Windows Documentation

Core File Operations

These functions allow you to perform fundamental operations on files and directories.

• CreateFile
• ReadFile
• WriteFile
• CloseHandle
• DeleteFile
• CopyFile
• MoveFile
• CreateDirectory
• RemoveDirectory

File Information and Attributes

Retrieve and set various properties of files and directories.

• GetFileAttributes
• SetFileAttributes
• GetFileSizeEx
• GetVolumeInformation
• FindFirstFile
• FindNextFile
• FindClose

Advanced File System Features

Explore more sophisticated file system functionalities.

• SetFilePointerEx
• DeviceIoControl
• Reparse Points
• Hard Links and Symbolic Links
• File Locking and Sharing

CreateFile

Syntax:

HANDLE CreateFile(
  _In      LPCTSTR lpFileName,
  _In      DWORD dwDesiredAccess,
  _In      DWORD dwShareMode,
  _In_opt  LPSECURITY_ATTRIBUTES lpSecurityAttributes,
  _In      DWORD dwCreationDisposition,
  _In      DWORD dwFlagsAndAttributes,
  _In_opt  HANDLE hTemplateFile
);

Description: Creates or opens a file or I/O device. It returns a handle to the specified device, which can be used for subsequent I/O operations.

Parameters:

• lpFileName: The name of the file or device to be created or opened.
• dwDesiredAccess: The requested access to the file or device.
• dwShareMode: A bitmask of flags that specify how the file or device should be shared.
• lpSecurityAttributes: A pointer to a SECURITY_ATTRIBUTES structure that specifies the security attributes of the file or device.
• dwCreationDisposition: An action to take if the file does or does not exist.
• dwFlagsAndAttributes: The file attributes and extended attributes for the file or directory.
• hTemplateFile: A handle to a template file with the attributes and extended attributes that are to be copied to the specified file.

Return Value: If the function succeeds, the return value is an open handle to the specified file or device. If the function fails, the return value is INVALID_HANDLE_VALUE.

ReadFile

Syntax:

BOOL ReadFile(
  _In        HANDLE       hFile,
  _Out       LPVOID       lpBuffer,
  _In        DWORD        nNumberOfBytesToRead,
  _Out_opt   LPDWORD      lpNumberOfBytesRead,
  _Inout_opt LPOVERLAPPED lpOverlapped
);

Description: Reads data from a file or input buffer into an array, starting at a specified offset. This function is the general-purpose file reading function.

Parameters:

• hFile: A handle to the file or device (CreateFile) that is to be read.
• lpBuffer: A pointer to the buffer that receives the data read from the file.
• nNumberOfBytesToRead: The maximum number of bytes to be read.
• lpNumberOfBytesRead: A pointer to a variable that receives the number of bytes actually read.
• lpOverlapped: A pointer to an OVERLAPPED structure.

Return Value: If the function succeeds, the return value is nonzero. If the function fails, the return value is zero.

WriteFile

Syntax:

BOOL WriteFile(
  _In        HANDLE       hFile,
  _In_const  LPVOID       lpBuffer,
  _In        DWORD        nNumberOfBytesToWrite,
  _Out_opt   LPDWORD      lpNumberOfBytesWritten,
  _Inout_opt LPOVERLAPPED lpOverlapped
);

Description: Writes data to a file or I/O device. It starts writing data to the file at the position indicated by the file-pointer.

Parameters:

• hFile: A handle to the file or device (CreateFile) that is to be written to.
• lpBuffer: A pointer to the buffer containing the data to be written to the file.
• nNumberOfBytesToWrite: The number of bytes to be written to the file.
• lpNumberOfBytesWritten: A pointer to a variable that receives the number of bytes actually written.
• lpOverlapped: A pointer to an OVERLAPPED structure.

Return Value: If the function succeeds, the return value is nonzero. If the function fails, the return value is zero.