This Change Adds initial Support for LongFiles in the VM,

They are:
1. Wrappers for OS APIs which  take or return PATHS

2. Fixing the usage of following Api's:

GetEnvironmentVariableW
SearchPathW
GetShortPathNameW
GetLongPathNameW
GetModuleFileName

Work remaining:
Remove fixed size buffers in the VM

src/classlibnative/bcltype/system.cpp

@@ -218,34 +218,19 @@ FCIMPL1(Object*, SystemNative::_GetEnvironmentVariable, StringObject* strVarUNSA
 
     HELPER_METHOD_FRAME_BEGIN_RET_2(refRetVal, strVar);
 
-    // We loop round getting the length of the env var and then trying to copy
-    // the value into a managed string. Usually we'll go through this loop
-    // precisely once, but the caution is ncessary in case the variable mutates
-    // beneath us.
-    int len, newLen;
+    int len;
 
     // Get the length of the environment variable.
-    WCHAR dummy;    // prefix complains if pass a null ptr in, so rely on the final length parm instead
-    len = WszGetEnvironmentVariable(strVar->GetBuffer(), &dummy, 0);
+    PathString envPath;    // prefix complains if pass a null ptr in, so rely on the final length parm instead
+    len = WszGetEnvironmentVariable(strVar->GetBuffer(), envPath);
 
-    while (len != 0)
+    if (len != 0)
     {
         // Allocate the string.
         refRetVal = StringObject::NewString(len);
-
-        // Get the value.
-        newLen = WszGetEnvironmentVariable(strVar->GetBuffer(), refRetVal->GetBuffer(), len);
-        if (newLen != (len - 1))
-        {
-            // The envvar changed, need to do this again. Let GC collect the
-            // string we just allocated.
-            refRetVal = NULL;
-
-            // Go back and try again.
-            len = newLen;
-        }
-        else
-            break;
+
+        wcscpy_s(refRetVal->GetBuffer(), len + 1, envPath);
+
     }
 
     HELPER_METHOD_FRAME_END();
@@ -297,15 +282,15 @@ FCIMPL0(StringObject*, SystemNative::_GetModuleFileName)
     }
     else
     {
-        SString wszFilePathString;
+        PathString wszFilePathString;
 
-        WCHAR * wszFile = wszFilePathString.OpenUnicodeBuffer(MAX_LONGPATH);
-        DWORD lgth = WszGetModuleFileName(NULL, wszFile, MAX_LONGPATH);
+
+        DWORD lgth = WszGetModuleFileName(NULL, wszFilePathString);
         if (!lgth)
         {
             COMPlusThrowWin32();
         }
-        wszFilePathString.CloseBuffer(lgth);
+
 
         refRetVal = StringObject::NewString(wszFilePathString.GetUnicode());
     }

src/debug/di/cordb.cpp

@@ -201,11 +201,11 @@ BOOL WINAPI DbgDllMain(HINSTANCE hInstance, DWORD dwReason, LPVOID lpReserved)
 
 #if defined(LOGGING)
             {
-                WCHAR   rcFile[_MAX_PATH];
-                WszGetModuleFileName(hInstance, rcFile, NumItems(rcFile));
+                PathString rcFile;
+                WszGetModuleFileName(hInstance, rcFile);
                 LOG((LF_CORDB, LL_INFO10000,
                     "DI::DbgDllMain: load right side support from file '%s'\n",
-                     rcFile));
+                     rcFile.GetUnicode()));
             }
 #endif
 

src/debug/di/module.cpp

@@ -2568,8 +2568,9 @@ HRESULT CordbModule::CreateReaderForInMemorySymbols(REFIID riid, void** ppObj)
 #ifndef FEATURE_PAL
             // PDB format - use diasymreader.dll with COM activation
             InlineSString<_MAX_PATH> ssBuf;
+            IfFailThrow(GetHModuleDirectory(GetModuleInst(), ssBuf));
             IfFailThrow(FakeCoCreateInstanceEx(CLSID_CorSymBinder_SxS,
-                                               GetHModuleDirectory(GetModuleInst(), ssBuf).GetUnicode(),
+                                               ssBuf.GetUnicode(),
                                                IID_ISymUnmanagedBinder,
                                                (void**)&pBinder,
                                                NULL));

src/debug/di/shimprocess.cpp

@@ -1823,50 +1823,41 @@ HRESULT ShimProcess::FindLoadedCLR(CORDB_ADDRESS * pClrInstanceId)
 HMODULE ShimProcess::GetDacModule()
 {
     HModuleHolder hDacDll;
-    WCHAR wszAccessDllPath[MAX_LONGPATH];
+    PathString wszAccessDllPath;
 
 #ifdef FEATURE_PAL
-    if (!PAL_GetPALDirectoryW(wszAccessDllPath, _countof(wszAccessDllPath)))
+    if (!PAL_GetPALDirectoryWrapper(wszAccessDllPath))
     {
         ThrowLastError();
     }
-    wcscat_s(wszAccessDllPath, _countof(wszAccessDllPath), MAKEDLLNAME_W(W("mscordaccore")));
+    PCWSTR eeFlavor = MAKEDLLNAME_W(W("mscordaccore"));
 #else
     //
     // Load the access DLL from the same directory as the the current CLR Debugging Services DLL.
     //
 
-    if (!WszGetModuleFileName(GetModuleInst(), wszAccessDllPath, NumItems(wszAccessDllPath)))
+    if (!WszGetModuleFileName(GetModuleInst(), wszAccessDllPath))
     {
         ThrowLastError();
     }
 
-    PWSTR pPathTail = wcsrchr(wszAccessDllPath, DIRECTORY_SEPARATOR_CHAR_W);
-    if (!pPathTail)
+	if (!SUCCEEDED(CopySystemDirectory(wszAccessDllPath, wszAccessDllPath)))
     {
         ThrowHR(E_INVALIDARG);
     }
-    pPathTail++;
 
     // Dac Dll is named:
     //   mscordaccore.dll  <-- coreclr
     //   mscordacwks.dll   <-- desktop
     PCWSTR eeFlavor = 
 #if defined(FEATURE_MAIN_CLR_MODULE_USES_CORE_NAME)
-        W("core");    
+        W("mscordaccore.dll");
 #else
-        W("wks");    
+        W("mscordacwks.dll");
 #endif
-
-    if (_snwprintf_s(pPathTail, 
-                     _countof(wszAccessDllPath) + (wszAccessDllPath - pPathTail),
-                     NumItems(wszAccessDllPath) - (pPathTail - wszAccessDllPath),
-                     MAKEDLLNAME_W(W("mscordac%s")), 
-                     eeFlavor) <= 0)
-    {
-        ThrowHR(E_INVALIDARG);
-    }
+
 #endif // FEATURE_PAL
+    wszAccessDllPath.Append(eeFlavor);
 
     hDacDll.Assign(WszLoadLibrary(wszAccessDllPath));
     if (!hDacDll)

src/debug/ee/debugger.cpp

@@ -2244,9 +2244,9 @@ HRESULT Debugger::StartupPhase2(Thread * pThread)
     if (!CORDebuggerAttached())
     {
         #define DBG_ATTACH_ON_STARTUP_ENV_VAR W("COMPlus_DbgAttachOnStartup")
-
+        PathString temp;
         // We explicitly just check the env because we don't want a switch this invasive to be global.
-        DWORD fAttach = WszGetEnvironmentVariable(DBG_ATTACH_ON_STARTUP_ENV_VAR, NULL, 0) > 0;
+        DWORD fAttach = WszGetEnvironmentVariable(DBG_ATTACH_ON_STARTUP_ENV_VAR, temp) > 0;
 
         if (fAttach)
         {
@@ -15166,8 +15166,7 @@ HRESULT Debugger::InitAppDomainIPC(void)
     } hEnsureCleanup(this);
 
     DWORD dwStrLen = 0;
-    SString szExeNamePathString;
-    WCHAR * szExeName = szExeNamePathString.OpenUnicodeBuffer(MAX_LONGPATH);
+    SString szExeName;
     int i;
 
     // all fields in the object can be zero initialized.
@@ -15216,15 +15215,14 @@ HRESULT Debugger::InitAppDomainIPC(void)
 
     // also initialize the process name
     dwStrLen = WszGetModuleFileName(NULL,
-                                    szExeName,
-                                    MAX_LONGPATH);
+                                    szExeName);
 
-    szExeNamePathString.CloseBuffer(dwStrLen);
+
     // If we couldn't get the name, then use a nice default.
     if (dwStrLen == 0)
     {
-        wcscpy_s(szExeName, COUNTOF(szExeName), W("<NoProcessName>"));
-        dwStrLen = (DWORD)wcslen(szExeName);
+        szExeName.Set(W("<NoProcessName>"));
+        dwStrLen = szExeName.GetCount();
     }
 
     // If we got the name, copy it into a buffer. dwStrLen is the

src/dlls/mscoree/delayload.cpp

@@ -376,16 +376,16 @@ FARPROC __stdcall CorDelayLoadHook(     // Always 0.
     // If we've not yet looked at our environment, then do so.
     if (!bInit)
     {
-        WCHAR       rcBreak[16];
+        PathString  rcBreak;
 
         // set DelayLoadBreak=[0|1]
-        if (WszGetEnvironmentVariable(W("DelayLoadBreak"), rcBreak, NumItems(rcBreak)))
+        if (WszGetEnvironmentVariable(W("DelayLoadBreak"), rcBreak))
         {
             // "1" means to break hard and display errors.
-            if (*rcBreak == '1')
+            if (rcBreak[0] == '1')
                 bBreak = 1;
             // "2" means no break, but display errors.
-            else if (*rcBreak == '2')
+            else if (rcBreak[0] == '2')
                 bBreak = 2;
             else
                 bBreak = false;