only truncate once for .done()

src/tus_file.c

@@ -990,12 +990,13 @@ tus_body_to_file(VRT_CTX, struct tus_file_core *fcore)
 VCL_BOOL
 tus_file_done(struct tus_file_core *fcore, struct tus_file_disk *fdisk, const char *url)
 {
-	int fd;
+	int fd, need_truncate;
 	size_t l = strlen(url);
 
 	if (l >= TUS_PATH_MAX)
 		return (0);
 
+	need_truncate = (fdisk->location_length == 0);
 	strcpy(fdisk->location, url);
 	fdisk->location_length = l;
 
@@ -1007,7 +1008,7 @@ tus_file_done(struct tus_file_core *fcore, struct tus_file_disk *fdisk, const ch
 	 * location
 	 */
 
-	if (fdisk->type == TUS_FINAL)
+	if (fdisk->type == TUS_FINAL || need_truncate == 0)
 		return (1);
 
 	assert(fdisk->type == TUS_SINGLE);