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dll: MountBroadcastDriveChange registry setting

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This commit is contained in:
Bill Zissimopoulos 2022-05-25 16:55:54 +01:00
parent f6e6660362
commit 41d69d7186
1 changed files with 73 additions and 7 deletions
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80
src/dll/mount.c
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@ -20,6 +20,7 @@
*/
#include <dll/library.h>
#include <dbt.h>
static INIT_ONCE FspMountInitOnce = INIT_ONCE_STATIC_INIT;
static NTSTATUS (NTAPI *FspNtOpenSymbolicLinkObject)(
@ -28,21 +29,30 @@ static NTSTATUS (NTAPI *FspNtMakeTemporaryObject)(
HANDLE Handle);
static NTSTATUS (NTAPI *FspNtClose)(
HANDLE Handle);
static BOOLEAN FspMountDoNotUseLauncher;
static BOOLEAN FspMountDoNotUseLauncherValue;
static BOOLEAN FspMountBroadcastDriveChangeValue;
static VOID FspMountInitializeFromRegistry(VOID)
{
DWORD MountDoNotUseLauncher;
DWORD Value;
DWORD Size;
LONG Result;
MountDoNotUseLauncher = 0;
Size = sizeof MountDoNotUseLauncher;
Value = 0;
Size = sizeof Value;
Result = RegGetValueW(HKEY_LOCAL_MACHINE, L"" FSP_FSCTL_PRODUCT_FULL_REGKEY,
L"MountDoNotUseLauncher",
RRF_RT_REG_DWORD, 0, &MountDoNotUseLauncher, &Size);
RRF_RT_REG_DWORD, 0, &Value, &Size);
if (ERROR_SUCCESS == Result)
FspMountDoNotUseLauncher = !!MountDoNotUseLauncher;
FspMountDoNotUseLauncherValue = !!Value;
Value = 0;
Size = sizeof Value;
Result = RegGetValueW(HKEY_LOCAL_MACHINE, L"" FSP_FSCTL_PRODUCT_FULL_REGKEY,
L"MountBroadcastDriveChange",
RRF_RT_REG_DWORD, 0, &Value, &Size);
if (ERROR_SUCCESS == Result)
FspMountBroadcastDriveChangeValue = !!Value;
}
static BOOL WINAPI FspMountInitialize(
@ -375,6 +385,46 @@ static NTSTATUS FspLauncherDefineDosDevice(
return !NT_SUCCESS(Result) ? Result : FspNtStatusFromWin32(ErrorCode);
}
static VOID FspMountBroadcastDriveChange(PWSTR MountPoint, WPARAM WParam)
{
/*
* DefineDosDeviceW (either directly or via the CSRSS) broadcasts a WM_DEVICECHANGE message
* when a drive is added/removed. Unfortunately on some systems this broadcast fails. The
* result is that Explorer does not receive the WM_DEVICECHANGE notification and does not
* become aware of the drive change. This results in only minor UI issues for local drives,
* but more seriously it makes network drives inaccessible from some Explorer windows.
*
* The problem is that BroadcastSystemMessage can hang indefinitely when supplied the flags
* NOHANG | FORCEIFHUNG | NOTIMEOUTIFNOTHUNG. The NOTIMEOUTIFNOTHUNG flag instructs the BSM
* API to not timeout an app that is not considered hung; however an app that is not hung may
* still fail to respond to a broadcasted message indefinitely. This can result in the BSM
* API never returning ("hanging").
*
* To resolve this we simply call BroadcastSystemMessage without NOTIMEOUTIFNOTHUNG.
*/
BOOLEAN IsLocalSystem;
DEV_BROADCAST_VOLUME DriveChange;
DWORD Flags, Recipients;
FspServiceContextCheck(0, &IsLocalSystem);
memset(&DriveChange, 0, sizeof DriveChange);
DriveChange.dbcv_size = sizeof DriveChange;
DriveChange.dbcv_devicetype = DBT_DEVTYP_VOLUME;
DriveChange.dbcv_flags = DBTF_NET;
DriveChange.dbcv_unitmask = 1 << (MountPoint[0] - 'a');
Flags = BSF_NOHANG | BSF_FORCEIFHUNG;
Recipients = BSM_APPLICATIONS | (IsLocalSystem ? BSM_ALLDESKTOPS : 0);
BroadcastSystemMessageW(
Flags,
&Recipients,
WM_DEVICECHANGE,
WParam,
(LPARAM)&DriveChange);
}
static NTSTATUS FspMountSet_Drive(PWSTR VolumeName, PWSTR MountPoint, PHANDLE PMountHandle)
{
NTSTATUS Result;
@ -384,7 +434,7 @@ static NTSTATUS FspMountSet_Drive(PWSTR VolumeName, PWSTR MountPoint, PHANDLE PM
Result = FspServiceContextCheck(0, &IsLocalSystem);
IsServiceContext = NT_SUCCESS(Result) && !IsLocalSystem;
if (IsServiceContext && !FspMountDoNotUseLauncher)
if (IsServiceContext && !FspMountDoNotUseLauncherValue)
{
/*
* If the current process is in the service context but not LocalSystem,
@ -402,6 +452,13 @@ static NTSTATUS FspMountSet_Drive(PWSTR VolumeName, PWSTR MountPoint, PHANDLE PM
{
if (!DefineDosDeviceW(DDD_RAW_TARGET_PATH, MountPoint, VolumeName))
return FspNtStatusFromWin32(GetLastError());
/*
* On some systems DefineDosDeviceW fails to properly broadcast the WM_DEVICECHANGE
* notification. So use a workaround. See comments in FspMountBroadcastDriveChange.
*/
if (FspMountBroadcastDriveChangeValue)
FspMountBroadcastDriveChange(MountPoint, DBT_DEVICEARRIVAL);
}
if (0 != FspNtOpenSymbolicLinkObject)
@ -457,9 +514,18 @@ static NTSTATUS FspMountRemove_Drive(PWSTR VolumeName, PWSTR MountPoint, HANDLE
*/
Result = FspLauncherDefineDosDevice(L'-', MountPoint, VolumeName);
else
{
Result = DefineDosDeviceW(DDD_RAW_TARGET_PATH | DDD_REMOVE_DEFINITION | DDD_EXACT_MATCH_ON_REMOVE,
MountPoint, VolumeName) ? STATUS_SUCCESS : FspNtStatusFromWin32(GetLastError());
/*
* On some systems DefineDosDeviceW fails to properly broadcast the WM_DEVICECHANGE
* notification. So use a workaround. See comments in FspMountBroadcastDriveChange.
*/
if (FspMountBroadcastDriveChangeValue)
FspMountBroadcastDriveChange(MountPoint, DBT_DEVICEREMOVECOMPLETE);
}
if (0 != MountHandle)
FspNtClose(MountHandle);