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CopyFileEx function

Copies an existing file to a new file, notifying the application of its progress through a callback function.

To perform this operation as a transacted operation, use the CopyFileTransacted function.

Syntax


BOOL WINAPI CopyFileEx(
  _In_      LPCTSTR lpExistingFileName,
  _In_      LPCTSTR lpNewFileName,
  _In_opt_  LPPROGRESS_ROUTINE lpProgressRoutine,
  _In_opt_  LPVOID lpData,
  _In_opt_  LPBOOL pbCancel,
  _In_      DWORD dwCopyFlags
);

Parameters

lpExistingFileName [in]

The name of an existing file.

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.

If lpExistingFileName does not exist, the CopyFileEx function fails, and the GetLastError function returns ERROR_FILE_NOT_FOUND.

lpNewFileName [in]

The name of the new file.

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.

lpProgressRoutine [in, optional]

The address of a callback function of type LPPROGRESS_ROUTINE that is called each time another portion of the file has been copied. This parameter can be NULL. For more information on the progress callback function, see the CopyProgressRoutine function.

lpData [in, optional]

The argument to be passed to the callback function. This parameter can be NULL.

pbCancel [in, optional]

If this flag is set to TRUE during the copy operation, the operation is canceled. Otherwise, the copy operation will continue to completion.

dwCopyFlags [in]

Flags that specify how the file is to be copied. This parameter can be a combination of the following values.

ValueMeaning
COPY_FILE_ALLOW_DECRYPTED_DESTINATION
0x00000008

An attempt to copy an encrypted file will succeed even if the destination copy cannot be encrypted.

COPY_FILE_COPY_SYMLINK
0x00000800

If the source file is a symbolic link, the destination file is also a symbolic link pointing to the same file that the source symbolic link is pointing to.

Windows Server 2003 and Windows XP:  This value is not supported.

COPY_FILE_FAIL_IF_EXISTS
0x00000001

The copy operation fails immediately if the target file already exists.

COPY_FILE_NO_BUFFERING
0x00001000

The copy operation is performed using unbuffered I/O, bypassing system I/O cache resources. Recommended for very large file transfers.

Windows Server 2003 and Windows XP:  This value is not supported.

COPY_FILE_OPEN_SOURCE_FOR_WRITE
0x00000004

The file is copied and the original file is opened for write access.

COPY_FILE_RESTARTABLE
0x00000002

Progress of the copy is tracked in the target file in case the copy fails. The failed copy can be restarted at a later time by specifying the same values for lpExistingFileName and lpNewFileName as those used in the call that failed. This can significantly slow down the copy operation as the new file may be flushed multiple times during the copy operation.

 

Return value

If the function succeeds, the return value is nonzero.

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

If lpProgressRoutine returns PROGRESS_CANCEL due to the user canceling the operation, CopyFileEx will return zero and GetLastError will return ERROR_REQUEST_ABORTED. In this case, the partially copied destination file is deleted.

If lpProgressRoutine returns PROGRESS_STOP due to the user stopping the operation, CopyFileEx will return zero and GetLastError will return ERROR_REQUEST_ABORTED. In this case, the partially copied destination file is left intact.

Remarks

This function preserves extended attributes, OLE structured storage, NTFS file system alternate data streams, security resource attributes, and file attributes.

Windows 7, Windows Server 2008 R2, Windows Server 2008, Windows Vista, Windows Server 2003, and Windows XP:  Security resource attributes (ATTRIBUTE_SECURITY_INFORMATION) for the existing file are not copied to the new file until Windows 8 and Windows Server 2012.

The security resource properties (ATTRIBUTE_SECURITY_INFORMATION) for the existing file are copied to the new file.

Windows 7, Windows Server 2008 R2, Windows Server 2008, Windows Vista, Windows Server 2003, and Windows XP:  Security resource properties for the existing file are not copied to the new file until Windows 8 and Windows Server 2012.

This function fails with ERROR_ACCESS_DENIED if the destination file already exists and has the FILE_ATTRIBUTE_HIDDEN or FILE_ATTRIBUTE_READONLY attribute set.

When encrypted files are copied using CopyFileEx, the function attempts to encrypt the destination file with the keys used in the encryption of the source file. If this cannot be done, this function attempts to encrypt the destination file with default keys. If both of these methods cannot be done, CopyFileEx fails with an ERROR_ENCRYPTION_FAILED error code. If you want CopyFileEx to complete the copy operation even if the destination file cannot be encrypted, include the COPY_FILE_ALLOW_DECRYPTED_DESTINATION as the value of the dwCopyFlags parameter in your call to CopyFileEx.

If COPY_FILE_COPY_SYMLINK is specified, the following rules apply:

  • If the source file is a symbolic link, the symbolic link is copied, not the target file.
  • If the source file is not a symbolic link, there is no change in behavior.
  • If the destination file is an existing symbolic link, the symbolic link is overwritten, not the target file.
  • If COPY_FILE_FAIL_IF_EXISTS is also specified, and the destination file is an existing symbolic link, the operation fails in all cases.

If COPY_FILE_COPY_SYMLINK is not specified, the following rules apply:

  • If COPY_FILE_FAIL_IF_EXISTS is also specified, and the destination file is an existing symbolic link, the operation fails only if the target of the symbolic link exists.
  • If COPY_FILE_FAIL_IF_EXISTS is not specified, there is no change in behavior.

Windows 7, Windows Server 2008 R2, Windows Server 2008, Windows Vista, Windows Server 2003, and Windows XP:  If you are writing an application that is optimizing file copy operations across a LAN, consider using the TransmitFile function from Windows Sockets (Winsock). TransmitFile supports high-performance network transfers and provides a simple interface to send the contents of a file to a remote computer. To use TransmitFile, you must write a Winsock client application that sends the file from the source computer as well as a Winsock server application that uses other Winsock functions to receive the file on the remote computer.

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

TechnologySupported

Server Message Block (SMB) 3.0 protocol

Yes

SMB 3.0 Transparent Failover (TFO)

Yes

SMB 3.0 with Scale-out File Shares (SO)

Yes

Cluster Shared Volume File System (CsvFS)

Yes

Resilient File System (ReFS)

Yes

 

Requirements

Minimum supported client

Windows XP [desktop apps only]

Minimum supported server

Windows Server 2003 [desktop apps only]

Header

WinBase.h (include Windows.h)

Library

Kernel32.lib

DLL

Kernel32.dll

Unicode and ANSI names

CopyFileExW (Unicode) and CopyFileExA (ANSI)

See also

CopyFile
CopyFileTransacted
CopyProgressRoutine
CreateFile
File Attribute Constants
File Management Functions
MoveFile
MoveFileWithProgress
Symbolic Links
TransmitFile

 

 

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