[bugfix] fn:available-environment-variables and fn:environment-variable should be deterministic within the execution scope

Author: adamretter

exist-core/src/main/java/org/exist/xquery/XQueryContext.java

@@ -51,6 +51,8 @@
 import com.evolvedbinary.j8fu.function.QuadFunctionE;
 import com.evolvedbinary.j8fu.tuple.Tuple2;
 import com.ibm.icu.text.Collator;
+import io.lacuna.bifurcan.IMap;
+import io.lacuna.bifurcan.LinearMap;
 import it.unimi.dsi.fastutil.Hash;
 import it.unimi.dsi.fastutil.objects.*;
 import net.jcip.annotations.Immutable;
@@ -372,7 +374,7 @@ public class XQueryContext implements BinaryValueManager, Context {
     protected Profiler profiler;
 
     //For holding the environment variables
-    private Map<String, String> envs;
+    private IMap<String, String> envs;
 
     private ContextUpdateListener updateListener = null;
 
@@ -2732,9 +2734,9 @@ public void resolveForwardReferences() throws XPathException {
      *
      * @return Map of environment variables
      */
-    public Map<String, String> getEnvironmentVariables() {
+    public io.lacuna.bifurcan.IMap<String, String> getEnvironmentVariables() {
         if (envs == null) {
-            envs = System.getenv();
+            envs = io.lacuna.bifurcan.Map.from(System.getenv());
         }
         return envs;
     }

exist-core/src/main/java/org/exist/xquery/functions/fn/FunEnvironment.java

@@ -21,8 +21,8 @@
  */
 package org.exist.xquery.functions.fn;
 
-import java.util.Map;
-
+import io.lacuna.bifurcan.IMap;
+import io.lacuna.bifurcan.ISet;
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
 import org.exist.dom.QName;
@@ -69,7 +69,7 @@ public FunEnvironment(final XQueryContext context, final FunctionSignature signa
     }
 
     @Override
-    public Sequence eval(Sequence[] args, Sequence contextSequence) throws XPathException {
+    public Sequence eval(final Sequence[] args, final Sequence contextSequence) throws XPathException {
 
         if (!context.getSubject().hasDbaRole()) {
             final String txt = "Permission denied, calling user '" + context.getSubject().getName() + "' must be a DBA to call this function.";
@@ -81,9 +81,9 @@ public Sequence eval(Sequence[] args, Sequence contextSequence) throws XPathExce
 
             final Sequence result = new ValueSequence();
 
-            final Map<String, String> env = context.getEnvironmentVariables();
-            for (final String key : env.keySet()) {
-                result.add(new StringValue(this, key));
+            final IMap<String, String> environmentVariables = context.getEnvironmentVariables();
+            for (final String environmentVariableName : environmentVariables.keys()) {
+                result.add(new StringValue(this, environmentVariableName));
             }
 
             return result;
@@ -96,7 +96,7 @@ public Sequence eval(Sequence[] args, Sequence contextSequence) throws XPathExce
 
             final String parameter = args[0].itemAt(0).getStringValue();
 
-            final String value = context.getEnvironmentVariables().get(parameter);
+            final String value = context.getEnvironmentVariables().get(parameter, null);
             if (value == null) {
                 return Sequence.EMPTY_SEQUENCE;
             }