MdePkg/Library/BaseLib/FilePaths.c

   1 /** @file
   2   Defines file-path manipulation functions.
   3
   4   Copyright (c) 2011 - 2017, Intel Corporation. All rights reserved.<BR>
   5   Copyright (c) 2018, Dell Technologies. All rights reserved.<BR>
   6   SPDX-License-Identifier: BSD-2-Clause-Patent
   7 **/
   8 #include  <Library/BaseMemoryLib.h>
   9 #include  <Library/BaseLib.h>
  10
  11 /**
  12   Removes the last directory or file entry in a path. For a path which is
  13   like L"fs0:startup.nsh", it's converted to L"fs0:".
  14
  15   @param[in,out] Path     A pointer to the path to modify.
  16
  17   @retval FALSE     Nothing was found to remove.
  18   @retval TRUE      A directory or file was removed.
  19 **/
  20 BOOLEAN
  21 EFIAPI
  22 PathRemoveLastItem(
  23   IN OUT CHAR16 *Path
  24   )
  25 {
  26   CHAR16        *Walker;
  27   CHAR16        *LastSlash;
  28   //
  29   // get directory name from path... ('chop' off extra)
  30   //
  31   for ( Walker = Path, LastSlash = NULL
  32       ; Walker != NULL && *Walker != CHAR_NULL
  33       ; Walker++
  34      ){
  35     if (*Walker == L'\\' && *(Walker + 1) != CHAR_NULL) {
  36       LastSlash = Walker+1;
  37     } else if (*Walker == L':' && *(Walker + 1) != L'\\' && *(Walker + 1) != CHAR_NULL) {
  38       LastSlash = Walker+1;
  39     }
  40   }
  41   if (LastSlash != NULL) {
  42     *LastSlash = CHAR_NULL;
  43     return (TRUE);
  44   }
  45   return (FALSE);
  46 }
  47
  48 /**
  49   Function to clean up paths.
  50
  51   - Single periods in the path are removed.
  52   - Double periods in the path are removed along with a single parent directory.
  53   - Forward slashes L'/' are converted to backward slashes L'\'.
  54
  55   This will be done inline and the existing buffer may be larger than required
  56   upon completion.
  57
  58   @param[in] Path       The pointer to the string containing the path.
  59
  60   @return       Returns Path, otherwise returns NULL to indicate that an error has occured.
  61 **/
  62 CHAR16*
  63 EFIAPI
  64 PathCleanUpDirectories(
  65   IN CHAR16 *Path
  66 )
  67 {
  68   CHAR16  *TempString;
  69
  70   if (Path == NULL) {
  71     return NULL;
  72   }
  73
  74   //
  75   // Replace the '/' with '\'
  76   //
  77   for (TempString = Path; *TempString != CHAR_NULL; TempString++) {
  78     if (*TempString == L'/') {
  79       *TempString = L'\\';
  80     }
  81   }
  82
  83   //
  84   // Replace the "\\" with "\"
  85   //
  86   while ((TempString = StrStr (Path, L"\\\\")) != NULL) {
  87     CopyMem (TempString, TempString + 1, StrSize (TempString + 1));
  88   }
  89
  90   //
  91   // Remove all the "\.". E.g.: fs0:\abc\.\def\.
  92   //
  93   while ((TempString = StrStr (Path, L"\\.\\")) != NULL) {
  94     CopyMem (TempString, TempString + 2, StrSize (TempString + 2));
  95   }
  96   if ((StrLen (Path) >= 2) && (StrCmp (Path + StrLen (Path) - 2, L"\\.") == 0)) {
  97     Path[StrLen (Path) - 1] = CHAR_NULL;
  98   }
  99
 100   //
 101   // Remove all the "\..". E.g.: fs0:\abc\..\def\..
 102   //
 103   while (((TempString = StrStr(Path, L"\\..")) != NULL) &&
 104          ((*(TempString + 3) == L'\\') || (*(TempString + 3) == CHAR_NULL))
 105         ) {
 106     *(TempString + 1) = CHAR_NULL;
 107     PathRemoveLastItem(Path);
 108     if (*(TempString + 3) != CHAR_NULL) {
 109       CopyMem (Path + StrLen (Path), TempString + 4, StrSize (TempString + 4));
 110     }
 111   }
 112
 113   return Path;
 114 }
 115