Merge devel code into the trunk.

[tinyos-2.x.git] / support / sdk / java / net / tinyos / util / Env.java

diff --git a/support/sdk/java/net/tinyos/util/Env.java b/support/sdk/java/net/tinyos/util/Env.java
new file mode 100644 (file)
index 0000000..be9b00a
--- /dev/null
+++ b/support/sdk/java/net/tinyos/util/Env.java
@@ -0,0 +1,50 @@
+// $Id$
+
+package net.tinyos.util;
+
+/**
+ * The <code>Env</code> class provides an implementation of
+ * <code>getenv</code> that actually works, unlike the one in
+ * <code>java.lang.System</code>.  The class cannot be instantiated.
+ *
+ * V1.1: provide wrapper so that getenv doesn't fail horribly when the
+ * native code is not found.
+ *
+ * @author   R M Yorston, David Gay
+ * @version  1.1
+ */
+public class Env {
+    static private boolean loaded;
+    static {
+       try {
+           java.lang.System.loadLibrary("getenv");
+           loaded = true;
+       }
+       catch (Throwable t) {
+           System.err.println("getenv JNI library not found. Env.getenv will not work");
+           System.err.println("(run the tos-install-jni tool, see man tos-install-jni for more details)\n");
+       }
+    }
+
+    private Env() {
+    }
+
+    /**
+     * Gets an environment variable. An environment variable is a
+     * system-dependent external variable that has a string value.
+     *
+     * @param  name    name of the environment variable
+     * @return the value of the variable, or <code>null</code> if the
+     * variable is not defined.
+     */
+    public static String getenv(String name) {
+       if (loaded) {
+           return igetenv(name);
+       }
+       else {
+           return null;
+       }
+    }
+
+    private static native String igetenv(String name);
+}