Add Emscripten/WebAssembly support#175
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Minimal changes to make the library compile and run correctly when targeting WebAssembly with Emscripten (GS_LIN/_LINUX platform macros, DONT_USE_XERCES_AS_XMLLIB, mvrxchange excluded): - UUID.cpp: Emscripten provides no libuuid; generate random (v4) UUIDs from std::random_device instead. - FilingWrapper.cpp: getpwuid() returns NULL under Emscripten; resolve the app data path from $HOME with a fallback to /home/web_user (the default MEMFS home directory). - XmlFileHelper: wasm32 defines size_t as unsigned long, which is a distinct type from Uint32 (unsigned int) even though both are 32 bit, unlike the other 32-bit targets the IS64BIT guard was written for. Compile the Uint32 overloads of ConvertInteger under Emscripten as well, otherwise calls with Uint32 arguments are ambiguous.
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Motivation
This makes libMVRgdtf compile and run correctly as WebAssembly with Emscripten, so the reference implementation can be used directly in browsers (and Node.js) with 100% file compatibility — e.g. for web-based GDTF/MVR viewers and visualizers — instead of re-implementing the formats in JS.
The library builds with the
GS_LIN/_LINUXplatform macros,DONT_USE_XERCES_AS_XMLLIB(bundled tinyxml2/rapidxml) and withoutBUILD_MVR_XCHANGE(raw TCP/mDNS is not available in a browser sandbox). Only three small platform issues needed changes:Changes
UUID.cpp— Emscripten has no libuuid and no/proc. Under__EMSCRIPTEN__, generate random (version 4) UUIDs usingstd::random_device, which maps to a secure entropy source in Emscripten.Wrapper/FilingWrapper.cpp—getpwuid()returnsNULLunder Emscripten, soGetFolderAppDataPathdereferenced a null pointer and produced an invalid path (which broke the working-folder extraction of GDTF/MVR archives). Use$HOMEwith a fallback to/home/web_user, the default MEMFS home directory.XmlFileHelper.{h,cpp}— wasm32 definessize_tasunsigned long, which is a distinct type fromUint32(unsigned int) even though both are 32-bit — unlike the 32-bit targets theIS64BITguard was written for. Compile theUint32overloads ofConvertIntegerunder Emscripten as well; otherwise calls withUint32arguments (e.g.GdtfMap::OnPrintToFile,GdtfConnector::OnReadFromNode) are ambiguous and fail to compile.All changes are guarded by
__EMSCRIPTEN__and do not affect any existing platform.Testing
Built with Emscripten 6.0.3 (
-fwasm-exceptions, embind bindings on top) and verified in Node.js and headless Chrome:GetParsingErrorCount(), identical results to the native Linux buildNote: for a fully working WASM build, the pending fixes #169 (root node name) and #170 (3DS/SVG buffer null check) are also needed, but they are independent of this PR.