reactos/sdk/lib/drivers/copysup/copysup.c

   1 /*
   2  *  ReactOS kernel
   3  *  Copyright (C) 2017 ReactOS Team
   4  *
   5  *  This program is free software; you can redistribute it and/or modify
   6  *  it under the terms of the GNU General Public License as published by
   7  *  the Free Software Foundation; either version 2 of the License, or
   8  *  (at your option) any later version.
   9  *
  10  *  This program is distributed in the hope that it will be useful,
  11  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  *  GNU General Public License for more details.
  14  *
  15  *  You should have received a copy of the GNU General Public License along
  16  *  with this program; if not, write to the Free Software Foundation, Inc.,
  17  *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  18  */
  19 /*
  20  * COPYRIGHT:        See COPYING in the top level directory
  21  * PROJECT:          ReactOS kernel
  22  * FILE:             sdk/lib/drivers/copysup/copysup.c
  23  * PURPOSE:          CopySup library
  24  * PROGRAMMER:       Pierre Schweitzer (pierre@reactos.org)
  25  */
  26
  27 /* INCLUDES *****************************************************************/
  28
  29 #include "copysup.h"
  30 #include <pseh/pseh2.h>
  31
  32 /* FUNCTIONS ****************************************************************/
  33
  34 /*
  35  * @implemented
  36  */
  37 BOOLEAN
  38 FsRtlCopyRead2(
  39     IN PFILE_OBJECT FileObject,
  40     IN PLARGE_INTEGER FileOffset,
  41     IN ULONG Length,
  42     IN BOOLEAN Wait,
  43     IN ULONG LockKey,
  44     OUT PVOID Buffer,
  45     OUT PIO_STATUS_BLOCK IoStatus,
  46     IN PDEVICE_OBJECT DeviceObject,
  47     IN PVOID TopLevelContext)
  48 {
  49     BOOLEAN Ret;
  50     ULONG PageCount;
  51     LARGE_INTEGER FinalOffset;
  52     PFSRTL_COMMON_FCB_HEADER Fcb;
  53     PFAST_IO_DISPATCH FastIoDispatch;
  54     PDEVICE_OBJECT RelatedDeviceObject;
  55
  56     PAGED_CODE();
  57
  58     Ret = TRUE;
  59     PageCount = ADDRESS_AND_SIZE_TO_SPAN_PAGES(FileOffset, Length);
  60
  61     /* Null-length read is always OK */
  62     if (Length == 0)
  63     {
  64         IoStatus->Information = 0;
  65         IoStatus->Status = STATUS_SUCCESS;
  66
  67         return TRUE;
  68     }
  69
  70     /* Check we don't overflow */
  71     FinalOffset.QuadPart = FileOffset->QuadPart + Length;
  72     if (FinalOffset.QuadPart <= 0)
  73     {
  74         return FALSE;
  75     }
  76
  77     /* Get the FCB (at least, its header) */
  78     Fcb = FileObject->FsContext;
  79
  80     FsRtlEnterFileSystem();
  81
  82     /* Acquire its resource (shared) */
  83     if (Wait)
  84     {
  85         ExAcquireResourceSharedLite(Fcb->Resource, TRUE);
  86     }
  87     else
  88     {
  89         if (!ExAcquireResourceSharedLite(Fcb->Resource, FALSE))
  90         {
  91             Ret = FALSE;
  92             goto CriticalSection;
  93         }
  94     }
  95
  96     /* If cache wasn't initialized, or FastIO isn't possible, fail */
  97     if (FileObject->PrivateCacheMap == NULL || Fcb->IsFastIoPossible == FastIoIsNotPossible)
  98     {
  99             Ret = FALSE;
 100             goto Resource;
 101     }
 102
 103     /* If FastIO is questionable, then, question! */
 104     if (Fcb->IsFastIoPossible == FastIoIsQuestionable)
 105     {
 106         RelatedDeviceObject = IoGetRelatedDeviceObject(FileObject);
 107         FastIoDispatch = RelatedDeviceObject->DriverObject->FastIoDispatch;
 108         ASSERT(FastIoDispatch != NULL);
 109         ASSERT(FastIoDispatch->FastIoCheckIfPossible != NULL);
 110
 111         /* If it's not possible, then fail */
 112         if (!FastIoDispatch->FastIoCheckIfPossible(FileObject, FileOffset, Length,
 113                                                    Wait, LockKey, TRUE, IoStatus, RelatedDeviceObject))
 114         {
 115             Ret = FALSE;
 116             goto Resource;
 117         }
 118     }
 119
 120     /* If we get beyond file end... */
 121     if (FinalOffset.QuadPart > Fcb->FileSize.QuadPart)
 122     {
 123         /* Fail if the offset was already beyond file end */
 124         if (FileOffset->QuadPart >= Fcb->FileSize.QuadPart)
 125         {
 126             IoStatus->Information = 0;
 127             IoStatus->Status = STATUS_END_OF_FILE;
 128             goto Resource;
 129         }
 130
 131         /* Otherwise, just fix read length */
 132         Length = (ULONG)(Fcb->FileSize.QuadPart - FileOffset->QuadPart);
 133     }
 134
 135     /* Set caller provided context as TLI */
 136     IoSetTopLevelIrp(TopLevelContext);
 137
 138     _SEH2_TRY
 139     {
 140         /* If we cannot wait, or if file is bigger than 4GB */
 141         if (!Wait || (FinalOffset.HighPart | Fcb->FileSize.HighPart) != 0)
 142         {
 143             /* Forward to Cc */
 144             Ret = CcCopyRead(FileObject, FileOffset, Length, Wait, Buffer, IoStatus);
 145             SetFlag(FileObject->Flags, FO_FILE_FAST_IO_READ);
 146
 147             /* Validate output */
 148             ASSERT(!Ret || (IoStatus->Status == STATUS_END_OF_FILE) || (((ULONGLONG)FileOffset->QuadPart + IoStatus->Information) <= (ULONGLONG)Fcb->FileSize.QuadPart));
 149         }
 150         else
 151         {
 152             /* Forward to Cc */
 153             CcFastCopyRead(FileObject, FileOffset->LowPart, Length, PageCount, Buffer, IoStatus);
 154             SetFlag(FileObject->Flags, FO_FILE_FAST_IO_READ);
 155
 156             /* Validate output */
 157             ASSERT((IoStatus->Status == STATUS_END_OF_FILE) || ((FileOffset->LowPart + IoStatus->Information) <= Fcb->FileSize.LowPart));
 158         }
 159
 160         /* If read was successful, update the byte offset in the FO */
 161         if (Ret)
 162         {
 163             FileObject->CurrentByteOffset.QuadPart = FileOffset->QuadPart + IoStatus->Information;
 164         }
 165     }
 166     _SEH2_EXCEPT(FsRtlIsNtstatusExpected(_SEH2_GetExceptionCode()) ?
 167                  EXCEPTION_EXECUTE_HANDLER : EXCEPTION_CONTINUE_SEARCH)
 168     {
 169         Ret = FALSE;
 170     }
 171     _SEH2_END;
 172
 173     /* Reset TLI */
 174     IoSetTopLevelIrp(NULL);
 175
 176 Resource:
 177     ExReleaseResourceLite(Fcb->Resource);
 178 CriticalSection:
 179     FsRtlExitFileSystem();
 180
 181     return Ret;
 182 }