api-impl: use liblog for android.util.Log; use Log.v for debugging prints and Log.w for stub tracing

src/api-impl-jni/android_graphics_Bitmap.c

@@ -16,7 +16,7 @@
 JNIEXPORT jlong JNICALL Java_android_graphics_Bitmap_native_1bitmap_1from_1path(JNIEnv *env, jobject this, jobject path)
 {
 	GdkPixbuf *pixbuf = gdk_pixbuf_new_from_file(_CSTRING(path), NULL);
-	printf(">>> made pixbuf from path: >%s<, >%p<\n", _CSTRING(path), pixbuf);
+	android_log_printf(ANDROID_LOG_VERBOSE, "["__FILE__"]", ">>> made pixbuf from path: >%s<, >%p<\n", _CSTRING(path), pixbuf);
 
 	sk_imageinfo_t info = {
 		.width = gdk_pixbuf_get_width(pixbuf),

src/api-impl-jni/android_util_Log.c

@@ -0,0 +1,51 @@
+#include <stdio.h>
+
+#include "defines.h"
+#include "util.h"
+
+/* copied from AOSP:
+**
+** Copyright 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.
+*/
+
+JNIEXPORT jint JNICALL Java_android_util_Log_println_1native(JNIEnv* env, jobject this, jint bufID, jint priority, jstring tagObj, jstring msgObj)
+{
+	const char* tag = NULL;
+	const char* msg = NULL;
+
+	if (msgObj == NULL) {
+//		jniThrowNullPointerException(env, "println needs a message");
+		fprintf(stderr, "Log.println_native: println needs a message\n");
+		return -1;
+	}
+
+	if (bufID < 0 || bufID >= LOG_ID_MAX) {
+//		jniThrowNullPointerException(env, "bad bufID");
+		fprintf(stderr, "Log.println_native: bad bufID\n");
+		return -1;
+	}
+
+	if (tagObj != NULL)
+		tag = (*env)->GetStringUTFChars(env, tagObj, NULL);
+	msg = (*env)->GetStringUTFChars(env, msgObj, NULL);
+
+	int res = __android_log_buf_write(bufID, priority, tag, msg);
+
+	if (tag != NULL)
+		(*env)->ReleaseStringUTFChars(env, tagObj, tag);
+	(*env)->ReleaseStringUTFChars(env, msgObj, msg);
+
+	return res;
+}

src/api-impl-jni/generated_headers/android_util_Log.h

@@ -29,11 +29,11 @@ extern "C" {
 #define android_util_Log_LOG_ID_SYSTEM 3L
 /*
  * Class:     android_util_Log
- * Method:    isLoggable
- * Signature: (Ljava/lang/String;I)Z
+ * Method:    println_native
+ * Signature: (IILjava/lang/String;Ljava/lang/String;)I
  */
-JNIEXPORT jboolean JNICALL Java_android_util_Log_isLoggable
-  (JNIEnv *, jclass, jstring, jint);
+JNIEXPORT jint JNICALL Java_android_util_Log_println_1native
+  (JNIEnv *, jclass, jint, jint, jstring, jstring);
 
 #ifdef __cplusplus
 }

src/api-impl-jni/util.c

@@ -1,3 +1,6 @@
+#include <dlfcn.h>
+#include <pthread.h>
+
 #include "util.h"
 
 struct handle_cache handle_cache = {0};
@@ -140,3 +143,50 @@ void extract_from_apk(const char *path, const char *target) {
 	JNIEnv *env = get_jni_env();
 	(*env)->CallStaticObjectMethod(env, handle_cache.asset_manager.class, handle_cache.asset_manager.extractFromAPK, _JSTRING(path), _JSTRING(target));
 }
+
+/* logging with fallback to stderr */
+
+typedef int __android_log_vprint_type(int prio, const char *tag, const char *fmt, va_list ap);
+
+static int fallback_verbose_log(int prio, const char *tag, const char *fmt, va_list ap)
+{
+	int ret;
+
+	static pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;
+	pthread_mutex_lock(&mutex);
+	static char buf[1024];
+	ret = vsnprintf(buf, sizeof(buf), fmt, ap);
+	fprintf(stderr, "%lu: %s\n", pthread_self(), buf);
+	pthread_mutex_unlock(&mutex);
+
+	return ret;
+}
+
+static int android_log_vprintf(int prio, const char *tag, const char *fmt, va_list ap)
+{
+
+	static __android_log_vprint_type *_android_log_vprintf = NULL;
+	if(!_android_log_vprintf) {
+		_android_log_vprintf = dlsym(RTLD_DEFAULT, "__android_log_vprint");
+
+		if(!_android_log_vprintf) {
+			_android_log_vprintf = &fallback_verbose_log;
+		}
+	}
+
+	return _android_log_vprintf(prio, tag, fmt, ap);
+}
+
+int android_log_printf(android_LogPriority prio, const char *tag, const char *fmt, ...)
+{
+	int ret;
+
+	va_list ap;
+	va_start(ap, fmt);
+
+	ret = android_log_vprintf(prio, tag, fmt, ap);
+
+	va_end(ap);
+
+	return ret;
+}

src/api-impl-jni/util.h

@@ -107,4 +107,32 @@ void extract_from_apk(const char *path, const char *target);
 
 void prepare_main_looper(JNIEnv* env);
 
+/* we don't (currently?) install the headers for liblog */
+typedef enum {
+	LOG_ID_MAIN = 0,
+	LOG_ID_RADIO = 1,
+	LOG_ID_EVENTS = 2,
+	LOG_ID_SYSTEM = 3,
+
+	LOG_ID_MAX
+} log_id_t;
+
+typedef enum android_LogPriority {
+    ANDROID_LOG_UNKNOWN = 0,
+    ANDROID_LOG_DEFAULT,    /* only for SetMinPriority() */
+    ANDROID_LOG_VERBOSE,
+    ANDROID_LOG_DEBUG,
+    ANDROID_LOG_INFO,
+    ANDROID_LOG_WARN,
+    ANDROID_LOG_ERROR,
+    ANDROID_LOG_FATAL,
+    ANDROID_LOG_SILENT,     /* only for SetMinPriority(); must be last */
+} android_LogPriority;
+
+/* TODO: do we really need the bufID, or can we use our function below which has a stderr fallback */
+int __android_log_buf_write(int bufID, int prio, const char *tag, const char *text);
+
+/* defined in util.c */
+int android_log_printf(android_LogPriority prio, const char *tag, const char *fmt, ...);
+
 #endif