry if a key has just been assigned a child allocation.
UpdateIndexNode() - Make sure the node exists on disk, and allocate an index record for it if it doesn't.
svn path=/branches/GSoC_2016/NTFS/; revision=75557
AddRun() - Allow for resizing the size of the data runs when the attribute isn't the last in the file record. Fix some comments.
CreateIndexBufferFromBTreeNode(), CreateIndexRootFromBTree - Fix math of IndexSize when checking if the index buffer is too large.
InternalSetResidentAttributeLength() - Allow changing the length of an attribute in the middle of a file record. Adjust the position of every attribute after the one being resized.
+MoveAttributes() - Moves a block of attributes to a new location in the file Record.
PrintAllVCNs() - Add consideration for an index allocation with a size of 0.
WriteAttribute() - Add optional parameter for a pointer to the file record being written to. If passed a file record, WriteAttribute() will skip reading the file record from disk, and will update the file record in memory before returning. This helps callers that use the file record after writing an attribute to stay in-sync with what's on disk.
svn path=/branches/GSoC_2016/NTFS/; revision=75554
-PrepareAttributeContext() - update to allocate memory for pRecord. Don't assume allocations are succeeding.
-ReleaseAttributeContext() - update to free memory for pRecord.
-InternalSetResidentAttributeLength() - Increase size of AttrContext->pRecord as needed. Update to return an NTSTATUS.
-SetResidentAttributeDataLength() - Fix bug that could occur when migrating resident attributes to non-resident if AttrContext->pRecord is too small for the new attribute.
-AddRun() - Fix a bug by reallocating AttrContext->pRecord if the record needs to be enlarged.
svn path=/branches/GSoC_2016/NTFS/; revision=75493
-CreateBTreeFromIndex() - Fix memory allocation; allocate sizeof(B_TREE_KEY) bytes for the key, not the size of the pointer. Add support for child nodes. Update parameter list.
-CreateIndexRootFromBTree() - Update Header->Flags if any of index root's keys have sub-nodes.
+CreateIndexBufferFromBTreeNode() - Converts a B-Tree node to an index buffer to be written to the index allocation.
+UpdateIndexAllocation() - Updates all of the stale nodes in an index allocation based on a PB_TREE.
+UpdateIndexNode() - Writes a B-Tree node into the index allocation.
+CreateBTreeKeyFromFilename() - Creates a PB_TREE_KEY based on a FILENAME_ATTRIBUTE.
-DestroyBTreeKey() - Destroy a child node, if present.
-DumpBTreeKey() - Dump a child node, if present.
-DumpBTreeNode() - Include Node->KeyCount in output.
-NtfsAddFilenameToDirectory() - Call UpdateIndexAllocation() prior to CreateIndexRootFromBTree().
-Update B_TREE_FILENAME_NODE with members to keep track of its existence on disk.
svn path=/branches/GSoC_2016/NTFS/; revision=75428
+PrintAllVCNs() - Diagnostic function which prints VCN of every node in an index allocation.
+GetAllocationOffsetFromVCN() - Calculates location of an index buffer from the node's VCN.
+GetInfoClassName() - Gets a string representation of an info class enumeration, to speed up development of unimplemented classes.
-NtfsSetInformation() & NtfsQueryInformation() - Use GetInfoClassName to report unhandled information classes.
-CompareTreeKeys() - Add a comment and clarify some comments.
-NtfsAddFilenameToDirectory() - Don't try to update the size of Index Root on disk if the attribute length hasn't changed.
svn path=/branches/GSoC_2016/NTFS/; revision=75424
-Add define for indexed flag for resident attributes, RA_INDEXED.
-CreateBTreeFromIndex() - Don't try to read index entries beyond attribute length.
-Move NtfsAddFileNameToDirectory() from dirctl.c to mft.c (no changes to function).
-SetResidentAttributeDataLength() - Don't try to free AttribData if it hasn't been allocated. Cast IndexRecord to PUCHAR for WriteAttribute(), and cast BitmapData to PCHAR for ReadAttribute() (make gcc happy).
-Replace magic number 16 with a define, NTFS_FILE_FIRST_USER_FILE.
svn path=/branches/GSoC_2016/NTFS/; revision=75371
-Add ATTR_RECORD_ALIGNMENT define to replace magic value of 8 when we need to adjust an attribute's beginning or length.
-Don't use int's.
-GetPackedByteCount() - Remove unused "bytes" variable.
svn path=/branches/GSoC_2016/NTFS/; revision=75288
FindAttribute() - Use * sizeof(WCHAR) in place bit-shifting wizardry.
IncreaseMftSize() - Remove two useless casts. Return error code if WriteAttribute() fails.
SetNonResidentAttributeDataLength() - Assert that AttrContext parameter describes a NonResident attribute. When migrating a resident attribute to non-resident, don't leak memory if FsRtlInitializeLargeMcb() throws an exception, and don't mark the attribute as non-resident until after the Mcb is initialized.
InternalSetResidentAttributeLength() and SetResidentAttributeLength() - Assert that AttrContext parameter describes a resident attribute.
AddNewMftEntry() - Simplify math of backing up and restoring reserved bits by changing BitmapData to PUCHAR type. Don't attempt to modify a volume with more than 2^32 clusters.
AddFixupArray() - Use ULONG in place of int.
svn path=/branches/GSoC_2016/NTFS/; revision=75284
NtfsSetEndOfFile() - Make fileNameAttribute and filename variables uppercase. Don't leak FileRecord if we can't truncate the file. Don't leak memory if there's no FileName attribute.
svn path=/branches/GSoC_2016/NTFS/; revision=75283
-NtfsOpenFile() - Replace an ExFreePool() with ExFreePoolWithTag().
-NtfsCreateFile() - Fix broken cast with BooleanFlagOn() macro.
-NtfsAddFilenameToDirectory() - Remove an extra cast. Return an error if we fail to allocate I30IndexRoot.
-NtfsGetNextPathElement(), NtfsWSubString(), NtfsGetFCBForFile() - Use PCWSTR in place of const PWCHAR or PWCHAR where it makes sense.
svn path=/branches/GSoC_2016/NTFS/; revision=75281
-CompareTreeKeys() - Assert that the first key isn't the dummy key.
-CreateIndexRootFromBTree() - Assert that CurrentKey->IndexEntry->Length isn't 0.
-DumpBTreeKey() - Use sizeof(WCHAR) in place of magic 2.
-NtfsInsertKey() - Check for allocation failure of NewKey.
svn path=/branches/GSoC_2016/NTFS/; revision=75280
-AddFileName() - Don't use dedicated buffer for FileNameNoPath, just point into FileObject->FileName's buffer. Don't use RtlCopyUnicodeString(), just update pointers.
-AddRun() - Fix an SEH2_YIELD with missing return statement.
-FreeClusters() - Use ULONG_MAX in place of 0xffffffff.
-NtfsDumpIndexRootAttribute() - Use consistent UpperCase naming convention. Use BooleanFlagOn() macro where appropriate. Replace magic 8 with sizeof(ULONGLONG).
-GetFileNameAttributeLength() - Add documentation.
svn path=/branches/GSoC_2016/NTFS/; revision=75279
NtfsAddFilenameToDirectory() - Add CaseSensitive parameter. Update to use new B-Tree code: First, the index is read and converted to a B-Tree in memory. Next, a key for the new file is inserted into the tree. Finally, the tree is converted back to an index root attribute which is written to disk.
+btree.c - Includes functions related to B-Trees (AKA B*Trees).
ntfs.h - Added several structures for representing B-Trees in memory.
Known limitations: For simplicity, only trees with a depth of one are currently supported (i.e. an ordered list of filenames). Directories that have or will require an index allocation to store all their filenames are still TODO. As a consequence, the user will only be able to create about 6 files in a directory.
svn path=/branches/GSoC_2016/NTFS/; revision=75223
Improve, add, or fix some DPRINTs. In particular, ULONG's should use %lu, not %u. Also, don't be silent about filesystem corruption.
NtfsFindMftRecord() - move CaseSensitive parameter before output parameter in parameter list.
svn path=/branches/GSoC_2016/NTFS/; revision=75199
Whether or not a filename should be interpreted as case-sensitive is dependent on a flag passed to the driver when a file is created (opened); it's separate from the namespace associated with the file being accessed.
svn path=/branches/GSoC_2016/NTFS/; revision=75178
-AddNewMftEntry() - Increase size of MFT as needed. Fix math for bitmap length. Don't assign file records to MFT indices 0x10 - 0x17; In Windows, these records aren't used unless they have to be, even though they are marked as unused in the bitmap.
+IncreaseMftSize() - Adds room for additional file records in the master file table.
-BrowseIndexEntries() - allow for the rare situation when a non-system file has an MFT index of 0x10.
svn path=/branches/GSoC_2016/NTFS/; revision=75056
-SetAttributeDataLength() has been split into two functions, SetNonResidentAttributeDataLength() and SetResidentAttributeDataLength(). This should improve code readibility and allows for resizing an attribute when there's no FileObject associated with it.
-Added "MftDataOffset" member to DEVICE_EXTENSION, which stores the offset of the Mft's $DATA attribute. (I'm starting to think it's better to add a member for offset to NTFS_ATTR_CONTEXT directly, but I'll save that level of restructuring for a future commit.)
svn path=/branches/GSoC_2016/NTFS/; revision=75055
AddFileName() - Add a parameter to receive the Mft index of the parent directory. Fix so the name of the file will be stored in the attribute, not the name of the directory.
NtfsCreateFile() - Open a file that was successfully created, instead of assuming failure.
NtfsCreateFileRecord() - Add the filename attribute of the created file to the parent directory's index.
+NtfsAddFilenameToDirectory() - Adds a $FILE_NAME attribute to a given directory index. Presently, a file can be created in an empty directory only.
AddNewMftEntry() - Add a parameter to receive the mft index where the new entry was stored.
svn path=/branches/GSoC_2016/NTFS/; revision=74970
[BOOTDATA] - Add a commented-out section to hivesys.inf which can add the required key to enable NTFS write support.
svn path=/branches/GSoC_2016/NTFS/; revision=74685
-Handle IRP_MJ_SET_INFORMATION IRP requests.
+NtfsSetEndOfFile() - Sets the end of file (file size) for a given file.
+NtfsSetInformation() - Sets the specified file information. At this point, only FileEndOfFileInformation is fully implemented. FileAllocationInformation is handled the same way and not truly implemented, but this works well enough for SetEndOfFile().
Overwriting a file in NTFS should now work in the majority of use cases.
svn path=/branches/GSoC_2016/NTFS/; revision=74675
-Modify SetAttributeDataLength() to allow a resident attribute to migrate to non-resident if the attribute grows too large to remain resident.
-Fix values returned by NtfsAllocateClusters() in case of error; return error codes, not 0.
svn path=/branches/GSoC_2016/NTFS/; revision=74524
-Add a new member to the NTFS_ATTR_CONTEXT struct, a LARGE_MCB. This allows an attribute context to describe the cluster mapping of a non-resident file while allowing that mapping to change dynamically, without the context itself needing to be resized. This fixes problems which sometimes arose from resizing files.
-Remove hacky code from NtfsWriteFile() for dealing with "stale" contexts. This fixes that issue.
-Update SetDataAttributeLength(), PrepareAttributeContext(), ReleaseAttributeContext(), FreeClusters(), and AddRun() for the new member.
-Update ReadAttribute() and WriteAttribute() to work with the changed structure. A very-soon-to-come commit will overhaul these functions so they'll operate directly on the LARGE_MCB, instead of converting to and from a packed list of data runs. (Sparse files are broken until then.)
-Rename "RunBufferOffset" to "RunBufferSize" in several places where appropriate.
-Fix, improve, and add some comments.
svn path=/branches/GSoC_2016/NTFS/; revision=74523
