DNA: support versioning structs & struct members

This is only to be used rarely because it's not forwards compatible.

Replace version patching of old 2.80 DNA with a more generic API.

4 files changed, 80 insertions, 1 deletions

diff --git a/source/blender/blenloader/CMakeLists.txt b/source/blender/blenloader/CMakeLists.txt
index efd64b1a328..b9bec1b97b3 100644
--- a/source/blender/blenloader/CMakeLists.txt
+++ b/source/blender/blenloader/CMakeLists.txt
@@ -54,6 +54,7 @@ set(SRC
 	intern/versioning_270.c
 	intern/versioning_280.c
 	intern/versioning_defaults.c
+	intern/versioning_dna.c
 	intern/versioning_legacy.c
 	intern/versioning_userdef.c
 	intern/writefile.c
diff --git a/source/blender/blenloader/intern/readfile.c b/source/blender/blenloader/intern/readfile.c
index c4fdb878b86..55a72e363e9 100644
--- a/source/blender/blenloader/intern/readfile.c
+++ b/source/blender/blenloader/intern/readfile.c
@@ -932,13 +932,30 @@ static void decode_blender_header(FileData *fd)
 static bool read_file_dna(FileData *fd, const char **r_error_message)
 {
 	BHead *bhead;
+	int subversion = 0;
 
 	for (bhead = blo_firstbhead(fd); bhead; bhead = blo_nextbhead(fd, bhead)) {
-		if (bhead->code == DNA1) {
+		if (bhead->code == GLOB) {
+			/* Before this, the subversion didn't exist in 'FileGlobal' so the subversion
+			 * value isn't accessible for the purpose of DNA versioning in this case. */
+			if (fd->fileversion <= 242) {
+				continue;
+			}
+			/* We can't use read_global because this needs 'DNA1' to be decoded,
+			 * however the first 4 chars are _always_ the subversion. */
+			FileGlobal *fg = (void *)&bhead[1];
+			BLI_STATIC_ASSERT(offsetof(FileGlobal, subvstr) == 0, "Must be first: subvstr");
+			char num[5];
+			memcpy(num, fg->subvstr, 4);
+			num[4] = 0;
+			subversion = atoi(num);
+		}
+		else if (bhead->code == DNA1) {
 			const bool do_endian_swap = (fd->flags & FD_FLAGS_SWITCH_ENDIAN) != 0;
 
 			fd->filesdna = DNA_sdna_from_data(&bhead[1], bhead->len, do_endian_swap, true, r_error_message);
 			if (fd->filesdna) {
+				blo_do_versions_dna(fd->filesdna, fd->fileversion, subversion);
 				fd->compflags = DNA_struct_get_compareflags(fd->filesdna, fd->memsdna);
 				/* used to retrieve ID names from (bhead+1) */
 				fd->id_name_offs = DNA_elem_offset(fd->filesdna, "ID", "char", "name[]");
diff --git a/source/blender/blenloader/intern/readfile.h b/source/blender/blenloader/intern/readfile.h
index 85416892f25..39a474dfe49 100644
--- a/source/blender/blenloader/intern/readfile.h
+++ b/source/blender/blenloader/intern/readfile.h
@@ -150,6 +150,8 @@ const char *bhead_id_name(const FileData *fd, const BHead *bhead);
 
 void blo_reportf_wrap(struct ReportList *reports, ReportType type, const char *format, ...) ATTR_PRINTF_FORMAT(3, 4);
 
+void blo_do_versions_dna(struct SDNA *sdna, const int versionfile, const int subversionfile);
+
 void blo_do_versions_oldnewmap_insert(struct OldNewMap *onm, const void *oldaddr, void *newaddr, int nr);
 void *blo_do_versions_newlibadr(struct FileData *fd, const void *lib, const void *adr);
 void *blo_do_versions_newlibadr_us(struct FileData *fd, const void *lib, const void *adr);
diff --git a/source/blender/blenloader/intern/versioning_dna.c b/source/blender/blenloader/intern/versioning_dna.c
new file mode 100644
index 00000000000..d379edd83f6
--- /dev/null
+++ b/source/blender/blenloader/intern/versioning_dna.c
@@ -0,0 +1,59 @@
+/*
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ */
+
+/** \file \ingroup blenloader
+ *
+ * Apply edits to DNA at load time
+ * to behave as if old files were written new names.
+ */
+
+#include "BLI_compiler_attrs.h"
+#include "BLI_utildefines.h"
+
+#include "DNA_genfile.h"
+#include "DNA_listBase.h"
+
+#include "BLO_readfile.h"
+#include "readfile.h"
+
+/**
+ * Manipulates SDNA before calling #DNA_struct_get_compareflags,
+ * allowing us to rename structs and struct members.
+ *
+ * \attention Changes here will cause breakages in forward compatbility,
+ * Use this only in the _rare_ cases when migrating to new naming is needed.
+ */
+void blo_do_versions_dna(SDNA *sdna, const int versionfile, const int subversionfile)
+{
+#define DNA_VERSION_ATLEAST(ver, subver) \
+	(versionfile > (ver) || (versionfile == (ver) && (subversionfile >= (subver))))
+
+	if (!DNA_VERSION_ATLEAST(280, 2)) {
+		/* Version files created in the 'blender2.8' branch
+		 * between October 2016, and November 2017 (>=280.0 and < 280.2). */
+		if (versionfile >= 280) {
+			DNA_sdna_patch_struct(sdna, "SceneLayer", "ViewLayer");
+			DNA_sdna_patch_struct(sdna, "SceneLayerEngineData", "ViewLayerEngineData");
+			DNA_sdna_patch_struct_member(sdna, "FileGlobal", "cur_render_layer", "cur_view_layer");
+			DNA_sdna_patch_struct_member(sdna, "ParticleEditSettings", "scene_layer", "view_layer");
+			DNA_sdna_patch_struct_member(sdna, "Scene", "active_layer", "active_view_layer");
+			DNA_sdna_patch_struct_member(sdna, "Scene", "render_layers", "view_layers");
+			DNA_sdna_patch_struct_member(sdna, "WorkSpace", "render_layer", "view_layer");
+		}
+	}
+
+#undef DNA_VERSION_ATLEAST
+}