Make WIMStructs reference-counted

[wimlib] / src / wim.c

diff --git a/src/wim.c b/src/wim.c
index e77d71704ece213305bf3b45e878793692e19813..e01131ddffabfdc1504fc3b828d762f880ba526e 100644 (file)
--- a/src/wim.c
+++ b/src/wim.c
@@ -146,12 +146,12 @@ new_wim_struct(void)
        if (!wim)
                return NULL;
 
+       wim->refcnt = 1;
        filedes_invalidate(&wim->in_fd);
        filedes_invalidate(&wim->out_fd);
        wim->out_solid_compression_type = wim_default_solid_compression_type();
        wim->out_solid_chunk_size = wim_default_solid_chunk_size(
                                        wim->out_solid_compression_type);
-       INIT_LIST_HEAD(&wim->subwims);
        return wim;
 }
 
@@ -867,6 +867,20 @@ can_modify_wim(WIMStruct *wim)
        return 0;
 }
 
+/* Free a WIMStruct after no more resources reference it.  */
+void
+finalize_wim_struct(WIMStruct *wim)
+{
+       if (filedes_valid(&wim->in_fd))
+               filedes_close(&wim->in_fd);
+       if (filedes_valid(&wim->out_fd))
+               filedes_close(&wim->out_fd);
+       wimlib_free_decompressor(wim->decompressor);
+       xml_free_info_struct(wim->xml_info);
+       FREE(wim->filename);
+       FREE(wim);
+}
+
 /* API function documented in wimlib.h  */
 WIMLIBAPI void
 wimlib_free(WIMStruct *wim)
@@ -874,31 +888,22 @@ wimlib_free(WIMStruct *wim)
        if (!wim)
                return;
 
-       while (!list_empty(&wim->subwims)) {
-               WIMStruct *subwim;
-
-               subwim = list_entry(wim->subwims.next, WIMStruct, subwim_node);
-               list_del(&subwim->subwim_node);
-               wimlib_free(subwim);
-       }
-
-       if (filedes_valid(&wim->in_fd))
-               filedes_close(&wim->in_fd);
-       if (filedes_valid(&wim->out_fd))
-               filedes_close(&wim->out_fd);
+       /* The blob table and image metadata are freed immediately, but other
+        * members of the WIMStruct such as the input file descriptor are
+        * retained until no more exported resources reference the WIMStruct. */
 
        free_blob_table(wim->blob_table);
-
-       wimlib_free_decompressor(wim->decompressor);
-
-       FREE(wim->filename);
-       xml_free_info_struct(wim->xml_info);
-       if (wim->image_metadata) {
-               for (unsigned i = 0; i < wim->hdr.image_count; i++)
+       wim->blob_table = NULL;
+       if (wim->image_metadata != NULL) {
+               for (int i = 0; i < wim->hdr.image_count; i++)
                        put_image_metadata(wim->image_metadata[i], NULL);
                FREE(wim->image_metadata);
+               wim->image_metadata = NULL;
        }
-       FREE(wim);
+
+       wimlib_assert(wim->refcnt > 0);
+       if (--wim->refcnt == 0)
+               finalize_wim_struct(wim);
 }
 
 static bool