Introducing reading zim file content through fileDescriptor instead of creating a file to avoid using storage twice for same zim file.

core/src/main/java/org/kiwix/kiwixmobile/core/main/CoreReaderFragment.kt

@@ -154,6 +154,7 @@ import org.kiwix.kiwixmobile.core.utils.dialog.KiwixDialog
 import org.kiwix.kiwixmobile.core.utils.files.FileUtils.deleteCachedFiles
 import org.kiwix.kiwixmobile.core.utils.files.FileUtils.readFile
 import java.io.File
+import java.io.FileDescriptor
 import java.io.IOException
 import java.text.SimpleDateFormat
 import java.util.Date
@@ -1386,13 +1387,20 @@ abstract class CoreReaderFragment :
     externalLinkOpener?.openExternalUrl(intent)
   }
 
-  protected fun openZimFile(file: File, isCustomApp: Boolean = false) {
+  protected fun openZimFile(
+    file: File?,
+    isCustomApp: Boolean = false,
+    fileDescriptor: FileDescriptor? = null
+  ) {
     if (hasPermission(Manifest.permission.READ_EXTERNAL_STORAGE) || isCustomApp) {
-      if (file.isFileExist()) {
+      if (file?.isFileExist() == true) {
-        openAndSetInContainer(file)
+        openAndSetInContainer(file = file)
+        updateTitle()
+      } else if (fileDescriptor != null) {
+        openAndSetInContainer(fileDescriptor = fileDescriptor)
         updateTitle()
       } else {
-        Log.w(TAG_KIWIX, "ZIM file doesn't exist at " + file.absolutePath)
+        Log.w(TAG_KIWIX, "ZIM file doesn't exist at " + file?.absolutePath)
         requireActivity().toast(R.string.error_file_not_found, Toast.LENGTH_LONG)
       }
     } else {
@@ -1419,16 +1427,21 @@ abstract class CoreReaderFragment :
     )
   }
 
-  private fun openAndSetInContainer(file: File) {
+  private fun openAndSetInContainer(file: File? = null, fileDescriptor: FileDescriptor? = null) {
     try {
-      if (isNotPreviouslyOpenZim(file.canonicalPath)) {
+      if (isNotPreviouslyOpenZim(file?.canonicalPath)) {
         webViewList.clear()
       }
     } catch (e: IOException) {
       e.printStackTrace()
     }
     zimReaderContainer?.let { zimReaderContainer ->
+      if (fileDescriptor != null) {
+        zimReaderContainer.setZimFileDescriptor(fileDescriptor)
+      } else {
         zimReaderContainer.setZimFile(file)
+      }
+
       val zimFileReader = zimReaderContainer.zimFileReader
       zimFileReader?.let { zimFileReader ->
         // uninitialized the service worker to fix https://github.com/kiwix/kiwix-android/issues/2561

core/src/main/java/org/kiwix/kiwixmobile/core/page/bookmark/adapter/BookmarkItem.kt

@@ -51,7 +51,7 @@ data class BookmarkItem(
   ) : this(
     zimId = zimFileReader.id,
     zimName = zimFileReader.name,
-    zimFilePath = zimFileReader.zimFile.canonicalPath,
+    zimFilePath = zimFileReader.zimFile?.canonicalPath,
     bookmarkUrl = url,
     title = title,
     favicon = zimFileReader.favicon

core/src/main/java/org/kiwix/kiwixmobile/core/page/history/adapter/HistoryListItem.kt

@@ -48,7 +48,7 @@ sealed class HistoryListItem : PageRelated {
     ) : this(
       zimId = zimFileReader.id,
       zimName = zimFileReader.name,
-      zimFilePath = zimFileReader.zimFile.canonicalPath,
+      zimFilePath = zimFileReader.zimFile?.canonicalPath ?: "",
       favicon = zimFileReader.favicon,
       historyUrl = url,
       title = title,

core/src/main/java/org/kiwix/kiwixmobile/core/page/notes/adapter/NoteListItem.kt

@@ -35,7 +35,7 @@ data class NoteListItem(
   ) : this(
     zimId = zimFileReader.id,
     title = title,
-    zimFilePath = zimFileReader.zimFile.canonicalPath,
+    zimFilePath = zimFileReader.zimFile?.canonicalPath,
     zimUrl = url,
     favicon = zimFileReader.favicon,
     noteFilePath = noteFilePath

core/src/main/java/org/kiwix/kiwixmobile/core/reader/ZimFileReader.kt

@@ -40,6 +40,7 @@ import org.kiwix.libzim.Item
 import org.kiwix.libzim.SuggestionSearch
 import org.kiwix.libzim.SuggestionSearcher
 import java.io.File
+import java.io.FileDescriptor
 import java.io.FileInputStream
 import java.io.IOException
 import java.io.InputStream
@@ -52,13 +53,14 @@ import javax.inject.Inject
 private const val TAG = "ZimFileReader"
 
 class ZimFileReader constructor(
-  val zimFile: File,
+  val zimFile: File?,
   private val jniKiwixReader: Archive,
   private val nightModeConfig: NightModeConfig,
   private val searcher: SuggestionSearcher = SuggestionSearcher(jniKiwixReader)
 ) {
   interface Factory {
     fun create(file: File): ZimFileReader?
+    fun create(fileDescriptor: FileDescriptor): ZimFileReader?
 
     class Impl @Inject constructor(private val nightModeConfig: NightModeConfig) :
       Factory {
@@ -76,6 +78,21 @@ class ZimFileReader constructor(
         } catch (ignore: Exception) { // for handing the error, if any zim file is corrupted
           null
         }
+
+      override fun create(fileDescriptor: FileDescriptor): ZimFileReader? =
+        try {
+          ZimFileReader(
+            null,
+            nightModeConfig = nightModeConfig,
+            jniKiwixReader = Archive(fileDescriptor)
+          ).also {
+            Log.e(TAG, "create: with fileDescriptor")
+          }
+        } catch (ignore: JNIKiwixException) {
+          null
+        } catch (ignore: Exception) { // for handing the error, if any zim file is corrupted
+          null
+        }
     }
   }
 

core/src/main/java/org/kiwix/kiwixmobile/core/reader/ZimReaderContainer.kt

@@ -21,6 +21,7 @@ import android.webkit.WebResourceResponse
 import org.kiwix.kiwixmobile.core.extensions.isFileExist
 import org.kiwix.kiwixmobile.core.reader.ZimFileReader.Factory
 import java.io.File
+import java.io.FileDescriptor
 import java.net.HttpURLConnection
 import javax.inject.Inject
 import javax.inject.Singleton
@@ -42,6 +43,12 @@ class ZimReaderContainer @Inject constructor(private val zimFileReaderFactory: F
       else null
   }
 
+  fun setZimFileDescriptor(fileDescriptor: FileDescriptor) {
+    zimFileReader =
+      if (fileDescriptor.valid()) zimFileReaderFactory.create(fileDescriptor)
+      else null
+  }
+
   fun getPageUrlFromTitle(title: String) = zimFileReader?.getPageUrlFrom(title)
 
   fun getRandomArticleUrl() = zimFileReader?.getRandomArticleUrl()

core/src/main/java/org/kiwix/kiwixmobile/core/webserver/ZimHostFragment.kt

@@ -487,13 +487,16 @@ class ZimHostFragment : BaseFragment(), ZimHostCallbacks, ZimHostContract.View {
         if (it is BookOnDisk) {
           zimReaderFactory.create(it.file)?.let { zimFileReader ->
             val booksOnDiskListItem =
-              (BookOnDisk(zimFileReader.zimFile, zimFileReader) as BooksOnDiskListItem)
+              zimFileReader.zimFile?.let { file ->
+                (BookOnDisk(file, zimFileReader) as BooksOnDiskListItem)
                   .apply {
                     isSelected = true
                   }
-            updatedBooksList.add(booksOnDiskListItem).also {
-              zimFileReader.dispose()
               }
+            if (booksOnDiskListItem != null) {
+              updatedBooksList.add(booksOnDiskListItem)
+            }
+            zimFileReader.dispose()
           }
         } else {
           updatedBooksList.add(it)

custom/src/main/java/org/kiwix/kiwixmobile/custom/main/CustomFileValidator.kt

@@ -22,13 +22,12 @@ import android.content.Context
 import android.content.pm.PackageManager
 import android.util.Log
 import androidx.core.content.ContextCompat
-import org.kiwix.kiwixmobile.core.extensions.isFileExist
 import org.kiwix.kiwixmobile.custom.BuildConfig
 import org.kiwix.kiwixmobile.custom.main.ValidationState.HasBothFiles
 import org.kiwix.kiwixmobile.custom.main.ValidationState.HasFile
 import org.kiwix.kiwixmobile.custom.main.ValidationState.HasNothing
 import java.io.File
-import java.io.FileOutputStream
+import java.io.FileDescriptor
 import java.io.IOException
 import javax.inject.Inject
 
@@ -44,10 +43,10 @@ class CustomFileValidator @Inject constructor(private val context: Context) {
   private fun detectInstallationState(
     obbFiles: List<File> = obbFiles(),
     zimFiles: List<File> = zimFiles(),
-    assetFile: File? = getFileFromPlayAssetDelivery()
+    assetFileDescriptor: FileDescriptor? = getFileFromPlayAssetDelivery()
   ): ValidationState {
     return when {
-      assetFile != null -> HasFile(assetFile)
+      assetFileDescriptor != null -> HasFile(null, assetFileDescriptor)
       obbFiles.isNotEmpty() && zimFiles().isNotEmpty() -> HasBothFiles(obbFiles[0], zimFiles[0])
       obbFiles.isNotEmpty() -> HasFile(obbFiles[0])
       zimFiles.isNotEmpty() -> HasFile(zimFiles[0])
@@ -56,30 +55,12 @@ class CustomFileValidator @Inject constructor(private val context: Context) {
   }
 
   @Suppress("NestedBlockDepth", "MagicNumber")
-  private fun getFileFromPlayAssetDelivery(): File? {
+  private fun getFileFromPlayAssetDelivery(): FileDescriptor? {
-    var zimFile: File? = null
     try {
       val context = context.createPackageContext(context.packageName, 0)
       val assetManager = context.assets
-      val inputStream = assetManager.open(BuildConfig.PLAY_ASSET_FILE)
+      val inputStream = assetManager.openFd(BuildConfig.PLAY_ASSET_FILE)
-      val filePath = ContextCompat.getExternalFilesDirs(context, null)[0]
+      return inputStream.fileDescriptor
-      zimFile = File(filePath, BuildConfig.PLAY_ASSET_FILE)
-      // Write zim file data if file does not exist or corrupted
-      if (!zimFile.isFileExist() || zimFile.length() == 0L) {
-        // Delete previously corrupted file
-        if (zimFile.isFileExist()) zimFile.delete()
-        zimFile.createNewFile()
-        FileOutputStream(zimFile).use { outputSteam ->
-          inputStream.use { inputStream ->
-            val buffer = ByteArray(1024)
-            var length: Int
-            while (inputStream.read(buffer).also { length = it } > 0) {
-              outputSteam.write(buffer, 0, length)
-            }
-            outputSteam.flush()
-          }
-        }
-      }
     } catch (packageNameNotFoundException: PackageManager.NameNotFoundException) {
       Log.w(
         "ASSET_PACKAGE_DELIVERY",
@@ -88,7 +69,7 @@ class CustomFileValidator @Inject constructor(private val context: Context) {
     } catch (ioException: IOException) {
       Log.w("ASSET_PACKAGE_DELIVERY", "Unable to copy the content of asset $ioException")
     }
-    return zimFile
+    return null
   }
 
   private fun obbFiles() = scanDirs(ContextCompat.getObbDirs(context), "obb")
@@ -124,6 +105,8 @@ class CustomFileValidator @Inject constructor(private val context: Context) {
 
 sealed class ValidationState {
   data class HasBothFiles(val obbFile: File, val zimFile: File) : ValidationState()
-  data class HasFile(val file: File) : ValidationState()
+  data class HasFile(val file: File?, val fileDescriptor: FileDescriptor? = null) :
+    ValidationState()
+
   object HasNothing : ValidationState()
 }

custom/src/main/java/org/kiwix/kiwixmobile/custom/main/CustomReaderFragment.kt

@@ -143,7 +143,13 @@ class CustomReaderFragment : CoreReaderFragment() {
     customFileValidator.validate(
       onFilesFound = {
         when (it) {
-          is ValidationState.HasFile -> openZimFile(it.file, true)
+          is ValidationState.HasFile -> {
+            if (it.fileDescriptor != null) {
+              openZimFile(null, true, it.fileDescriptor)
+            } else {
+              openZimFile(it.file, true)
+            }
+          }
           is ValidationState.HasBothFiles -> {
             it.zimFile.delete()
             openZimFile(it.obbFile, true)