add unload_dso

dtool/src/dtoolutil/load_dso.cxx

@@ -28,11 +28,16 @@ load_dso(const Filename &)
   return (void *) NULL;
 }
 
+bool
+unload_dso(void *dso_handle) {
+ return false;
+}
+
 string
 load_dso_error()
 {
   ostringstream ps2errmsg;
-  ps2errmsg << "load_dso_error() unsupported on PS2.  (CSN)";
+  ps2errmsg << "load_dso_error() unsupported on PS2";
 
   return ps2errmsg.str();
 }
@@ -53,6 +58,14 @@ load_dso(const Filename &filename) {
   return LoadLibrary(os_specific.c_str());
 }
 
+bool
+unload_dso(void *dso_handle) {
+  HMODULE dll_handle = (HMODULE) dso_handle;
+
+  // true indicates success
+  return FreeLibrary(dll_handle);
+}
+
 string
 load_dso_error() {
   DWORD last_error = GetLastError();
@@ -136,6 +149,11 @@ load_dso(const Filename &filename) {
   return dlopen(os_specific.c_str(), RTLD_NOW);
 }
 
+bool
+unload_dso(void *dso_handle) {
+  return dlclose(dso_handle)==0;
+}
+
 string
 load_dso_error() {
   return dlerror();

dtool/src/dtoolutil/load_dso.h

@@ -29,6 +29,10 @@
 EXPCL_DTOOL void *
 load_dso(const Filename &filename);
 
+// true indicates success
+EXPCL_DTOOL bool
+unload_dso(void *dso_handle);
+
 // Returns the error message from the last failed load_dso() call.
 
 EXPCL_DTOOL string