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MyFSD_GetDiskFreeSpaceW (Compact 2013)

  • Article

3/26/2014

This function obtains information about the amount of space available on a disk volume in an installable file system. Applications do not call this function directly. Instead, they use the corresponding standard Win32 function GetDiskFreeSpaceEx. File System Disk Manager (FSDMGR) determines the file system type and calls the MyFSD_GetDiskFreeSpaceW implementation of the function.

Syntax

BOOL MyFSD_GetDiskFreeSpaceW( 
  PVOLUME pVolume, 
  PCWSTR pwsPathName, 
  PDWORD pSectorsPerCluster,
  PDWORD pBytesPerSector, 
  PDWORD pFreeClusters, 
  PDWORD pClusters
);

Parameters

  • pVolume
    [in] Pointer to the value that a file system driver (FSD) defines in its DLL and passes to the FSDMGR_RegisterVolume function when registering the volume. The definition of this parameter can point to private structures.
  • pwsPathName
    [in] Pointer to a null-terminated string that specifies a directory in the file system to on which to return information. The concept of a current directory does not exist. You must specify the complete directory path.
  • pSectorsPerCluster
    [out] Pointer to a variable that receives the number of sectors per cluster.
  • pBytesPerSector
    [out] Pointer to a variable that receives the number of bytes per sector.
  • pFreeClusters
    [out] Pointer to a variable that receives the number of free clusters on the disk that are available to the user associated with the calling thread.
  • pClusters
    [out] Pointer to a variable that receives the number of clusters on the disk that are available to the user associated with the calling thread.

Return Value

Nonzero indicates success. Zero indicates failure. To get extended error information, call GetLastError.

Remarks

An FSD exports this function if it supports the GetDiskFreeSpaceEx function. All FSD functions can be called on re-entry. Therefore, take this into account when developing an FSD.

FSDMGR is a DLL that manages all OS interaction with installable files systems. Each installable file system requires an FSD, which is a DLL that supports an installable file system. The name of the DLL for an FSD and the names of the functions it exports start with the name of the associated installable file system. For example, if the name of file system is MyFSD, its DLL is MyFSD.dll, and its exported functions are prefaced with MyFSD_*.

FSDMGR provides service functions to FSDs. The FSDMGR_RegisterVolume, the FSDMGR_CreateFileHandle, and the FSDMGR_CreateSearchHandle functions record a DWORD of volume-specific data that an FSD associates with a volume. This volume-specific data is passed as the first parameter of these three functions.

Applications that access an installable file system use standard Win32 functions. For example, when an application creates a folder on a device that contains an installable file system, it calls the CreateDirectory function. FSDMGR recognizes that the path is to a device containing an installable file system and calls the appropriate function, which in the case of the MyFSD file system is MyFSD_CreateDirectoryW. That is, the application calls CreateDirectory, causing FSDMGR to call **MyFSD_CreateDirectoryW.

Requirements

Header

fsdmgr.h

Library

Fsdmgr.lib

See Also

Reference

MyFSD Functions
CreateDirectory
FSDMGR_CreateSearchHandle
GetDiskFreeSpaceEx
FSDMGR_CreateFileHandle
FSDMGR_RegisterVolume
MyFSD_CreateDirectoryW