Windows API Reference

File System Core APIs

This section details the core Windows APIs for interacting with the file system. These APIs provide fundamental operations for managing files, directories, and volumes.

File and Directory Operations

• CreateFile

  Creates or opens a file or I/O device. It returns a handle that can be used to access the file or device.

• ReadFile

  Reads data from a file or I/O device. It fills a buffer with data read from the specified file or device.

• WriteFile

  Writes data to a file or I/O device. It writes the specified buffer to the specified file or device.

• CloseHandle

  Closes an open object handle. This is crucial for releasing resources.

• GetFileAttributes

  Retrieves attributes for a specified file or directory.

• SetFileAttributes

  Sets the attributes for a specified file or directory.

• DeleteFile

  Deletes a specified file.

• CreateDirectory

  Creates a new directory.

• RemoveDirectory

  Removes an empty directory.

• CopyFile

  Copies an existing file to a new location.

• MoveFile

  Moves an existing file or directory from one location to another.

Directory Enumeration

• FindFirstFile

  Begins the enumeration of a directory or the file system.

• FindNextFile

  Continues a directory or file system search.

• FindClose

  Closes the search handle supplied by a previous call to FindFirstFile or FindNextFile.

Volume Information

• GetLogicalDrives

  Retrieves a bitmask of the currently available disk drives.

• GetDriveType

  Determines the type of the specified disk drive.

• GetVolumeInformation

  Retrieves information about a file system and a specified volume to include volume label, file system name, and serial number.

CreateFile Function

Syntax

HANDLE CreateFile(
  LPCSTR                lpFileName,
  DWORD                 dwDesiredAccess,
  DWORD                 dwShareMode,
  LPSECURITY_ATTRIBUTES lpSecurityAttributes,
  DWORD                 dwCreationDisposition,
  DWORD                 dwFlagsAndAttributes,
  HANDLE                hTemplateFile
);

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 bitmap of the modes that wish to share an Handle to an object with other threads.
• lpSecurityAttributes: A pointer to a SECURITY_ATTRIBUTES structure that contains security information for the file or directory.
• dwCreationDisposition: An action to take if the file exists, and what to do if it does not exist.
• dwFlagsAndAttributes: The file system attributes and flags for the file or directory.
• hTemplateFile: A handle to the template file for the file being created.

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.

See full documentation

ReadFile Function

Syntax

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

Parameters

• hFile: A handle to the file or device (CreateFile returns this handle).
• lpBuffer: A buffer that receives the data read from the specified file or device.
• nNumberOfBytesToRead: The maximum number of bytes to be read.
• lpNumberOfBytesRead: A pointer to a variable that receives the number of bytes 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.

See full documentation

WriteFile Function

Syntax

BOOL WriteFile(
  HANDLE       hFile,
  LPCVOID      lpBuffer,
  DWORD        nNumberOfBytesToWrite,
  LPDWORD      lpNumberOfBytesWritten,
  LPOVERLAPPED lpOverlapped
);

Parameters

• hFile: A handle to the file or device (CreateFile returns this handle).
• lpBuffer: A pointer to a buffer that contains the data to be written to the specified file or device.
• nNumberOfBytesToWrite: The number of bytes to be written to the file or device.
• lpNumberOfBytesWritten: A pointer to a variable that receives the number of bytes 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.

See full documentation

FindFirstFile Function

Syntax

HANDLE FindFirstFile(
  LPCSTR            lpFileName,
  LPWIN32_FIND_DATAA lpFindFileData
);

Parameters

• lpFileName: The root directory and the path for a file or for a set of files.
• lpFindFileData: A pointer to a WIN32_FIND_DATA structure that receives information about a found file or directory.

Return Value

If the function succeeds, the return value is a search handle used by subsequent calls to the FindNextFile function. If the function fails, the return value is INVALID_HANDLE_VALUE.

See full documentation