androidmedia: Split jni code to gstjniutils.c

1 files changed, 484 insertions, 0 deletions

diff --git a/sys/androidmedia/gstjniutils.c b/sys/androidmedia/gstjniutils.c
new file mode 100644
index 000000000..9d8a4777f
--- /dev/null
+++ b/sys/androidmedia/gstjniutils.c
@@ -0,0 +1,484 @@
+/*
+ * Copyright (C) 2012, Collabora Ltd.
+ *   Author: Sebastian Dröge <sebastian.droege@collabora.co.uk>
+ * Copyright (C) 2013, Fluendo S.A.
+ *   Author: Andoni Morales <amorales@fluendo.com>
+ * Copyright (C) 2014, Sebastian Dröge <sebastian@centricular.com>
+ * Copyright (C) 2014, Collabora Ltd.
+ *   Author: Matthieu Bouron <matthieu.bouron@collabora.com>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation
+ * version 2.1 of the License.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301 USA
+ *
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include <gst/gst.h>
+#include <pthread.h>
+#include <gmodule.h>
+
+#include "gstjniutils.h"
+
+static GModule *java_module;
+static jint (*get_created_java_vms) (JavaVM ** vmBuf, jsize bufLen,
+    jsize * nVMs);
+static jint (*create_java_vm) (JavaVM ** p_vm, JNIEnv ** p_env, void *vm_args);
+static JavaVM *java_vm;
+static gboolean initialized = FALSE;
+static gboolean started_java_vm = FALSE;
+static pthread_key_t current_jni_env;
+
+/* getExceptionSummary() and getStackTrace() taken from Android's
+ *   platform/libnativehelper/JNIHelp.cpp
+ * Modified to work with normal C strings and without C++.
+ *
+ * Copyright (C) 2006 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/*
+ * Returns a human-readable summary of an exception object. The buffer will
+ * be populated with the "binary" class name and, if present, the
+ * exception message.
+ */
+static gchar *
+getExceptionSummary (JNIEnv * env, jthrowable exception)
+{
+  GString *gs = g_string_new ("");
+  jclass exceptionClass = NULL, classClass = NULL;
+  jmethodID classGetNameMethod, getMessage;
+  jstring classNameStr = NULL, messageStr = NULL;
+  const char *classNameChars, *messageChars;
+
+  /* get the name of the exception's class */
+  exceptionClass = (*env)->GetObjectClass (env, exception);
+  classClass = (*env)->GetObjectClass (env, exceptionClass);
+  classGetNameMethod =
+      (*env)->GetMethodID (env, classClass, "getName", "()Ljava/lang/String;");
+
+  classNameStr =
+      (jstring) (*env)->CallObjectMethod (env, exceptionClass,
+      classGetNameMethod);
+
+  if (classNameStr == NULL) {
+    if ((*env)->ExceptionCheck (env))
+      (*env)->ExceptionClear (env);
+    g_string_append (gs, "<error getting class name>");
+    goto done;
+  }
+
+  classNameChars = (*env)->GetStringUTFChars (env, classNameStr, NULL);
+  if (classNameChars == NULL) {
+    if ((*env)->ExceptionCheck (env))
+      (*env)->ExceptionClear (env);
+    g_string_append (gs, "<error getting class name UTF-8>");
+    goto done;
+  }
+
+  g_string_append (gs, classNameChars);
+
+  (*env)->ReleaseStringUTFChars (env, classNameStr, classNameChars);
+
+  /* if the exception has a detail message, get that */
+  getMessage =
+      (*env)->GetMethodID (env, exceptionClass, "getMessage",
+      "()Ljava/lang/String;");
+  messageStr = (jstring) (*env)->CallObjectMethod (env, exception, getMessage);
+  if (messageStr == NULL) {
+    if ((*env)->ExceptionCheck (env))
+      (*env)->ExceptionClear (env);
+    goto done;
+  }
+  g_string_append (gs, ": ");
+
+  messageChars = (*env)->GetStringUTFChars (env, messageStr, NULL);
+  if (messageChars != NULL) {
+    g_string_append (gs, messageChars);
+    (*env)->ReleaseStringUTFChars (env, messageStr, messageChars);
+  } else {
+    if ((*env)->ExceptionCheck (env))
+      (*env)->ExceptionClear (env);
+    g_string_append (gs, "<error getting message>");
+  }
+
+done:
+  if (exceptionClass)
+    (*env)->DeleteLocalRef (env, exceptionClass);
+  if (classClass)
+    (*env)->DeleteLocalRef (env, classClass);
+  if (classNameStr)
+    (*env)->DeleteLocalRef (env, classNameStr);
+  if (messageStr)
+    (*env)->DeleteLocalRef (env, messageStr);
+
+  return g_string_free (gs, FALSE);
+}
+
+/*
+ * Returns an exception (with stack trace) as a string.
+ */
+static gchar *
+getStackTrace (JNIEnv * env, jthrowable exception)
+{
+  GString *gs = g_string_new ("");
+  jclass stringWriterClass = NULL, printWriterClass = NULL;
+  jclass exceptionClass = NULL;
+  jmethodID stringWriterCtor, stringWriterToStringMethod;
+  jmethodID printWriterCtor, printStackTraceMethod;
+  jobject stringWriter = NULL, printWriter = NULL;
+  jstring messageStr = NULL;
+  const char *utfChars;
+
+  stringWriterClass = (*env)->FindClass (env, "java/io/StringWriter");
+
+  if (stringWriterClass == NULL) {
+    g_string_append (gs, "<error getting java.io.StringWriter class>");
+    goto done;
+  }
+
+  stringWriterCtor =
+      (*env)->GetMethodID (env, stringWriterClass, "<init>", "()V");
+  stringWriterToStringMethod =
+      (*env)->GetMethodID (env, stringWriterClass, "toString",
+      "()Ljava/lang/String;");
+
+  printWriterClass = (*env)->FindClass (env, "java/io/PrintWriter");
+  if (printWriterClass == NULL) {
+    g_string_append (gs, "<error getting java.io.PrintWriter class>");
+    goto done;
+  }
+
+  printWriterCtor =
+      (*env)->GetMethodID (env, printWriterClass, "<init>",
+      "(Ljava/io/Writer;)V");
+  stringWriter = (*env)->NewObject (env, stringWriterClass, stringWriterCtor);
+  if (stringWriter == NULL) {
+    if ((*env)->ExceptionCheck (env))
+      (*env)->ExceptionClear (env);
+    g_string_append (gs, "<error creating new StringWriter instance>");
+    goto done;
+  }
+
+  printWriter =
+      (*env)->NewObject (env, printWriterClass, printWriterCtor, stringWriter);
+  if (printWriter == NULL) {
+    if ((*env)->ExceptionCheck (env))
+      (*env)->ExceptionClear (env);
+    g_string_append (gs, "<error creating new PrintWriter instance>");
+    goto done;
+  }
+
+  exceptionClass = (*env)->GetObjectClass (env, exception);
+  printStackTraceMethod =
+      (*env)->GetMethodID (env, exceptionClass, "printStackTrace",
+      "(Ljava/io/PrintWriter;)V");
+  (*env)->CallVoidMethod (env, exception, printStackTraceMethod, printWriter);
+  if ((*env)->ExceptionCheck (env)) {
+    (*env)->ExceptionClear (env);
+    g_string_append (gs, "<exception while printing stack trace>");
+    goto done;
+  }
+
+  messageStr = (jstring) (*env)->CallObjectMethod (env, stringWriter,
+      stringWriterToStringMethod);
+  if (messageStr == NULL) {
+    if ((*env)->ExceptionCheck (env))
+      (*env)->ExceptionClear (env);
+    g_string_append (gs, "<failed to call StringWriter.toString()>");
+    goto done;
+  }
+
+  utfChars = (*env)->GetStringUTFChars (env, messageStr, NULL);
+  if (utfChars == NULL) {
+    if ((*env)->ExceptionCheck (env))
+      (*env)->ExceptionClear (env);
+    g_string_append (gs, "<failed to get UTF chars for message>");
+    goto done;
+  }
+
+  g_string_append (gs, utfChars);
+
+  (*env)->ReleaseStringUTFChars (env, messageStr, utfChars);
+
+done:
+  if (stringWriterClass)
+    (*env)->DeleteLocalRef (env, stringWriterClass);
+  if (printWriterClass)
+    (*env)->DeleteLocalRef (env, printWriterClass);
+  if (exceptionClass)
+    (*env)->DeleteLocalRef (env, exceptionClass);
+  if (stringWriter)
+    (*env)->DeleteLocalRef (env, stringWriter);
+  if (printWriter)
+    (*env)->DeleteLocalRef (env, printWriter);
+  if (messageStr)
+    (*env)->DeleteLocalRef (env, messageStr);
+
+  return g_string_free (gs, FALSE);
+}
+
+static JNIEnv *
+gst_amc_jni_attach_current_thread (void)
+{
+  JNIEnv *env;
+  JavaVMAttachArgs args;
+
+  GST_DEBUG ("Attaching thread %p", g_thread_self ());
+  args.version = JNI_VERSION_1_6;
+  args.name = NULL;
+  args.group = NULL;
+
+  if ((*java_vm)->AttachCurrentThread (java_vm, &env, &args) < 0) {
+    GST_ERROR ("Failed to attach current thread");
+    return NULL;
+  }
+
+  return env;
+}
+
+static void
+gst_amc_jni_detach_current_thread (void *env)
+{
+  GST_DEBUG ("Detaching thread %p", g_thread_self ());
+  (*java_vm)->DetachCurrentThread (java_vm);
+}
+
+static gboolean
+check_nativehelper (void)
+{
+  GModule *module;
+  void **jni_invocation = NULL;
+  gboolean ret = FALSE;
+
+  module = g_module_open (NULL, G_MODULE_BIND_LOCAL);
+  if (!module)
+    return ret;
+
+  /* Check if libnativehelper is loaded in the process and if
+   * it has these awful wrappers for JNI_CreateJavaVM and
+   * JNI_GetCreatedJavaVMs that crash the app if you don't
+   * create a JniInvocation instance first. If it isn't we
+   * just fail here and don't initialize anything.
+   * See this code for reference:
+   * https://android.googlesource.com/platform/libnativehelper/+/master/JniInvocation.cpp
+   */
+  if (!g_module_symbol (module, "_ZN13JniInvocation15jni_invocation_E",
+          (gpointer *) & jni_invocation)) {
+    ret = TRUE;
+  } else {
+    ret = (jni_invocation != NULL && *jni_invocation != NULL);
+  }
+
+  g_module_close (module);
+
+  return ret;
+}
+
+static gboolean
+load_java_module (const gchar * name)
+{
+  java_module = g_module_open (name, G_MODULE_BIND_LOCAL);
+  if (!java_module)
+    goto load_failed;
+
+  if (!g_module_symbol (java_module, "JNI_CreateJavaVM",
+          (gpointer *) & create_java_vm))
+    goto symbol_error;
+
+  if (!g_module_symbol (java_module, "JNI_GetCreatedJavaVMs",
+          (gpointer *) & get_created_java_vms))
+    goto symbol_error;
+
+  return TRUE;
+
+load_failed:
+  {
+    GST_ERROR ("Failed to load Java module '%s': %s", GST_STR_NULL (name),
+        g_module_error ());
+    return FALSE;
+  }
+symbol_error:
+  {
+    GST_ERROR ("Failed to locate required JNI symbols in '%s': %s",
+        GST_STR_NULL (name), g_module_error ());
+    g_module_close (java_module);
+    java_module = NULL;
+    return FALSE;
+  }
+}
+
+static gboolean
+gst_amc_jni_initialize_java_vm (void)
+{
+  jsize n_vms;
+
+  /* Returns TRUE if we can safely
+   * a) get the current VMs and
+   * b) start a VM if none is started yet
+   *
+   * FIXME: On Android >= 4.4 we won't be able to safely start a
+   * VM on our own without using private C++ API!
+   */
+  if (!check_nativehelper ()) {
+    GST_ERROR ("Can't safely check for VMs or start a VM");
+    return FALSE;
+  }
+
+  if (!load_java_module (NULL)) {
+    if (!load_java_module ("libdvm"))
+      return FALSE;
+  }
+
+  n_vms = 0;
+  if (get_created_java_vms (&java_vm, 1, &n_vms) < 0)
+    goto get_created_failed;
+
+  if (n_vms > 0) {
+    GST_DEBUG ("Successfully got existing Java VM %p", java_vm);
+  } else {
+    JNIEnv *env;
+    JavaVMInitArgs vm_args;
+    JavaVMOption options[4];
+
+    GST_DEBUG ("Found no existing Java VM, trying to start one");
+
+    options[0].optionString = "-verbose:jni";
+    options[1].optionString = "-verbose:gc";
+    options[2].optionString = "-Xcheck:jni";
+    options[3].optionString = "-Xdebug";
+
+    vm_args.version = JNI_VERSION_1_4;
+    vm_args.options = options;
+    vm_args.nOptions = 4;
+    vm_args.ignoreUnrecognized = JNI_TRUE;
+    if (create_java_vm (&java_vm, &env, &vm_args) < 0)
+      goto create_failed;
+    GST_DEBUG ("Successfully created Java VM %p", java_vm);
+
+    started_java_vm = TRUE;
+  }
+
+  return java_vm != NULL;
+
+get_created_failed:
+  {
+    GST_ERROR ("Failed to get already created VMs");
+    g_module_close (java_module);
+    java_module = NULL;
+    return FALSE;
+  }
+create_failed:
+  {
+    GST_ERROR ("Failed to create a Java VM");
+    g_module_close (java_module);
+    java_module = NULL;
+    return FALSE;
+  }
+}
+
+static void
+gst_amc_jni_set_error_string (JNIEnv * env, GQuark domain, gint code,
+    GError ** err, const gchar * message)
+{
+  jthrowable exception;
+
+  if (!err) {
+    if ((*env)->ExceptionCheck (env))
+      (*env)->ExceptionClear (env);
+    return;
+  }
+
+  if ((*env)->ExceptionCheck (env)) {
+    if ((exception = (*env)->ExceptionOccurred (env))) {
+      gchar *exception_description, *exception_stacktrace;
+
+      /* Clear exception so that we can call Java methods again */
+      (*env)->ExceptionClear (env);
+
+      exception_description = getExceptionSummary (env, exception);
+      exception_stacktrace = getStackTrace (env, exception);
+      g_set_error (err, domain, code, "%s: %s\n%s", message,
+          exception_description, exception_stacktrace);
+      g_free (exception_description);
+      g_free (exception_stacktrace);
+
+      (*env)->DeleteLocalRef (env, exception);
+    } else {
+      (*env)->ExceptionClear (env);
+      g_set_error (err, domain, code, "%s", message);
+    }
+  } else {
+    g_set_error (err, domain, code, "%s", message);
+  }
+}
+
+G_GNUC_PRINTF (5, 6)
+     void gst_amc_jni_set_error (JNIEnv * env, GQuark domain, gint code,
+    GError ** err, const gchar * format, ...)
+{
+  gchar *message;
+  va_list var_args;
+
+  va_start (var_args, format);
+  message = g_strdup_vprintf (format, var_args);
+  va_end (var_args);
+
+  gst_amc_jni_set_error_string (env, domain, code, err, message);
+
+  g_free (message);
+}
+
+
+gboolean
+gst_amc_jni_initialize (void)
+{
+  if (!initialized) {
+    pthread_key_create (&current_jni_env, gst_amc_jni_detach_current_thread);
+    initialized = gst_amc_jni_initialize_java_vm ();
+  }
+  return initialized;
+}
+
+JNIEnv *
+gst_amc_jni_get_env (void)
+{
+  JNIEnv *env;
+
+  if ((env = pthread_getspecific (current_jni_env)) == NULL) {
+    env = gst_amc_jni_attach_current_thread ();
+    pthread_setspecific (current_jni_env, env);
+  }
+
+  return env;
+}
+
+gboolean
+gst_amc_jni_is_vm_started (void)
+{
+  return started_java_vm;
+}