From b3dfe37aeac0fbe3c036dcb65cf3760a0e796849 Mon Sep 17 00:00:00 2001
From: Sergei Zimmerman <sergei@zimmerman.foo>
Date: Wed, 19 Nov 2025 01:50:19 +0300
Subject: [PATCH] libstore/filetransfer: Handle exceptions in progressCallback

---
 src/libstore/filetransfer.cc | 17 ++++++++++-------
 1 file changed, 10 insertions(+), 7 deletions(-)

diff --git a/src/libstore/filetransfer.cc b/src/libstore/filetransfer.cc
index ba5e000b3..c3ad763e4 100644
--- a/src/libstore/filetransfer.cc
+++ b/src/libstore/filetransfer.cc
@@ -277,14 +277,17 @@ struct curlFileTransfer : public FileTransfer
             return ((TransferItem *) userp)->headerCallback(contents, size, nmemb);
         }
 
-        int progressCallback(curl_off_t dltotal, curl_off_t dlnow)
-        {
-            try {
-                act.progress(dlnow, dltotal);
-            } catch (nix::Interrupted &) {
-                assert(getInterrupted());
-            }
+        int progressCallback(curl_off_t dltotal, curl_off_t dlnow) noexcept
+        try {
+            act.progress(dlnow, dltotal);
             return getInterrupted();
+        } catch (nix::Interrupted &) {
+            assert(getInterrupted());
+            return 1;
+        } catch (...) {
+            /* Something unexpected has happened like logger throwing an exception. */
+            callbackException = std::current_exception();
+            return 1;
         }
 
         static int progressCallbackWrapper(