drivers/filters/fltmgr/Object.c

   1 /*
   2 * PROJECT:         Filesystem Filter Manager
   3 * LICENSE:         GPL - See COPYING in the top level directory
   4 * FILE:            drivers/filters/fltmgr/Object.c
   5 * PURPOSE:         Miscellaneous library functions
   6 * PROGRAMMERS:     Ged Murphy (gedmurphy@reactos.org)
   7 */
   8
   9 // NOTE: Split this file into filter object and device object functions
  10 // when the code base grows sufficiently
  11
  12 /* INCLUDES ******************************************************************/
  13
  14 #include "fltmgr.h"
  15 #include "fltmgrint.h"
  16
  17 #define NDEBUG
  18 #include <debug.h>
  19
  20
  21 /* DATA *********************************************************************/
  22
  23 #define ExpChangePushlock(x, y, z) InterlockedCompareExchangePointer((PVOID*)x, (PVOID)y, (PVOID)z)
  24
  25 //
  26 // Pushlock bits
  27 //
  28 #define EX_PUSH_LOCK_LOCK_V             ((ULONG_PTR)0x0)
  29 #define EX_PUSH_LOCK_LOCK               ((ULONG_PTR)0x1)
  30 #define EX_PUSH_LOCK_WAITING            ((ULONG_PTR)0x2)
  31 #define EX_PUSH_LOCK_WAKING             ((ULONG_PTR)0x4)
  32 #define EX_PUSH_LOCK_MULTIPLE_SHARED    ((ULONG_PTR)0x8)
  33 #define EX_PUSH_LOCK_SHARE_INC          ((ULONG_PTR)0x10)
  34 #define EX_PUSH_LOCK_PTR_BITS           ((ULONG_PTR)0xf)
  35
  36 /* EXPORTED FUNCTIONS ******************************************************/
  37
  38
  39 NTSTATUS
  40 FLTAPI
  41 FltObjectReference(_Inout_ PVOID Object)
  42 {
  43     if (!FltpExAcquireRundownProtection(&((PFLT_OBJECT)Object)->RundownRef))
  44     {
  45         return STATUS_FLT_DELETING_OBJECT;
  46     }
  47
  48     return STATUS_SUCCESS;
  49 }
  50
  51 VOID
  52 FLTAPI
  53 FltObjectDereference(_Inout_ PVOID Object)
  54 {
  55     FltpExReleaseRundownProtection(&((PFLT_OBJECT)Object)->RundownRef);
  56 }
  57
  58
  59 _Acquires_lock_(_Global_critical_region_)
  60 _IRQL_requires_max_(APC_LEVEL)
  61 VOID
  62 FLTAPI
  63 FltAcquirePushLockExclusive(_Inout_ _Requires_lock_not_held_(*_Curr_) _Acquires_lock_(*_Curr_) PEX_PUSH_LOCK PushLock)
  64 {
  65     KeEnterCriticalRegion();
  66
  67     /* Try acquiring the lock */
  68     if (InterlockedBitTestAndSet((PLONG)PushLock, EX_PUSH_LOCK_LOCK_V))
  69     {
  70         /* Someone changed it, use the slow path */
  71         ExfAcquirePushLockExclusive(PushLock);
  72     }
  73
  74     /* Sanity check */
  75     FLT_ASSERT(PushLock->Locked);
  76 }
  77
  78
  79 _Acquires_lock_(_Global_critical_region_)
  80 _IRQL_requires_max_(APC_LEVEL)
  81 VOID
  82 FLTAPI
  83 FltAcquirePushLockShared(_Inout_ _Requires_lock_not_held_(*_Curr_) _Acquires_lock_(*_Curr_) PEX_PUSH_LOCK PushLock)
  84 {
  85     EX_PUSH_LOCK NewValue;
  86
  87     KeEnterCriticalRegion();
  88
  89     /* Try acquiring the lock */
  90     NewValue.Value = EX_PUSH_LOCK_LOCK | EX_PUSH_LOCK_SHARE_INC;
  91     if (ExpChangePushlock(PushLock, NewValue.Ptr, 0))
  92     {
  93         /* Someone changed it, use the slow path */
  94         ExfAcquirePushLockShared(PushLock);
  95     }
  96
  97     /* Sanity checks */
  98     ASSERT(PushLock->Locked);
  99 }
 100
 101 _Releases_lock_(_Global_critical_region_)
 102 _IRQL_requires_max_(APC_LEVEL)
 103 VOID
 104 FLTAPI
 105 FltReleasePushLock(_Inout_ _Requires_lock_held_(*_Curr_) _Releases_lock_(*_Curr_) PEX_PUSH_LOCK PushLock)
 106 {
 107     EX_PUSH_LOCK OldValue = *PushLock;
 108     EX_PUSH_LOCK NewValue;
 109
 110     /* Sanity checks */
 111     FLT_ASSERT(OldValue.Locked);
 112
 113     /* Check if the pushlock is shared */
 114     if (OldValue.Shared > 1)
 115     {
 116         /* Decrease the share count */
 117         NewValue.Value = OldValue.Value - EX_PUSH_LOCK_SHARE_INC;
 118     }
 119     else
 120     {
 121         /* Clear the pushlock entirely */
 122         NewValue.Value = 0;
 123     }
 124
 125     /* Check if nobody is waiting on us and try clearing the lock here */
 126     if ((OldValue.Waiting) ||
 127         (ExpChangePushlock(PushLock, NewValue.Ptr, OldValue.Ptr) !=
 128          OldValue.Ptr))
 129     {
 130         /* We have waiters, use the long path */
 131         ExfReleasePushLock(PushLock);
 132     }
 133
 134     KeLeaveCriticalRegion();
 135 }
 136
 137
 138
 139 /* INTERNAL FUNCTIONS ******************************************************/
 140
 141 VOID
 142 FltpExInitializeRundownProtection(_Out_ PEX_RUNDOWN_REF RundownRef)
 143 {
 144     ExInitializeRundownProtection(RundownRef);
 145 }
 146
 147 BOOLEAN
 148 FltpExAcquireRundownProtection(_Inout_ PEX_RUNDOWN_REF RundownRef)
 149 {
 150     return ExAcquireRundownProtection(RundownRef);
 151 }
 152
 153 BOOLEAN
 154 FltpExReleaseRundownProtection(_Inout_ PEX_RUNDOWN_REF RundownRef)
 155 {
 156     ExReleaseRundownProtection(RundownRef);
 157     return TRUE;
 158 }
 159
 160 BOOLEAN
 161 FltpExRundownCompleted(_Inout_ PEX_RUNDOWN_REF RundownRef)
 162 {
 163     return _InterlockedExchange((PLONG)RundownRef, 1);
 164 }
 165
 166 NTSTATUS
 167 NTAPI
 168 FltpObjectRundownWait(_Inout_ PEX_RUNDOWN_REF RundownRef)
 169 {
 170     //return FltpExWaitForRundownProtectionRelease(RundownRef);
 171     return 0;
 172 }
 173
 174 NTSTATUS
 175 FltpGetBaseDeviceObjectName(_In_ PDEVICE_OBJECT DeviceObject,
 176                             _Inout_ PUNICODE_STRING ObjectName)
 177 {
 178     PDEVICE_OBJECT BaseDeviceObject;
 179     NTSTATUS Status;
 180
 181     /*
 182     * Get the lowest device object on the stack, which may be the
 183     * object we were passed, and lookup the name for that object
 184     */
 185     BaseDeviceObject = IoGetDeviceAttachmentBaseRef(DeviceObject);
 186     Status = FltpGetObjectName(BaseDeviceObject, ObjectName);
 187     ObDereferenceObject(BaseDeviceObject);
 188
 189     return Status;
 190 }
 191
 192 NTSTATUS
 193 FltpGetObjectName(_In_ PVOID Object,
 194                   _Inout_ PUNICODE_STRING ObjectName)
 195 {
 196     POBJECT_NAME_INFORMATION ObjectNameInfo = NULL;
 197     OBJECT_NAME_INFORMATION LocalNameInfo;
 198     ULONG ReturnLength;
 199     NTSTATUS Status;
 200
 201     if (ObjectName == NULL)
 202         return STATUS_INVALID_PARAMETER;
 203
 204     /* Get the size of the buffer required to hold the nameinfo */
 205     Status = ObQueryNameString(Object,
 206                                &LocalNameInfo,
 207                                sizeof(LocalNameInfo),
 208                                &ReturnLength);
 209     if (Status == STATUS_INFO_LENGTH_MISMATCH)
 210     {
 211         ObjectNameInfo = ExAllocatePoolWithTag(PagedPool,
 212                                                ReturnLength,
 213                                                FM_TAG_UNICODE_STRING);
 214         if (ObjectNameInfo == NULL) return STATUS_INSUFFICIENT_RESOURCES;
 215
 216         /* Get the actual name info now we have the buffer to hold it */
 217         Status = ObQueryNameString(Object,
 218                                    ObjectNameInfo,
 219                                    ReturnLength,
 220                                    &ReturnLength);
 221     }
 222
 223
 224     if (NT_SUCCESS(Status))
 225     {
 226         /* Make sure the buffer we were passed is large enough to hold the string */
 227         if (ObjectName->MaximumLength < ObjectNameInfo->Name.Length)
 228         {
 229             /* It wasn't, let's enlarge the buffer */
 230             Status = FltpReallocateUnicodeString(ObjectName,
 231                                                  ObjectNameInfo->Name.Length,
 232                                                  FALSE);
 233
 234         }
 235
 236         if (NT_SUCCESS(Status))
 237         {
 238             /* Copy the object name into the callers buffer */
 239             RtlCopyUnicodeString(ObjectName, &ObjectNameInfo->Name);
 240         }
 241     }
 242
 243     if (ObjectNameInfo)
 244     {
 245         ExFreePoolWithTag(ObjectNameInfo, FM_TAG_UNICODE_STRING);
 246     }
 247
 248     return Status;
 249 }
 250
 251 ULONG
 252 FltpObjectPointerReference(_In_ PFLT_OBJECT Object)
 253 {
 254     PULONG Result;
 255
 256     /* Store the old count and increment */
 257     Result = &Object->PointerCount;
 258     InterlockedIncrementSizeT(&Object->PointerCount);
 259
 260     /* Return the initial value */
 261     return *Result;
 262 }
 263
 264 VOID
 265 FltpObjectPointerDereference(_In_ PFLT_OBJECT Object)
 266 {
 267     if (InterlockedDecrementSizeT(&Object->PointerCount) == 0)
 268     {
 269         // Cleanup
 270         FLT_ASSERT(FALSE);
 271     }
 272 }