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 /**
  18   Trim the leading and trailing spaces for a give Unicode string.
  19
  20   @param[in]  String              The Unicode string to trim.
  21
  22   @return  A pointer to the trimmed string.
  23
  24 **/
  25 CHAR16 *
  26 TrimString (
  27   IN CHAR16    *String
  28   )
  29 {
  30   CHAR16       *TempString;
  31
  32   for ( ; *String != L'\0' && *String == L' '; String++) {
  33     ;
  34   }
  35
  36   TempString = String + StrLen (String) - 1;
  37   while ((TempString >= String) && (*TempString == L' ')) {
  38     TempString--;
  39   }
  40
  41   *(TempString + 1) = L'\0';
  42
  43   return String;
  44 }
  45
  46 /**
  47   Replace the content of a Unicode string with the content of another Unicode
  48   string.
  49
  50   @param[in]  Destination         A pointer to a Unicode string.
  51   @param[in]  Source              A pointer to a Unicode string.
  52
  53 **/
  54 VOID
  55 ReplaceLeft (
  56   IN CHAR16         *Destination,
  57   IN CONST CHAR16   *Source
  58   )
  59 {
  60   CONST CHAR16      *EndString;
  61
  62   EndString = Source + StrLen (Source);
  63   while (Source <= EndString) {
  64     *Destination++ = *Source++;
  65   }
  66 }
  67
  68 /**
  69   Remove one or more consecutive backslashes starting from the second character
  70   of a given Unicode string.
  71
  72   @param[in]  String              A pointer to a Unicode string.
  73
  74   @return  A pointer to the modified string.
  75
  76 **/
  77 CHAR16 *
  78 ExcludeTrailingBackslashes (
  79   IN CHAR16                    *String
  80   )
  81 {
  82   CHAR16                       *TempString;
  83
  84   switch (*(String + 1)) {
  85   case L'\\':
  86     break;
  87   case L'\0':
  88   default:
  89     String++;
  90     goto Exit;
  91   }
  92
  93   TempString = String;
  94   while (*TempString != L'\0' && *TempString == L'\\') {
  95     TempString++;
  96   }
  97
  98   if (TempString - 1 > String) {
  99     ReplaceLeft (String + 1, TempString);
 100   }
 101
 102   String++;
 103
 104 Exit:
 105   return String;
 106 }
 107
 108 /**
 109   Mangle a filename by cutting off trailing whitespaces, "\\", "." and "..".
 110
 111   @param[in] FileName Filename.
 112
 113   @retval The mangled Filename.
 114
 115 **/
 116 CHAR16 *
 117 MangleFileName (
 118   IN CHAR16        *FileName
 119   )
 120 {
 121   CHAR16           *FileNameSavedPointer;
 122   CHAR16           *TempFileName;
 123   UINTN            BackslashesNo;
 124
 125   if (FileName == NULL || *FileName == L'\0') {
 126     FileName = NULL;
 127     goto Exit;
 128   }
 129
 130   FileName = TrimString (FileName);
 131   if (*FileName == L'\0') {
 132     goto Exit;
 133   }
 134
 135   if ((StrLen (FileName) > 1) && (FileName[StrLen (FileName) - 1] == L'\\')) {
 136     FileName[StrLen (FileName) - 1] = L'\0';
 137   }
 138
 139   FileNameSavedPointer = FileName;
 140
 141   if (FileName[0] == L'.') {
 142     if (FileName[1] == L'.') {
 143       if (FileName[2] == L'\0') {
 144         goto Exit;
 145       } else {
 146         FileName += 2;
 147       }
 148     } else if (FileName[1] == L'\0') {
 149       goto Exit;
 150     }
 151   }
 152
 153   while (*FileName != L'\0') {
 154     if (*FileName == L'\\') {
 155       FileName = ExcludeTrailingBackslashes (FileName);
 156     } else if (*FileName == L'.') {
 157       switch (*(FileName + 1)) {
 158       case L'\0':
 159         *FileName = L'\0';
 160         break;
 161       case L'\\':
 162         TempFileName = FileName + 1;
 163         TempFileName = ExcludeTrailingBackslashes (TempFileName);
 164         ReplaceLeft (FileName, TempFileName);
 165         break;
 166       case '.':
 167         if ((*(FileName - 1) != L'\\') && ((*(FileName + 2) != L'\\') ||
 168                                            (*(FileName + 2) != L'\0'))) {
 169           FileName++;
 170           continue;
 171         }
 172
 173         BackslashesNo = 0;
 174         TempFileName = FileName - 1;
 175         while (TempFileName >= FileNameSavedPointer) {
 176           if (*TempFileName == L'\\') {
 177             if (++BackslashesNo == 2) {
 178               break;
 179             }
 180           }
 181
 182           TempFileName--;
 183         }
 184
 185         TempFileName++;
 186
 187         if ((*TempFileName == L'.') && (*(TempFileName + 1) == L'.')) {
 188           FileName += 2;
 189         } else {
 190           if (*(FileName + 2) != L'\0') {
 191             ReplaceLeft (TempFileName, FileName + 3);
 192             if (*(TempFileName - 1) == L'\\') {
 193               FileName = TempFileName;
 194               ExcludeTrailingBackslashes (TempFileName - 1);
 195               TempFileName = FileName;
 196             }
 197           } else {
 198             *TempFileName = L'\0';
 199           }
 200
 201           FileName = TempFileName;
 202         }
 203
 204         break;
 205       default:
 206         FileName++;
 207       }
 208     } else {
 209       FileName++;
 210     }
 211   }
 212
 213   FileName = FileNameSavedPointer;
 214   if ((StrLen (FileName) > 1) && (FileName [StrLen (FileName) - 1] == L'\\')) {
 215     FileName [StrLen (FileName) - 1] = L'\0';
 216   }
 217
 218 Exit:
 219   return FileName;
 220 }