reactos/ntoskrnl/ob/object.c

   1 /*
   2  * COPYRIGHT:     See COPYING in the top level directory
   3  * PROJECT:       ReactOS kernel
   4  * FILE:          ntoskrnl/ob/object.c
   5  * PURPOSE:       Implements generic object managment functions
   6  * PROGRAMMER:    David Welch (welch@cwcom.net)
   7  * UPDATE HISTORY:
   8  *               10/06/98: Created
   9  */
  10
  11 /* INCLUDES *****************************************************************/
  12
  13 #include <wchar.h>
  14 #include <ddk/ntddk.h>
  15 #include <internal/ob.h>
  16 #include <internal/string.h>
  17 #include <internal/id.h>
  18
  19 #define NDEBUG
  20 #include <internal/debug.h>
  21
  22 /* FUNCTIONS ************************************************************/
  23
  24 VOID ObInitializeObject(POBJECT_HEADER ObjectHeader,
  25                         PHANDLE Handle,
  26                         ACCESS_MASK DesiredAccess,
  27                         POBJECT_TYPE Type,
  28                         POBJECT_ATTRIBUTES ObjectAttributes)
  29 {
  30    ObjectHeader->HandleCount = 1;
  31    ObjectHeader->RefCount = 1;
  32    ObjectHeader->ObjectType = Type;
  33    ObjectHeader->Permanent = FALSE;
  34    RtlInitUnicodeString(&(ObjectHeader->Name),NULL);
  35    if (Handle != NULL)
  36      {
  37         ObCreateHandle(PsGetCurrentProcess(),
  38                        HEADER_TO_BODY(ObjectHeader),
  39                        DesiredAccess,
  40                        FALSE,
  41                        Handle);
  42      }
  43 }
  44
  45 NTSTATUS ObFindObject(POBJECT_ATTRIBUTES ObjectAttributes,
  46                       PVOID* ReturnedObject,
  47                       PWSTR* RemainingPath)
  48 {
  49    PVOID NextObject;
  50    PVOID CurrentObject;
  51    POBJECT_HEADER CurrentHeader;
  52    NTSTATUS Status;
  53    PWSTR Path;
  54    PWSTR current;
  55
  56    DPRINT("ObFindObject(ObjectAttributes %x, ReturnedObject %x, "
  57           "RemainingPath %x)\n",ObjectAttributes,ReturnedObject,RemainingPath);
  58    DPRINT("ObjectAttributes->ObjectName->Buffer %x\n",
  59           ObjectAttributes->ObjectName->Buffer);
  60
  61    if (ObjectAttributes->RootDirectory == NULL)
  62      {
  63         ObReferenceObjectByPointer(NameSpaceRoot,
  64                                    DIRECTORY_TRAVERSE,
  65                                    NULL,
  66                                    UserMode);
  67         CurrentObject = NameSpaceRoot;
  68      }
  69    else
  70      {
  71         Status = ObReferenceObjectByHandle(ObjectAttributes->RootDirectory,
  72                                            DIRECTORY_TRAVERSE,
  73                                            NULL,
  74                                            UserMode,
  75                                            &CurrentObject,
  76                                            NULL);
  77         if (!NT_SUCCESS(Status))
  78           {
  79              return(Status);
  80           }
  81      }
  82
  83    Path = ObjectAttributes->ObjectName->Buffer;
  84
  85    if (Path[0] == 0)
  86      {
  87         *ReturnedObject = CurrentObject;
  88         return(STATUS_SUCCESS);
  89      }
  90
  91    if (Path[0] != '\\')
  92      {
  93         return(STATUS_UNSUCCESSFUL);
  94      }
  95
  96    current = Path;
  97
  98    while (TRUE)
  99      {
 100         DPRINT("current %w\n",current);
 101         CurrentHeader = BODY_TO_HEADER(CurrentObject);
 102         if (CurrentHeader->ObjectType->Parse == NULL)
 103           {
 104              break;
 105           }
 106         NextObject = CurrentHeader->ObjectType->Parse(CurrentObject,
 107                                                       &current);
 108         if (NextObject == NULL)
 109           {
 110              break;
 111           }
 112         ObDereferenceObject(CurrentObject);
 113         CurrentObject = NextObject;
 114      }
 115
 116    *RemainingPath = current;
 117    *ReturnedObject = CurrentObject;
 118
 119    return(STATUS_SUCCESS);
 120 }
 121
 122 PVOID ObCreateObject(PHANDLE Handle,
 123                      ACCESS_MASK DesiredAccess,
 124                      POBJECT_ATTRIBUTES ObjectAttributes,
 125                      POBJECT_TYPE Type)
 126 {
 127    PVOID Parent = NULL;
 128    PWSTR RemainingPath = NULL;
 129    POBJECT_HEADER Header;
 130    NTSTATUS Status;
 131
 132    assert_irql(PASSIVE_LEVEL);
 133
 134    DPRINT("ObCreateObject(Handle %x, ObjectAttributes %x, Type %x)\n");
 135    if (ObjectAttributes != NULL &&
 136        ObjectAttributes->ObjectName != NULL)
 137      {
 138         DPRINT("ObjectAttributes->ObjectName->Buffer %w\n",
 139                ObjectAttributes->ObjectName->Buffer);
 140      }
 141
 142    if (ObjectAttributes != NULL &&
 143        ObjectAttributes->ObjectName != NULL)
 144      {
 145         ObFindObject(ObjectAttributes,
 146                      &Parent,
 147                      &RemainingPath);
 148      }
 149
 150    Header = (POBJECT_HEADER)ExAllocatePool(NonPagedPool,
 151                                            OBJECT_ALLOC_SIZE(Type));
 152    ObInitializeObject(Header,
 153                       Handle,
 154                       DesiredAccess,
 155                       Type,
 156                       ObjectAttributes);
 157    if (Header->ObjectType != NULL &&
 158        Header->ObjectType->Create != NULL)
 159      {
 160         Status = Header->ObjectType->Create(HEADER_TO_BODY(Header),
 161                                             Parent,
 162                                             RemainingPath,
 163                                             ObjectAttributes);
 164         if (!NT_SUCCESS(Status))
 165           {
 166              return(NULL);
 167           }
 168      }
 169    return(HEADER_TO_BODY(Header));
 170 }
 171
 172 NTSTATUS ObReferenceObjectByPointer(PVOID ObjectBody,
 173                                     ACCESS_MASK DesiredAccess,
 174                                     POBJECT_TYPE ObjectType,
 175                                     KPROCESSOR_MODE AccessMode)
 176 /*
 177  * FUNCTION: Increments the pointer reference count for a given object
 178  * ARGUMENTS:
 179  *         ObjectBody = Object's body
 180  *         DesiredAccess = Desired access to the object
 181  *         ObjectType = Points to the object type structure
 182  *         AccessMode = Type of access check to perform
 183  * RETURNS: Status
 184  */
 185 {
 186    POBJECT_HEADER ObjectHeader;
 187
 188    DPRINT("ObReferenceObjectByPointer(ObjectBody %x, ObjectType %x)\n",
 189           ObjectBody,ObjectType);
 190
 191    ObjectHeader = BODY_TO_HEADER(ObjectBody);
 192
 193    if (ObjectType != NULL && ObjectHeader->ObjectType != ObjectType)
 194      {
 195         DPRINT("Failed (type was %x %w)\n",ObjectHeader->ObjectType,
 196                ObjectHeader->ObjectType->TypeName.Buffer);
 197         return(STATUS_UNSUCCESSFUL);
 198      }
 199
 200    ObjectHeader->RefCount++;
 201
 202    return(STATUS_SUCCESS);
 203 }
 204
 205 NTSTATUS ObPerformRetentionChecks(POBJECT_HEADER Header)
 206 {
 207    DPRINT("ObPerformRetentionChecks(Header %x), RefCount %d, HandleCount %d\n",
 208            Header,Header->RefCount,Header->HandleCount);
 209
 210    if (Header->RefCount <  0 || Header->HandleCount < 0)
 211      {
 212         DbgPrint("Object %x/%x has invalid reference or handle count\n",
 213                  Header,HEADER_TO_BODY(Header));
 214         KeBugCheck(0);
 215      }
 216
 217    if (Header->RefCount == 0 && Header->HandleCount == 0 &&
 218        !Header->Permanent)
 219      {
 220         if (Header->ObjectType != NULL &&
 221             Header->ObjectType->Delete != NULL)
 222           {
 223              Header->ObjectType->Delete(HEADER_TO_BODY(Header));
 224           }
 225         if (Header->Name.Buffer != NULL)
 226           {
 227              ObRemoveEntry(Header);
 228           }
 229         DPRINT("ObPerformRetentionChecks() = Freeing object\n");
 230         ExFreePool(Header);
 231      }
 232    return(STATUS_SUCCESS);
 233 }
 234
 235 ULONG ObGetReferenceCount(PVOID ObjectBody)
 236 {
 237    POBJECT_HEADER Header = BODY_TO_HEADER(ObjectBody);
 238
 239    return(Header->RefCount);
 240 }
 241
 242 VOID ObDereferenceObject(PVOID ObjectBody)
 243 /*
 244  * FUNCTION: Decrements a given object's reference count and performs
 245  * retention checks
 246  * ARGUMENTS:
 247  *        ObjectBody = Body of the object
 248  */
 249 {
 250    POBJECT_HEADER Header = BODY_TO_HEADER(ObjectBody);
 251
 252    DPRINT("ObDeferenceObject(ObjectBody %x) RefCount %d\n",ObjectBody,
 253           Header->RefCount);
 254
 255    Header->RefCount--;
 256
 257    ObPerformRetentionChecks(Header);
 258 }