Refactoring AnsiConsoleSupport (#266)

src/main/java/org/fusesource/jansi/AnsiConsole.java

@@ -31,6 +31,9 @@
 import org.fusesource.jansi.io.AnsiProcessor;
 import org.fusesource.jansi.io.FastBufferedOutputStream;
 
+import static org.fusesource.jansi.internal.AnsiConsoleSupportHolder.getCLibrary;
+import static org.fusesource.jansi.internal.AnsiConsoleSupportHolder.getKernel32;
+
 /**
  * Provides consistent access to an ANSI aware console PrintStream or an ANSI codes stripping PrintStream
  * if not on a terminal (see
@@ -155,10 +158,21 @@ public class AnsiConsole {
      */
     public static final String JANSI_GRACEFUL = "jansi.graceful";
 
+    /**
+     * The {@code jansi.providers} system property can be set to control which internal provider
+     * will be used.  If this property is not set, the {@code ffm} provider will be used if available,
+     * else the {@code jni} one will be used.  If set, this property is interpreted as a comma
+     * separated list of provider names to try in order.
+     */
     public static final String JANSI_PROVIDERS = "jansi.providers";
+    /**
+     * The name of the {@code jni} provider.
+     */
     public static final String JANSI_PROVIDER_JNI = "jni";
+    /**
+     * The name of the {@code ffm} provider.
+     */
     public static final String JANSI_PROVIDER_FFM = "ffm";
-    public static final String JANSI_PROVIDERS_DEFAULT = JANSI_PROVIDER_FFM + "," + JANSI_PROVIDER_JNI;
 
     /**
      * @deprecated this field will be made private in a future release, use {@link #sysOut()} instead
@@ -536,12 +550,4 @@ static synchronized void initStreams() {
             initialized = true;
         }
     }
-
-    private static AnsiConsoleSupport.Kernel32 getKernel32() {
-        return AnsiConsoleSupport.getInstance().getKernel32();
-    }
-
-    private static AnsiConsoleSupport.CLibrary getCLibrary() {
-        return AnsiConsoleSupport.getInstance().getCLibrary();
-    }
 }

src/main/java/org/fusesource/jansi/AnsiMain.java

@@ -23,10 +23,11 @@
 import java.io.InputStream;
 import java.io.InputStreamReader;
 import java.io.PrintStream;
-import java.nio.charset.StandardCharsets;
 import java.util.Properties;
 
 import org.fusesource.jansi.Ansi.Attribute;
+import org.fusesource.jansi.internal.AnsiConsoleSupport;
+import org.fusesource.jansi.internal.AnsiConsoleSupportHolder;
 import org.fusesource.jansi.internal.JansiLoader;
 import org.fusesource.jansi.internal.MingwSupport;
 
@@ -56,9 +57,8 @@ public static void main(String... args) throws IOException {
 
         System.out.println();
 
-        System.out.println("jansi.providers= "
-                + System.getProperty(AnsiConsole.JANSI_PROVIDERS, AnsiConsole.JANSI_PROVIDERS_DEFAULT));
-        String provider = AnsiConsoleSupport.getInstance().getProviderName();
+        System.out.println("jansi.providers= " + System.getProperty(AnsiConsole.JANSI_PROVIDERS, ""));
+        String provider = AnsiConsoleSupportHolder.getProviderName();
         System.out.println("Selected provider: " + provider);
 
         if (AnsiConsole.JANSI_PROVIDER_JNI.equals(provider)) {
@@ -204,8 +204,8 @@ private static void diagnoseTty(boolean stderr) {
         int isatty;
         int width;
         if (AnsiConsole.IS_WINDOWS) {
-            long console = AnsiConsoleSupport.getInstance().getKernel32().getStdHandle(!stderr);
-            isatty = AnsiConsoleSupport.getInstance().getKernel32().isTty(console);
+            long console = AnsiConsoleSupportHolder.getKernel32().getStdHandle(!stderr);
+            isatty = AnsiConsoleSupportHolder.getKernel32().isTty(console);
             if ((AnsiConsole.IS_CONEMU || AnsiConsole.IS_CYGWIN || AnsiConsole.IS_MSYSTEM) && isatty == 0) {
                 MingwSupport mingw = new MingwSupport();
                 String name = mingw.getConsoleName(!stderr);
@@ -217,12 +217,12 @@ private static void diagnoseTty(boolean stderr) {
                     width = 0;
                 }
             } else {
-                width = AnsiConsoleSupport.getInstance().getKernel32().getTerminalWidth(console);
+                width = AnsiConsoleSupportHolder.getKernel32().getTerminalWidth(console);
             }
         } else {
             int fd = stderr ? AnsiConsoleSupport.CLibrary.STDERR_FILENO : AnsiConsoleSupport.CLibrary.STDOUT_FILENO;
-            isatty = AnsiConsoleSupport.getInstance().getCLibrary().isTty(fd);
-            width = AnsiConsoleSupport.getInstance().getCLibrary().getTerminalWidth(fd);
+            isatty = AnsiConsoleSupportHolder.getCLibrary().isTty(fd);
+            width = AnsiConsoleSupportHolder.getCLibrary().getTerminalWidth(fd);
         }
 
         System.out.println("isatty(STD" + (stderr ? "ERR" : "OUT") + "_FILENO): " + isatty + ", System."

src/main/java/org/fusesource/jansi/WindowsSupport.java

@@ -15,18 +15,16 @@
  */
 package org.fusesource.jansi;
 
+import org.fusesource.jansi.internal.AnsiConsoleSupportHolder;
+
 public class WindowsSupport {
 
     public static String getLastErrorMessage() {
-        int errorCode = getKernel32().getLastError();
+        int errorCode = AnsiConsoleSupportHolder.getKernel32().getLastError();
         return getErrorMessage(errorCode);
     }
 
     public static String getErrorMessage(int errorCode) {
-        return getKernel32().getErrorMessage(errorCode);
-    }
-
-    private static AnsiConsoleSupport.Kernel32 getKernel32() {
-        return AnsiConsoleSupport.getInstance().getKernel32();
+        return AnsiConsoleSupportHolder.getKernel32().getErrorMessage(errorCode);
     }
 }

src/main/java/org/fusesource/jansi/AnsiConsoleSupport.java → src/main/java/org/fusesource/jansi/internal/AnsiConsoleSupport.java

@@ -13,7 +13,7 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-package org.fusesource.jansi;
+package org.fusesource.jansi.internal;
 
 import java.io.IOException;
 import java.io.OutputStream;
@@ -56,8 +56,4 @@ interface Kernel32 {
     CLibrary getCLibrary();
 
     Kernel32 getKernel32();
-
-    static AnsiConsoleSupport getInstance() {
-        return AnsiConsoleSupportHolder.get();
-    }
 }

src/main/java/org/fusesource/jansi/internal/AnsiConsoleSupportHolder.java

@@ -0,0 +1,127 @@
+/*
+ * Copyright (C) 2009-2023 the original author(s).
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.fusesource.jansi.internal;
+
+import static org.fusesource.jansi.AnsiConsole.JANSI_PROVIDERS;
+
+public final class AnsiConsoleSupportHolder {
+
+    private static final String PROVIDER_NAME;
+    private static final AnsiConsoleSupport.CLibrary CLIBRARY;
+    private static final AnsiConsoleSupport.Kernel32 KERNEL32;
+    private static final Throwable ERR;
+
+    private static AnsiConsoleSupport getDefaultProvider() {
+        try {
+            // Call the specialized constructor to check whether the module has native access enabled
+            // If not, fallback to JNI to avoid the JDK printing warnings in stderr
+            return (AnsiConsoleSupport) Class.forName("org.fusesource.jansi.internal.ffm.AnsiConsoleSupportImpl")
+                    .getConstructor(boolean.class)
+                    .newInstance(true);
+        } catch (Throwable ignored) {
+        }
+
+        return new org.fusesource.jansi.internal.jni.AnsiConsoleSupportImpl();
+    }
+
+    private static AnsiConsoleSupport findProvider(String providerList) {
+        String[] providers = providerList.split(",");
+
+        RuntimeException error = null;
+
+        for (String provider : providers) {
+            try {
+                return (AnsiConsoleSupport)
+                        Class.forName("org.fusesource.jansi.internal." + provider + ".AnsiConsoleSupportImpl")
+                                .getConstructor()
+                                .newInstance();
+            } catch (Throwable t) {
+                if (error == null) {
+                    error = new RuntimeException("Unable to create AnsiConsoleSupport provider");
+                }
+
+                error.addSuppressed(t);
+            }
+        }
+
+        // User does not specify any provider, falling back to the default
+        if (error == null) {
+            return getDefaultProvider();
+        }
+
+        throw error;
+    }
+
+    static {
+        String providerList = System.getProperty(JANSI_PROVIDERS);
+
+        AnsiConsoleSupport ansiConsoleSupport = null;
+        Throwable err = null;
+
+        try {
+            if (providerList == null) {
+                ansiConsoleSupport = getDefaultProvider();
+            } else {
+                ansiConsoleSupport = findProvider(providerList);
+            }
+        } catch (Throwable e) {
+            err = e;
+        }
+
+        String providerName = null;
+        AnsiConsoleSupport.CLibrary clib = null;
+        AnsiConsoleSupport.Kernel32 kernel32 = null;
+
+        if (ansiConsoleSupport != null) {
+            try {
+                providerName = ansiConsoleSupport.getProviderName();
+                clib = ansiConsoleSupport.getCLibrary();
+                kernel32 = OSInfo.isWindows() ? ansiConsoleSupport.getKernel32() : null;
+            } catch (Throwable e) {
+                err = e;
+            }
+        }
+
+        PROVIDER_NAME = providerName;
+        CLIBRARY = clib;
+        KERNEL32 = kernel32;
+        ERR = err;
+    }
+
+    public static String getProviderName() {
+        return PROVIDER_NAME;
+    }
+
+    public static AnsiConsoleSupport.CLibrary getCLibrary() {
+        if (CLIBRARY == null) {
+            throw new RuntimeException("Unable to get the instance of CLibrary", ERR);
+        }
+
+        return CLIBRARY;
+    }
+
+    public static AnsiConsoleSupport.Kernel32 getKernel32() {
+        if (KERNEL32 == null) {
+            if (OSInfo.isWindows()) {
+                throw new RuntimeException("Unable to get the instance of Kernel32", ERR);
+            } else {
+                throw new UnsupportedOperationException("Not Windows");
+            }
+        }
+
+        return KERNEL32;
+    }
+}

src/main/java/org/fusesource/jansi/ffm/AnsiConsoleSupportFfm.java → src/main/java/org/fusesource/jansi/internal/ffm/AnsiConsoleSupportImpl.java

@@ -13,21 +13,30 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-package org.fusesource.jansi.ffm;
+package org.fusesource.jansi.internal.ffm;
 
 import java.io.IOException;
 import java.io.OutputStream;
 import java.lang.foreign.Arena;
 import java.lang.foreign.MemorySegment;
 import java.lang.foreign.ValueLayout;
 
-import org.fusesource.jansi.AnsiConsoleSupport;
+import org.fusesource.jansi.internal.AnsiConsoleSupport;
 import org.fusesource.jansi.internal.OSInfo;
 import org.fusesource.jansi.io.AnsiProcessor;
 
-import static org.fusesource.jansi.ffm.Kernel32.*;
+import static org.fusesource.jansi.internal.ffm.Kernel32.*;
+
+public final class AnsiConsoleSupportImpl implements AnsiConsoleSupport {
+
+    public AnsiConsoleSupportImpl() {}
+
+    public AnsiConsoleSupportImpl(boolean checkNativeAccess) {
+        if (checkNativeAccess && !AnsiConsoleSupportImpl.class.getModule().isNativeAccessEnabled()) {
+            throw new UnsupportedOperationException("Native access is not enabled for the current module");
+        }
+    }
 
-public class AnsiConsoleSupportFfm implements AnsiConsoleSupport {
     @Override
     public String getProviderName() {
         return "ffm";
@@ -88,7 +97,7 @@ public int getLastError() {
 
             @Override
             public String getErrorMessage(int errorCode) {
-                return org.fusesource.jansi.ffm.Kernel32.getErrorMessage(errorCode);
+                return org.fusesource.jansi.internal.ffm.Kernel32.getErrorMessage(errorCode);
             }
 
             @Override

src/main/java/org/fusesource/jansi/ffm/Kernel32.java → src/main/java/org/fusesource/jansi/internal/ffm/Kernel32.java

@@ -13,7 +13,7 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-package org.fusesource.jansi.ffm;
+package org.fusesource.jansi.internal.ffm;
 
 import java.io.IOException;
 import java.lang.foreign.AddressLayout;
@@ -309,7 +309,8 @@ public static String getErrorMessage(int errorCode) {
         int bufferSize = 160;
         try (Arena arena = Arena.ofConfined()) {
             MemorySegment data = arena.allocate(bufferSize);
-            FormatMessageW(FORMAT_MESSAGE_FROM_SYSTEM, null, errorCode, 0, data, bufferSize, null);
+            FormatMessageW(
+                    FORMAT_MESSAGE_FROM_SYSTEM, MemorySegment.NULL, errorCode, 0, data, bufferSize, MemorySegment.NULL);
             return new String(data.toArray(JAVA_BYTE), StandardCharsets.UTF_16LE).trim();
         }
     }