ktaglib: implement iostream/file shim

ktaglib/src/main/cpp/AndroidIOStream.cpp

@@ -1,65 +0,0 @@
-//
-// Created by oxycblt on 12/12/24.
-//
-
-#include "AndroidIOStream.h"
-
-
-AndroidIOStream::AndroidIOStream(JNIEnv *env, jobject &fileRef) : env(env), fileRef(fileRef) {}
-
-AndroidIOStream::~AndroidIOStream() {}
-
-/*!
- * Returns the stream name in the local file system encoding.
- */
-TagLib::FileName AndroidIOStream::name() const {
-    return TagLib::FileName();
-};
-
-/*!
- * Reads a block of size \a length at the current get pointer.
- */
-TagLib::ByteVector AndroidIOStream::readBlock(size_t length) {
-    return {};
-};
-
-void AndroidIOStream::writeBlock(const TagLib::ByteVector &data) {
-    throw std::runtime_error("Not implemented");
-};
-
-void AndroidIOStream::insert(const TagLib::ByteVector &data,
-            TagLib::offset_t start, size_t replace) {
-    throw std::runtime_error("Not implemented");
-};
-
-void AndroidIOStream::removeBlock(TagLib::offset_t start, size_t length) {
-    throw std::runtime_error("Not implemented");
-};
-
-bool AndroidIOStream::readOnly() const {
-    return true;
-};
-
-bool AndroidIOStream::isOpen() const {
-
-};
-
-void AndroidIOStream::seek(TagLib::offset_t offset, Position p) {
-
-};
-
-void AndroidIOStream::clear() {
-
-}
-
-TagLib::offset_t AndroidIOStream::tell() const {
-    return 0;
-};
-
-TagLib::offset_t AndroidIOStream::length() {
-    return 0;
-};
-
-void AndroidIOStream::truncate(TagLib::offset_t length) {
-
-};

ktaglib/src/main/cpp/CMakeLists.txt

@@ -46,7 +46,7 @@ set_target_properties(
 add_library(${CMAKE_PROJECT_NAME} SHARED
         # List C/C++ source files with relative paths to this CMakeLists.txt.
         ktaglib.cpp
-        AndroidIOStream.cpp)
+        JVMInputStream.cpp)
 
 # Specifies libraries CMake should link to your target library. You
 # can link libraries from various origins, such as libraries defined in this

ktaglib/src/main/cpp/JVMInputStream.cpp

@@ -0,0 +1,101 @@
+//
+// Created by oxycblt on 12/12/24.
+//
+
+#include "JVMInputStream.h"
+
+#include <cmath>
+
+// TODO: Handle stream exceptions
+
+JVMInputStream::JVMInputStream(JNIEnv *env, jobject inputStream) :
+        env(env), inputStream(inputStream) {
+    if (!env->IsInstanceOf(inputStream, env->FindClass("org/oxycblt/ktaglib/NativeInputStream"))) {
+        throw std::runtime_error("oStream is not an instance of TagLibOStream");
+    }
+    jclass inputStreamClass = env->FindClass("org/oxycblt/ktaglib/NativeInputStream");
+    inputStreamNameMethod = env->GetMethodID(inputStreamClass, "name", "()Ljava/lang/String;");
+    inputStreamReadBlockMethod = env->GetMethodID(inputStreamClass, "readBlock", "(J)[B");
+    inputStreamIsOpenMethod = env->GetMethodID(inputStreamClass, "isOpen", "()Z");
+    inputStreamSeekFromBeginningMethod = env->GetMethodID(inputStreamClass, "seekFromBeginning",
+                                                          "(J)V");
+    inputStreamSeekFromCurrentMethod = env->GetMethodID(inputStreamClass, "seekFromCurrent",
+                                                        "(J)V");
+    inputStreamSeekFromEndMethod = env->GetMethodID(inputStreamClass, "seekFromEnd", "(J)V");
+    inputStreamClearMethod = env->GetMethodID(inputStreamClass, "clear", "()V");
+    inputStreamTellMethod = env->GetMethodID(inputStreamClass, "tell", "()J");
+    inputStreamLengthMethod = env->GetMethodID(inputStreamClass, "length", "()J");
+}
+
+JVMInputStream::~JVMInputStream() {}
+
+TagLib::FileName JVMInputStream::name() const {
+    auto name = (jstring) env->CallObjectMethod(inputStream, inputStreamNameMethod);
+    const char *nameChars = env->GetStringUTFChars(name, nullptr);
+    auto fileName = TagLib::FileName(nameChars);
+    env->ReleaseStringUTFChars(name, nameChars);
+    return fileName;
+}
+
+TagLib::ByteVector JVMInputStream::readBlock(size_t length) {
+    auto data = (jbyteArray) env->CallObjectMethod(inputStream, inputStreamReadBlockMethod, length);
+    jsize dataLength = env->GetArrayLength(data);
+    auto dataBytes = env->GetByteArrayElements(data, nullptr);
+    TagLib::ByteVector byteVector(reinterpret_cast<const char *>(dataBytes), dataLength);
+    env->ReleaseByteArrayElements(data, dataBytes, JNI_ABORT);
+    return byteVector;
+}
+
+void JVMInputStream::writeBlock(const TagLib::ByteVector &data) {
+    throw std::runtime_error("Not implemented");
+}
+
+void JVMInputStream::insert(const TagLib::ByteVector &data,
+                            TagLib::offset_t start, size_t replace) {
+    throw std::runtime_error("Not implemented");
+}
+
+void JVMInputStream::removeBlock(TagLib::offset_t start, size_t length) {
+    throw std::runtime_error("Not implemented");
+}
+
+bool JVMInputStream::readOnly() const {
+    return true;
+}
+
+bool JVMInputStream::isOpen() const {
+    return env->CallBooleanMethod(inputStream, inputStreamIsOpenMethod);
+}
+
+void JVMInputStream::seek(TagLib::offset_t offset, Position p) {
+    auto joffset = static_cast<jlong>(std::llround(offset));
+    switch (p) {
+        case Beginning:
+            env->CallVoidMethod(inputStream, inputStreamSeekFromBeginningMethod, joffset);
+            break;
+        case Current:
+            env->CallVoidMethod(inputStream, inputStreamSeekFromCurrentMethod, joffset);
+            break;
+        case End:
+            env->CallVoidMethod(inputStream, inputStreamSeekFromEndMethod, joffset);
+            break;
+    }
+}
+
+void JVMInputStream::clear() {
+    env->CallVoidMethod(inputStream, inputStreamClearMethod);
+}
+
+TagLib::offset_t JVMInputStream::tell() const {
+    jlong jposition = env->CallLongMethod(inputStream, inputStreamTellMethod);
+    return static_cast<TagLib::offset_t>(jposition);
+}
+
+TagLib::offset_t JVMInputStream::length() {
+    jlong jlength = env->CallLongMethod(inputStream, inputStreamLengthMethod);
+    return static_cast<TagLib::offset_t>(jlength);
+}
+
+void JVMInputStream::truncate(TagLib::offset_t length) {
+    throw std::runtime_error("Not implemented");
+}

ktaglib/src/main/cpp/JVMInputStream.h

@@ -2,21 +2,21 @@
 // Created by oxycblt on 12/12/24.
 //
 
-#ifndef AUXIO_ANDROIDIOSTREAM_H
+#ifndef AUXIO_JVMINPUTSTREAM_H
-#define AUXIO_ANDROIDIOSTREAM_H
+#define AUXIO_JVMINPUTSTREAM_H
 
 #include <jni.h>
 
 #include "taglib/tiostream.h"
 
-class AndroidIOStream : public  TagLib::IOStream {
+class JVMInputStream : public  TagLib::IOStream {
 public:
-    AndroidIOStream(JNIEnv *env, jobject &fileRef);
+    JVMInputStream(JNIEnv *env, jobject inputStream);
 
-    ~AndroidIOStream();
+    ~JVMInputStream();
 
-    AndroidIOStream(const AndroidIOStream &) = delete;
+    JVMInputStream(const JVMInputStream &) = delete;
-    AndroidIOStream &operator=(const AndroidIOStream &) = delete;
+    JVMInputStream &operator=(const JVMInputStream &) = delete;
 
     /*!
      * Returns the stream name in the local file system encoding.
@@ -99,8 +99,18 @@ public:
 
 private:
     JNIEnv *env;
-    jobject &fileRef;
+    jobject inputStream;
+    jmethodID inputStreamNameMethod;
+    jmethodID inputStreamReadBlockMethod;
+    jmethodID inputStreamIsOpenMethod;
+    jmethodID inputStreamSeekFromBeginningMethod;
+    jmethodID inputStreamSeekFromCurrentMethod;
+    jmethodID inputStreamSeekFromEndMethod;
+    jmethodID inputStreamClearMethod;
+    jmethodID inputStreamTellMethod;
+    jmethodID inputStreamLengthMethod;
+
 };
 
 
-#endif //AUXIO_ANDROIDIOSTREAM_H
+#endif //AUXIO_JVMINPUTSTREAM_H

ktaglib/src/main/cpp/ktaglib.cpp

@@ -1,16 +1,16 @@
 #include <jni.h>
 #include <string>
 
-#include "AndroidIOStream.h"
+#include "JVMInputStream.h"
 #include <taglib/fileref.h>
 #include <taglib/tag.h>
 
 extern "C" JNIEXPORT jobject JNICALL
-Java_org_oxycblt_ktaglib_KTagLib_load(
+Java_org_oxycblt_ktaglib_KTagLib_openNative(
         JNIEnv* env,
         jobject /* this */,
-        jobject fileRef) {
+        jobject inputStream) {
-    AndroidIOStream stream { env, fileRef };
+    JVMInputStream stream { env, inputStream };
     TagLib::FileRef file { &stream };
     if (file.isNull()) {
         return nullptr;
@@ -27,7 +27,8 @@ Java_org_oxycblt_ktaglib_KTagLib_load(
 
     jclass tagClass = env->FindClass("org/oxycblt/ktaglib/Tag");
     jmethodID tagInit = env->GetMethodID(tagClass, "<init>", "(Ljava/util/Map;Ljava/util/Map;[B)V");
-    // Create tag
+
     jobject tagObj = env->NewObject(tagClass, tagInit, id3v2, vorbis, coverData);
+
     return tagObj;
 }

ktaglib/src/main/java/org/oxycblt/ktaglib/AndroidInputStream.kt

@@ -0,0 +1,55 @@
+package org.oxycblt.ktaglib
+
+import android.content.Context
+import java.io.FileInputStream
+import java.nio.ByteBuffer
+
+class AndroidInputStream(
+    context: Context,
+    fileRef: FileRef
+) : NativeInputStream {
+    private val fileName = fileRef.fileName
+    private val fd = requireNotNull(context.contentResolver.openFileDescriptor(fileRef.uri, "r")) {
+        "Failed to open file descriptor for ${fileRef.fileName}"
+    }
+    private val fis = FileInputStream(fd.fileDescriptor)
+    private val channel = fis.channel
+
+    override fun name() = fileName
+
+    override fun readBlock(length: Long): ByteArray {
+        val buffer = ByteBuffer.allocate(length.toInt())
+        channel.read(buffer)
+        return buffer.array()
+    }
+
+    override fun isOpen(): Boolean {
+        return channel.isOpen
+    }
+
+    override fun seekFromBeginning(offset: Long) {
+        channel.position(offset)
+    }
+
+    override fun seekFromCurrent(offset: Long) {
+        channel.position(channel.position() + offset)
+    }
+
+    override fun seekFromEnd(offset: Long) {
+        channel.position(channel.size() - offset)
+    }
+
+    override fun clear() {
+        // Nothing to clear
+    }
+
+    override fun tell() = channel.position()
+
+    override fun length() = channel.size()
+
+    fun close() {
+        channel.close()
+        fis.close()
+        fd.close()
+    }
+}

ktaglib/src/main/java/org/oxycblt/ktaglib/KTagLib.kt

@@ -1,23 +1,32 @@
 package org.oxycblt.ktaglib
 
-import java.io.InputStream
+import android.content.Context
+import android.net.Uri
 
 object KTagLib {
-    // Used to load the 'ktaglib' library on application startup.
     init {
         System.loadLibrary("ktaglib")
     }
 
     /**
-     * A native method that is implemented by the 'ktaglib' native library,
+     * Open a file and extract a tag.
-     * which is packaged with this application.
+     *
+     * Note: This method is blocking and should be handled as such if
+     * calling from a coroutine.
      */
-    external fun load(fileRef: FileRef): Tag?
+    fun open(context: Context, ref: FileRef): Tag? {
+        val inputStream = AndroidInputStream(context, ref)
+        val tag = openNative(inputStream)
+        inputStream.close()
+        return tag
+    }
+
+    private external fun openNative(ioStream: AndroidInputStream): Tag?
 }
 
 data class FileRef(
     val fileName: String,
-    val inputStream: InputStream
+    val uri: Uri
 )
 
 data class Tag(

ktaglib/src/main/java/org/oxycblt/ktaglib/NativeInputStream.kt

@@ -0,0 +1,27 @@
+package org.oxycblt.ktaglib
+
+/**
+ * Java interface for the read-only methods in TagLib's IOStream API.
+ *
+ * The vast majority of IO shim between Taglib/KTaglib should occur here
+ * to minimize JNI calls.
+ */
+interface NativeInputStream {
+    fun name(): String
+
+    fun readBlock(length: Long): ByteArray
+
+    fun isOpen(): Boolean
+
+    fun seekFromBeginning(offset: Long)
+
+    fun seekFromCurrent(offset: Long)
+
+    fun seekFromEnd(offset: Long)
+
+    fun clear()
+
+    fun tell(): Long
+
+    fun length(): Long
+}