[Sablevm-developer] Patch for Runtime.nativeLoad()

[Archie C. <ar...@de...>]

Here's a patch to fix a problem with Runtime.nativeLoad(). The
problem is that if the dlopen() operation fails, the error message
is lost. This caused me a lot of head scratching the other day
trying to figure out why something wasn't working.

With this patch the underlying error message (from lt_dlerror())
will appear in the Exception message string.

Thanks,
-Archie

__________________________________________________________________________
Archie Cobbs     *     Packet Design     *     http://www.packetdesign.com

--- sablevm-class-library-1.0.5/src/java/lang/Runtime.java.orig	Thu Nov 14 16:52:41 2002
+++ sablevm-class-library-1.0.5/src/java/lang/Runtime.java	Thu Nov 14 16:51:11 2002
@@ -629,8 +629,10 @@
     SecurityManager sm = securityManager; // Be thread-safe!
     if (sm != null)
       sm.checkLink(filename);
-    if (nativeLoad(filename) == 0)
-      throw new UnsatisfiedLinkError("Could not load library " + filename);
+    String errmsg = nativeLoad(filename);
+    if (errmsg != null)
+      throw new UnsatisfiedLinkError("Could not load library " + filename
+				     + ": " + errmsg);
   }
 
   /**
@@ -747,9 +749,9 @@
    * already been mapped to a true filename.
    *
    * @param filename the file to load
-   * @return 0 on failure, nonzero on success
+   * @return error message on failure, null on success
    */
-  private native int nativeLoad(String filename);
+  private native String nativeLoad(String filename);
 
   /**
    * Map a system-independent "short name" to the full file name, and append
--- sablevm-1.0.5/src/libsablevm/java_lang_Runtime.h.orig	Thu Nov 14 17:08:12 2002
+++ sablevm-1.0.5/src/libsablevm/java_lang_Runtime.h	Thu Nov 14 17:07:27 2002
@@ -93,9 +93,9 @@
 /*
  * Class:     java_lang_Runtime
  * Method:    nativeLoad
- * Signature: (Ljava/lang/String;)I
+ * Signature: (Ljava/lang/String;)Ljava/lang/String;
  */
-  JNIEXPORT jint JNICALL Java_java_lang_Runtime_nativeLoad
+  JNIEXPORT jstring JNICALL Java_java_lang_Runtime_nativeLoad
     (JNIEnv *, jobject, jstring);
 
 /*
--- sablevm-1.0.5/src/libsablevm/java_lang_Runtime.c.orig	Thu Nov 14 16:56:03 2002
+++ sablevm-1.0.5/src/libsablevm/java_lang_Runtime.c	Thu Nov 14 17:11:15 2002
@@ -166,16 +166,17 @@
 /*
  * Class:     java_lang_Runtime
  * Method:    nativeLoad
- * Signature: (Ljava/lang/String;)I
+ * Signature: (Ljava/lang/String;)Ljava/lang/String;
  */
 
-JNIEXPORT jint JNICALL
+JNIEXPORT jstring JNICALL
 Java_java_lang_Runtime_nativeLoad (JNIEnv *_env, jobject this,
 				   jstring _filename)
 {
   _svmt_JNIEnv *env = _svmf_cast_svmt_JNIEnv (_env);
   _svmt_JavaVM *vm = env->vm;
-  jint result = 0;
+  const char *errmsg = "unknown error";
+  jstring result = NULL;
 
   _svmf_resuming_java (env);
 
@@ -207,6 +208,7 @@
 
     if (handle == NULL)
       {
+	errmsg = lt_dlerror();
 	_svmm_gfree_utf_chars (filename);
 	goto end;
       }
@@ -215,7 +217,7 @@
       {
 	if (native_library->handle == handle)
 	  {
-	    result = 1;
+	    errmsg = NULL;
 	    _svmm_gfree_utf_chars (filename);
 	    goto end;
 	  }
@@ -257,7 +259,7 @@
     class_loader_info->native_library_list_tail =
       &(*(class_loader_info->native_library_list_tail))->next;
 
-    result = 1;
+    errmsg = NULL;
 
   end:
 
@@ -272,6 +274,14 @@
 	  {
 	    goto end;
 	  }
+      }
+
+    if (errmsg != NULL)
+      {
+	/* as we do nothing else after, we can safely ignore the return
+	   value (any exception being also set in the environment) */
+	result = _svmf_get_jni_frame_native_local (env);
+	_svmf_get_string (env, errmsg, result);
       }
   }