refactor: migrate BlobProvider.java to Kotlin

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/modules/blob/BlobProvider.kt

@@ -0,0 +1,115 @@
+/*
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+package com.facebook.react.modules.blob
+
+import android.content.ContentProvider
+import android.content.ContentValues
+import android.database.Cursor
+import android.net.Uri
+import android.os.ParcelFileDescriptor
+import com.facebook.infer.annotation.Nullsafe
+import com.facebook.react.ReactApplication
+import java.io.FileNotFoundException
+import java.io.IOException
+import java.util.concurrent.ExecutorService
+import java.util.concurrent.Executors
+
+public final class BlobProvider : ContentProvider() {
+  private val executor: ExecutorService = Executors.newSingleThreadExecutor()
+
+  override fun onCreate(): Boolean = true
+
+  override fun query(
+    uri: Uri,
+    projection: Array<String>?,
+    selection: String?,
+    selectionArgs: Array<String>?,
+    sortOrder: String?
+  ): Cursor? = null;
+
+  override fun getType(uri: Uri): String? = null
+
+  override fun insert(uri: Uri, values: ContentValues?): Uri? = null
+
+  override fun delete(uri: Uri, selection: String?, selectionArgs: Array<String>?): Int = 0
+
+  override fun update(
+    uri: Uri,
+    values: ContentValues?,
+    selection: String?,
+    selectionArgs: Array<String>?
+  ): Int = 0
+
+  @Throws(FileNotFoundException::class)
+  override fun openFile(uri: Uri, mode: String): ParcelFileDescriptor? {
+    if (mode != "r") {
+      throw FileNotFoundException("Cannot open $uri in mode '$mode'")
+    }
+
+    var blobModule: BlobModule? = null
+    val context = context?.applicationContext ?: null
+    if (context is ReactApplication) {
+      val host = (context as ReactApplication).reactNativeHost
+      val reactContext = host.reactInstanceManager.currentReactContext
+        ?: throw RuntimeException("No ReactContext associated with BlobProvider")
+      blobModule = reactContext.getNativeModule(BlobModule::class.java)
+    }
+
+    if (blobModule == null) {
+      throw RuntimeException("No blob module associated with BlobProvider")
+    }
+
+    val data = blobModule.resolve(uri)
+      ?: throw FileNotFoundException("Cannot open $uri, blob not found.")
+
+    val pipe: Array<ParcelFileDescriptor>
+    try {
+      pipe = ParcelFileDescriptor.createPipe()
+    } catch (exception: IOException) {
+      return null
+    }
+    val readSide = pipe[0]
+    val writeSide = pipe[1]
+
+    if (data.size <= PIPE_CAPACITY) {
+      // If the blob length is less than or equal to pipe capacity (64 KB),
+      // we can write the data synchronously to the pipe buffer.
+      try {
+        ParcelFileDescriptor.AutoCloseOutputStream(writeSide).use { outputStream ->
+          outputStream.write(data)
+        }
+      } catch (exception: IOException) {
+        return null
+      }
+    } else {
+      // For blobs larger than 64 KB, a synchronous write would fill up the whole buffer
+      // and block forever, because there are no readers to empty the buffer.
+      // Writing from a separate thread allows us to return the read side descriptor
+      // immediately so that both writer and reader can work concurrently.
+      // Reading from the pipe empties the buffer and allows the next chunks to be written.
+      val writer =
+        Runnable {
+          try {
+            ParcelFileDescriptor.AutoCloseOutputStream(writeSide)
+              .use { outputStream ->
+                outputStream.write(data)
+              }
+          } catch (exception: IOException) {
+            // no-op
+          }
+        }
+      executor.submit(writer)
+    }
+
+    return readSide
+  }
+
+  private companion object {
+    private const val PIPE_CAPACITY = 65536
+  }
+}