reactos/sdk/lib/drivers/ntoskrnl_vista/fsrtl.c

   1 /*
   2  * PROJECT:         ReactOS Kernel - Vista+ APIs
   3  * LICENSE:         GPL v2 - See COPYING in the top level directory
   4  * FILE:            lib/drivers/ntoskrnl_vista/fsrtl.c
   5  * PURPOSE:         FsRtl functions of Vista+
   6  * PROGRAMMERS:     Pierre Schweitzer <pierre@reactos.org>
   7  */
   8
   9 #include <ntdef.h>
  10 #include <ntifs.h>
  11
  12 NTKERNELAPI
  13 NTSTATUS
  14 NTAPI
  15 FsRtlRemoveDotsFromPath(IN PWSTR OriginalString,
  16                         IN USHORT PathLength,
  17                         OUT USHORT *NewLength)
  18 {
  19     USHORT Length, ReadPos, WritePos;
  20
  21     Length = PathLength / sizeof(WCHAR);
  22
  23     if (Length == 3 && OriginalString[0] == '\\' && OriginalString[1] == '.' && OriginalString[2] == '.')
  24     {
  25         return STATUS_IO_REPARSE_DATA_INVALID;
  26     }
  27
  28     if (Length == 2 && OriginalString[0] == '.' && OriginalString[1] == '.')
  29     {
  30         return STATUS_IO_REPARSE_DATA_INVALID;
  31     }
  32
  33     if (Length > 2 && OriginalString[0] == '.' && OriginalString[1] == '.' && OriginalString[2] == '\\')
  34     {
  35         return STATUS_IO_REPARSE_DATA_INVALID;
  36     }
  37
  38     for (ReadPos = 0, WritePos = 0; ReadPos < Length; ++WritePos)
  39     {
  40         for (; ReadPos > 0 && ReadPos < Length; ++ReadPos)
  41         {
  42             if (ReadPos < Length - 1 && OriginalString[ReadPos] == '\\' && OriginalString[ReadPos + 1] == '\\')
  43             {
  44                 continue;
  45             }
  46
  47             if (OriginalString[ReadPos] != '.')
  48             {
  49                 break;
  50             }
  51
  52             if (ReadPos == Length - 1)
  53             {
  54                 if (OriginalString[ReadPos - 1] == '\\')
  55                 {
  56                     if (WritePos > 1)
  57                     {
  58                         --WritePos;
  59                     }
  60
  61                     continue;
  62                 }
  63
  64                 OriginalString[WritePos] = '.';
  65                 ++WritePos;
  66                 continue;
  67             }
  68
  69             if (OriginalString[ReadPos + 1] == '\\')
  70             {
  71                 if (OriginalString[ReadPos - 1] != '\\')
  72                 {
  73                     OriginalString[WritePos] = '.';
  74                     ++WritePos;
  75                     continue;
  76                 }
  77             }
  78             else
  79             {
  80                 if (OriginalString[ReadPos + 1] != '.' || OriginalString[ReadPos - 1] != '\\' ||
  81                     ((ReadPos != Length - 2) && OriginalString[ReadPos + 2] != '\\'))
  82                 {
  83                     OriginalString[WritePos] = '.';
  84                     ++WritePos;
  85                     continue;
  86                 }
  87
  88                 for (WritePos -= 2; (SHORT)WritePos > 0 && OriginalString[WritePos] != '\\'; --WritePos);
  89
  90                 if ((SHORT)WritePos < 0 || OriginalString[WritePos] != '\\')
  91                 {
  92                     return STATUS_IO_REPARSE_DATA_INVALID;
  93                 }
  94
  95                 if (WritePos == 0 && ReadPos == Length - 2)
  96                 {
  97                     WritePos = 1;
  98                 }
  99             }
 100
 101             ++ReadPos;
 102         }
 103
 104         if (ReadPos >= Length)
 105         {
 106             break;
 107         }
 108
 109         OriginalString[WritePos] = OriginalString[ReadPos];
 110         ++ReadPos;
 111     }
 112
 113     *NewLength = WritePos * sizeof(WCHAR);
 114
 115     while (WritePos < Length)
 116     {
 117         OriginalString[WritePos++] = UNICODE_NULL;
 118     }
 119
 120     return STATUS_SUCCESS;
 121 }