Fix for issue 23908 - error message reports the exact error when a native extension fails to load.

runtime/bin/extensions_linux.cc

Index: runtime/bin/extensions_linux.cc
diff --git a/runtime/bin/extensions_linux.cc b/runtime/bin/extensions_linux.cc
index 23ee6ed29f3b87961517fbbcaffc172dfb26d6e2..7494b08ee1f63aed433220c62905c9d22611af8c 100644
--- a/runtime/bin/extensions_linux.cc
+++ b/runtime/bin/extensions_linux.cc
@@ -2,6 +2,7 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
+#include "platform/assert.h"
 #include "platform/globals.h"
 #if defined(TARGET_OS_LINUX)
 
@@ -15,15 +16,27 @@ namespace bin {
 const char* kPrecompiledLibraryName = "libprecompiled.so";
 const char* kPrecompiledSymbolName = "_kInstructionsSnapshot";
 
-void* Extensions::LoadExtensionLibrary(const char* library_file) {
-  return dlopen(library_file, RTLD_LAZY);
+Dart_Handle Extensions::LoadExtensionLibrary(const char* library_file,
+                                             void** library_handle) {
+  ASSERT(library_handle != NULL);
+  *library_handle = dlopen(library_file, RTLD_LAZY);
+  if (*library_handle == NULL) {
+    return Dart_NewApiError(dlerror());
+  }
+  return Dart_Null();
 }
 
-void* Extensions::ResolveSymbol(void* lib_handle, const char* symbol) {
+Dart_Handle Extensions::ResolveSymbol(void* lib_handle,
+                                      const char* symbol,
+                                      void** init_function) {
+  ASSERT(init_function != NULL);
   dlerror();
-  void* result = dlsym(lib_handle, symbol);
-  if (dlerror() != NULL) return NULL;
-  return result;
+  *init_function = dlsym(lib_handle, symbol);
+  char* err_str = dlerror();
+  if (err_str != NULL) {
+    return Dart_NewApiError(err_str);
+  }
+  return Dart_Null();
 }
 
 }  // namespace bin