src/inc/clr/fs/path.h

   1 //
   2 // Copyright (c) Microsoft. All rights reserved.
   3 // Licensed under the MIT license. See LICENSE file in the project root for full license information.
   4 //
   5 //
   6
   7 //
   8 // This header provides general path-related file system services.
   9
  10 #ifndef _clr_fs_Path_h_
  11 #define _clr_fs_Path_h_
  12
  13 #include "clrtypes.h"
  14 #include "cor.h" // SELECTANY
  15
  16 #include "strsafe.h"
  17
  18 #include "clr/str.h"
  19
  20 #ifndef LONG_FORMAT_PATH_PREFIX
  21     #define LONG_FORMAT_PATH_PREFIX W("\\\\?\\")
  22 #endif
  23
  24 namespace clr
  25 {
  26     namespace fs
  27     {
  28         // This list taken from ndp/clr/src/bcl/system/io/path.cs
  29         SELECTANY WCHAR const g_rgInvalidPathChars[] =
  30             { W('"'), W('<'), W('>'), W('|'), W('\0'), (WCHAR)1, (WCHAR)2, (WCHAR)3, (WCHAR)4, (WCHAR)5, (WCHAR)6,
  31               (WCHAR)7, (WCHAR)8, (WCHAR)9, (WCHAR)10, (WCHAR)11, (WCHAR)12, (WCHAR)13, (WCHAR)14,
  32               (WCHAR)15, (WCHAR)16, (WCHAR)17, (WCHAR)18, (WCHAR)19, (WCHAR)20, (WCHAR)21, (WCHAR)22,
  33               (WCHAR)23, (WCHAR)24, (WCHAR)25, (WCHAR)26, (WCHAR)27, (WCHAR)28, (WCHAR)29, (WCHAR)30,
  34               (WCHAR)31 };
  35
  36         class Path
  37         {
  38         public:
  39             //-----------------------------------------------------------------------------------------
  40             static inline bool
  41             Exists(
  42                 LPCWSTR wzPath)
  43             {
  44                 DWORD attrs = WszGetFileAttributes(wzPath);
  45                 return (attrs != INVALID_FILE_ATTRIBUTES);
  46             }
  47
  48             //-----------------------------------------------------------------------------------------
  49             // Returns true if wzPath represents a long format path (i.e., prefixed with '\\?\').
  50             static inline bool
  51             HasLongFormatPrefix(LPCWSTR wzPath)
  52             {
  53                 _ASSERTE(!clr::str::IsNullOrEmpty(wzPath)); // Must check this first.
  54                 return wcscmp(wzPath, LONG_FORMAT_PATH_PREFIX) == 0;
  55             }
  56
  57             //-----------------------------------------------------------------------------------------
  58             static inline bool
  59             HasUncPrefix(LPCWSTR wzPath)
  60             {
  61                 _ASSERTE(!clr::str::IsNullOrEmpty(wzPath)); // Must check this first.
  62                 return wzPath[0] != W('\0') && wzPath[0] == W('\\')
  63                     && wzPath[1] != W('\0') && wzPath[1] == W('\\')
  64                     && wzPath[2] != W('\0') && wzPath[2] != W('?');
  65             }
  66
  67             //-----------------------------------------------------------------------------------------
  68             static inline bool
  69             HasDrivePrefix(LPCWSTR wzPath)
  70             {
  71                 _ASSERTE(!clr::str::IsNullOrEmpty(wzPath)); // Must check this first.
  72                 return wzPath[0] != W('\0')
  73                     && wzPath[1] != W('\0') && wzPath[1] == W(':')
  74                     && ((wzPath[0] >= W('a') && wzPath[0] <= W('z')) ||
  75                         (wzPath[0] >= W('A') && wzPath[0] <= W('Z')));
  76             }
  77
  78             //-----------------------------------------------------------------------------------------
  79             // Returns true if wzPath represents a relative path.
  80             static inline bool
  81             IsRelative(LPCWSTR wzPath)
  82             {
  83                 _ASSERTE(!clr::str::IsNullOrEmpty(wzPath)); // Must check this first.
  84                 return !HasLongFormatPrefix(wzPath)
  85                     && !HasUncPrefix(wzPath)
  86                     && (!HasDrivePrefix(wzPath) || wzPath[2] != W('\\'));
  87             }
  88
  89             //-----------------------------------------------------------------------------------------
  90             // Combines two path parts. wzPathLeft must be a directory path and may be either absolute
  91             // or relative. wzPathRight may be a directory or file path and must be relative. The
  92             // result is placed in wzBuffer and the number of chars written is placed in pcchBuffer on
  93             // success; otherwise an error HRESULT is returned.
  94             static HRESULT
  95             Combine(LPCWSTR wzPathLeft, LPCWSTR wzPathRight, __out DWORD *pcchBuffer, __out_ecount(*pcchBuffer) LPWSTR wzBuffer)
  96             {
  97                 STATIC_CONTRACT_NOTHROW;
  98
  99                 HRESULT hr = S_OK;
 100
 101                 if (clr::str::IsNullOrEmpty(wzPathLeft) || clr::str::IsNullOrEmpty(wzPathRight) || pcchBuffer == nullptr)
 102                     return E_INVALIDARG;
 103
 104                 LPWSTR wzBuf = wzBuffer;
 105                 size_t cchBuf = *pcchBuffer;
 106
 107                 IfFailRet(StringCchCopyExW(wzBuf, cchBuf, wzPathLeft, &wzBuf, &cchBuf, STRSAFE_NULL_ON_FAILURE));
 108                 IfFailRet(StringCchCatExW(wzBuf, cchBuf, wzBuf[-1] == W('\\') ? W("") : W("\\"), &wzBuf, &cchBuf, STRSAFE_NULL_ON_FAILURE));
 109                 IfFailRet(StringCchCatExW(wzBuf, cchBuf, wzPathRight, &wzBuf, &cchBuf, STRSAFE_NULL_ON_FAILURE));
 110
 111                 return S_OK;
 112             }
 113
 114             //-----------------------------------------------------------------------------------------
 115             // Checks if the path provided is valid within the specified constraints.
 116             // ***NOTE: does not yet check for invalid path characters.
 117             static bool
 118             IsValid(LPCWSTR wzPath, DWORD cchPath, bool fAllowLongFormat)
 119             {
 120                 if (clr::str::IsNullOrEmpty(wzPath))
 121                     return false;
 122
 123                 bool fIsLongFormat = HasLongFormatPrefix(wzPath);
 124
 125                 if (fIsLongFormat && !fAllowLongFormat)
 126                     return false;
 127
 128                 if (!fIsLongFormat && cchPath > _MAX_PATH)
 129                     return false;
 130
 131                 return true;
 132             }
 133         };
 134     }
 135 }
 136
 137 #endif // _clr_fs_Path_h_