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Programmatic Refresh of a File System

, 17 Apr 2005
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How to force the file system to refresh.

Introduction

This is a short article, written after many hours spent on the problem of refreshing a CD file system after burning. At the end, the solution I've found is very very simple, so I've decided to explain it here.

The function

I've used a call to the BroadcastSystemMessage function to send a WM_DEVICECHANGE message to Windows (XP in my case). The function is defined as follows (found on MSDN):

long BroadcastSystemMessage(      
    DWORD dwFlags,
    LPDWORD lpdwRecipients,
    UINT uiMessage,
    WPARAM wParam,
    LPARAM lParam
);

To set the correct parameters for the call, I've initialized a DEV_BROADCAST_VOLUME struct, which is defined as:

typedef struct _DEV_BROADCAST_VOLUME {
  DWORD dbcv_size;
  DWORD dbcv_devicetype;
  DWORD dbcv_reserved;
  DWORD dbcv_unitmask;
  WORD dbcv_flags;
} DEV_BROADCAST_VOLUME, *PDEV_BROADCAST_VOLUME;

The code of my function is here:

bool RefreshFileSystem(char cdrive)
{
  DEV_BROADCAST_VOLUME hdr;
  long result;

  hdr.dbcv_size       =  sizeof(DEV_BROADCAST_VOLUME);
  hdr.dbcv_devicetype =  DBT_DEVTYP_VOLUME;
  hdr.dbcv_reserved = 0;
  cdrive = (char)_totupper(cdrive));  // thanks to Blake Miller
  hdr.dbcv_unitmask = 1 << (cdrive-'A');
  hdr.dbcv_flags  = DBTF_MEDIA;

  result = BroadcastSystemMessage(BSF_NOHANG|BSF_POSTMESSAGE,
                         NULL, WM_DEVICECHANGE, DBT_DEVICEARRIVAL,
                         (LPARAM)&hdr);
  return (result>=0);
}

I've heard of someone who used this kind of a solution but unfortunately the system crashed. I'm trying to find out what has caused the crash.

License

This article has no explicit license attached to it but may contain usage terms in the article text or the download files themselves. If in doubt please contact the author via the discussion board below.

A list of licenses authors might use can be found here

About the Author

shaman74
Web Developer
Italy Italy
No Biography provided

Comments and Discussions

 
GeneralRe: Hhhhhhhhhhhhhhh ! Pinmembershaman7414-Apr-05 20:52 
GeneralRe: Hhhhhhhhhhhhhhh ! PinmemberMX-Mauro18-Apr-05 1:20 
GeneralRe: Hhhhhhhhhhhhhhh ! PinmemberAndy N18-Apr-05 13:15 

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