fix export overwrite if changed

src/control/jobs/control_jobs.c

@@ -1,6 +1,6 @@
 /*
     This file is part of darktable,
-    Copyright (C) 2010-2025 darktable developers.
+    Copyright (C) 2010-2026 darktable developers.
 
     darktable is free software: you can redistribute it and/or modify
     it under the terms of the GNU General Public License as published by
@@ -92,6 +92,7 @@ typedef struct dt_control_export_t
                                    // resets things like overwrite
                                    // once the export
   // is dispatched, but we have to keep that information
+  void *fdata;
   gboolean high_quality, upscale, export_masks, is_scaling;
   double scale_factor;
   char style[128];
@@ -1815,12 +1816,10 @@ static int32_t _control_export_job_run(dt_job_t *job)
     dt_imageio_get_storage_by_index(settings->storage_index);
   g_assert(mstorage);
   dt_imageio_module_data_t *sdata = settings->sdata;
+  dt_imageio_module_data_t *fdata = settings->fdata;
 
   gboolean tag_change = FALSE;
 
-  // get a thread-safe fdata struct (one jpeg struct per thread etc):
-  dt_imageio_module_data_t *fdata = mformat->get_params(mformat);
-
   if(mstorage->initialize_store)
   {
     if(mstorage->initialize_store(mstorage, sdata, &mformat, &fdata,
@@ -2553,6 +2552,7 @@ void dt_control_export(GList *imgid_list,
   data->max_height = max_height;
   data->format_index = format_index;
   data->storage_index = storage_index;
+
   dt_imageio_module_storage_t *mstorage = dt_imageio_get_storage_by_index(storage_index);
   g_assert(mstorage);
   // get shared storage param struct (global sequence counter, one picasa connection etc)
@@ -2565,6 +2565,19 @@ void dt_control_export(GList *imgid_list,
     return;
   }
   data->sdata = sdata;
+
+  dt_imageio_module_format_t *mformat = dt_imageio_get_format_by_index(format_index);
+  g_assert(mformat);
+  void *fdata = mformat->get_params(mformat);
+  if(fdata == NULL)
+  {
+    dt_control_log(_("failed to get parameters from format module `%s', aborting export.."),
+                   mformat->name());
+    dt_control_job_dispose(job);
+    return;
+  }
+  data->fdata = fdata;
+
   data->high_quality = high_quality;
   data->export_masks = export_masks;
   data->upscale = ((max_width == 0 && max_height == 0)

src/imageio/storage/disk.c

@@ -1,6 +1,6 @@
 /*
     This file is part of darktable,
-    Copyright (C) 2010-2025 darktable developers.
+    Copyright (C) 2010-2026 darktable developers.
 
     darktable is free software: you can redistribute it and/or modify
     it under the terms of the GNU General Public License as published by
@@ -18,6 +18,7 @@
 
 #include "bauhaus/bauhaus.h"
 #include "common/darktable.h"
+#include "common/datetime.h"
 #include "common/exif.h"
 #include "common/image.h"
 #include "common/image_cache.h"
@@ -34,6 +35,7 @@
 #include "imageio/imageio_common.h"
 #include "imageio/imageio_module.h"
 #include "imageio/storage/imageio_storage_api.h"
+#include <glib-2.0/gio/gio.h>
 #ifdef GDK_WINDOWING_QUARTZ
 #include "osx/osx.h"
 #endif
@@ -452,16 +454,38 @@ int store(dt_imageio_module_storage_t *self,
       // of the changes.
       if(g_file_test(filename, G_FILE_TEST_EXISTS))
       {
+        GFile *gfile = g_file_new_for_path(filename);
+
+        GFileInfo *info = g_file_query_info
+          (gfile,
+           G_FILE_ATTRIBUTE_TIME_MODIFIED,
+           G_FILE_QUERY_INFO_NONE,
+           NULL,
+           NULL);
+
+        GTimeSpan export_file_timestamp = 0;
+
+        if(info)
+        {
+          if (g_file_info_has_attribute(info, G_FILE_ATTRIBUTE_TIME_MODIFIED))
+          {
+            time_t mtime = g_file_info_get_attribute_uint64(info, G_FILE_ATTRIBUTE_TIME_MODIFIED);
+            GDateTime *gdt = g_date_time_new_from_unix_local(mtime);
+            export_file_timestamp = dt_datetime_gdatetime_to_gtimespan(gdt);
+            g_date_time_unref(gdt);
+          }
+          g_object_unref(info);
+        }
+        g_object_unref(gfile);
+
         // get the image data
         const dt_image_t *img = dt_image_cache_get(imgid, 'r');
         const GTimeSpan change_timestamp = img ? img->change_timestamp : 0;
-        const GTimeSpan export_timestamp = img ? img->export_timestamp : 0;
-
         dt_image_cache_read_release(img);
 
-        // check if the export timestamp in the database is more recent than the change
-        // date, if yes skip the image
-        if(export_timestamp > change_timestamp)
+        // check if the exported file is more recent than the change date.
+        // if yes skip the image
+        if(export_file_timestamp > change_timestamp)
         {
           dt_pthread_mutex_unlock(&darktable.plugin_threadsafe);
           dt_print(DT_DEBUG_ALWAYS, "[export_job] skipping (not modified since export) `%s'", filename);