Embed git properties in code; improve AFSocket.getVersion, selftest

By embedding the actual git commit information and project version into
the Java code, we can make debugging a lot easier, especially in
environments that don't keep the META-INF files around that we relied
upon earlier (e.g., Android).

This relies on latest changes in kohlschutter-parent 1.5.5-SNAPSHOT,
which is required for building junixsocket.

junixsocket-common/src/main/java-unresolved-properties/org/newsclub/net/unix/GitProperties.java

@@ -0,0 +1,50 @@
+/*
+ * junixsocket
+ *
+ * Copyright 2009-2023 Christian Kohlschütter
+ *
+ * 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.newsclub.net.unix;
+
+import java.util.Collections;
+import java.util.LinkedHashMap;
+import java.util.Map;
+
+/**
+ * Git properties that are populated upon build time.
+ *
+ * Also see {@code src/main/unresolved-java/.../GitProperties.java}
+ * 
+ * @author Christian Kohlschütter
+ */
+final class GitProperties {
+  private static final Map<String, String> MAP = new LinkedHashMap<>();
+
+  static {
+    MAP.put("git.build.version", "${git.build.version}"); // junixsocket version
+    MAP.put("git.commit.id.abbrev", "${git.commit.id.abbrev}");
+    MAP.put("git.commit.id.describe", "${git.commit.id.abbrev}");
+    MAP.put("git.commit.id.full", "${git.commit.id.full}");
+    MAP.put("git.commit.time", "${git.commit.time}");
+    MAP.put("git.dirty", "${git.dirty}");
+  }
+
+  private GitProperties() {
+    throw new IllegalStateException("No instances");
+  }
+
+  static Map<String, String> getGitProperties() {
+    return Collections.unmodifiableMap(MAP);
+  }
+}

junixsocket-common/src/main/java/org/newsclub/net/unix/AFSocket.java

@@ -335,6 +335,11 @@ public static void ensureSupported() throws UnsupportedOperationException {
    * @see #supports(AFSocketCapability)
    */
   public static final String getVersion() {
+    String v = GitProperties.getGitProperties().get("git.build.version");
+    if (v != null && !v.startsWith("$")) {
+      return v;
+    }
+
     try {
       return NativeLibraryLoader.getJunixsocketVersion();
     } catch (IOException e) {

junixsocket-common/src/main/java/org/newsclub/net/unix/NativeLibraryLoader.java

@@ -76,6 +76,12 @@ private List<LibraryCandidate> tryProviderClass(String providerClassname, String
 
   public static String getJunixsocketVersion() throws IOException {
     // NOTE: This can't easily be tested from within the junixsocket-common Maven build
+
+    String v = GitProperties.getGitProperties().get("git.build.version");
+    if (v != null && !v.startsWith("$")) {
+      return v;
+    }
+
     return getArtifactVersion(AFSocket.class, "junixsocket-common");
   }
 

junixsocket-common/src/test/java/org/newsclub/net/unix/SelftestDiagnosticsHelper.java

@@ -18,6 +18,7 @@
 package org.newsclub.net.unix;
 
 import java.io.File;
+import java.util.Map;
 
 /**
  * Some bridging code that allows junixsocket-selftest to do some in-depth diagnostics.
@@ -45,4 +46,15 @@ public static Throwable initError() {
   public static File tempDir() {
     return NativeLibraryLoader.tempDir();
   }
+
+  /**
+   * Returns git properties determined upon Maven build time.
+   *
+   * For performance reasons, these will not be correctly resolves when developing in Eclipse.
+   *
+   * @return The properties.
+   */
+  public static Map<String, String> gitProperties() {
+    return GitProperties.getGitProperties();
+  }
 }

junixsocket-selftest/src/main/java/org/newsclub/net/unix/selftest/Selftest.java

@@ -34,6 +34,7 @@
 import java.nio.file.Files;
 import java.nio.file.Path;
 import java.util.ArrayList;
+import java.util.Collections;
 import java.util.HashSet;
 import java.util.LinkedHashMap;
 import java.util.LinkedHashSet;
@@ -350,20 +351,25 @@ public void printExplanation() throws IOException {
     out.println("and file a new bug report with the output below.");
     out.println();
     out.println("junixsocket selftest version " + AFUNIXSocket.getVersion());
+
+    Map<String, String> gitProperties = new LinkedHashMap<>(retrieveGitProperties());
     try (InputStream in = getClass().getResourceAsStream(
         "/META-INF/maven/com.kohlschutter.junixsocket/junixsocket-selftest/git.properties")) {
-      Properties props = new Properties();
       if (in != null) {
+        Properties props = new Properties();
         props.load(in);
-        out.println();
-        out.println("Git properties:");
-        out.println();
         for (String key : new TreeSet<>(props.stringPropertyNames())) {
-          out.println(key + ": " + props.getProperty(key));
+          gitProperties.put(key, props.getProperty(key));
         }
       }
     }
     out.println();
+    out.println("Git properties:");
+    out.println();
+    for (Map.Entry<String, String> en : gitProperties.entrySet()) {
+      out.println(en.getKey() + ": " + en.getValue());
+    }
+    out.println();
   }
 
   public void dumpSystemProperties() {
@@ -856,6 +862,16 @@ private static File retrieveTempDir() {
     }
   }
 
+  @SuppressWarnings("unchecked")
+  private static Map<String, String> retrieveGitProperties() {
+    try {
+      Class<?> clazz = Class.forName("org.newsclub.net.unix.SelftestDiagnosticsHelper");
+      return (Map<String, String>) clazz.getMethod("gitProperties").invoke(null);
+    } catch (Exception e) {
+      return Collections.emptyMap();
+    }
+  }
+
   private static final class ModuleResult {
     private final Result result;
     private final TestExecutionSummary summary;