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   //
  30   // get directory name from path... ('chop' off extra)
  31   //
  32   for ( Walker = Path, LastSlash = NULL
  33         ; Walker != NULL && *Walker != CHAR_NULL
  34         ; Walker++
  35         )
  36   {
  37     if ((*Walker == L'\\') && (*(Walker + 1) != CHAR_NULL)) {
  38       LastSlash = Walker+1;
  39     } else if ((*Walker == L':') && (*(Walker + 1) != L'\\') && (*(Walker + 1) != CHAR_NULL)) {
  40       LastSlash = Walker+1;
  41     }
  42   }
  43
  44   if (LastSlash != NULL) {
  45     *LastSlash = CHAR_NULL;
  46     return (TRUE);
  47   }
  48
  49   return (FALSE);
  50 }
  51
  52 /**
  53   Function to clean up paths.
  54
  55   - Single periods in the path are removed.
  56   - Double periods in the path are removed along with a single parent directory.
  57   - Forward slashes L'/' are converted to backward slashes L'\'.
  58
  59   This will be done inline and the existing buffer may be larger than required
  60   upon completion.
  61
  62   @param[in] Path       The pointer to the string containing the path.
  63
  64   @return       Returns Path, otherwise returns NULL to indicate that an error has occurred.
  65 **/
  66 CHAR16 *
  67 EFIAPI
  68 PathCleanUpDirectories (
  69   IN CHAR16  *Path
  70   )
  71 {
  72   CHAR16  *TempString;
  73
  74   if (Path == NULL) {
  75     return NULL;
  76   }
  77
  78   //
  79   // Replace the '/' with '\'
  80   //
  81   for (TempString = Path; *TempString != CHAR_NULL; TempString++) {
  82     if (*TempString == L'/') {
  83       *TempString = L'\\';
  84     }
  85   }
  86
  87   //
  88   // Replace the "\\" with "\"
  89   //
  90   while ((TempString = StrStr (Path, L"\\\\")) != NULL) {
  91     CopyMem (TempString, TempString + 1, StrSize (TempString + 1));
  92   }
  93
  94   //
  95   // Remove all the "\.". E.g.: fs0:\abc\.\def\.
  96   //
  97   while ((TempString = StrStr (Path, L"\\.\\")) != NULL) {
  98     CopyMem (TempString, TempString + 2, StrSize (TempString + 2));
  99   }
 100
 101   if ((StrLen (Path) >= 2) && (StrCmp (Path + StrLen (Path) - 2, L"\\.") == 0)) {
 102     Path[StrLen (Path) - 1] = CHAR_NULL;
 103   }
 104
 105   //
 106   // Remove all the "\..". E.g.: fs0:\abc\..\def\..
 107   //
 108   while (((TempString = StrStr (Path, L"\\..")) != NULL) &&
 109          ((*(TempString + 3) == L'\\') || (*(TempString + 3) == CHAR_NULL))
 110          )
 111   {
 112     *(TempString + 1) = CHAR_NULL;
 113     PathRemoveLastItem (Path);
 114     if (*(TempString + 3) != CHAR_NULL) {
 115       CopyMem (Path + StrLen (Path), TempString + 4, StrSize (TempString + 4));
 116     }
 117   }
 118
 119   return Path;
 120 }