fix: preserve exec permissions on jspawnhelper in bundled JDK ([#1537](#1537))

Fix:
- Move the permission loop in includeJdk into a doLast block so it runs
  after the copy, and re-apply the exec bit from the source JDK for files
  that should be executable.
- Extend setExecutablePermissions to also cover the IDE runtime/ path
  (not just resources/), since the runtime's jspawnhelper had the same issue.
- Add JAVA_HOME / JDK_HOME env var support in Platform.getJavaHome(),
  inside the existing "If the JDK is set in the environment" fallback block,
  so users can point Processing at a different JDK when the bundle is absent.

Author: ZanDev32

app/build.gradle.kts

@@ -437,9 +437,20 @@ tasks.register<Copy>("includeJdk") {
     destinationDir = composeResources("jdk").get().asFile
 
     dirPermissions { unix("rwx------") }
-    fileTree(destinationDir).files.forEach { file ->
-        file.setWritable(true, false)
-        file.setReadable(true, false)
+    // Preserve executable permissions on binaries (bin/*, jspawnhelper, jexec, etc.)
+    // https://github.com/processing/processing4/issues/1537
+    doLast {
+        fileTree(destinationDir).files.forEach { file ->
+            // Copy preserves the source exec bit, but some environments strip it.
+            // Re-apply exec on files that should be executable.
+            val sourceFile = File(Jvm.current().javaHome.absolutePath,
+                file.relativeTo(destinationDir).path)
+            if (sourceFile.canExecute()) {
+                file.setExecutable(true, false)
+            }
+            file.setWritable(true, false)
+            file.setReadable(true, false)
+        }
     }
 }
 tasks.register<Copy>("includeSharedAssets"){
@@ -633,6 +644,10 @@ tasks.register("setExecutablePermissions") {
             include("**/resources/**/*.dylib")
             include("**/resources/**/*.so")
             include("**/resources/**/*.exe")
+            // Also cover the IDE runtime (jspawnhelper, jexec, bin/*) — same issue
+            // https://github.com/processing/processing4/issues/1537
+            include("**/runtime/**/bin/**")
+            include("**/runtime/**/lib/**")
         }.forEach { file ->
             if (file.isFile) {
                 file.setExecutable(true, false)

app/src/processing/app/Platform.java

@@ -371,7 +371,7 @@ static public File getContentFile(String name) {
   }
 
   static public File getJavaHome() {
-    // Get the build in JDK location from the Jetpack Compose resources
+    // Get the built-in JDK location from the Jetpack Compose resources
     var resourcesDir = System.getProperty("compose.application.resources.dir");
     if(resourcesDir != null) {
       var jdkFolder = new File(resourcesDir,"jdk");
@@ -381,6 +381,16 @@ static public File getJavaHome() {
     }
 
     // If the JDK is set in the environment, use that.
+    // if not, fall back to the java.home system property.
+    for (String envKey : new String[] { "JAVA_HOME", "JDK_HOME" }) {
+      String envPath = System.getenv(envKey);
+      if (envPath != null && !envPath.isEmpty()) {
+        File envHome = new File(envPath);
+        if (new File(envHome, "bin/java" + (Platform.isWindows() ? ".exe" : "")).canExecute()) {
+          return envHome;
+        }
+      }
+    }
     var home = System.getProperty("java.home");
     if(home != null){
       return new File(home);