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CreateFileTransacted function

[Microsoft strongly recommends developers utilize alternative means to achieve your application’s needs. Many scenarios that TxF was developed for can be achieved through simpler and more readily available techniques. Furthermore, TxF may not be available in future versions of Microsoft Windows. For more information, and alternatives to TxF, please see Alternatives to using Transactional NTFS.]

Creates or opens a file, file stream, or directory as a transacted operation. The function returns a handle that can be used to access the object.

To perform this operation as a nontransacted operation or to access objects other than files (for example, named pipes, physical devices, mailslots), use the CreateFile function.

For more information about transactions, see the Remarks section of this topic.

Syntax


HANDLE WINAPI CreateFileTransacted(
  _In_        LPCTSTR lpFileName,
  _In_        DWORD dwDesiredAccess,
  _In_        DWORD dwShareMode,
  _In_opt_    LPSECURITY_ATTRIBUTES lpSecurityAttributes,
  _In_        DWORD dwCreationDisposition,
  _In_        DWORD dwFlagsAndAttributes,
  _In_opt_    HANDLE hTemplateFile,
  _In_        HANDLE hTransaction,
  _In_opt_    PUSHORT pusMiniVersion,
  _Reserved_  PVOID pExtendedParameter
);

Parameters

lpFileName [in]

The name of an object to be created or opened.

The object must reside on the local computer; otherwise, the function fails and the last error code is set to ERROR_TRANSACTIONS_UNSUPPORTED_REMOTE.

In the ANSI version of this function, the name is limited to MAX_PATH characters. To extend this limit to 32,767 wide characters, call the Unicode version of the function and prepend "\\?\" to the path. For more information, see Naming a File. For information on special device names, see Defining an MS-DOS Device Name.

To create a file stream, specify the name of the file, a colon, and then the name of the stream. For more information, see File Streams.

dwDesiredAccess [in]

The access to the object, which can be summarized as read, write, both or neither (zero). The most commonly used values are GENERIC_READ, GENERIC_WRITE, or both (GENERIC_READ | GENERIC_WRITE). For more information, see Generic Access Rights and File Security and Access Rights.

If this parameter is zero, the application can query file, directory, or device attributes without accessing that file or device. For more information, see the Remarks section of this topic.

You cannot request an access mode that conflicts with the sharing mode that is specified in an open request that has an open handle. For more information, see Creating and Opening Files.

dwShareMode [in]

The sharing mode of an object, which can be read, write, both, delete, all of these, or none (refer to the following table).

If this parameter is zero and CreateFileTransacted succeeds, the object cannot be shared and cannot be opened again until the handle is closed. For more information, see the Remarks section of this topic.

You cannot request a sharing mode that conflicts with the access mode that is specified in an open request that has an open handle, because that would result in the following sharing violation: ERROR_SHARING_VIOLATION. For more information, see Creating and Opening Files.

To enable a process to share an object while another process has the object open, use a combination of one or more of the following values to specify the access mode they can request to open the object.

Note  The sharing options for each open handle remain in effect until that handle is closed, regardless of process context.

ValueMeaning
0
0x00000000

Disables subsequent open operations on an object to request any type of access to that object.

FILE_SHARE_DELETE
0x00000004

Enables subsequent open operations on an object to request delete access.

Otherwise, other processes cannot open the object if they request delete access.

If this flag is not specified, but the object has been opened for delete access, the function fails.

FILE_SHARE_READ
0x00000001

Enables subsequent open operations on an object to request read access.

Otherwise, other processes cannot open the object if they request read access.

If this flag is not specified, but the object has been opened for read access, the function fails.

FILE_SHARE_WRITE
0x00000002

Enables subsequent open operations on an object to request write access.

Otherwise, other processes cannot open the object if they request write access.

If this flag is not specified, but the object has been opened for write access or has a file mapping with write access, the function fails.

 

lpSecurityAttributes [in, optional]

A pointer to a SECURITY_ATTRIBUTES structure that contains an optional security descriptor and also determines whether or not the returned handle can be inherited by child processes. The parameter can be NULL.

If the lpSecurityAttributes parameter is NULL, the handle returned by CreateFileTransacted cannot be inherited by any child processes your application may create and the object associated with the returned handle gets a default security descriptor.

The bInheritHandle member of the structure specifies whether the returned handle can be inherited.

The lpSecurityDescriptor member of the structure specifies a security descriptor for an object, but may also be NULL.

If lpSecurityDescriptor member is NULL, the object associated with the returned handle is assigned a default security descriptor.

CreateFileTransacted ignores the lpSecurityDescriptor member when opening an existing file, but continues to use the bInheritHandle member.

For more information, see the Remarks section of this topic.

dwCreationDisposition [in]

An action to take on files that exist and do not exist.

For more information, see the Remarks section of this topic.

This parameter must be one of the following values, which cannot be combined.

ValueMeaning
CREATE_ALWAYS
2

Creates a new file, always.

If the specified file exists and is writable, the function overwrites the file, the function succeeds, and last-error code is set to ERROR_ALREADY_EXISTS (183).

If the specified file does not exist and is a valid path, a new file is created, the function succeeds, and the last-error code is set to zero.

For more information, see the Remarks section of this topic.

CREATE_NEW
1

Creates a new file, only if it does not already exist.

If the specified file exists, the function fails and the last-error code is set to ERROR_FILE_EXISTS (80).

If the specified file does not exist and is a valid path to a writable location, a new file is created.

OPEN_ALWAYS
4

Opens a file, always.

If the specified file exists, the function succeeds and the last-error code is set to ERROR_ALREADY_EXISTS (183).

If the specified file does not exist and is a valid path to a writable location, the function creates a file and the last-error code is set to zero.

OPEN_EXISTING
3

Opens a file or device, only if it exists.

If the specified file does not exist, the function fails and the last-error code is set to ERROR_FILE_NOT_FOUND (2).

For more information, see the Remarks section of this topic.

TRUNCATE_EXISTING
5

Opens a file and truncates it so that its size is zero bytes, only if it exists.

If the specified file does not exist, the function fails and the last-error code is set to ERROR_FILE_NOT_FOUND (2).

The calling process must open the file with the GENERIC_WRITE bit set as part of the dwDesiredAccess parameter.

 

dwFlagsAndAttributes [in]

The file attributes and flags, FILE_ATTRIBUTE_NORMAL being the most common default value.

This parameter can include any combination of the available file attributes (FILE_ATTRIBUTE_*). All other file attributes override FILE_ATTRIBUTE_NORMAL.

This parameter can also contain combinations of flags (FILE_FLAG_*) for control of buffering behavior, access modes, and other special-purpose flags. These combine with any FILE_ATTRIBUTE_* values.

This parameter can also contain Security Quality of Service (SQOS) information by specifying the SECURITY_SQOS_PRESENT flag. Additional SQOS-related flags information is presented in the table following the attributes and flags tables.

Note  

When CreateFileTransacted opens an existing file, it generally combines the file flags with the file attributes of the existing file, and ignores any file attributes supplied as part of dwFlagsAndAttributes. Special cases are detailed in Creating and Opening Files.

The following file attributes and flags are used only for file objects, not other types of objects that CreateFileTransacted opens (additional information can be found in the Remarks section of this topic). For more advanced access to file attributes, see SetFileAttributes. For a complete list of all file attributes with their values and descriptions, see File Attribute Constants.

AttributeMeaning
FILE_ATTRIBUTE_ARCHIVE
32 (0x20)

The file should be archived. Applications use this attribute to mark files for backup or removal.

FILE_ATTRIBUTE_ENCRYPTED
16384 (0x4000)

The file or directory is encrypted. For a file, this means that all data in the file is encrypted. For a directory, this means that encryption is the default for newly created files and subdirectories. For more information, see File Encryption.

This flag has no effect if FILE_ATTRIBUTE_SYSTEM is also specified.

FILE_ATTRIBUTE_HIDDEN
2 (0x2)

The file is hidden. Do not include it in an ordinary directory listing.

FILE_ATTRIBUTE_NORMAL
128 (0x80)

The file does not have other attributes set. This attribute is valid only if used alone.

FILE_ATTRIBUTE_OFFLINE
4096 (0x1000)

The data of a file is not immediately available. This attribute indicates that file data is physically moved to offline storage. This attribute is used by Remote Storage, the hierarchical storage management software. Applications should not arbitrarily change this attribute.

FILE_ATTRIBUTE_READONLY
1 (0x1)

The file is read only. Applications can read the file, but cannot write to or delete it.

FILE_ATTRIBUTE_SYSTEM
4 (0x4)

The file is part of or used exclusively by an operating system.

FILE_ATTRIBUTE_TEMPORARY
256 (0x100)

The file is being used for temporary storage. File systems avoid writing data back to mass storage if sufficient cache memory is available, because an application deletes a temporary file after a handle is closed. In that case, the system can entirely avoid writing the data. Otherwise, the data is written after the handle is closed.

 

FlagMeaning
FILE_FLAG_BACKUP_SEMANTICS
0x02000000

The file is being opened or created for a backup or restore operation. The system ensures that the calling process overrides file security checks when the process has SE_BACKUP_NAME and SE_RESTORE_NAME privileges. For more information, see Changing Privileges in a Token.

You must set this flag to obtain a handle to a directory. A directory handle can be passed to some functions instead of a file handle. For more information, see Directory Handles.

FILE_FLAG_DELETE_ON_CLOSE
0x04000000

The file is to be deleted immediately after the last transacted writer handle to the file is closed, provided that the transaction is still active. If a file has been marked for deletion and a transacted writer handle is still open after the transaction completes, the file will not be deleted.

If there are existing open handles to a file, the call fails unless they were all opened with the FILE_SHARE_DELETE share mode.

Subsequent open requests for the file fail, unless the FILE_SHARE_DELETE share mode is specified.

FILE_FLAG_NO_BUFFERING
0x20000000

The file is being opened with no system caching. This flag does not affect hard disk caching or memory mapped files. When combined with FILE_FLAG_OVERLAPPED, the flag gives maximum asynchronous performance, because the I/O does not rely on the synchronous operations of the memory manager. However, some I/O operations take more time, because data is not being held in the cache. Also, the file metadata may still be cached. To flush the metadata to disk, use the FlushFileBuffers function.

An application must meet certain requirements when working with files that are opened with FILE_FLAG_NO_BUFFERING:

  • File access must begin at byte offsets within a file that are integer multiples of the volume sector size.
  • File access must be for numbers of bytes that are integer multiples of the volume sector size. For example, if the sector size is 512 bytes, an application can request reads and writes of 512, 1024, 1536, or 2048 bytes, but not of 335, 981, or 7171 bytes.
  • Buffer addresses for read and write operations should be sector aligned, which means aligned on addresses in memory that are integer multiples of the volume sector size. Depending on the disk, this requirement may not be enforced.

One way to align buffers on integer multiples of the volume sector size is to use VirtualAlloc to allocate the buffers. It allocates memory that is aligned on addresses that are integer multiples of the operating system's memory page size. Because both memory page and volume sector sizes are powers of 2, this memory is also aligned on addresses that are integer multiples of a volume sector size. Memory pages are 4 or 8 KB in size; sectors are 512 bytes (hard disks), 2048 bytes (CD), or 4096 bytes (hard disks), and therefore, volume sectors can never be larger than memory pages.

An application can determine a volume sector size by calling the GetDiskFreeSpace function.

FILE_FLAG_OPEN_NO_RECALL
0x00100000

The file data is requested, but it should continue to be located in remote storage. It should not be transported back to local storage. This flag is for use by remote storage systems.

FILE_FLAG_OPEN_REPARSE_POINT
0x00200000

Normal reparse point processing will not occur; CreateFileTransacted will attempt to open the reparse point. When a file is opened, a file handle is returned, whether or not the filter that controls the reparse point is operational. This flag cannot be used with the CREATE_ALWAYS flag. If the file is not a reparse point, then this flag is ignored.

FILE_FLAG_OVERLAPPED
0x40000000

The file is being opened or created for asynchronous I/O. When the operation is complete, the event specified in the OVERLAPPED structure is set to the signaled state. Operations that take a significant amount of time to process return ERROR_IO_PENDING.

If this flag is specified, the file can be used for simultaneous read and write operations. The system does not maintain the file pointer, therefore you must pass the file position to the read and write functions in the OVERLAPPED structure or update the file pointer.

If this flag is not specified, then I/O operations are serialized, even if the calls to the read and write functions specify an OVERLAPPED structure.

FILE_FLAG_POSIX_SEMANTICS
0x0100000

The file is to be accessed according to POSIX rules. This includes allowing multiple files with names, differing only in case, for file systems that support that naming. Use care when using this option, because files created with this flag may not be accessible by applications that are written for MS-DOS or 16-bit Windows.

FILE_FLAG_RANDOM_ACCESS
0x10000000

The file is to be accessed randomly. The system can use this as a hint to optimize file caching.

FILE_FLAG_SESSION_AWARE
0x00800000

The file or device is being opened with session awareness. If this flag is not specified, then per-session devices (such as a redirected USB device) cannot be opened by processes running in session 0. This flag has no effect for callers not in session 0. This flag is supported only on server editions of Windows.

Windows Server 2008 R2, Windows Server 2008, and Windows Server 2003:  This flag is not supported before Windows Server 2012.

FILE_FLAG_SEQUENTIAL_SCAN
0x08000000

The file is to be accessed sequentially from beginning to end. The system can use this as a hint to optimize file caching. If an application moves the file pointer for random access, optimum caching may not occur. However, correct operation is still guaranteed.

Specifying this flag can increase performance for applications that read large files using sequential access. Performance gains can be even more noticeable for applications that read large files mostly sequentially, but occasionally skip over small ranges of bytes.

This flag has no effect if the file system does not support cached I/O and FILE_FLAG_NO_BUFFERING.

FILE_FLAG_WRITE_THROUGH
0x80000000

Write operations will not go through any intermediate cache, they will go directly to disk.

If FILE_FLAG_NO_BUFFERING is not also specified, so that system caching is in effect, then the data is written to the system cache, but is flushed to disk without delay.

If FILE_FLAG_NO_BUFFERING is also specified, so that system caching is not in effect, then the data is immediately flushed to disk without going through the system cache. The operating system also requests a write-through the hard disk cache to persistent media. However, not all hardware supports this write-through capability.

 

The dwFlagsAndAttributes parameter can also specify Security Quality of Service information. For more information, see Impersonation Levels. When the calling application specifies the SECURITY_SQOS_PRESENT flag as part of dwFlagsAndAttributes, it can also contain one or more of the following values.

Security flagMeaning
SECURITY_ANONYMOUS

Impersonates a client at the Anonymous impersonation level.

SECURITY_CONTEXT_TRACKING

The security tracking mode is dynamic. If this flag is not specified, the security tracking mode is static.

SECURITY_DELEGATION

Impersonates a client at the Delegation impersonation level.

SECURITY_EFFECTIVE_ONLY

Only the enabled aspects of the client's security context are available to the server. If you do not specify this flag, all aspects of the client's security context are available.

This allows the client to limit the groups and privileges that a server can use while impersonating the client.

SECURITY_IDENTIFICATION

Impersonates a client at the Identification impersonation level.

SECURITY_IMPERSONATION

Impersonate a client at the impersonation level. This is the default behavior if no other flags are specified along with the SECURITY_SQOS_PRESENT flag.

 

hTemplateFile [in, optional]

A valid handle to a template file with the GENERIC_READ access right. The template file supplies file attributes and extended attributes for the file that is being created. This parameter can be NULL.

When opening an existing file, CreateFileTransacted ignores the template file.

When opening a new EFS-encrypted file, the file inherits the DACL from its parent directory.

hTransaction [in]

A handle to the transaction. This handle is returned by the CreateTransaction function.

pusMiniVersion [in, optional]

The miniversion to be opened. If the transaction specified in hTransaction is not the transaction that is modifying the file, this parameter should be NULL. Otherwise, this parameter can be a miniversion identifier returned by the FSCTL_TXFS_CREATE_MINIVERSION control code, or one of the following values.

ValueMeaning
TXFS_MINIVERSION_COMMITTED_VIEW
0x0000

The view of the file as of its last commit.

TXFS_MINIVERSION_DIRTY_VIEW
0xFFFF

The view of the file as it is being modified by the transaction.

TXFS_MINIVERSION_DEFAULT_VIEW
0xFFFE

Either the committed or dirty view of the file, depending on the context. A transaction that is modifying the file gets the dirty view, while a transaction that is not modifying the file gets the committed view.

 

pExtendedParameter

This parameter is reserved and must be NULL.

Return value

If the function succeeds, the return value is an open handle to the specified file, device, named pipe, or mail slot.

If the function fails, the return value is INVALID_HANDLE_VALUE. To get extended error information, call GetLastError.

Remarks

When using the handle returned by CreateFileTransacted, use the transacted version of file I/O functions instead of the standard file I/O functions where appropriate. For more information, see Programming Considerations for Transactional NTFS.

When opening a transacted handle to a directory, that handle must have FILE_WRITE_DATA (FILE_ADD_FILE) and FILE_APPEND_DATA (FILE_ADD_SUBDIRECTORY) permissions. These are included in FILE_GENERIC_WRITE permissions. You should open directories with fewer permissions if you are just using the handle to create files or subdirectories; otherwise, sharing violations can occur.

You cannot open a file with FILE_EXECUTE access level when that file is a part of another transaction (that is, another application opened it by calling CreateFileTransacted). This means that CreateFileTransacted fails if the access level FILE_EXECUTE or FILE_ALL_ACCESS is specified

When a non-transacted application calls CreateFileTransacted with MAXIMUM_ALLOWED specified for lpSecurityAttributes, a handle is opened with the same access level every time. When a transacted application calls CreateFileTransacted with MAXIMUM_ALLOWED specified for lpSecurityAttributes, a handle is opened with a differing amount of access based on whether the file is locked by a transaction. For example, if the calling application has FILE_EXECUTE access level for a file, the application only obtains this access if the file that is being opened is either not locked by a transaction, or is locked by a transaction and the application is already a transacted reader for that file.

See Transactional NTFS for a complete description of transacted operations.

Use the CloseHandle function to close an object handle returned by CreateFileTransacted when the handle is no longer needed, and prior to committing or rolling back the transaction.

Some file systems, such as the NTFS file system, support compression or encryption for individual files and directories. On volumes that are formatted for that kind of file system, a new file inherits the compression and encryption attributes of its directory.

You cannot use CreateFileTransacted to control compression on a file or directory. For more information, see File Compression and Decompression, and File Encryption.

Symbolic link behavior—If the call to this function creates a new file, there is no change in behavior.

If FILE_FLAG_OPEN_REPARSE_POINT is specified:

  • If an existing file is opened and it is a symbolic link, the handle returned is a handle to the symbolic link.
  • If TRUNCATE_EXISTING or FILE_FLAG_DELETE_ON_CLOSE are specified, the file affected is a symbolic link.

If FILE_FLAG_OPEN_REPARSE_POINT is not specified:

  • If an existing file is opened and it is a symbolic link, the handle returned is a handle to the target.
  • If CREATE_ALWAYS, TRUNCATE_EXISTING, or FILE_FLAG_DELETE_ON_CLOSE are specified, the file affected is the target.

A multi-sector write is not guaranteed to be atomic unless you are using a transaction (that is, the handle created is a transacted handle). A single-sector write is atomic. Multi-sector writes that are cached may not always be written to the disk; therefore, specify FILE_FLAG_WRITE_THROUGH to ensure that an entire multi-sector write is written to the disk without caching.

As stated previously, if the lpSecurityAttributes parameter is NULL, the handle returned by CreateFileTransacted cannot be inherited by any child processes your application may create. The following information regarding this parameter also applies:

  • If bInheritHandle is not FALSE, which is any nonzero value, then the handle can be inherited. Therefore it is critical this structure member be properly initialized to FALSE if you do not intend the handle to be inheritable.
  • The access control lists (ACL) in the default security descriptor for a file or directory are inherited from its parent directory.
  • The target file system must support security on files and directories for the lpSecurityDescriptor to have an effect on them, which can be determined by using GetVolumeInformation

In Windows 8 and Windows Server 2012, this function is supported by the following technologies.

TechnologySupported

Server Message Block (SMB) 3.0 protocol

No

SMB 3.0 Transparent Failover (TFO)

No

SMB 3.0 with Scale-out File Shares (SO)

No

Cluster Shared Volume File System (CsvFS)

No

Resilient File System (ReFS)

No

 

Note that SMB 3.0 does not support TxF.

Files

If you try to create a file on a floppy drive that does not have a floppy disk or a CD-ROM drive that does not have a CD, the system displays a message for the user to insert a disk or a CD. To prevent the system from displaying this message, call the SetErrorMode function with SEM_FAILCRITICALERRORS.

For more information, see Creating and Opening Files.

If you rename or delete a file and then restore it shortly afterward, the system searches the cache for file information to restore. Cached information includes its short/long name pair and creation time.

If you call CreateFileTransacted on a file that is pending deletion as a result of a previous call to DeleteFile, the function fails. The operating system delays file deletion until all handles to the file are closed. GetLastError returns ERROR_ACCESS_DENIED.

The dwDesiredAccess parameter can be zero, allowing the application to query file attributes without accessing the file if the application is running with adequate security settings. This is useful to test for the existence of a file without opening it for read and/or write access, or to obtain other statistics about the file or directory. See Obtaining and Setting File Information and GetFileInformationByHandle.

When an application creates a file across a network, it is better to use GENERIC_READ | GENERIC_WRITE than to use GENERIC_WRITE alone. The resulting code is faster, because the redirector can use the cache manager and send fewer SMBs with more data. This combination also avoids an issue where writing to a file across a network can occasionally return ERROR_ACCESS_DENIED.

File Streams

On NTFS file systems, you can use CreateFileTransacted to create separate streams within a file.

For more information, see File Streams.

Directories

An application cannot create a directory by using CreateFileTransacted, therefore only the OPEN_EXISTING value is valid for dwCreationDisposition for this use case. To create a directory, the application must call CreateDirectoryTransacted, CreateDirectory or CreateDirectoryEx.

To open a directory using CreateFileTransacted, specify the FILE_FLAG_BACKUP_SEMANTICS flag as part of dwFlagsAndAttributes. Appropriate security checks still apply when this flag is used without SE_BACKUP_NAME and SE_RESTORE_NAME privileges.

When using CreateFileTransacted to open a directory during defragmentation of a FAT or FAT32 file system volume, do not specify the MAXIMUM_ALLOWED access right. Access to the directory is denied if this is done. Specify the GENERIC_READ access right instead.

For more information, see About Directory Management.

Requirements

Minimum supported client

Windows Vista [desktop apps only]

Minimum supported server

Windows Server 2008 [desktop apps only]

Header

WinBase.h (include Windows.h)

Library

Kernel32.lib

DLL

Kernel32.dll

Unicode and ANSI names

CreateFileTransactedW (Unicode) and CreateFileTransactedA (ANSI)

See also

Overview Topics
File Compression and Decompression
File Encryption
File Management Functions
File Security and Access Rights
File Streams
Programming Considerations for Transactional NTFS
Transactional NTFS (TxF)
Functions
CloseHandle
CopyFileTransacted
CreateDirectoryTransacted
DeleteFileTransacted
FindFirstFileTransacted
GetFileAttributesTransacted
MoveFileTransacted
ReadFile
WriteFile

 

 

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