From 120fe44f4f563d584bc0718f29b6dcab96312230 Mon Sep 17 00:00:00 2001
From: mosandlt <10558666+mosandlt@users.noreply.github.com>
Date: Thu, 2 Jul 2026 05:47:14 +0200
Subject: [PATCH] fix(cmd,csync): don't silently ignore a missing --exclude
 file

nextcloudcmd's ExcludedFiles::reloadExcludeFiles() dropped a
registered exclude file from the list without any warning when
QFile::exists() returned false, and still reported success. A
mistyped or unresolved --exclude path (e.g. a relative path that
resolves differently under cron than interactively) therefore made
nextcloudcmd sync everything with zero exclusions and no diagnostic
in the log.

- csync_exclude.cpp: log a qWarning when a registered exclude file
  can't be found, instead of silently erasing it.
- cmd.cpp: fail fast with qFatal when a user-supplied --exclude path
  doesn't exist, instead of only discovering it deep inside
  reloadExcludeFiles() with no way to distinguish "path is wrong"
  from "path was never wrong to begin with".

Fixes #4621

Signed-off-by: mosandlt <10558666+mosandlt@users.noreply.github.com>
---
 src/cmd/cmd.cpp             | 9 +++++++++
 src/csync/csync_exclude.cpp | 1 +
 2 files changed, 10 insertions(+)

diff --git a/src/cmd/cmd.cpp b/src/cmd/cmd.cpp
index 78be38da19d61..d55582588d64a 100644
--- a/src/cmd/cmd.cpp
+++ b/src/cmd/cmd.cpp
@@ -547,6 +547,15 @@ int main(int argc, char **argv)
 
     // Always try to load the user-provided exclude list if one is specified
     if (hasUserExcludeFile) {
+        if (!QFile::exists(options.exclude)) {
+            // A user-supplied --exclude path that can't be found is a
+            // configuration error, not something to silently ignore:
+            // reloadExcludeFiles() below drops missing files without
+            // failing, which previously made the whole sync run with
+            // no exclusions and no diagnostic (see nextcloud/desktop#4621).
+            qFatal("Exclude list file supplied via --exclude does not exist: %s", qUtf8Printable(options.exclude));
+            return EXIT_FAILURE;
+        }
         engine.excludedFiles().addExcludeFilePath(options.exclude);
     }
     // Load the system list if available, or if there's no user-provided list
diff --git a/src/csync/csync_exclude.cpp b/src/csync/csync_exclude.cpp
index 72e585aea7bc1..438fa9aac3851 100644
--- a/src/csync/csync_exclude.cpp
+++ b/src/csync/csync_exclude.cpp
@@ -346,6 +346,7 @@ bool ExcludedFiles::reloadExcludeFiles()
             const auto &excludeFile = *excludeFileIt;
             QFile file(excludeFile);
             if (!file.exists()) {
+                qWarning() << "Exclude list file does not exist, skipping:" << excludeFile;
                 excludeFileIt = excludeFiles.erase(excludeFileIt);
                 continue;
             }