Index: trunk/src/hid_cam.c
===================================================================
--- trunk/src/hid_cam.c	(revision 24108)
+++ trunk/src/hid_cam.c	(revision 24109)
@@ -107,7 +107,7 @@
 }
 
 
-void pcb_derive_default_filename(const char *pcbfile, pcb_hid_attribute_t * filename_attrib, const char *suffix)
+char *pcb_derive_default_filename_(const char *pcbfile, const char *suffix)
 {
 	char *buf;
 	const char *pf;
@@ -133,12 +133,18 @@
 			}
 		}
 		strcat(buf, suffix);
-		if (filename_attrib->default_val.str_value)
-			free((void *) filename_attrib->default_val.str_value);
-		filename_attrib->default_val.str_value = buf;
 	}
+
+	return buf;
 }
 
+void pcb_derive_default_filename(const char *pcbfile, pcb_hid_attribute_t * filename_attrib, const char *suffix)
+{
+	if (filename_attrib->default_val.str_value)
+		free((char *)filename_attrib->default_val.str_value);
+	filename_attrib->default_val.str_value = pcb_derive_default_filename_(pcbfile, suffix);
+}
+
 /* remove leading and trailing whitespace */
 static char *strip(char *s)
 {
Index: trunk/src/hid_cam.h
===================================================================
--- trunk/src/hid_cam.h	(revision 24108)
+++ trunk/src/hid_cam.h	(revision 24109)
@@ -84,4 +84,8 @@
    look it up. Copies result in dest (which should be at least PCB_DERIVE_FN_SUFF_LEN bytes wide). */
 void pcb_derive_default_filename(const char *pcbfile, pcb_hid_attribute_t * filename_attrib, const char *suffix);
 
+/* Same as pcb_derive_default_filename() but returns an allocated string
+   directly, instead  of manipulating an attribute */
+char *pcb_derive_default_filename_(const char *pcbfile, const char *suffix);
+
 #endif