Change to discardOldestFileIfNeeded sorting

CHANGELOG.md

@@ -14,6 +14,9 @@
 * Sanity check the allocation in the installation of `bugsnag-plugin-android-ndk` to avoid a possible crash when allocation fails
   [#2191](https://github.com/bugsnag/bugsnag-android/pull/2191)
 
+* Added deterministic sorting for `discardOldestFileIfNeeded` method to avoid potential crashes when files are being written while sorting the queue
+  [#2181](https://github.com/bugsnag/bugsnag-android/pull/2189)
+
 ## 6.13.0 (2025-04-15)
 
 ### Enhancements

bugsnag-android-core/src/main/java/com/bugsnag/android/FileStore.kt

@@ -114,11 +114,21 @@ internal abstract class FileStore(
         if (isStorageDirValid(storageDir)) {
             val listFiles = storageDir.listFiles() ?: return
             if (listFiles.size < maxStoreCount) return
-            val sortedListFiles = listFiles.sortedBy { it.lastModified() }
+
+            // Store lastModified to ensure it doesn't change during sort
+            val timestampedFiles = listFiles.mapTo(ArrayList(listFiles.size)) { file ->
+                FileWithTimestamp(file, file.lastModified())
+            }
+
+            // Sort by cached lastModified timesstamps
+            timestampedFiles.sort()
+
             // Number of files to discard takes into account that a new file may need to be written
             val numberToDiscard = listFiles.size - maxStoreCount + 1
             var discardedCount = 0
-            for (file in sortedListFiles) {
+
+            for (fileMeta in timestampedFiles) {
+                val file = fileMeta.file
                 if (discardedCount == numberToDiscard) {
                     return
                 } else if (!queuedFiles.contains(file)) {
@@ -188,3 +198,15 @@ internal abstract class FileStore(
         }
     }
 }
+
+/**
+ * A data holder for associating a {@link File} with its last modified timestamp.
+ *
+ * @param file The file to associate with a timestamp.
+ * @param timestamp The last modified time of the file, cached to ensure consistent ordering.
+ */
+private data class FileWithTimestamp(val file: File, val timestamp: Long) : Comparable<FileWithTimestamp> {
+    override fun compareTo(other: FileWithTimestamp): Int {
+        return timestamp.compareTo(other.timestamp)
+    }
+}