Workaround[lwjgl]: Implement mitigation for an early EMUI linker hang.

app_pojavlauncher/src/main/java/net/kdt/pojavlaunch/Tools.java

@@ -87,6 +87,7 @@
 import java.util.Arrays;
 import java.util.Date;
 import java.util.List;
+import java.util.Locale;
 import java.util.Map;
 
 @SuppressWarnings("IOStreamConstructor")
@@ -1093,6 +1094,23 @@ public static int mesureTextviewHeight(TextView t) {
         return t.getMeasuredHeight();
     }
 
+    /**
+     * Check if the device is one of the devices that may be affected by the hanging linker issue.
+     * The device is affected if the linker causes the process to lock up when dlopen() is called within
+     * dl_iterate_phdr().
+     * For now, the only affected firmware that I know of is Android 5.1, EMUI 3.1 on MTK-based Huawei
+     * devices.
+     * @return if the device is affected by the hanging linker issue.
+     */
+    public static boolean deviceHasHangingLinker() {
+        // Android Oreo and onwards have GSIs and most phone firmwares at that point were not modified
+        // *that* intrusively. So assume that we are not affected.
+        if(SDK_INT >= Build.VERSION_CODES.O) return false;
+        // Since the affected function in LWJGL is rarely used (and when used, it's mainly for debug prints)
+        // we can make the search scope a bit more broad and check if we are running on a Huawei device.
+        return Build.MANUFACTURER.toLowerCase(Locale.ROOT).contains("huawei");
+    }
+
     public static class RenderersList {
         public final List<String> rendererIds;
         public final String[] rendererDisplayNames;

app_pojavlauncher/src/main/java/net/kdt/pojavlaunch/utils/JREUtils.java

@@ -196,6 +196,8 @@ public static void setJavaEnvironment(Activity activity, String jreHome) throws
             envMap.put("POJAV_ZINK_PREFER_SYSTEM_DRIVER", "1");
         if(PREF_VSYNC_IN_ZINK)
             envMap.put("POJAV_VSYNC_IN_ZINK", "1");
+        if(Tools.deviceHasHangingLinker())
+            envMap.put("POJAV_EMUI_ITERATOR_MITIGATE", "1");
 
 
         // The OPEN GL version is changed according

app_pojavlauncher/src/main/jni/input_bridge_v3.c

@@ -61,6 +61,7 @@ jint JNI_OnLoad(JavaVM* vm, __attribute__((unused)) void* reserved) {
         pojav_environ->mouseDownBuffer = (*pojav_environ->runtimeJNIEnvPtr_JRE)->GetDirectBufferAddress(pojav_environ->runtimeJNIEnvPtr_JRE, mouseDownBufferJ);
         hookExec();
         installLinkerBugMitigation();
+        installEMUIIteratorMititgation();
     }
 
     if(pojav_environ->dalvikJavaVMPtr == vm) {
@@ -294,6 +295,43 @@ void installLinkerBugMitigation() {
     }
 }
 
+/**
+ * This function is meant as a substitute for SharedLibraryUtil.getLibraryPath() that just returns 0
+ * (thus making the parent Java function return null). This is done to avoid using the LWJGL's default function,
+ * which will hang the crappy EMUI linker by dlopen()ing inside of dl_iterate_phdr().
+ * @return 0, to make the parent Java function return null immediately.
+ * For reference: https://github.com/PojavLauncherTeam/lwjgl3/blob/fix_huawei_hang/modules/lwjgl/core/src/main/java/org/lwjgl/system/SharedLibraryUtil.java
+ */
+jint getLibraryPath_fix(__attribute__((unused)) JNIEnv *env,
+                        __attribute__((unused)) jclass class,
+                        __attribute__((unused)) jlong pLibAddress,
+                        __attribute__((unused)) jlong sOutAddress,
+                        __attribute__((unused)) jint bufSize){
+    return 0;
+}
+
+/**
+ * Install the linker hang mitigation that is meant to prevent linker hangs on old EMUI firmware.
+ */
+void installEMUIIteratorMititgation() {
+    if(getenv("POJAV_EMUI_ITERATOR_MITIGATE") == NULL) return;
+    __android_log_print(ANDROID_LOG_INFO, "EMUIIteratorFix", "Installing...");
+    JNIEnv* env = pojav_environ->runtimeJNIEnvPtr_JRE;
+    jclass sharedLibraryUtil = (*env)->FindClass(env, "org/lwjgl/system/SharedLibraryUtil");
+    if(sharedLibraryUtil == NULL) {
+        __android_log_print(ANDROID_LOG_ERROR, "EMUIIteratorFix", "Failed to find the target class");
+        (*env)->ExceptionClear(env);
+        return;
+    }
+    JNINativeMethod getLibraryPathMethod[] = {
+            {"getLibraryPath", "(JJI)I", &getLibraryPath_fix}
+    };
+    if((*env)->RegisterNatives(env, sharedLibraryUtil, getLibraryPathMethod, 1) != 0) {
+        __android_log_print(ANDROID_LOG_ERROR, "EMUIIteratorFix", "Failed to register the mitigation method");
+        (*env)->ExceptionClear(env);
+    }
+}
+
 void critical_set_stackqueue(jboolean use_input_stack_queue) {
     pojav_environ->isUseStackQueueCall = (int) use_input_stack_queue;
 }

app_pojavlauncher/src/main/jni/utils.h

@@ -11,5 +11,6 @@ jstring convertStringJVM(JNIEnv* srcEnv, JNIEnv* dstEnv, jstring srcStr);
 
 void hookExec();
 void installLinkerBugMitigation();
+void installEMUIIteratorMititgation();
 JNIEXPORT jstring JNICALL Java_org_lwjgl_glfw_CallbackBridge_nativeClipboard(JNIEnv* env, jclass clazz, jint action, jbyteArray copySrc);