Merge pull request #312 from dmlloyd/wsl

Add detection for WSL

os/src/main/java/io/smallrye/common/os/Linux.java

@@ -0,0 +1,57 @@
+package io.smallrye.common.os;
+
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+
+/**
+ * Utilities pertaining to the Linux operating system.
+ */
+public final class Linux {
+    private Linux() {
+    }
+
+    /**
+     * {@return true if the operating system is the Windows Subsystem for Linux, or false if it is not}
+     */
+    public static boolean isWSL() {
+        return WSL.version >= 1;
+    }
+
+    /**
+     * {@return true if the WSL version is 2 or later, or false if it is not}
+     */
+    public static boolean isWSLv2() {
+        return WSL.version >= 2;
+    }
+
+    /**
+     * Lazy constants for WSL.
+     */
+    private static final class WSL {
+        private static final int version;
+
+        static {
+            if (OS.current() != OS.LINUX) {
+                version = 0;
+            } else {
+                int v;
+                try {
+                    String procVersion = Files.readString(Path.of("/proc/version"));
+                    if (procVersion.contains("Microsoft")) {
+                        // likely version 1
+                        v = 1;
+                    } else if (procVersion.contains("microsoft")) {
+                        // likely version 2 or newer
+                        v = 2;
+                    } else {
+                        v = 0;
+                    }
+                } catch (IOException e) {
+                    v = 0;
+                }
+                version = v;
+            }
+        }
+    }
+}