Fix loading native libraries from native search paths provided by the host

Fixed a couple of issues outside Windows regarding the directory separator char, path separator char, and absolute path determination.

Fixes #1680

Author: Koundinya Veluri

src/inc/clr/fs/path.h

@@ -36,6 +36,25 @@ namespace clr
         class Path
         {
         public:
+#if !PLATFORM_UNIX
+            static const CHAR DirectorySeparatorChar = '\\';
+#else // PLATFORM_UNIX
+            static const CHAR DirectorySeparatorChar = '/';
+#endif
+
+#if !PLATFORM_UNIX
+            static const CHAR PathSeparatorChar = ';';
+#else // PLATFORM_UNIX
+            static const CHAR PathSeparatorChar = ':';
+#endif // !PLATFORM_UNIX
+
+#if !PLATFORM_UNIX
+            static const CHAR VolumeSeparatorChar = ':';
+#else // PLATFORM_UNIX
+            static const CHAR VolumeSeparatorChar = '/';
+#endif // !PLATFORM_UNIX
+
+        public:
             //-----------------------------------------------------------------------------------------
             static inline bool
             Exists(
@@ -54,36 +73,41 @@ namespace clr
                 return wcscmp(wzPath, LONG_FORMAT_PATH_PREFIX) == 0;
             }
 
-            //-----------------------------------------------------------------------------------------
-            static inline bool
-            HasUncPrefix(LPCWSTR wzPath)
-            {
-                _ASSERTE(!clr::str::IsNullOrEmpty(wzPath)); // Must check this first.
-                return wzPath[0] != W('\0') && wzPath[0] == W('\\')
-                    && wzPath[1] != W('\0') && wzPath[1] == W('\\')
-                    && wzPath[2] != W('\0') && wzPath[2] != W('?');
-            }
-
-            //-----------------------------------------------------------------------------------------
-            static inline bool
-            HasDrivePrefix(LPCWSTR wzPath)
-            {
-                _ASSERTE(!clr::str::IsNullOrEmpty(wzPath)); // Must check this first.
-                return wzPath[0] != W('\0')
-                    && wzPath[1] != W('\0') && wzPath[1] == W(':')
-                    && ((wzPath[0] >= W('a') && wzPath[0] <= W('z')) ||
-                        (wzPath[0] >= W('A') && wzPath[0] <= W('Z')));
-            }
-
             //-----------------------------------------------------------------------------------------
             // Returns true if wzPath represents a relative path.
             static inline bool
             IsRelative(LPCWSTR wzPath)
             {
-                _ASSERTE(!clr::str::IsNullOrEmpty(wzPath)); // Must check this first.
-                return !HasLongFormatPrefix(wzPath)
-                    && !HasUncPrefix(wzPath)
-                    && (!HasDrivePrefix(wzPath) || wzPath[2] != W('\\'));
+                _ASSERTE(wzPath != nullptr);
+
+                // Similar to System.IO.Path.IsRelative()
+#if PLATFORM_UNIX
+                if(wzPath[0] == VolumeSeparatorChar)
+                {
+                    return false;
+                }
+#else
+                // Check for a paths like "C:\..." or "\\...". Additional notes:
+                // - "\\?\..." - long format paths are considered as absolute paths due to the "\\" prefix
+                // - "\..." - these paths are relative, as they depend on the current drive
+                // - "C:..." and not "C:\..." - these paths are relative, as they depend on the current directory for drive C
+                if (wzPath[0] != W('\0') &&
+                    wzPath[1] == VolumeSeparatorChar &&
+                    wzPath[2] == DirectorySeparatorChar &&
+                    (
+                        (wzPath[0] >= W('A') && wzPath[0] <= W('Z')) ||
+                        (wzPath[0] >= W('a') && wzPath[0] <= W('z'))
+                    ))
+                {
+                    return false;
+                }
+                if(wzPath[0] == DirectorySeparatorChar && wzPath[1] == DirectorySeparatorChar)
+                {
+                    return false;
+                }
+#endif
+
+                return true;
             }
 
             //-----------------------------------------------------------------------------------------
@@ -105,7 +129,8 @@ namespace clr
                 size_t cchBuf = *pcchBuffer;
 
                 IfFailRet(StringCchCopyExW(wzBuf, cchBuf, wzPathLeft, &wzBuf, &cchBuf, STRSAFE_NULL_ON_FAILURE));
-                IfFailRet(StringCchCatExW(wzBuf, cchBuf, wzBuf[-1] == W('\\') ? W("") : W("\\"), &wzBuf, &cchBuf, STRSAFE_NULL_ON_FAILURE));
+                const WCHAR directorySeparatorWString[] = {DirectorySeparatorChar, W('\0')};
+                IfFailRet(StringCchCatExW(wzBuf, cchBuf, wzBuf[-1] == DirectorySeparatorChar ? W("") : directorySeparatorWString, &wzBuf, &cchBuf, STRSAFE_NULL_ON_FAILURE));
                 IfFailRet(StringCchCatExW(wzBuf, cchBuf, wzPathRight, &wzBuf, &cchBuf, STRSAFE_NULL_ON_FAILURE));
 
                 return S_OK;

src/vm/appdomainnative.cpp

@@ -31,6 +31,8 @@
 #include "../binder/inc/clrprivbindercoreclr.h"
 #endif
 
+#include "clr/fs/path.h"
+using namespace clr::fs;
 
 //************************************************************************
 inline AppDomain *AppDomainNative::ValidateArg(APPDOMAINREF pThis)
@@ -1578,7 +1580,7 @@ void QCALLTYPE AppDomainNative::SetNativeDllSearchDirectories(__in_z LPCWSTR wsz
         while (itr != end)
         {
             start = itr;
-            BOOL found = sDirectories.Find(itr, W(';'));
+            BOOL found = sDirectories.Find(itr, Path::PathSeparatorChar);
             if (!found)
             {
                 itr = end;
@@ -1595,9 +1597,9 @@ void QCALLTYPE AppDomainNative::SetNativeDllSearchDirectories(__in_z LPCWSTR wsz
 
             if (len > 0)
             {
-                if (qualifiedPath[len-1]!='\\')
+                if (qualifiedPath[len - 1] != Path::DirectorySeparatorChar)
                 {
-                    qualifiedPath.Append('\\');
+                    qualifiedPath.Append(Path::DirectorySeparatorChar);
                 }
 
                 NewHolder<SString> stringHolder (new SString(qualifiedPath));

src/vm/dllimport.cpp

@@ -56,6 +56,9 @@
 #include "fxretarget.h"
 #endif
 
+#include "clr/fs/path.h"
+using namespace clr::fs;
+
 // remove when we get an updated SDK
 #define LOAD_LIBRARY_SEARCH_DLL_LOAD_DIR 0x00000100
 #define LOAD_LIBRARY_SEARCH_DEFAULT_DIRS 0x00001000
@@ -6144,48 +6147,6 @@ LPVOID NDirect::NDirectGetEntryPoint(NDirectMethodDesc *pMD, HINSTANCE hMod)
     RETURN pMD->FindEntryPoint(hMod);
 }
 
-static BOOL AbsolutePath(LPCWSTR wszLibName)
-{
-    CONTRACTL
-    {
-        NOTHROW;
-        GC_NOTRIGGER;
-        MODE_ANY;
-
-        PRECONDITION(CheckPointer(wszLibName));
-    }
-    CONTRACTL_END;
-
-    // check for UNC or a drive
-    WCHAR* ptr = (WCHAR*) wszLibName;
-    WCHAR* start = ptr;
-
-    // Check for UNC path
-    while(*ptr)
-    {
-        if(*ptr != W('\\'))
-            break;
-        ptr++;
-    }
-
-    if((ptr - wszLibName) == 2)
-        return TRUE;
-    else
-    {
-        // Check to see if there is a colon indicating a drive or protocal
-        for(ptr = start; *ptr; ptr++)
-        {
-            if(*ptr == W(':'))
-                break;
-        }
-        if(*ptr != NULL)
-            return TRUE;
-    }
-
-    // We did not find a UNC/drive/protocol path
-    return FALSE;
-}
-
 VOID NDirectMethodDesc::SetNDirectTarget(LPVOID pTarget)
 {
     CONTRACTL
@@ -7078,7 +7039,7 @@ HINSTANCE NDirect::LoadLibraryModule( NDirectMethodDesc * pMD, LoadLibErrorTrack
         }
 #endif // !FEATURE_CORECLR
 
-        if (AbsolutePath(wszLibName))
+        if (!Path::IsRelative(wszLibName))
         {
             DWORD flags = loadWithAlteredPathFlags;
             if ((dllImportSearchPathFlag & LOAD_LIBRARY_SEARCH_DLL_LOAD_DIR) != 0)
@@ -7173,7 +7134,7 @@ HINSTANCE NDirect::LoadLibraryModule( NDirectMethodDesc * pMD, LoadLibErrorTrack
         {
             SString qualifiedPath(*(i.GetPath()));
             qualifiedPath.Append(wszLibName);
-            if (AbsolutePath(qualifiedPath))
+            if (!Path::IsRelative(qualifiedPath))
             {
                 hmod = LocalLoadLibraryHelper(qualifiedPath, loadWithAlteredPathFlags, pErrorTracker);
             }