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   This program and the accompanying materials
   6   are licensed and made available under the terms and conditions of the BSD License
   7   which accompanies this distribution.  The full text of the license may be found at
   8   http://opensource.org/licenses/bsd-license.php.
   9
  10   THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
  11   WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
  12 **/
  13 #include  <Library/BaseMemoryLib.h>
  14 #include  <Library/BaseLib.h>
  15
  16 /**
  17   Removes the last directory or file entry in a path. For a path which is
  18   like L"fs0:startup.nsh", it's converted to L"fs0:".
  19
  20   @param[in,out] Path     A pointer to the path to modify.
  21
  22   @retval FALSE     Nothing was found to remove.
  23   @retval TRUE      A directory or file was removed.
  24 **/
  25 BOOLEAN
  26 EFIAPI
  27 PathRemoveLastItem(
  28   IN OUT CHAR16 *Path
  29   )
  30 {
  31   CHAR16        *Walker;
  32   CHAR16        *LastSlash;
  33   //
  34   // get directory name from path... ('chop' off extra)
  35   //
  36   for ( Walker = Path, LastSlash = NULL
  37       ; Walker != NULL && *Walker != CHAR_NULL
  38       ; Walker++
  39      ){
  40     if (*Walker == L'\\' && *(Walker + 1) != CHAR_NULL) {
  41       LastSlash = Walker+1;
  42     } else if (*Walker == L':' && *(Walker + 1) != L'\\' && *(Walker + 1) != CHAR_NULL) {
  43       LastSlash = Walker+1;
  44     }
  45   }
  46   if (LastSlash != NULL) {
  47     *LastSlash = CHAR_NULL;
  48     return (TRUE);
  49   }
  50   return (FALSE);
  51 }
  52
  53 /**
  54   Function to clean up paths.
  55
  56   - Single periods in the path are removed.
  57   - Double periods in the path are removed along with a single parent directory.
  58   - Forward slashes L'/' are converted to backward slashes L'\'.
  59
  60   This will be done inline and the existing buffer may be larger than required
  61   upon completion.
  62
  63   @param[in] Path       The pointer to the string containing the path.
  64
  65   @return       Returns Path, otherwise returns NULL to indicate that an error has occured.
  66 **/
  67 CHAR16*
  68 EFIAPI
  69 PathCleanUpDirectories(
  70   IN CHAR16 *Path
  71 )
  72 {
  73   CHAR16  *TempString;
  74
  75   if (Path == NULL) {
  76     return NULL;
  77   }
  78
  79   //
  80   // Replace the '/' with '\'
  81   //
  82   for (TempString = Path; *TempString != CHAR_NULL; TempString++) {
  83     if (*TempString == L'/') {
  84       *TempString = L'\\';
  85     }
  86   }
  87
  88   //
  89   // Remove all the "\.". E.g.: fs0:\abc\.\def\.
  90   //
  91   while ((TempString = StrStr (Path, L"\\.\\")) != NULL) {
  92     CopyMem (TempString, TempString + 2, StrSize (TempString + 2));
  93   }
  94   if ((StrLen (Path) >= 2) && (StrCmp (Path + StrLen (Path) - 2, L"\\.") == 0)) {
  95     Path[StrLen (Path) - 1] = CHAR_NULL;
  96   }
  97
  98   //
  99   // Remove all the "\..". E.g.: fs0:\abc\..\def\..
 100   //
 101   while (((TempString = StrStr(Path, L"\\..")) != NULL) &&
 102          ((*(TempString + 3) == L'\\') || (*(TempString + 3) == CHAR_NULL))
 103         ) {
 104     *(TempString + 1) = CHAR_NULL;
 105     PathRemoveLastItem(Path);
 106     CopyMem (Path + StrLen (Path), TempString + 3, StrSize (TempString + 3));
 107   }
 108
 109   //
 110   // Replace the "\\" with "\"
 111   //
 112   while ((TempString = StrStr (Path, L"\\\\")) != NULL) {
 113     CopyMem (TempString, TempString + 1, StrSize (TempString + 1));
 114   }
 115
 116   return Path;
 117 }
 118