Catch debug log FileNotFoundExceptions (DEV) (#3259)

* On low storage, the system may clean caches without asking, if the parent dir of the debuglog is deleted, writing will fail with an exception.
Catch that exception, and try to recreate the path+file, otherwise fail silently.

* Update logsize after retry as log could have been deleted.

Co-authored-by: harambasicluka <64483219+harambasicluka@users.noreply.github.com>
Co-authored-by: AlexanderAlferov <64849422+AlexanderAlferov@users.noreply.github.com>

Corona-Warn-App/src/main/java/de/rki/coronawarnapp/bugreporting/debuglog/internal/LogWriter.kt

 package de.rki.coronawarnapp.bugreporting.debuglog.internal
 
+import android.annotation.SuppressLint
+import android.util.Log
 import kotlinx.coroutines.flow.MutableStateFlow
 import kotlinx.coroutines.sync.Mutex
 import kotlinx.coroutines.sync.withLock
 import timber.log.Timber
 import java.io.File
+import java.io.FileNotFoundException
 import javax.inject.Inject
 
+@Suppress("BlockingMethodInNonBlockingContext")
+@SuppressLint("LogNotTimber")
 class LogWriter @Inject constructor(val logFile: File) {
     private var ioLimiter = 0
     private val mutex = Mutex()
@@ -34,7 +39,28 @@ class LogWriter @Inject constructor(val logFile: File) {
     }
 
     suspend fun write(formattedLine: String): Unit = mutex.withLock {
-        logFile.appendText(formattedLine + "\n", Charsets.UTF_8)
+        val performWrite = {
+            logFile.appendText(formattedLine + "\n", Charsets.UTF_8)
+        }
+
+        try {
+            performWrite()
+        } catch (e: FileNotFoundException) {
+            Log.e(TAG, "Log file didn't exist when we tried to write, retry.")
+
+            try {
+                logFile.parentFile?.mkdirs()
+                logFile.createNewFile()
+                logFile.writeText("Logfile was deleted.\n")
+
+                performWrite()
+
+                updateLogSize()
+            } catch (e: Exception) {
+                Log.e(TAG, "LogWrite retry failed, something is just wrong...", e)
+                return@withLock
+            }
+        }
 
         if (ioLimiter % 10 == 0) {
             updateLogSize()
@@ -42,4 +68,8 @@ class LogWriter @Inject constructor(val logFile: File) {
         }
         ioLimiter++
     }
+
+    companion object {
+        private const val TAG = "LogWriter"
+    }
 }

Corona-Warn-App/src/test/java/de/rki/coronawarnapp/bugreporting/debuglog/internal/LogWriterTest.kt

@@ -45,4 +45,27 @@ class LogWriterTest : BaseIOTest() {
             logSize.value shouldBe 0L
         }
     }
+
+    /**
+     * e.g. System cache cleaning interferring
+     */
+    @Test
+    fun `if the file is deleted after setup we try to recreate it and do not crash`() = runBlockingTest {
+        createInstance().apply {
+            setup()
+            write("ABC")
+            logFile.readText() shouldBe "ABC\n"
+
+            logSize.value shouldBe 4L
+
+            logFile.delete()
+            logFile.parentFile!!.delete()
+            logFile.exists() shouldBe false
+
+            write("DEF")
+            logFile.readText() shouldBe "Logfile was deleted.\nDEF\n"
+
+            logSize.value shouldBe 25L
+        }
+    }
 }