MdeModulePkg/Universal/Disk/UdfDxe/FileName.c

   1 /** @file
   2   Helper functions for mangling file names in UDF/ECMA-167 file systems.
   3
   4   Copyright (C) 2014-2017 Paulo Alcantara <pcacjr@zytor.com>
   5
   6   This program and the accompanying materials are licensed and made available
   7   under the terms and conditions of the BSD License which accompanies this
   8   distribution.  The full text of the license may be found at
   9   http://opensource.org/licenses/bsd-license.php
  10
  11   THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS, WITHOUT
  12   WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
  13 **/
  14
  15 #include "Udf.h"
  16
  17 CHAR16 *
  18 TrimString (
  19   IN CHAR16    *String
  20   )
  21 {
  22   CHAR16       *TempString;
  23
  24   for ( ; *String != L'\0' && *String == L' '; String++) {
  25     ;
  26   }
  27
  28   TempString = String + StrLen (String) - 1;
  29   while ((TempString >= String) && (*TempString == L' ')) {
  30     TempString--;
  31   }
  32
  33   *(TempString + 1) = L'\0';
  34
  35   return String;
  36 }
  37
  38 VOID
  39 ReplaceLeft (
  40   IN CHAR16         *Destination,
  41   IN CONST CHAR16   *Source
  42   )
  43 {
  44   CONST CHAR16      *EndString;
  45
  46   EndString = Source + StrLen (Source);
  47   while (Source <= EndString) {
  48     *Destination++ = *Source++;
  49   }
  50 }
  51
  52 CHAR16 *
  53 ExcludeTrailingBackslashes (
  54   IN CHAR16                    *String
  55   )
  56 {
  57   CHAR16                       *TempString;
  58
  59   switch (*(String + 1)) {
  60   case L'\\':
  61     break;
  62   case L'\0':
  63   default:
  64     String++;
  65     goto Exit;
  66   }
  67
  68   TempString = String;
  69   while (*TempString != L'\0' && *TempString == L'\\') {
  70     TempString++;
  71   }
  72
  73   if (TempString - 1 > String) {
  74     ReplaceLeft (String + 1, TempString);
  75   }
  76
  77   String++;
  78
  79 Exit:
  80   return String;
  81 }
  82
  83 /**
  84   Mangle a filename by cutting off trailing whitespaces, "\\", "." and "..".
  85
  86   @param[in] FileName Filename.
  87
  88   @retval @p FileName Filename mangled.
  89
  90 **/
  91 CHAR16 *
  92 MangleFileName (
  93   IN CHAR16        *FileName
  94   )
  95 {
  96   CHAR16           *FileNameSavedPointer;
  97   CHAR16           *TempFileName;
  98   UINTN            BackslashesNo;
  99
 100   if (FileName == NULL || *FileName == L'\0') {
 101     FileName = NULL;
 102     goto Exit;
 103   }
 104
 105   FileName = TrimString (FileName);
 106   if (*FileName == L'\0') {
 107     goto Exit;
 108   }
 109
 110   if ((StrLen (FileName) > 1) && (FileName[StrLen (FileName) - 1] == L'\\')) {
 111     FileName[StrLen (FileName) - 1] = L'\0';
 112   }
 113
 114   FileNameSavedPointer = FileName;
 115
 116   if (FileName[0] == L'.') {
 117     if (FileName[1] == L'.') {
 118       if (FileName[2] == L'\0') {
 119         goto Exit;
 120       } else {
 121         FileName += 2;
 122       }
 123     } else if (FileName[1] == L'\0') {
 124       goto Exit;
 125     }
 126   }
 127
 128   while (*FileName != L'\0') {
 129     if (*FileName == L'\\') {
 130       FileName = ExcludeTrailingBackslashes (FileName);
 131     } else if (*FileName == L'.') {
 132       switch (*(FileName + 1)) {
 133       case L'\0':
 134         *FileName = L'\0';
 135         break;
 136       case L'\\':
 137         TempFileName = FileName + 1;
 138         TempFileName = ExcludeTrailingBackslashes (TempFileName);
 139         ReplaceLeft (FileName, TempFileName);
 140         break;
 141       case '.':
 142         if ((*(FileName - 1) != L'\\') && ((*(FileName + 2) != L'\\') ||
 143                                            (*(FileName + 2) != L'\0'))) {
 144           FileName++;
 145           continue;
 146         }
 147
 148         BackslashesNo = 0;
 149         TempFileName = FileName - 1;
 150         while (TempFileName >= FileNameSavedPointer) {
 151           if (*TempFileName == L'\\') {
 152             if (++BackslashesNo == 2) {
 153               break;
 154             }
 155           }
 156
 157           TempFileName--;
 158         }
 159
 160         TempFileName++;
 161
 162         if ((*TempFileName == L'.') && (*(TempFileName + 1) == L'.')) {
 163           FileName += 2;
 164         } else {
 165           if (*(FileName + 2) != L'\0') {
 166             ReplaceLeft (TempFileName, FileName + 3);
 167             if (*(TempFileName - 1) == L'\\') {
 168               FileName = TempFileName;
 169               ExcludeTrailingBackslashes (TempFileName - 1);
 170               TempFileName = FileName;
 171             }
 172           } else {
 173             *TempFileName = L'\0';
 174           }
 175
 176           FileName = TempFileName;
 177         }
 178
 179         break;
 180       default:
 181         FileName++;
 182       }
 183     } else {
 184       FileName++;
 185     }
 186   }
 187
 188   FileName = FileNameSavedPointer;
 189   if ((StrLen (FileName) > 1) && (FileName [StrLen (FileName) - 1] == L'\\')) {
 190     FileName [StrLen (FileName) - 1] = L'\0';
 191   }
 192
 193 Exit:
 194   return FileName;
 195 }