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CreateHardLinkTransacted 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.]

Establishes a hard link between an existing file and a new file as a transacted operation. This function is only supported on the NTFS file system, and only for files, not directories.

Syntax


BOOL WINAPI CreateHardLinkTransacted(
  _In_        LPCTSTR lpFileName,
  _In_        LPCTSTR lpExistingFileName,
  _Reserved_  LPSECURITY_ATTRIBUTES lpSecurityAttributes,
  _In_        HANDLE hTransaction
);

Parameters

lpFileName [in]

The name of the new file.

This parameter cannot specify the name of a directory.

lpExistingFileName [in]

The name of the existing file.

This parameter cannot specify the name of a directory.

lpSecurityAttributes

Reserved; must be NULL.

hTransaction [in]

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

Return value

If the function succeeds, the return value is nonzero.

If the function fails, the return value is zero (0). To get extended error information, call GetLastError.

The maximum number of hard links that can be created with this function is 1023 per file. If more than 1023 links are created for a file, an error results.

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

Remarks

Any directory entry for a file that is created with CreateFileTransacted or CreateHardLinkTransacted is a hard link to an associated file. An additional hard link that is created with the CreateHardLinkTransacted function allows you to have multiple directory entries for a file, that is, multiple hard links to the same file, which can be different names in the same directory, or the same or different names in different directories. However, all hard links to a file must be on the same volume.

Because hard links are only directory entries for a file, when an application modifies a file through any hard link, all applications that use any other hard link to the file see the changes. Also, all of the directory entries are updated if the file changes. For example, if a file size changes, all of the hard links to the file show the new file size.

The security descriptor belongs to the file to which a hard link points. The link itself is only a directory entry, and does not have a security descriptor. Therefore, when you change the security descriptor of a hard link, you a change the security descriptor of the underlying file, and all hard links that point to the file allow the newly specified access. You cannot give a file different security descriptors on a per-hard-link basis.

This function does not modify the security descriptor of the file to be linked to, even if security descriptor information is passed in the lpSecurityAttributes parameter.

Use DeleteFileTransacted to delete hard links. You can delete them in any order regardless of the order in which they are created.

Flags, attributes, access, and sharing that are specified in CreateFileTransacted operate on a per-file basis. That is, if you open a file that does not allow sharing, another application cannot share the file by creating a new hard link to the file.

When you create a hard link on the NTFS file system, the file attribute information in the directory entry is refreshed only when the file is opened, or when GetFileInformationByHandle is called with the handle of a specific file.

Symbolic links:  If the path points to a symbolic link, the function creates a hard link to the target.

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.

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

CreateHardLinkTransactedW (Unicode) and CreateHardLinkTransactedA (ANSI)

See also

CreateFileTransacted
DeleteFileTransacted
File Management Functions
Hard Links and Junctions
Symbolic Links
Transactional NTFS

 

 

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