MdePkg/Library/BaseLib/FilePaths.c

   1 /** @file
   2   Defines file-path manipulation functions.
   3
   4   Copyright (c) 2011 - 2016, 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 by changing the last
  18   L'\' to a CHAR_NULL. For a path which is like L"fs0:startup.nsh",
  19   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 == L':') && *(Walker + 1) != CHAR_NULL) {
  42       LastSlash = Walker+1;
  43     }
  44   }
  45   if (LastSlash != NULL) {
  46     *LastSlash = CHAR_NULL;
  47     return (TRUE);
  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 occured.
  65 **/
  66 CHAR16*
  67 EFIAPI
  68 PathCleanUpDirectories(
  69   IN CHAR16 *Path
  70   )
  71 {
  72   CHAR16  *TempString;
  73   UINTN   TempSize;
  74
  75   if (Path==NULL) {
  76     return(NULL);
  77   }
  78   //
  79   // Fix up the '/' vs '\'
  80   //
  81   for (TempString = Path ; TempString != NULL && *TempString != CHAR_NULL ; TempString++) {
  82     if (*TempString == L'/') {
  83       *TempString = L'\\';
  84     }
  85   }
  86   //
  87   // Fix up the ..
  88   //
  89   while ((TempString = StrStr(Path, L"\\..\\")) != NULL) {
  90     *TempString = CHAR_NULL;
  91     TempString  += 4;
  92     PathRemoveLastItem(Path);
  93     TempSize = StrSize(TempString);
  94     CopyMem(Path+StrLen(Path), TempString, TempSize);
  95   }
  96   if ((TempString = StrStr(Path, L"\\..")) != NULL && *(TempString + 3) == CHAR_NULL) {
  97     *TempString = CHAR_NULL;
  98     if (!PathRemoveLastItem(Path)) {
  99       *TempString = L'\\';
 100     }
 101   }
 102   //
 103   // Fix up the .
 104   //
 105   while ((TempString = StrStr(Path, L"\\.\\")) != NULL) {
 106     *TempString = CHAR_NULL;
 107     TempString  += 2;
 108     TempSize = StrSize(TempString);
 109     CopyMem(Path+StrLen(Path), TempString, TempSize);
 110   }
 111   if ((TempString = StrStr(Path, L"\\.")) != NULL && *(TempString + 2) == CHAR_NULL) {
 112     *(TempString + 1) = CHAR_NULL;
 113   }
 114
 115   while ((TempString = StrStr(Path, L"\\\\")) != NULL) {
 116     *TempString = CHAR_NULL;
 117     TempString  += 1;
 118     TempSize = StrSize(TempString);
 119     CopyMem(Path+StrLen(Path), TempString, TempSize);
 120   }
 121   if ((TempString = StrStr(Path, L"\\\\")) != NULL && *(TempString + 1) == CHAR_NULL) {
 122     *(TempString) = CHAR_NULL;
 123   }
 124
 125   return (Path);
 126 }
 127