android: handle null query results in ShareActivity

If contentResolver.query returns null, or the URI is invalid, skip processing and log instead of crashing.
Also, use 'use' for the cursor instead of 'let' to automatically close the cursor after processing.

Fixes tailscale/corp#24293

Signed-off-by: kari-ts <kari@tailscale.com>

android/src/main/java/com/tailscale/ipn/ShareActivity.kt

@@ -92,38 +92,37 @@ class ShareActivity : ComponentActivity() {
           }
         }
 
-    val pendingFiles: List<Ipn.OutgoingFile> =
-        uris?.filterNotNull()?.mapNotNull {
-          contentResolver?.query(it, null, null, null, null)?.let { c ->
-            val nameCol = c.getColumnIndex(OpenableColumns.DISPLAY_NAME)
-            val sizeCol = c.getColumnIndex(OpenableColumns.SIZE)
-            c.moveToFirst()
-            val name: String =
-                c.getString(nameCol)
-                    ?: run {
-                      // For some reason, some content resolvers don't return a name.
-                      // Try to build a name from a random integer plus file extension
-                      // (if type can be determined), else just a random integer.
-                      val rand = Random.nextLong()
-                      contentResolver.getType(it)?.let { mimeType ->
-                        MimeTypeMap.getSingleton().getExtensionFromMimeType(mimeType)?.let {
-                            extension ->
-                          "$rand.$extension"
-                        } ?: "$rand"
-                      } ?: "$rand"
+        val pendingFiles: List<Ipn.OutgoingFile> =
+        uris?.filterNotNull()?.mapNotNull { uri ->
+            contentResolver?.query(uri, null, null, null, null)?.use { cursor ->
+                val nameCol = cursor.getColumnIndex(OpenableColumns.DISPLAY_NAME)
+                val sizeCol = cursor.getColumnIndex(OpenableColumns.SIZE)
+
+                if (cursor.moveToFirst()) {
+                    val name: String = cursor.getString(nameCol)
+                        ?: generateFallbackName(uri)
+                    val size: Long = cursor.getLong(sizeCol)
+                    Ipn.OutgoingFile(Name = name, DeclaredSize = size).apply {
+                        this.uri = uri
                     }
-            val size = c.getLong(sizeCol)
-            c.close()
-            val file = Ipn.OutgoingFile(Name = name, DeclaredSize = size)
-            file.uri = it
-            file
-          }
-        } ?: emptyList()
+                } else {
+                    TSLog.e(TAG, "Cursor is empty for URI: $uri")
+                    null
+                }
+            }
+        } ?: emptyList()    
 
     if (pendingFiles.isEmpty()) {
       TSLog.e(TAG, "Share failure - no files extracted from intent")
     }
 
     requestedTransfers.set(pendingFiles)
   }
+
+  private fun generateFallbackName(uri: Uri): String {
+    val randomId = Random.nextLong()
+    val mimeType = contentResolver?.getType(uri)
+    val extension = mimeType?.let { MimeTypeMap.getSingleton().getExtensionFromMimeType(it) }
+    return if (extension != null) "$randomId.$extension" else randomId.toString()
+}
 }