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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

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About the Author

shaman74
Web Developer
Italy Italy
No Biography provided

Comments and Discussions

 
GeneralC# code - Works for me on network drives Pinmembertheit851412-Jun-11 17:00 
GeneralPossible crash causess PinmemberSimon Owen25-Jun-06 21:58 
Questionquery Pinmemberachalshah717-Mar-06 1:52 
GeneralSHChangeNotify PinmemberCabbi9-Jun-05 2:53 
Generalcan't refresh CDRW content PinsussSergey Apollonov23-May-05 19:34 
GeneralCode Correction : Drive Letter PinmemberBlake Miller12-Apr-05 4:30 
GeneralRe: Code Correction : Drive Letter Pinmembershaman7412-Apr-05 5:17 
GeneralHhhhhhhhhhhhhhh ! PinmemberKochise7-Apr-05 23:24 
The Windows bug I have for so long, because Windows don't refresh the CD content if you change it while you are in a modal dialog or the infamous SHBrowseForFolder !
 
My Lord ! So simple and elegant solution, thanks for the info !
 
Kochise
 
In Code we trust !
GeneralRe: Hhhhhhhhhhhhhhh ! Pinmembershaman747-Apr-05 23:32 
GeneralRe: Hhhhhhhhhhhhhhh ! PinmemberOutlook14-Apr-05 10:41 
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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