#1663 Improve FileSystem detection - read from mount and fallback to file writing

app/src/main/java/org/kiwix/kiwixmobile/di/modules/KiwixModule.kt

@@ -22,7 +22,11 @@ import android.content.Context
 import android.location.LocationManager
 import dagger.Module
 import dagger.Provides
+import org.kiwix.kiwixmobile.core.utils.SharedPreferenceUtil
 import org.kiwix.kiwixmobile.di.KiwixScope
+import org.kiwix.kiwixmobile.zim_manager.Fat32Checker
+import org.kiwix.kiwixmobile.zim_manager.FileWritingFileSystemChecker
+import org.kiwix.kiwixmobile.zim_manager.MountFileSystemChecker
 
 @Module
 object KiwixModule {
@@ -31,4 +35,13 @@ object KiwixModule {
   @JvmStatic
   internal fun provideLocationManager(context: Context): LocationManager =
     context.getSystemService(Context.LOCATION_SERVICE) as LocationManager
+
+  @Provides
+  @KiwixScope
+  @JvmStatic
+  internal fun provideFat32Checker(sharedPreferenceUtil: SharedPreferenceUtil): Fat32Checker =
+    Fat32Checker(
+      sharedPreferenceUtil,
+      listOf(MountFileSystemChecker(), FileWritingFileSystemChecker())
+    )
 }

app/src/main/java/org/kiwix/kiwixmobile/zim_manager/Fat32Checker.kt

@@ -18,7 +18,6 @@
 package org.kiwix.kiwixmobile.zim_manager
 
 import android.os.FileObserver
-import android.util.Log
 import io.reactivex.Flowable
 import io.reactivex.functions.BiFunction
 import io.reactivex.processors.BehaviorProcessor
@@ -28,11 +27,15 @@ import org.kiwix.kiwixmobile.zim_manager.Fat32Checker.FileSystemState.CanWrite4G
 import org.kiwix.kiwixmobile.zim_manager.Fat32Checker.FileSystemState.CannotWrite4GbFile
 import org.kiwix.kiwixmobile.zim_manager.Fat32Checker.FileSystemState.NotEnoughSpaceFor4GbFile
 import org.kiwix.kiwixmobile.zim_manager.Fat32Checker.FileSystemState.Unknown
+import org.kiwix.kiwixmobile.zim_manager.FileSystemCapability.CANNOT_WRITE_4GB
+import org.kiwix.kiwixmobile.zim_manager.FileSystemCapability.CAN_WRITE_4GB
+import org.kiwix.kiwixmobile.zim_manager.FileSystemCapability.INCONCLUSIVE
 import java.io.File
-import java.io.RandomAccessFile
-import javax.inject.Inject
 
-class Fat32Checker @Inject constructor(sharedPreferenceUtil: SharedPreferenceUtil) {
+class Fat32Checker constructor(
+  sharedPreferenceUtil: SharedPreferenceUtil,
+  private val fileSystemCheckers: List<FileSystemChecker>
+) {
   val fileSystemStates: BehaviorProcessor<FileSystemState> = BehaviorProcessor.create()
   private var fileObserver: FileObserver? = null
   private val requestCheckSystemFileType = BehaviorProcessor.createDefault(Unit)
@@ -59,10 +62,7 @@ class Fat32Checker @Inject constructor(sharedPreferenceUtil: SharedPreferenceUti
 
   private fun fileObserver(it: String?): FileObserver {
     return object : FileObserver(it, MOVED_FROM or DELETE) {
-      override fun onEvent(
-        event: Int,
-        path: String?
-      ) {
+      override fun onEvent(event: Int, path: String?) {
         requestCheckSystemFileType.onNext(Unit)
       }
     }.apply { startWatching() }
@@ -77,20 +77,16 @@ class Fat32Checker @Inject constructor(sharedPreferenceUtil: SharedPreferenceUti
     }
 
   private fun canCreate4GbFile(storage: String): Boolean {
-    val path = "$storage/large_file_test.txt"
-    File(path).deleteIfExists()
-    try {
-      RandomAccessFile(path, "rw").use {
-        it.setLength(FOUR_GIGABYTES_IN_BYTES)
-        return@canCreate4GbFile true
+    fileSystemCheckers.forEach {
+      when (it.checkFilesystemSupports4GbFiles(storage)) {
+        CAN_WRITE_4GB -> return@canCreate4GbFile true
+        CANNOT_WRITE_4GB -> return@canCreate4GbFile false
+        INCONCLUSIVE -> {
+          /*do nothing*/
+        }
       }
-    } catch (e: Exception) {
-      e.printStackTrace()
-      Log.d("Fat32Checker", e.message)
-      return false
-    } finally {
-      File(path).deleteIfExists()
     }
+    return false
   }
 
   companion object {
@@ -105,7 +101,3 @@ class Fat32Checker @Inject constructor(sharedPreferenceUtil: SharedPreferenceUti
     object Unknown : FileSystemState()
   }
 }
-
-private fun File.deleteIfExists() {
-  if (exists()) delete()
-}

app/src/main/java/org/kiwix/kiwixmobile/zim_manager/FileSystemChecker.kt

@@ -0,0 +1,29 @@
+/*
+ * Kiwix Android
+ * Copyright (c) 2020 Kiwix <android.kiwix.org>
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+package org.kiwix.kiwixmobile.zim_manager
+
+interface FileSystemChecker {
+  fun checkFilesystemSupports4GbFiles(path: String): FileSystemCapability
+}
+
+enum class FileSystemCapability {
+  CAN_WRITE_4GB,
+  CANNOT_WRITE_4GB,
+  INCONCLUSIVE
+}

app/src/main/java/org/kiwix/kiwixmobile/zim_manager/FileWritingFileSystemChecker.kt

@@ -0,0 +1,49 @@
+/*
+ * Kiwix Android
+ * Copyright (c) 2020 Kiwix <android.kiwix.org>
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+package org.kiwix.kiwixmobile.zim_manager
+
+import android.util.Log
+import org.kiwix.kiwixmobile.zim_manager.FileSystemCapability.CANNOT_WRITE_4GB
+import org.kiwix.kiwixmobile.zim_manager.FileSystemCapability.CAN_WRITE_4GB
+import java.io.File
+import java.io.RandomAccessFile
+
+class FileWritingFileSystemChecker : FileSystemChecker {
+  override fun checkFilesystemSupports4GbFiles(path: String): FileSystemCapability {
+    with(File("$path/large_file_test.txt")) {
+      deleteIfExists()
+      try {
+        RandomAccessFile(this.path, "rw").use {
+          it.setLength(Fat32Checker.FOUR_GIGABYTES_IN_BYTES)
+          return@checkFilesystemSupports4GbFiles CAN_WRITE_4GB
+        }
+      } catch (e: Exception) {
+        e.printStackTrace()
+        Log.d("Fat32Checker", e.message)
+        return@checkFilesystemSupports4GbFiles CANNOT_WRITE_4GB
+      } finally {
+        deleteIfExists()
+      }
+    }
+  }
+}
+
+private fun File.deleteIfExists() {
+  if (exists()) delete()
+}

app/src/main/java/org/kiwix/kiwixmobile/zim_manager/MountFileSystemChecker.kt

@@ -0,0 +1,72 @@
+/*
+ * Kiwix Android
+ * Copyright (c) 2020 Kiwix <android.kiwix.org>
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+package org.kiwix.kiwixmobile.zim_manager
+
+import org.kiwix.kiwixmobile.zim_manager.FileSystemCapability.CANNOT_WRITE_4GB
+import org.kiwix.kiwixmobile.zim_manager.FileSystemCapability.CAN_WRITE_4GB
+import org.kiwix.kiwixmobile.zim_manager.FileSystemCapability.INCONCLUSIVE
+import java.io.File
+
+class MountFileSystemChecker : FileSystemChecker {
+  override fun checkFilesystemSupports4GbFiles(path: String) =
+    recursivelyDetermineFilesystem(mountPoints(), path)
+
+  private fun recursivelyDetermineFilesystem(
+    mountPoints: List<MountInfo>,
+    path: String
+  ): FileSystemCapability =
+    mountPoints.maxBy { it.matchCount(path) }
+      ?.takeIf { it.matchCount(path) > 0 }
+      ?.let {
+        when {
+          it.isVirtual -> recursivelyDetermineFilesystem(mountPoints, it.device)
+          it.supports4GBFiles -> CAN_WRITE_4GB
+          it.doesNotSupport4GBFiles -> CANNOT_WRITE_4GB
+          else -> INCONCLUSIVE
+        }
+      } ?: INCONCLUSIVE
+
+  private fun mountPoints() =
+    File("proc/mounts")
+      .takeIf(File::exists)
+      ?.readLines()
+      ?.map { MountInfo(it.split(" ")) }
+      ?: emptyList()
+}
+
+data class MountInfo(val device: String, val mountPoint: String, val fileSystem: String) {
+  constructor(split: List<String>) : this(split[0], split[1], split[2])
+
+  fun matchCount(storage: String) = storage.split("/")
+    .zip(mountPoint.split("/"))
+    .fold(0, { acc, pair ->
+      if (pair.first == pair.second) acc + 1
+      else acc
+    })
+
+  val isVirtual = VIRTUAL_FILE_SYSTEMS.contains(fileSystem)
+  val supports4GBFiles = SUPPORTS_4GB_FILE_SYSTEMS.contains(fileSystem)
+  val doesNotSupport4GBFiles = DOES_NOT_SUPPORT_4GB_FILE_SYSTEMS.contains(fileSystem)
+
+  companion object {
+    private val VIRTUAL_FILE_SYSTEMS = listOf("fuse", "sdcardfs", "tmpfs")
+    private val SUPPORTS_4GB_FILE_SYSTEMS = listOf("ext4", "exfat")
+    private val DOES_NOT_SUPPORT_4GB_FILE_SYSTEMS = listOf("fat32")
+  }
+}