Index: openacs-4/packages/proctoring-support/tcl/proctoring-procs.tcl
===================================================================
RCS file: /usr/local/cvsroot/openacs-4/packages/proctoring-support/tcl/Attic/proctoring-procs.tcl,v
diff -u -N -r1.1.2.8 -r1.1.2.9
--- openacs-4/packages/proctoring-support/tcl/proctoring-procs.tcl	16 Mar 2021 17:11:22 -0000	1.1.2.8
+++ openacs-4/packages/proctoring-support/tcl/proctoring-procs.tcl	6 Apr 2021 14:10:55 -0000	1.1.2.9
@@ -180,3 +180,36 @@
           and (end_time is null or end_time >= cast(current_timestamp as time))
     }]
 }
+
+ad_proc -private ::proctoring::picture_already_received_p {
+    -object_id:required
+    -user_id:required
+    -file:required
+} {
+    Returns if the picture is the same the users sent the last time
+    they uploaded a proctoring file.
+
+    @param object_id id of the proctored object
+    @param user_id id of the proctored user
+    @param file an absolute path to a file in the filesystem
+
+    @return boolean
+} {
+    set cache_name proctoring_checksums_cache
+
+    # Make sure the checksum of current file is not the same as the
+    # one we have in the cache.
+    set checksum [ns_md file -digest sha1 $file]
+    set already_received_p false
+    if {[ns_cache_get $cache_name ${object_id}_${user_id} cached_checksum]} {
+        if {$checksum eq $cached_checksum} {
+            set already_received_p true
+        }
+    }
+
+    # Update in any case the cache to renew the expiration
+    ns_cache_eval -force -- $cache_name ${object_id}_${user_id} set v $checksum
+
+    return $already_received_p
+}
+