Change lookup path for Dart native extensions shared libraries.

runtime/bin/extensions_linux.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // 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 "bin/extensions.h"
 #include <dlfcn.h>
 
-void* Extensions::LoadExtensionLibrary(const char* library_name) {
-  const char* strings[4] = { "./lib", library_name, ".so", NULL };
-  char* library_path = Concatenate(strings);
-  void* lib_handle = dlopen(library_path, RTLD_LAZY);
-  free(library_path);
+void* Extensions::LoadExtensionLibrary(const char* library_path) {

[Mads Ager (google), 2012/03/14 10:29:47]

The splitting up of the path into path and extension name should be done in
platform independent code. Then you can pass two pointers to here?

[Bill Hesse, 2012/03/14 17:15:04]

Done.

+  const char* library_path_strings[2] = { library_path, NULL };
+  char* mutable_library_path = Concatenate(library_path_strings);

[Mads Ager (google), 2012/03/14 10:29:47]

This is just a strdup?

[Bill Hesse, 2012/03/14 17:15:04]

This is moved to the platform-independent code, and it is a strdup to remove
constness.
On 2012/03/14 10:29:47, Mads Ager wrote:

+
+  char* last_path_separator =
+      strrchr(mutable_library_path, '/');
+  if (last_path_separator == NULL) {
+    free(mutable_library_path);
+    return Dart_Error("Cannot find path separator in resolved extension name");
+  }
+  char* extension_name = last_path_separator + 1;
+  *last_path_separator = '\0';
+
+  const char* strings[5] = { mutable_library_path, "/lib",
+                             extension_name, ".so", NULL };
+  char* library_file_path = Concatenate(strings);
+  fprintf(stderr, "%s\n", library_file_path);
+  void* lib_handle = dlopen(library_file_path, RTLD_LAZY);
+  free(library_file_path);
+  free(mutable_library_path);
   return lib_handle;
 }
 
 void* Extensions::ResolveSymbol(void* lib_handle, const char* symbol) {
   void* result = dlsym(lib_handle, symbol);
   if (dlerror() != NULL) return NULL;
   return result;
 }