Merge pull request #29 from treyzania/master

Made the build script more flexible across different platforms.

build.rs

@@ -1,19 +1,55 @@
 use std::env;
 
+#[cfg(target_os = "linux")]
+fn find_default_java_home() -> String {
+    String::from("/usr/lib/jvm/default-java") // This might just be Debian, not sure.
+}
+
+#[cfg(target_os = "macos")]
+fn find_default_java_home() -> String {
+    /*
+     * FIXME Find version dynamically.
+     * Use: /usr/libexec/java_home -v 1.8
+     *
+     * Someone that uses macOS should figure this out.
+     */
+    String::from("/Library/Java/JavaVirtualMachines/jdk1.8.0_51.jdk/Contents/Home")
+}
+
+#[cfg(target_os = "windows")]
+fn find_default_java_home() -> String {
+    /*
+     * Windows is silly about how it handles programs.  32-bit programs install to
+     * `Program Files (x86)` on 64-bit machines, but programs that match bitness install to the
+     * normal `Program Files` directory.
+     *
+     * Someone that actually uses Windows should figure this out.
+     */
+    String::from("C:\\Program Files\\Java\\jre8") // FIXME Find version dynamically.
+}
+
 fn main() {
 
     // Try to determine the Java home directory so that we can link to `libjvm`.
-    let java_home =
-        env::var("JAVA_HOME")
-        .ok()
-        .unwrap_or("/Library/Java/JavaVirtualMachines/jdk1.8.0_51.jdk/Contents/Home".to_string());
+    let java_home = env::var("JAVA_HOME").ok().unwrap_or(find_default_java_home());
 
+    // I don't have this on my machine, so I'm not 100% sure what it does.
     print!("cargo:rustc-link-search=native=");
     println!("{}/jre/lib/server", java_home);
 
-    print!("cargo:rustc-link-search=native=");
-    println!("{}/jre/lib/amd64/server", java_home);
+    if cfg!(target_arch = "x86_64") {
+        print!("cargo:rustc-link-search=native=");
+        println!("{}/jre/lib/amd64/server", java_home);
+    } else if cfg!(target_arch = "x86") {
+        print!("cargo:rustc-link-search=native=");
+        println!("{}/jre/lib/i386/server", java_home);
+    } else {
+        panic!("rucaja is not currently supported on your architecture")
+    }
+
+    /*
+     * We still need to do annoying things like setting LD_LIBRARY_PATH when we run the executable.
+     * It might be better to determine all this at runtime after all.
+     */
 
-    print!("cargo:rustc-link-search=native=");
-    println!("{}/jre/lib/i386/server", java_home);
 }