CcCopyWriteEx function

The CcCopyWriteEx routine copies data from a user buffer to a cached file. The I/O byte count for the operation is charged to the issuing thread.


  PFILE_OBJECT   FileObject,
  ULONG          Length,
  BOOLEAN        Wait,
  PVOID          Buffer,
  PETHREAD       IoIssuerThread



A pointer to a file object for the cached file to which the data is to be written.


A pointer to a variable that specifies the starting byte offset within the cached file.


The length in bytes of the data to be written.


Set to TRUE if the caller can be put into a wait state until all the data has been copied, FALSE otherwise.


A pointer to the buffer from which the data is to be copied.


The thread issuing the write request. For a file system with disk I/O accounting enabled, this is the thread the I/O is charged to. If IoIssuerThread is NULL, the I/O is charged to the current thread.

Return Value

The CcCopyWriteEx routine returns TRUE if the data was copied successfully, FALSE otherwise.


If Wait is TRUE, CcCopyWriteEx is guaranteed to complete the copy request and return TRUE. If the required pages of the cached file are already resident in memory, the data will be copied immediately and no blocking will occur. If any needed pages are not resident, the caller will be put in a wait state until all required pages have been made resident and the data can be copied.

If Wait is FALSE, CcCopyWriteEx will refuse to block, and will return FALSE, if the required pages of the cached file are not already resident in memory or if the FO_WRITE_THROUGH flag is set on the file object.

If any failure occurs, CcCopyWriteEx raises a status exception for that particular failure. For example, if a pool allocation failure occurs, CcCopyWriteEx raises an exception with the STATUS_INSUFFICIENT_RESOURCES status; if an I/O error occurs, CcCopyWriteEx raises the status exception of the I/O error. Therefore, to gain control if a failure occurs, the driver should wrap the call to CcCopyWriteEx in a try-except or try-finally statement.

To cache a file, use CcInitializeCacheMap.


Windows version Available starting with Windows 8.
Target Platform Universal
Header ntifs.h (include Ntifs.h, FltKernel.h)
Library NtosKrnl.lib
DLL NtosKrnl.exe

See Also