Use platform delegate systemcall sendfile

app/src/main/java/com/hippo/Native.kt

@@ -18,6 +18,8 @@
 package com.hippo
 
 import android.os.ParcelFileDescriptor
+import android.system.Int64Ref
+import android.system.Os
 import java.io.FileDescriptor
 
 object Native {
@@ -27,22 +29,19 @@ object Native {
 
     @JvmStatic
     external fun getFd(fd: FileDescriptor?): Int
+}
 
-    @JvmStatic
-    external fun sendfile(from: Int, to: Int)
+private fun sendFileTotally(from: FileDescriptor, to: FileDescriptor) {
+    Os.sendfile(to, from, Int64Ref(0), Long.MAX_VALUE)
 }
 
 val FileDescriptor.fd
     get() = Native.getFd(this)
 
-infix fun ParcelFileDescriptor.receivefrom(fd: FileDescriptor) {
-    Native.sendfile(fd.fd, getFd())
+infix fun ParcelFileDescriptor.sendTo(fd: FileDescriptor) {
+    sendFileTotally(fileDescriptor, fd)
 }
 
-infix fun ParcelFileDescriptor.copyTo(fd: FileDescriptor) {
-    Native.sendfile(getFd(), fd.fd)
-}
-
-infix fun ParcelFileDescriptor.copyTo(fd: ParcelFileDescriptor) {
-    Native.sendfile(getFd(), fd.fd)
+infix fun ParcelFileDescriptor.sendTo(fd: ParcelFileDescriptor) {
+    sendFileTotally(fileDescriptor, fd.fileDescriptor)
 }

app/src/main/java/com/hippo/ehviewer/EhDB.kt

@@ -21,7 +21,6 @@ import android.os.ParcelFileDescriptor
 import android.os.ParcelFileDescriptor.MODE_READ_ONLY
 import androidx.paging.PagingSource
 import androidx.room.Room.databaseBuilder
-import com.hippo.Native
 import com.hippo.ehviewer.EhApplication.Companion.ehDatabase
 import com.hippo.ehviewer.client.data.GalleryInfo
 import com.hippo.ehviewer.dao.BasicDao
@@ -34,6 +33,7 @@ import com.hippo.ehviewer.dao.HistoryInfo
 import com.hippo.ehviewer.dao.LocalFavoriteInfo
 import com.hippo.ehviewer.dao.QuickSearch
 import com.hippo.ehviewer.download.DownloadManager
+import com.hippo.sendTo
 
 object EhDB {
     private const val CUR_DB_VER = 4
@@ -379,7 +379,7 @@ object EhDB {
             val dbFile = context.getDatabasePath(ehExportName)
             context.contentResolver.openFileDescriptor(uri, "rw")!!.use { toFd ->
                 ParcelFileDescriptor.open(dbFile, MODE_READ_ONLY).use { fromFd ->
-                    Native.sendfile(fromFd.fd, toFd.fd)
+                    fromFd sendTo toFd
                 }
             }
             return true

app/src/main/java/com/hippo/ehviewer/spider/SpiderDen.kt

@@ -22,7 +22,7 @@ import coil.decode.DecodeUtils
 import coil.decode.FrameDelayRewritingSource
 import coil.decode.isGif
 import coil.disk.DiskCache
-import com.hippo.copyTo
+import com.hippo.sendTo
 import com.hippo.ehviewer.EhApplication
 import com.hippo.ehviewer.EhApplication.Companion.application
 import com.hippo.ehviewer.EhDB
@@ -119,7 +119,7 @@ class SpiderDen(private val mGalleryInfo: GalleryInfo) {
                 val file = dir.createFile(generateImageFilename(index, extension)) ?: return false
                 (file.openOutputStream() as FileOutputStream).use { outputStream ->
                     ParcelFileDescriptor.open(data.toFile(), MODE_READ_WRITE).use {
-                        it copyTo outputStream.fd
+                        it sendTo outputStream.fd
                     }
                 }
             }