drivers/filters/fltmgr/Context.c

   1 /*
   2 * PROJECT:         Filesystem Filter Manager
   3 * LICENSE:         GPL - See COPYING in the top level directory
   4 * FILE:            drivers/filters/fltmgr/Context.c
   5 * PURPOSE:         Contains context routines
   6 * PROGRAMMERS:     Ged Murphy (gedmurphy@reactos.org)
   7 */
   8
   9 /* INCLUDES ******************************************************************/
  10
  11 #include "fltmgr.h"
  12 #include "fltmgrint.h"
  13
  14 #define NDEBUG
  15 #include <debug.h>
  16
  17
  18 /* DATA *********************************************************************/
  19
  20 static
  21 BOOLEAN
  22 IsContextTypeValid(
  23     _In_ FLT_CONTEXT_TYPE ContextType
  24 );
  25
  26 static
  27 NTSTATUS
  28 SetupContextHeader(
  29     _In_ PFLT_FILTER Filter,
  30     _In_ PCFLT_CONTEXT_REGISTRATION ContextPtr,
  31     _Out_ PALLOCATE_CONTEXT_HEADER ContextHeader
  32 );
  33
  34 /* EXPORTED FUNCTIONS ******************************************************/
  35
  36
  37
  38
  39 /* INTERNAL FUNCTIONS ******************************************************/
  40
  41
  42 NTSTATUS
  43 FltpRegisterContexts(_In_ PFLT_FILTER Filter,
  44                      _In_ const FLT_CONTEXT_REGISTRATION *Context)
  45 {
  46     PCFLT_CONTEXT_REGISTRATION ContextPtr;
  47     PALLOCATE_CONTEXT_HEADER ContextHeader, Prev;
  48     PVOID Buffer;
  49     ULONG BufferSize = 0;
  50     USHORT i;
  51     NTSTATUS Status;
  52
  53     /* Loop through all entries in the context registration array */
  54     ContextPtr = Context;
  55     while (ContextPtr)
  56     {
  57         /* Bail if we found the terminator */
  58         if (ContextPtr->ContextType == FLT_CONTEXT_END)
  59             break;
  60
  61         /* Make sure we have a valid context  */
  62         if (IsContextTypeValid(ContextPtr->ContextType))
  63         {
  64             /* Each context is backed by a crtl struct. Reserve space for it */
  65             BufferSize += sizeof(STREAM_LIST_CTRL);
  66         }
  67
  68         /* Move to the next entry */
  69         ContextPtr++;
  70     }
  71
  72     /* Bail if we found no valid registration requests */
  73     if (BufferSize == 0)
  74     {
  75         return STATUS_SUCCESS;
  76     }
  77
  78     /* Allocate the pool that'll hold the context crtl structs */
  79     Buffer = ExAllocatePoolWithTag(NonPagedPool, BufferSize, FM_TAG_CONTEXT_REGISTA);
  80     if (!Buffer) return STATUS_INSUFFICIENT_RESOURCES;
  81
  82     RtlZeroMemory(Buffer, BufferSize);
  83
  84     /* Setup our loop data */
  85     ContextHeader = Buffer;
  86     Prev = NULL;
  87     Status = STATUS_SUCCESS;
  88
  89     for (i = 0; i < MAX_CONTEXT_TYPES; i++)
  90     {
  91         ContextPtr = (PFLT_CONTEXT_REGISTRATION)Context;
  92         while (ContextPtr)
  93         {
  94             /* We don't support variable sized contents yet */
  95             FLT_ASSERT(ContextPtr->Size != FLT_VARIABLE_SIZED_CONTEXTS);
  96
  97             /* Bail if we found the terminator */
  98             if (ContextPtr->ContextType == FLT_CONTEXT_END)
  99                 break;
 100
 101             /* Size and pooltag are only checked when ContextAllocateCallback is null */
 102             if (ContextPtr->ContextAllocateCallback == FALSE && ContextPtr->PoolTag == FALSE)
 103             {
 104                 Status = STATUS_FLT_INVALID_CONTEXT_REGISTRATION;
 105                 goto Quit;
 106             }
 107
 108             /* Make sure we have a valid context  */
 109             if (IsContextTypeValid(ContextPtr->ContextType))
 110             {
 111                 Status = SetupContextHeader(Filter, ContextPtr, ContextHeader);
 112                 if (NT_SUCCESS(Status))
 113                 {
 114                     if (Prev)
 115                     {
 116                         Prev->Next = ContextHeader;
 117                     }
 118
 119                     Filter->SupportedContexts[i] = ContextHeader;
 120                 }
 121             }
 122
 123             Prev = ContextHeader;
 124
 125             /* Move to the next entry */
 126             ContextPtr++;
 127         }
 128     }
 129
 130 Quit:
 131     if (NT_SUCCESS(Status))
 132     {
 133         Filter->SupportedContextsListHead = Buffer;
 134     }
 135     else
 136     {
 137         ExFreePoolWithTag(Buffer, FM_TAG_CONTEXT_REGISTA);
 138         //FIXME: Cleanup anything that SetupContextHeader may have allocated
 139     }
 140
 141     return Status;
 142 }
 143
 144
 145 /* PRIVATE FUNCTIONS ******************************************************/
 146
 147 static
 148 BOOLEAN
 149 IsContextTypeValid(_In_ FLT_CONTEXT_TYPE ContextType)
 150 {
 151     switch (ContextType)
 152     {
 153     case FLT_VOLUME_CONTEXT:
 154     case FLT_INSTANCE_CONTEXT:
 155     case FLT_FILE_CONTEXT:
 156     case FLT_STREAM_CONTEXT:
 157     case FLT_STREAMHANDLE_CONTEXT:
 158     case FLT_TRANSACTION_CONTEXT:
 159         return TRUE;
 160     }
 161
 162     return FALSE;
 163 }
 164
 165 static
 166 NTSTATUS
 167 SetupContextHeader(_In_ PFLT_FILTER Filter,
 168                    _In_ PCFLT_CONTEXT_REGISTRATION ContextPtr,
 169                    _Out_ PALLOCATE_CONTEXT_HEADER ContextHeader)
 170 {
 171     return 0;
 172 }