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   SPDX-License-Identifier: BSD-2-Clause-Patent
   7 **/
   8
   9 #include "Udf.h"
  10
  11 /**
  12   Trim the leading and trailing spaces for a give Unicode string.
  13
  14   @param[in]  String              The Unicode string to trim.
  15
  16   @return  A pointer to the trimmed string.
  17
  18 **/
  19 CHAR16 *
  20 TrimString (
  21   IN CHAR16  *String
  22   )
  23 {
  24   CHAR16  *TempString;
  25
  26   for ( ; *String != L'\0' && *String == L' '; String++) {
  27   }
  28
  29   TempString = String + StrLen (String) - 1;
  30   while ((TempString >= String) && (*TempString == L' ')) {
  31     TempString--;
  32   }
  33
  34   *(TempString + 1) = L'\0';
  35
  36   return String;
  37 }
  38
  39 /**
  40   Replace the content of a Unicode string with the content of another Unicode
  41   string.
  42
  43   @param[in]  Destination         A pointer to a Unicode string.
  44   @param[in]  Source              A pointer to a Unicode string.
  45
  46 **/
  47 VOID
  48 ReplaceLeft (
  49   IN CHAR16        *Destination,
  50   IN CONST CHAR16  *Source
  51   )
  52 {
  53   CONST CHAR16  *EndString;
  54
  55   EndString = Source + StrLen (Source);
  56   while (Source <= EndString) {
  57     *Destination++ = *Source++;
  58   }
  59 }
  60
  61 /**
  62   Remove one or more consecutive backslashes starting from the second character
  63   of a given Unicode string.
  64
  65   @param[in]  String              A pointer to a Unicode string.
  66
  67   @return  A pointer to the modified string.
  68
  69 **/
  70 CHAR16 *
  71 ExcludeTrailingBackslashes (
  72   IN CHAR16  *String
  73   )
  74 {
  75   CHAR16  *TempString;
  76
  77   switch (*(String + 1)) {
  78     case L'\\':
  79       break;
  80     case L'\0':
  81     default:
  82       String++;
  83       goto Exit;
  84   }
  85
  86   TempString = String;
  87   while (*TempString != L'\0' && *TempString == L'\\') {
  88     TempString++;
  89   }
  90
  91   if (TempString - 1 > String) {
  92     ReplaceLeft (String + 1, TempString);
  93   }
  94
  95   String++;
  96
  97 Exit:
  98   return String;
  99 }
 100
 101 /**
 102   Mangle a filename by cutting off trailing whitespaces, "\\", "." and "..".
 103
 104   @param[in] FileName Filename.
 105
 106   @retval The mangled Filename.
 107
 108 **/
 109 CHAR16 *
 110 MangleFileName (
 111   IN CHAR16  *FileName
 112   )
 113 {
 114   CHAR16  *FileNameSavedPointer;
 115   CHAR16  *TempFileName;
 116   UINTN   BackslashesNo;
 117
 118   if ((FileName == NULL) || (*FileName == L'\0')) {
 119     FileName = NULL;
 120     goto Exit;
 121   }
 122
 123   FileName = TrimString (FileName);
 124   if (*FileName == L'\0') {
 125     goto Exit;
 126   }
 127
 128   if ((StrLen (FileName) > 1) && (FileName[StrLen (FileName) - 1] == L'\\')) {
 129     FileName[StrLen (FileName) - 1] = L'\0';
 130   }
 131
 132   FileNameSavedPointer = FileName;
 133
 134   if (FileName[0] == L'.') {
 135     if (FileName[1] == L'.') {
 136       if (FileName[2] == L'\0') {
 137         goto Exit;
 138       } else {
 139         FileName += 2;
 140       }
 141     } else if (FileName[1] == L'\0') {
 142       goto Exit;
 143     }
 144   }
 145
 146   while (*FileName != L'\0') {
 147     if (*FileName == L'\\') {
 148       FileName = ExcludeTrailingBackslashes (FileName);
 149     } else if (*FileName == L'.') {
 150       switch (*(FileName + 1)) {
 151         case L'\0':
 152           *FileName = L'\0';
 153           break;
 154         case L'\\':
 155           TempFileName = FileName + 1;
 156           TempFileName = ExcludeTrailingBackslashes (TempFileName);
 157           ReplaceLeft (FileName, TempFileName);
 158           break;
 159         case '.':
 160           if ((*(FileName - 1) != L'\\') && ((*(FileName + 2) != L'\\') ||
 161                                              (*(FileName + 2) != L'\0')))
 162           {
 163             FileName++;
 164             continue;
 165           }
 166
 167           BackslashesNo = 0;
 168           TempFileName  = FileName - 1;
 169           while (TempFileName >= FileNameSavedPointer) {
 170             if (*TempFileName == L'\\') {
 171               if (++BackslashesNo == 2) {
 172                 break;
 173               }
 174             }
 175
 176             TempFileName--;
 177           }
 178
 179           TempFileName++;
 180
 181           if ((*TempFileName == L'.') && (*(TempFileName + 1) == L'.')) {
 182             FileName += 2;
 183           } else {
 184             if (*(FileName + 2) != L'\0') {
 185               ReplaceLeft (TempFileName, FileName + 3);
 186               if (*(TempFileName - 1) == L'\\') {
 187                 FileName = TempFileName;
 188                 ExcludeTrailingBackslashes (TempFileName - 1);
 189                 TempFileName = FileName;
 190               }
 191             } else {
 192               *TempFileName = L'\0';
 193             }
 194
 195             FileName = TempFileName;
 196           }
 197
 198           break;
 199         default:
 200           FileName++;
 201       }
 202     } else {
 203       FileName++;
 204     }
 205   }
 206
 207   FileName = FileNameSavedPointer;
 208   if ((StrLen (FileName) > 1) && (FileName[StrLen (FileName) - 1] == L'\\')) {
 209     FileName[StrLen (FileName) - 1] = L'\0';
 210   }
 211
 212 Exit:
 213   return FileName;
 214 }