[GR-9875] Define TruffleRuby.graalvm_home

PullRequest: truffleruby/2061

Author: eregon

doc/user/truffleruby-additions.md

@@ -33,6 +33,8 @@ standard `RUBY_ENGINE_VERSION` constant.
 TruffleRuby provides these non-standard methods and classes that provide
 additional functionality in the `TruffleRuby` module.
 
+`TruffleRuby.graalvm_home` returns the GraalVM home or `nil` if running outside of GraalVM (e.g., TruffleRuby standalone).
+
 `TruffleRuby.jit?` reports if the GraalVM Compiler is available and will be
 used.
 

lib/truffle/rbconfig.rb

@@ -59,7 +59,7 @@ module RbConfig
   libs = ''
 
   prefix = ruby_home
-  graalvm_home = Truffle::System.get_java_property 'org.graalvm.home'
+  graalvm_home = TruffleRuby.graalvm_home
   extra_bindirs = if graalvm_home
                     jre_bin = "#{graalvm_home}/jre/bin"
                     ["#{graalvm_home}/bin", *(jre_bin if File.directory?(jre_bin))]

spec/truffle/launcher_spec.rb

@@ -328,7 +328,7 @@ def should_print_full_java_command(options, env: {})
       out.should include("--jvm")
     end
 
-    if Truffle::System.get_java_property 'org.graalvm.home'
+    if TruffleRuby.graalvm_home
       # These options are only shown in GraalVM, as they are not available in a standalone distribution
       out.should include("--polyglot")
     end

spec/truffle/truffleruby/no_other_methods_spec.rb

@@ -12,7 +12,7 @@
 
   it "contains no other public methods" do
     (TruffleRuby.methods - Module.new.methods).sort.should == %i{
-      full_memory_barrier graal? jit? native? revision sulong? cexts? synchronized
+      full_memory_barrier graal? graalvm_home jit? native? revision sulong? cexts? synchronized
     }.sort
   end
 

src/main/java/org/truffleruby/extra/TruffleRubyNodes.java

@@ -9,12 +9,16 @@
  */
 package org.truffleruby.extra;
 
+import com.oracle.truffle.api.dsl.Cached;
+import org.jcodings.specific.UTF8Encoding;
 import org.truffleruby.RubyContext;
 import org.truffleruby.RubyLanguage;
 import org.truffleruby.builtins.CoreMethod;
 import org.truffleruby.builtins.CoreMethodArrayArgumentsNode;
 import org.truffleruby.builtins.CoreMethodNode;
 import org.truffleruby.builtins.CoreModule;
+import org.truffleruby.core.rope.CodeRange;
+import org.truffleruby.core.string.StringNodes;
 import org.truffleruby.extra.ffi.Pointer;
 
 import com.oracle.truffle.api.CompilerDirectives.TruffleBoundary;
@@ -25,6 +29,27 @@
 @CoreModule("TruffleRuby")
 public abstract class TruffleRubyNodes {
 
+    @CoreMethod(names = "graalvm_home", onSingleton = true)
+    public abstract static class GraalvmHomeNode extends CoreMethodArrayArgumentsNode {
+
+        @Specialization
+        protected Object graalvmHome(
+                @Cached StringNodes.MakeStringNode makeStringNode) {
+            String value = getProperty("org.graalvm.home");
+            if (value == null) {
+                return nil;
+            } else {
+                return makeStringNode.executeMake(value, UTF8Encoding.INSTANCE, CodeRange.CR_UNKNOWN);
+            }
+        }
+
+        @TruffleBoundary
+        private static String getProperty(String key) {
+            return System.getProperty(key);
+        }
+
+    }
+
     @CoreMethod(names = "jit?", onSingleton = true)
     public abstract static class GraalNode extends CoreMethodArrayArgumentsNode {