Add platform::DLOpen and platform::DLClose.

Signed-off-by: Vassil Vassilev <vvasilev@cern.ch>

include/cling/Utils/Platform.h

@@ -28,6 +28,25 @@ namespace platform {
   ///
   bool GetSystemLibraryPaths(llvm::SmallVectorImpl<std::string>& Paths);
 
+  ///\brief Open a handle to a shared library. On Unix the lib is opened with
+  /// RTLD_LAZY|RTLD_GLOBAL flags.
+  ///
+  /// \param [in] Path - Library to open
+  /// \param [out] Err - Write errors to this string when given
+  ///
+  /// \returns the library handle
+  ///
+  const void* DLOpen(const std::string& Path, std::string* Err = nullptr);
+
+  ///\brief Close a handle to a shared library.
+  ///
+  /// \param [in] Lib - Handle to library from previous call to DLOpen
+  /// \param [out] Err - Write errors to this string when given
+  ///
+  /// \returns the library handle
+  ///
+  void DLClose(const void* Lib, std::string* Err = nullptr);
+
   ///\brief Returns a normalized version of the given Path
   ///
   std::string NormalizePath(const std::string& Path);

lib/Interpreter/DynamicLibraryManager.cpp

@@ -18,18 +18,9 @@
 #include "llvm/Support/Path.h"
 #include "llvm/Support/raw_ostream.h"
 
-#include <algorithm>
-#include <iostream>
-#include <stdio.h>
-#include <stdlib.h>
+#include <system_error>
 #include <sys/stat.h>
 
-#ifdef LLVM_ON_WIN32
-#include <Windows.h>
-#else
-#include <dlfcn.h>
-#endif
-
 namespace cling {
   DynamicLibraryManager::DynamicLibraryManager(const InvocationOptions& Opts)
     : m_Opts(Opts), m_Callbacks(0) {
@@ -213,20 +204,10 @@ namespace cling {
     if (m_LoadedLibraries.find(canonicalLoadedLib) != m_LoadedLibraries.end())
       return kLoadLibAlreadyLoaded;
 
-    std::string errMsg;
     // TODO: !permanent case
-#if defined(LLVM_ON_WIN32)
-    HMODULE dyLibHandle = LoadLibraryEx(canonicalLoadedLib.c_str(), NULL,
-                                        DONT_RESOLVE_DLL_REFERENCES);
-    if (!dyLibHandle)
-      platform::GetLastErrorAsString(errMsg, "LoadLibraryEx");
-#else
-    const void* dyLibHandle = dlopen(canonicalLoadedLib.c_str(),
-                                     RTLD_LAZY|RTLD_GLOBAL);
-    if (const char* DyLibError = dlerror()) {
-      errMsg = DyLibError;
-    }
-#endif
+
+    std::string errMsg;
+    DyLibHandle dyLibHandle = platform::DLOpen(canonicalLoadedLib, &errMsg);
     if (!dyLibHandle) {
       llvm::errs() << "cling::DynamicLibraryManager::loadLibrary(): " << errMsg
                    << '\n';
@@ -258,17 +239,10 @@ namespace cling {
       }
     }
 
-    std::string errMsg;
     // TODO: !permanent case
-#if defined(LLVM_ON_WIN32)
-    if (FreeLibrary((HMODULE)dyLibHandle) == 0)
-      platform::GetLastErrorAsString(errMsg, "FreeLibrary");
-#else
-    dlclose(const_cast<void*>(dyLibHandle));
-    if (const char* DyLibError = dlerror()) {
-      errMsg = DyLibError;
-    }
-#endif
+
+    std::string errMsg;
+    platform::DLClose(dyLibHandle, &errMsg);
     if (!errMsg.empty()) {
       llvm::errs() << "cling::DynamicLibraryManager::unloadLibrary(): "
                    << errMsg << '\n';

lib/Utils/PlatformPosix.cpp

@@ -13,6 +13,7 @@
 
 #include "cling/Utils/Paths.h"
 #include <string>
+#include <dlfcn.h>
 #include <unistd.h>
 
 // PATH_MAX
@@ -37,6 +38,23 @@ std::string GetCwd() {
   return std::string();
 }
 
+const void* DLOpen(const std::string& Path, std::string* Err) {
+  void* Lib = dlopen(Path.c_str(), RTLD_LAZY|RTLD_GLOBAL);
+  if (Err) {
+    if (const char* DyLibError = ::dlerror())
+      *Err = DyLibError;
+  }
+  return Lib;
+}
+
+void DLClose(const void* Lib, std::string* Err) {
+  ::dlclose(const_cast<void*>(Lib));
+  if (Err) {
+    if (const char* DyLibError = ::dlerror())
+      *Err = DyLibError;
+  }
+}
+
 std::string NormalizePath(const std::string& Path) {
   char Buf[PATH_MAXC];
   if (const char* Result = ::realpath(Path.c_str(), Buf))

lib/Utils/PlatformWin.cpp

@@ -475,6 +475,22 @@ std::string NormalizePath(const std::string& Path) {
   return std::string();
 }
 
+const void* DLOpen(const std::string& Path, std::string* Err) {
+  HMODULE dyLibHandle = ::LoadLibraryExA(Path.c_str(), NULL,
+                                         DONT_RESOLVE_DLL_REFERENCES);
+  if (!dyLibHandle && Err)
+    GetLastErrorAsString(*Err, "LoadLibraryEx");
+
+  return reinterpret_cast<void*>(dyLibHandle);
+}
+
+void DLClose(const void* Lib, std::string* Err) {
+  if (::FreeLibrary(reinterpret_cast<HMODULE>(const_cast<void*>(Lib))) == 0) {
+    if (Err)
+      GetLastErrorAsString(*Err, "FreeLibrary");
+  }
+}
+
 bool GetSystemLibraryPaths(llvm::SmallVectorImpl<std::string>& Paths) {
   char Buf[MAX_PATHC];
   // Generic form of C:\Windows\System32