when cached snapshot is corrupted fall back to loading from backend

app/src/main/java/com/stevesoltys/seedvault/repo/SnapshotManager.kt

@@ -133,7 +133,12 @@ internal class SnapshotManager(
         val file = File(snapshotFolder, snapshotHandle.name)
         snapshotFolder.mkdirs()
         val inputStream = if (file.isFile) {
-            loader.loadFile(file, snapshotHandle.hash)
+            try {
+                loader.loadFile(file, snapshotHandle.hash)
+            } catch (e: Exception) {
+                log.error(e) { "Error loading $snapshotHandle from local cache. Trying backend..." }
+                loader.loadFile(snapshotHandle, file)
+            }
         } else {
             loader.loadFile(snapshotHandle, file)
         }

app/src/test/java/com/stevesoltys/seedvault/repo/SnapshotManagerTest.kt

@@ -34,6 +34,7 @@ import java.io.IOException
 import java.io.InputStream
 import java.io.OutputStream
 import java.nio.file.Path
+import java.security.GeneralSecurityException
 import java.security.MessageDigest
 import kotlin.random.Random
 
@@ -132,6 +133,26 @@ internal class SnapshotManagerTest : TransportTest() {
         assertEquals(listOf(snapshot), snapshotManager.loadCachedSnapshots())
     }
 
+    @Test
+    fun `snapshot corrupted on cache falls back to backend`(@TempDir tmpDir: Path) = runBlocking {
+        val snapshotManager = getSnapshotManager(File(tmpDir.toString()))
+        val snapshot = snapshot { token = 1337 }
+        val snapshotData = snapshot.toByteArray()
+        val inputStream = ByteArrayInputStream(snapshotData)
+        val snapshotHandle = AppBackupFileType.Snapshot(repoId, chunkId1)
+        val file = getSnapshotFolder(tmpDir, snapshotHandle.name)
+
+        every { crypto.repoId } returns repoId
+        coEvery { loader.loadFile(file, snapshotHandle.hash) } throws GeneralSecurityException()
+        coEvery { loader.loadFile(snapshotHandle, file) } returns inputStream
+
+        assertEquals(listOf(snapshot), snapshotManager.onSnapshotsLoaded(listOf(snapshotHandle)))
+
+        coVerify { // did load from backend
+            loader.loadFile(snapshotHandle, file)
+        }
+    }
+
     @Test
     fun `failing to load a snapshot isn't fatal`(@TempDir tmpDir: Path) = runBlocking {
         val snapshotManager = getSnapshotManager(File(tmpDir.toString()))