CopyFileExW function (winbase.h)
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 CopyFileExW(
[in] LPCWSTR lpExistingFileName,
[in] LPCWSTR lpNewFileName,
[in, optional] LPPROGRESS_ROUTINE lpProgressRoutine,
[in, optional] LPVOID lpData,
[in, optional] LPBOOL pbCancel,
[in] DWORD dwCopyFlags
);
Parameters
[in] lpExistingFileName
The name of an existing file.
By default, the name is limited to MAX_PATH characters. To extend this limit to 32,767 wide characters, prepend "\\?\" to the path. For more information, see Naming Files, Paths, and Namespaces.
Tip
Starting with Windows 10, Version 1607, you can opt-in to remove the MAX_PATH limitation without prepending "\\?\". See the "Maximum Path Length Limitation" section of Naming Files, Paths, and Namespaces for details.
If lpExistingFileName does not exist, the CopyFileEx function fails, and the GetLastError function returns ERROR_FILE_NOT_FOUND.
[in] lpNewFileName
The name of the new file.
By default, the name is limited to MAX_PATH characters. To extend this limit to 32,767 wide characters, prepend "\\?\" to the path. For more information, see Naming Files, Paths, and Namespaces.
Tip
Starting with Windows 10, Version 1607, you can opt-in to remove the MAX_PATH limitation without prepending "\\?\". See the "Maximum Path Length Limitation" section of Naming Files, Paths, and Namespaces for details.
[in, optional] lpProgressRoutine
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.
[in, optional] lpData
The argument to be passed to the callback function. This parameter can be NULL.
[in, optional] pbCancel
If this flag is set to TRUE during the copy operation, the operation is canceled. Otherwise, the copy operation will continue to completion.
[in] dwCopyFlags
Flags that specify how the file is to be copied. This parameter can be a combination of the following values.
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_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.
| Technology | Supported |
|---|---|
| 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 |
Note
The winbase.h header defines CopyFileEx as an alias which automatically selects the ANSI or Unicode version of this function based on the definition of the UNICODE preprocessor constant. Mixing usage of the encoding-neutral alias with code that not encoding-neutral can lead to mismatches that result in compilation or runtime errors. For more information, see Conventions for Function Prototypes.
Requirements
| Requirement | Value |
|---|---|
| Minimum supported client | Windows XP [desktop apps | UWP apps] |
| Minimum supported server | Windows Server 2003 [desktop apps | UWP apps] |
| Target Platform | Windows |
| Header | winbase.h (include Windows.h) |
| Library | Kernel32.lib |
| DLL | Kernel32.dll |