Retrieve the Free Space on a Mac OS Volume

· Jun 30, 08:08 AM

On the REALbasic mailing list, there is some interest in retrieving the amount of free space available on a Mac OS volume. It turns out that this information can be easily retrieved using a File Manager function.

Function FreeSpace(extends theVolume as FolderItem) As UInt64
  #if targetMacOS
    soft declare function FSGetVolumeInfo Lib "Carbon.framework" (volume as Int16, volumeIndex as Integer, actualVolume as Ptr, whichInfo as UInt32, info as Ptr, volumeName as Ptr, rootDirectory as Ptr) as Int16
    const sizeOfFSVolumeInfo = 126
    dim theInfo as new MemoryBlock(sizeOfFSVolumeInfo)
    const kFSVolInfoSizes = &h0040
    dim OSErr as Int16 = FSGetVolumeInfo(theVolume.MacVRefNum, 0, nil, kFSVolInfoSizes, theInfo, nil, nil)
    if OSErr <> 0 then
      break
      return 0
    end if
    return theInfo.UInt64Value(48)
  #endif
End Function

I’ve also added the method to macoslib .

The Apple documentation for FSGetVolumeInfo notes that changes to the free space value may not be immediately available. If you do not see what you expect, you should read the documentation for FSGetVolumeInfo.

---

Comment

  1. Charles, Just a reminer, this has been a part of the Carbon Library Declares forever.

    — Jordan · Jul 1, 12:57 AM · #

  2. I have a fairly recent version of that project, and I couldn’t find it.

    — charles · Jul 1, 09:43 AM · #

Commenting is closed for this article.