Ability to change a resource UID from API

* Works for text, binary and imported resources
* Allows better clean up of duplicate files.

TODO (future PRs):

* Use this API for assigning new UIDs to copied files.
* Use this API for UID conflict on FS scanning (if more than one file has the same UID, the newer one(s) should get assigned a different UID).

11 files changed, 256 insertions, 8 deletions

diff --git a/core/io/resource_format_binary.cpp b/core/io/resource_format_binary.cpp
index ba6ad16ca8..45e1301930 100644
--- a/core/io/resource_format_binary.cpp
+++ b/core/io/resource_format_binary.cpp
@@ -1045,10 +1045,10 @@ void ResourceLoaderBinary::open(Ref<FileAccess> p_f, bool p_no_resources, bool p
 #ifdef TOOLS_ENABLED
 					// Silence a warning that can happen during the initial filesystem scan due to cache being regenerated.
 					if (ResourceLoader::get_resource_uid(res_path) != er.uid) {
-						WARN_PRINT(String(res_path + ": In external resource #" + itos(i) + ", invalid UUID: " + ResourceUID::get_singleton()->id_to_text(er.uid) + " - using text path instead: " + er.path).utf8().get_data());
+						WARN_PRINT(String(res_path + ": In external resource #" + itos(i) + ", invalid UID: " + ResourceUID::get_singleton()->id_to_text(er.uid) + " - using text path instead: " + er.path).utf8().get_data());
 					}
 #else
-					WARN_PRINT(String(res_path + ": In external resource #" + itos(i) + ", invalid UUID: " + ResourceUID::get_singleton()->id_to_text(er.uid) + " - using text path instead: " + er.path).utf8().get_data());
+					WARN_PRINT(String(res_path + ": In external resource #" + itos(i) + ", invalid UID: " + ResourceUID::get_singleton()->id_to_text(er.uid) + " - using text path instead: " + er.path).utf8().get_data());
 #endif
 				}
 			}
@@ -2209,12 +2209,130 @@ Error ResourceFormatSaverBinaryInstance::save(const String &p_path, const Ref<Re
 	return OK;
 }
 
+Error ResourceFormatSaverBinaryInstance::set_uid(const String &p_path, ResourceUID::ID p_uid) {
+	Ref<FileAccess> f = FileAccess::open(p_path, FileAccess::READ);
+	ERR_FAIL_COND_V_MSG(f.is_null(), ERR_CANT_OPEN, "Cannot open file '" + p_path + "'.");
+
+	Ref<FileAccess> fw;
+
+	local_path = p_path.get_base_dir();
+
+	uint8_t header[4];
+	f->get_buffer(header, 4);
+	if (header[0] == 'R' && header[1] == 'S' && header[2] == 'C' && header[3] == 'C') {
+		// Compressed.
+		Ref<FileAccessCompressed> fac;
+		fac.instantiate();
+		Error err = fac->open_after_magic(f);
+		ERR_FAIL_COND_V_MSG(err != OK, err, "Cannot open file '" + p_path + "'.");
+		f = fac;
+
+		Ref<FileAccessCompressed> facw;
+		facw.instantiate();
+		facw->configure("RSCC");
+		err = facw->open_internal(p_path + ".uidren", FileAccess::WRITE);
+		ERR_FAIL_COND_V_MSG(err, ERR_FILE_CORRUPT, "Cannot create file '" + p_path + ".uidren'.");
+
+		fw = facw;
+
+	} else if (header[0] != 'R' || header[1] != 'S' || header[2] != 'R' || header[3] != 'C') {
+		// Not a binary resource.
+		return ERR_FILE_UNRECOGNIZED;
+	} else {
+		fw = FileAccess::open(p_path + ".uidren", FileAccess::WRITE);
+		ERR_FAIL_COND_V_MSG(fw.is_null(), ERR_CANT_CREATE, "Cannot create file '" + p_path + ".uidren'.");
+
+		uint8_t magich[4] = { 'R', 'S', 'R', 'C' };
+		fw->store_buffer(magich, 4);
+	}
+
+	big_endian = f->get_32();
+	bool use_real64 = f->get_32();
+	f->set_big_endian(big_endian != 0); //read big endian if saved as big endian
+#ifdef BIG_ENDIAN_ENABLED
+	fw->store_32(!big_endian);
+#else
+	fw->store_32(big_endian);
+#endif
+	fw->set_big_endian(big_endian != 0);
+	fw->store_32(use_real64); //use real64
+
+	uint32_t ver_major = f->get_32();
+	uint32_t ver_minor = f->get_32();
+	uint32_t ver_format = f->get_32();
+
+	if (ver_format < FORMAT_VERSION_CAN_RENAME_DEPS) {
+		fw.unref();
+
+		{
+			Ref<DirAccess> da = DirAccess::create(DirAccess::ACCESS_FILESYSTEM);
+			da->remove(p_path + ".uidren");
+		}
+
+		// Use the old approach.
+
+		WARN_PRINT("This file is old, so it does not support UIDs, opening and resaving '" + p_path + "'.");
+		return ERR_UNAVAILABLE;
+	}
+
+	if (ver_format > FORMAT_VERSION || ver_major > VERSION_MAJOR) {
+		ERR_FAIL_V_MSG(ERR_FILE_UNRECOGNIZED,
+				vformat("File '%s' can't be loaded, as it uses a format version (%d) or engine version (%d.%d) which are not supported by your engine version (%s).",
+						local_path, ver_format, ver_major, ver_minor, VERSION_BRANCH));
+	}
+
+	// Since we're not actually converting the file contents, leave the version
+	// numbers in the file untouched.
+	fw->store_32(ver_major);
+	fw->store_32(ver_minor);
+	fw->store_32(ver_format);
+
+	save_ustring(fw, get_ustring(f)); //type
+
+	fw->store_64(f->get_64()); //metadata offset
+
+	uint32_t flags = f->get_32();
+	flags |= ResourceFormatSaverBinaryInstance::FORMAT_FLAG_UIDS;
+	f->get_64(); // Skip previous UID
+
+	fw->store_32(flags);
+	fw->store_64(p_uid);
+
+	//rest of file
+	uint8_t b = f->get_8();
+	while (!f->eof_reached()) {
+		fw->store_8(b);
+		b = f->get_8();
+	}
+
+	f.unref();
+
+	bool all_ok = fw->get_error() == OK;
+
+	if (!all_ok) {
+		return ERR_CANT_CREATE;
+	}
+
+	fw.unref();
+
+	Ref<DirAccess> da = DirAccess::create(DirAccess::ACCESS_RESOURCES);
+	da->remove(p_path);
+	da->rename(p_path + ".uidren", p_path);
+	return OK;
+}
+
 Error ResourceFormatSaverBinary::save(const Ref<Resource> &p_resource, const String &p_path, uint32_t p_flags) {
 	String local_path = ProjectSettings::get_singleton()->localize_path(p_path);
 	ResourceFormatSaverBinaryInstance saver;
 	return saver.save(local_path, p_resource, p_flags);
 }
 
+Error ResourceFormatSaverBinary::set_uid(const String &p_path, ResourceUID::ID p_uid) {
+	String local_path = ProjectSettings::get_singleton()->localize_path(p_path);
+	ResourceFormatSaverBinaryInstance saver;
+	return saver.set_uid(local_path, p_uid);
+}
+
 bool ResourceFormatSaverBinary::recognize(const Ref<Resource> &p_resource) const {
 	return true; //all recognized
 }
diff --git a/core/io/resource_format_binary.h b/core/io/resource_format_binary.h
index 36613dbd58..2e8988005f 100644
--- a/core/io/resource_format_binary.h
+++ b/core/io/resource_format_binary.h
@@ -170,6 +170,7 @@ public:
 		RESERVED_FIELDS = 11
 	};
 	Error save(const String &p_path, const Ref<Resource> &p_resource, uint32_t p_flags = 0);
+	Error set_uid(const String &p_path, ResourceUID::ID p_uid);
 	static void write_variant(Ref<FileAccess> f, const Variant &p_property, HashMap<Ref<Resource>, int> &resource_map, HashMap<Ref<Resource>, int> &external_resources, HashMap<StringName, int> &string_map, const PropertyInfo &p_hint = PropertyInfo());
 };
 
@@ -177,6 +178,7 @@ class ResourceFormatSaverBinary : public ResourceFormatSaver {
 public:
 	static ResourceFormatSaverBinary *singleton;
 	virtual Error save(const Ref<Resource> &p_resource, const String &p_path, uint32_t p_flags = 0);
+	virtual Error set_uid(const String &p_path, ResourceUID::ID p_uid);
 	virtual bool recognize(const Ref<Resource> &p_resource) const;
 	virtual void get_recognized_extensions(const Ref<Resource> &p_resource, List<String> *p_extensions) const;
 
diff --git a/core/io/resource_importer.cpp b/core/io/resource_importer.cpp
index a4f4d705ee..dc1de6b9ce 100644
--- a/core/io/resource_importer.cpp
+++ b/core/io/resource_importer.cpp
@@ -31,6 +31,7 @@
 #include "resource_importer.h"
 
 #include "core/config/project_settings.h"
+#include "core/io/config_file.h"
 #include "core/os/os.h"
 #include "core/variant/variant_parser.h"
 
@@ -484,3 +485,18 @@ void ResourceFormatImporter::add_importer(const Ref<ResourceImporter> &p_importe
 		importers.push_back(p_importer);
 	}
 }
+
+/////
+
+Error ResourceFormatImporterSaver::set_uid(const String &p_path, ResourceUID::ID p_uid) {
+	Ref<ConfigFile> cf;
+	cf.instantiate();
+	Error err = cf->load(p_path + ".import");
+	if (err != OK) {
+		return err;
+	}
+	cf->set_value("remap", "uid", ResourceUID::get_singleton()->id_to_text(p_uid));
+	cf->save(p_path + ".import");
+
+	return OK;
+}
diff --git a/core/io/resource_importer.h b/core/io/resource_importer.h
index b104a9dffe..0089544caa 100644
--- a/core/io/resource_importer.h
+++ b/core/io/resource_importer.h
@@ -32,6 +32,7 @@
 #define RESOURCE_IMPORTER_H
 
 #include "core/io/resource_loader.h"
+#include "core/io/resource_saver.h"
 
 class ResourceImporter;
 
@@ -149,4 +150,11 @@ public:
 
 VARIANT_ENUM_CAST(ResourceImporter::ImportOrder);
 
+class ResourceFormatImporterSaver : public ResourceFormatSaver {
+	GDCLASS(ResourceFormatImporterSaver, ResourceFormatSaver)
+
+public:
+	virtual Error set_uid(const String &p_path, ResourceUID::ID p_uid) override;
+};
+
 #endif // RESOURCE_IMPORTER_H
diff --git a/core/io/resource_saver.cpp b/core/io/resource_saver.cpp
index de450a8420..9809b9a48f 100644
--- a/core/io/resource_saver.cpp
+++ b/core/io/resource_saver.cpp
@@ -47,6 +47,12 @@ Error ResourceFormatSaver::save(const Ref<Resource> &p_resource, const String &p
 	return (Error)res;
 }
 
+Error ResourceFormatSaver::set_uid(const String &p_path, ResourceUID::ID p_uid) {
+	Error err = ERR_FILE_UNRECOGNIZED;
+	GDVIRTUAL_CALL(_set_uid, p_path, p_uid, err);
+	return err;
+}
+
 bool ResourceFormatSaver::recognize(const Ref<Resource> &p_resource) const {
 	bool success = false;
 	GDVIRTUAL_CALL(_recognize, p_resource, success);
@@ -85,6 +91,7 @@ bool ResourceFormatSaver::recognize_path(const Ref<Resource> &p_resource, const
 
 void ResourceFormatSaver::_bind_methods() {
 	GDVIRTUAL_BIND(_save, "resource", "path", "flags");
+	GDVIRTUAL_BIND(_set_uid, "path", "uid");
 	GDVIRTUAL_BIND(_recognize, "resource");
 	GDVIRTUAL_BIND(_get_recognized_extensions, "resource");
 	GDVIRTUAL_BIND(_recognize_path, "resource", "path");
@@ -146,6 +153,23 @@ Error ResourceSaver::save(const Ref<Resource> &p_resource, const String &p_path,
 	return err;
 }
 
+Error ResourceSaver::set_uid(const String &p_path, ResourceUID::ID p_uid) {
+	String path = p_path;
+
+	ERR_FAIL_COND_V_MSG(path.is_empty(), ERR_INVALID_PARAMETER, "Can't update UID to empty path. Provide non-empty path.");
+
+	Error err = ERR_FILE_UNRECOGNIZED;
+
+	for (int i = 0; i < saver_count; i++) {
+		err = saver[i]->set_uid(path, p_uid);
+		if (err == OK) {
+			break;
+		}
+	}
+
+	return err;
+}
+
 void ResourceSaver::set_save_callback(ResourceSavedCallback p_callback) {
 	save_callback = p_callback;
 }
diff --git a/core/io/resource_saver.h b/core/io/resource_saver.h
index f25463d71f..2043947963 100644
--- a/core/io/resource_saver.h
+++ b/core/io/resource_saver.h
@@ -42,12 +42,14 @@ protected:
 	static void _bind_methods();
 
 	GDVIRTUAL3R(int64_t, _save, Ref<Resource>, String, uint32_t)
+	GDVIRTUAL2R(Error, _set_uid, String, ResourceUID::ID)
 	GDVIRTUAL1RC(bool, _recognize, Ref<Resource>)
 	GDVIRTUAL1RC(Vector<String>, _get_recognized_extensions, Ref<Resource>)
 	GDVIRTUAL2RC(bool, _recognize_path, Ref<Resource>, String)
 
 public:
 	virtual Error save(const Ref<Resource> &p_resource, const String &p_path, uint32_t p_flags = 0);
+	virtual Error set_uid(const String &p_path, ResourceUID::ID p_uid);
 	virtual bool recognize(const Ref<Resource> &p_resource) const;
 	virtual void get_recognized_extensions(const Ref<Resource> &p_resource, List<String> *p_extensions) const;
 	virtual bool recognize_path(const Ref<Resource> &p_resource, const String &p_path) const;
@@ -88,6 +90,8 @@ public:
 	static void add_resource_format_saver(Ref<ResourceFormatSaver> p_format_saver, bool p_at_front = false);
 	static void remove_resource_format_saver(Ref<ResourceFormatSaver> p_format_saver);
 
+	static Error set_uid(const String &p_path, ResourceUID::ID p_uid);
+
 	static void set_timestamp_on_save(bool p_timestamp) { timestamp_on_save = p_timestamp; }
 	static bool get_timestamp_on_save() { return timestamp_on_save; }
 
diff --git a/core/register_core_types.cpp b/core/register_core_types.cpp
index 81866ee7e4..700174bdae 100644
--- a/core/register_core_types.cpp
+++ b/core/register_core_types.cpp
@@ -84,6 +84,7 @@
 static Ref<ResourceFormatSaverBinary> resource_saver_binary;
 static Ref<ResourceFormatLoaderBinary> resource_loader_binary;
 static Ref<ResourceFormatImporter> resource_format_importer;
+static Ref<ResourceFormatImporterSaver> resource_format_importer_saver;
 static Ref<ResourceFormatLoaderImage> resource_format_image;
 static Ref<TranslationLoaderPO> resource_format_po;
 static Ref<ResourceFormatSaverCrypto> resource_format_saver_crypto;
@@ -144,6 +145,9 @@ void register_core_types() {
 	resource_format_importer.instantiate();
 	ResourceLoader::add_resource_format_loader(resource_format_importer);
 
+	resource_format_importer_saver.instantiate();
+	ResourceSaver::add_resource_format_saver(resource_format_importer_saver);
+
 	resource_format_image.instantiate();
 	ResourceLoader::add_resource_format_loader(resource_format_image);
 
@@ -389,6 +393,9 @@ void unregister_core_types() {
 	ResourceLoader::remove_resource_format_loader(resource_format_importer);
 	resource_format_importer.unref();
 
+	ResourceSaver::remove_resource_format_saver(resource_format_importer_saver);
+	resource_format_importer_saver.unref();
+
 	ResourceLoader::remove_resource_format_loader(resource_format_po);
 	resource_format_po.unref();
 
diff --git a/doc/classes/ResourceFormatSaver.xml b/doc/classes/ResourceFormatSaver.xml
index 1f2af6d157..b0c57bc7cb 100644
--- a/doc/classes/ResourceFormatSaver.xml
+++ b/doc/classes/ResourceFormatSaver.xml
@@ -43,5 +43,13 @@
 				Returns [constant OK] on success, or an [enum Error] constant in case of failure.
 			</description>
 		</method>
+		<method name="_set_uid" qualifiers="virtual">
+			<return type="int" enum="Error" />
+			<param index="0" name="path" type="String" />
+			<param index="1" name="uid" type="int" />
+			<description>
+				Sets a new UID for the resource at the given [param path]. Returns [constant OK] on success, or an [enum Error] constant in case of failure.
+			</description>
+		</method>
 	</methods>
 </class>
diff --git a/editor/editor_file_system.cpp b/editor/editor_file_system.cpp
index 28424d53b1..4efc7c3055 100644
--- a/editor/editor_file_system.cpp
+++ b/editor/editor_file_system.cpp
@@ -433,7 +433,7 @@ bool EditorFileSystem::_test_for_reimport(const String &p_path, bool p_only_impo
 	}
 
 	if (!found_uid) {
-		return true; //UUID not found, old format, reimport.
+		return true; //UID not found, old format, reimport.
 	}
 
 	Ref<ResourceImporter> importer = ResourceFormatImporter::get_singleton()->get_importer_by_name(importer_name);
@@ -868,7 +868,7 @@ void EditorFileSystem::_scan_new_dir(EditorFileSystemDirectory *p_dir, Ref<DirAc
 				}
 
 				if (fc->uid == ResourceUID::INVALID_ID) {
-					// imported files should always have a UUID, so attempt to fetch it.
+					// imported files should always have a UID, so attempt to fetch it.
 					fi->uid = ResourceLoader::get_resource_uid(path);
 				}
 
@@ -2319,14 +2319,14 @@ ResourceUID::ID EditorFileSystem::_resource_saver_get_resource_id_for_path(const
 		}
 
 		if (p_generate) {
-			return ResourceUID::get_singleton()->create_id(); // Just create a new one, we will be notified of save anyway and fetch the right UUID at that time, to keep things simple.
+			return ResourceUID::get_singleton()->create_id(); // Just create a new one, we will be notified of save anyway and fetch the right UID at that time, to keep things simple.
 		} else {
 			return ResourceUID::INVALID_ID;
 		}
 	} else if (fs->files[cpos]->uid != ResourceUID::INVALID_ID) {
 		return fs->files[cpos]->uid;
 	} else if (p_generate) {
-		return ResourceUID::get_singleton()->create_id(); // Just create a new one, we will be notified of save anyway and fetch the right UUID at that time, to keep things simple.
+		return ResourceUID::get_singleton()->create_id(); // Just create a new one, we will be notified of save anyway and fetch the right UID at that time, to keep things simple.
 	} else {
 		return ResourceUID::INVALID_ID;
 	}
diff --git a/scene/resources/resource_format_text.cpp b/scene/resources/resource_format_text.cpp
index ade8875935..d80a4004a4 100644
--- a/scene/resources/resource_format_text.cpp
+++ b/scene/resources/resource_format_text.cpp
@@ -449,10 +449,10 @@ Error ResourceLoaderText::load() {
 #ifdef TOOLS_ENABLED
 				// Silence a warning that can happen during the initial filesystem scan due to cache being regenerated.
 				if (ResourceLoader::get_resource_uid(path) != uid) {
-					WARN_PRINT(String(res_path + ":" + itos(lines) + " - ext_resource, invalid UUID: " + uidt + " - using text path instead: " + path).utf8().get_data());
+					WARN_PRINT(String(res_path + ":" + itos(lines) + " - ext_resource, invalid UID: " + uidt + " - using text path instead: " + path).utf8().get_data());
 				}
 #else
-				WARN_PRINT(String(res_path + ":" + itos(lines) + " - ext_resource, invalid UUID: " + uidt + " - using text path instead: " + path).utf8().get_data());
+				WARN_PRINT(String(res_path + ":" + itos(lines) + " - ext_resource, invalid UID: " + uidt + " - using text path instead: " + path).utf8().get_data());
 #endif
 			}
 		}
@@ -2237,6 +2237,35 @@ Error ResourceFormatSaverTextInstance::save(const String &p_path, const Ref<Reso
 	return OK;
 }
 
+Error ResourceLoaderText::set_uid(Ref<FileAccess> p_f, ResourceUID::ID p_uid) {
+	open(p_f, true);
+	ERR_FAIL_COND_V(error != OK, error);
+	ignore_resource_parsing = true;
+
+	Ref<FileAccess> fw;
+
+	fw = FileAccess::open(local_path + ".uidren", FileAccess::WRITE);
+	if (is_scene) {
+		fw->store_string("[gd_scene load_steps=" + itos(resources_total) + " format=" + itos(FORMAT_VERSION) + " uid=\"" + ResourceUID::get_singleton()->id_to_text(p_uid) + "\"]");
+	} else {
+		fw->store_string("[gd_resource type=\"" + res_type + "\" load_steps=" + itos(resources_total) + " format=" + itos(FORMAT_VERSION) + " uid=\"" + ResourceUID::get_singleton()->id_to_text(p_uid) + "\"]");
+	}
+
+	uint8_t c = f->get_8();
+	while (!f->eof_reached()) {
+		fw->store_8(c);
+		c = f->get_8();
+	}
+
+	bool all_ok = fw->get_error() == OK;
+
+	if (!all_ok) {
+		return ERR_CANT_CREATE;
+	}
+
+	return OK;
+}
+
 Error ResourceFormatSaverText::save(const Ref<Resource> &p_resource, const String &p_path, uint32_t p_flags) {
 	if (p_path.ends_with(".tscn") && !Ref<PackedScene>(p_resource).is_valid()) {
 		return ERR_FILE_UNRECOGNIZED;
@@ -2246,6 +2275,35 @@ Error ResourceFormatSaverText::save(const Ref<Resource> &p_resource, const Strin
 	return saver.save(p_path, p_resource, p_flags);
 }
 
+Error ResourceFormatSaverText::set_uid(const String &p_path, ResourceUID::ID p_uid) {
+	String lc = p_path.to_lower();
+	if (!lc.ends_with(".tscn") && !lc.ends_with(".tres")) {
+		return ERR_FILE_UNRECOGNIZED;
+	}
+
+	String local_path = ProjectSettings::get_singleton()->localize_path(p_path);
+	Error err = OK;
+	{
+		Ref<FileAccess> fo = FileAccess::open(p_path, FileAccess::READ);
+		if (fo.is_null()) {
+			ERR_FAIL_V(ERR_CANT_OPEN);
+		}
+
+		ResourceLoaderText loader;
+		loader.local_path = local_path;
+		loader.res_path = loader.local_path;
+		err = loader.set_uid(fo, p_uid);
+	}
+
+	if (err == OK) {
+		Ref<DirAccess> da = DirAccess::create(DirAccess::ACCESS_RESOURCES);
+		da->remove(local_path);
+		da->rename(local_path + ".uidren", local_path);
+	}
+
+	return err;
+}
+
 bool ResourceFormatSaverText::recognize(const Ref<Resource> &p_resource) const {
 	return true; // All resources recognized!
 }
diff --git a/scene/resources/resource_format_text.h b/scene/resources/resource_format_text.h
index f96511fb74..0f95e2fbfd 100644
--- a/scene/resources/resource_format_text.h
+++ b/scene/resources/resource_format_text.h
@@ -106,6 +106,7 @@ class ResourceLoaderText {
 	VariantParser::ResourceParser rp;
 
 	friend class ResourceFormatLoaderText;
+	friend class ResourceFormatSaverText;
 
 	Error error = OK;
 
@@ -117,6 +118,7 @@ public:
 	void set_local_path(const String &p_local_path);
 	Ref<Resource> get_resource();
 	Error load();
+	Error set_uid(Ref<FileAccess> p_f, ResourceUID::ID p_uid);
 	int get_stage() const;
 	int get_stage_count() const;
 	void set_translation_remapped(bool p_remapped);
@@ -195,6 +197,7 @@ class ResourceFormatSaverText : public ResourceFormatSaver {
 public:
 	static ResourceFormatSaverText *singleton;
 	virtual Error save(const Ref<Resource> &p_resource, const String &p_path, uint32_t p_flags = 0);
+	virtual Error set_uid(const String &p_path, ResourceUID::ID p_uid);
 	virtual bool recognize(const Ref<Resource> &p_resource) const;
 	virtual void get_recognized_extensions(const Ref<Resource> &p_resource, List<String> *p_extensions) const;