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   This program and the accompanying materials
   7   are licensed and made available under the terms and conditions of the BSD License
   8   which accompanies this 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,
  12   WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
  13 **/
  14 #include  <Library/BaseMemoryLib.h>
  15 #include  <Library/BaseLib.h>
  16
  17 /**
  18   Removes the last directory or file entry in a path. For a path which is
  19   like L"fs0:startup.nsh", it's converted to L"fs0:".
  20
  21   @param[in,out] Path     A pointer to the path to modify.
  22
  23   @retval FALSE     Nothing was found to remove.
  24   @retval TRUE      A directory or file was removed.
  25 **/
  26 BOOLEAN
  27 EFIAPI
  28 PathRemoveLastItem(
  29   IN OUT CHAR16 *Path
  30   )
  31 {
  32   CHAR16        *Walker;
  33   CHAR16        *LastSlash;
  34   //
  35   // get directory name from path... ('chop' off extra)
  36   //
  37   for ( Walker = Path, LastSlash = NULL
  38       ; Walker != NULL && *Walker != CHAR_NULL
  39       ; Walker++
  40      ){
  41     if (*Walker == L'\\' && *(Walker + 1) != CHAR_NULL) {
  42       LastSlash = Walker+1;
  43     } else if (*Walker == L':' && *(Walker + 1) != L'\\' && *(Walker + 1) != CHAR_NULL) {
  44       LastSlash = Walker+1;
  45     }
  46   }
  47   if (LastSlash != NULL) {
  48     *LastSlash = CHAR_NULL;
  49     return (TRUE);
  50   }
  51   return (FALSE);
  52 }
  53
  54 /**
  55   Function to clean up paths.
  56
  57   - Single periods in the path are removed.
  58   - Double periods in the path are removed along with a single parent directory.
  59   - Forward slashes L'/' are converted to backward slashes L'\'.
  60
  61   This will be done inline and the existing buffer may be larger than required
  62   upon completion.
  63
  64   @param[in] Path       The pointer to the string containing the path.
  65
  66   @return       Returns Path, otherwise returns NULL to indicate that an error has occured.
  67 **/
  68 CHAR16*
  69 EFIAPI
  70 PathCleanUpDirectories(
  71   IN CHAR16 *Path
  72 )
  73 {
  74   CHAR16  *TempString;
  75
  76   if (Path == NULL) {
  77     return NULL;
  78   }
  79
  80   //
  81   // Replace the '/' with '\'
  82   //
  83   for (TempString = Path; *TempString != CHAR_NULL; TempString++) {
  84     if (*TempString == L'/') {
  85       *TempString = L'\\';
  86     }
  87   }
  88
  89   //
  90   // Remove all the "\.". E.g.: fs0:\abc\.\def\.
  91   //
  92   while ((TempString = StrStr (Path, L"\\.\\")) != NULL) {
  93     CopyMem (TempString, TempString + 2, StrSize (TempString + 2));
  94   }
  95   if ((StrLen (Path) >= 2) && (StrCmp (Path + StrLen (Path) - 2, L"\\.") == 0)) {
  96     Path[StrLen (Path) - 1] = CHAR_NULL;
  97   }
  98
  99   //
 100   // Remove all the "\..". E.g.: fs0:\abc\..\def\..
 101   //
 102   while (((TempString = StrStr(Path, L"\\..")) != NULL) &&
 103          ((*(TempString + 3) == L'\\') || (*(TempString + 3) == CHAR_NULL))
 104         ) {
 105     *(TempString + 1) = CHAR_NULL;
 106     PathRemoveLastItem(Path);
 107     if (*(TempString + 3) != CHAR_NULL) {
 108       CopyMem (Path + StrLen (Path), TempString + 4, StrSize (TempString + 4));
 109     }
 110   }
 111
 112   //
 113   // Replace the "\\" with "\"
 114   //
 115   while ((TempString = StrStr (Path, L"\\\\")) != NULL) {
 116     CopyMem (TempString, TempString + 1, StrSize (TempString + 1));
 117   }
 118
 119   return Path;
 120 }
 121