added load resource pack with offset feature

updated variables to use size_t

removed line break to make code style more consistent

added conditional check to return an error if offset field is used when loading a ZIP package

fixed typo

formatted file

added commit regarding self contained exe files

handled error loging for load zip file with offset

spelling tweak

updated conditional statement for magic check

udpated error message when load Zip file with offset is called

fix CI

Trying to fix CI

fix CI done

Added error message for loading self-contained exe with offset.

Updated documentation.

Fix indent

final fix indent

Updated documentation.

fix indents

Updated doc based on suggestion

Final fix

fixed format

core/io/file_access_pack.cpp

@@ -34,9 +34,9 @@
 
 #include <stdio.h>
 
-Error PackedData::add_pack(const String &p_path, bool p_replace_files) {
+Error PackedData::add_pack(const String &p_path, bool p_replace_files, size_t p_offset) {
 	for (int i = 0; i < sources.size(); i++) {
-		if (sources[i]->try_open_pack(p_path, p_replace_files)) {
+		if (sources[i]->try_open_pack(p_path, p_replace_files, p_offset)) {
 			return OK;
 		}
 	}
@@ -123,15 +123,24 @@ PackedData::~PackedData() {
 
 //////////////////////////////////////////////////////////////////
 
-bool PackedSourcePCK::try_open_pack(const String &p_path, bool p_replace_files) {
+bool PackedSourcePCK::try_open_pack(const String &p_path, bool p_replace_files, size_t p_offset) {
 	FileAccess *f = FileAccess::open(p_path, FileAccess::READ);
 	if (!f) {
 		return false;
 	}
 
+	f->seek(p_offset);
+
 	uint32_t magic = f->get_32();
 
 	if (magic != PACK_HEADER_MAGIC) {
+		// loading with offset feature not supported for self contained exe files
+		if (p_offset != 0) {
+			f->close();
+			memdelete(f);
+			ERR_FAIL_V_MSG(false, "Loading self-contained executable with offset not supported.");
+		}
+
 		//maybe at the end.... self contained exe
 		f->seek_end();
 		f->seek(f->get_position() - 4);
@@ -191,7 +200,7 @@ bool PackedSourcePCK::try_open_pack(const String &p_path, bool p_replace_files)
 		uint64_t size = f->get_64();
 		uint8_t md5[16];
 		f->get_buffer(md5, 16);
-		PackedData::get_singleton()->add_path(p_path, path, ofs, size, md5, this, p_replace_files);
+		PackedData::get_singleton()->add_path(p_path, path, ofs + p_offset, size, md5, this, p_replace_files);
 	}
 
 	f->close();

core/io/file_access_pack.h

@@ -108,7 +108,7 @@ public:
 	_FORCE_INLINE_ bool is_disabled() const { return disabled; }
 
 	static PackedData *get_singleton() { return singleton; }
-	Error add_pack(const String &p_path, bool p_replace_files);
+	Error add_pack(const String &p_path, bool p_replace_files, size_t p_offset);
 
 	_FORCE_INLINE_ FileAccess *try_open_path(const String &p_path);
 	_FORCE_INLINE_ bool has_path(const String &p_path);
@@ -119,14 +119,14 @@ public:
 
 class PackSource {
 public:
-	virtual bool try_open_pack(const String &p_path, bool p_replace_files) = 0;
+	virtual bool try_open_pack(const String &p_path, bool p_replace_files, size_t p_offset) = 0;
 	virtual FileAccess *get_file(const String &p_path, PackedData::PackedFile *p_file) = 0;
 	virtual ~PackSource() {}
 };
 
 class PackedSourcePCK : public PackSource {
 public:
-	virtual bool try_open_pack(const String &p_path, bool p_replace_files);
+	virtual bool try_open_pack(const String &p_path, bool p_replace_files, size_t p_offset);
 	virtual FileAccess *get_file(const String &p_path, PackedData::PackedFile *p_file);
 };
 

core/io/file_access_zip.cpp

@@ -147,8 +147,11 @@ unzFile ZipArchive::get_file_handle(String p_file) const {
 	return pkg;
 }
 
-bool ZipArchive::try_open_pack(const String &p_path, bool p_replace_files) {
+bool ZipArchive::try_open_pack(const String &p_path, bool p_replace_files, size_t p_offset = 0) {
 	//printf("opening zip pack %ls, %i, %i\n", p_name.c_str(), p_name.extension().nocasecmp_to("zip"), p_name.extension().nocasecmp_to("pcz"));
+	// load with offset feature only supported for PCK files
+	ERR_FAIL_COND_V_MSG(p_offset != 0, false, "Invalid PCK data. Note that loading files with a non-zero offset isn't supported with ZIP archives.");
+
 	if (p_path.get_extension().nocasecmp_to("zip") != 0 && p_path.get_extension().nocasecmp_to("pcz") != 0) {
 		return false;
 	}

core/io/file_access_zip.h

@@ -69,7 +69,7 @@ public:
 
 	bool file_exists(String p_name) const;
 
-	virtual bool try_open_pack(const String &p_path, bool p_replace_files);
+	virtual bool try_open_pack(const String &p_path, bool p_replace_files, size_t p_offset);
 	FileAccess *get_file(const String &p_path, PackedData::PackedFile *p_file);
 
 	static ZipArchive *get_singleton();

core/project_settings.cpp

@@ -256,12 +256,12 @@ void ProjectSettings::_get_property_list(List<PropertyInfo> *p_list) const {
 	}
 }
 
-bool ProjectSettings::_load_resource_pack(const String &p_pack, bool p_replace_files) {
+bool ProjectSettings::_load_resource_pack(const String &p_pack, bool p_replace_files, int p_offset) {
 	if (PackedData::get_singleton()->is_disabled()) {
 		return false;
 	}
 
-	bool ok = PackedData::get_singleton()->add_pack(p_pack, p_replace_files) == OK;
+	bool ok = PackedData::get_singleton()->add_pack(p_pack, p_replace_files, p_offset) == OK;
 
 	if (!ok) {
 		return false;
@@ -957,7 +957,7 @@ void ProjectSettings::_bind_methods() {
 	ClassDB::bind_method(D_METHOD("localize_path", "path"), &ProjectSettings::localize_path);
 	ClassDB::bind_method(D_METHOD("globalize_path", "path"), &ProjectSettings::globalize_path);
 	ClassDB::bind_method(D_METHOD("save"), &ProjectSettings::save);
-	ClassDB::bind_method(D_METHOD("load_resource_pack", "pack", "replace_files"), &ProjectSettings::_load_resource_pack, DEFVAL(true));
+	ClassDB::bind_method(D_METHOD("load_resource_pack", "pack", "replace_files", "offset"), &ProjectSettings::_load_resource_pack, DEFVAL(true), DEFVAL(0));
 	ClassDB::bind_method(D_METHOD("property_can_revert", "name"), &ProjectSettings::property_can_revert);
 	ClassDB::bind_method(D_METHOD("property_get_revert", "name"), &ProjectSettings::property_get_revert);
 

core/project_settings.h

@@ -96,7 +96,7 @@ protected:
 
 	void _convert_to_last_version(int p_from_version);
 
-	bool _load_resource_pack(const String &p_pack, bool p_replace_files = true);
+	bool _load_resource_pack(const String &p_pack, bool p_replace_files = true, int p_offset = 0);
 
 	void _add_property_info_bind(const Dictionary &p_info);
 

doc/classes/ProjectSettings.xml

@@ -92,9 +92,12 @@
 			</argument>
 			<argument index="1" name="replace_files" type="bool" default="true">
 			</argument>
+			<argument index="2" name="offset" type="int" default="0">
+			</argument>
 			<description>
 				Loads the contents of the .pck or .zip file specified by [code]pack[/code] into the resource filesystem ([code]res://[/code]). Returns [code]true[/code] on success.
 				[b]Note:[/b] If a file from [code]pack[/code] shares the same path as a file already in the resource filesystem, any attempts to load that file will use the file from [code]pack[/code] unless [code]replace_files[/code] is set to [code]false[/code].
+				[b]Note:[/b] The optional [code]offset[/code] parameter can be used to specify the offset in bytes to the start of the resource pack. This is only supported for .pck files.
 			</description>
 		</method>
 		<method name="localize_path" qualifiers="const">