80 lines
5.2 KiB
Markdown
80 lines
5.2 KiB
Markdown
# 12 — Network stack & the impossible catalog
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> Three link-time stubs (`libcurl_stub.a`, `libgit2_stub.a`, `libnng_stub.a`) gate a cluster
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> of features. Two are revivable in the browser (HTTP libraries, local history); one is
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> genuinely impossible (the IPC socket transport). This doc covers those plus the full
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> catalog of what stays off and **why** — so the "everything web-feasible should work" policy
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> has a clear boundary.
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## curl → emscripten Fetch (revives HTTP libraries)
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`wasm/stubs/curl_stub.c` makes `curl_easy_init()` return `NULL`, so
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`KICAD_CURL_EASY`'s ctor throws `"Unable to initialize CURL session"`
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(`common/kicad_curl/kicad_curl_easy.cpp:127-130`). That kills: the HTTP schematic library
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(`SCH_IO_HTTP_LIB`, which is otherwise compiled and registered — see [08](08-importers.md)),
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the update check, and PCM downloads.
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**The right move is *not* porting libcurl** (browsers can't do raw TCP; the real libcurl-wasm
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ports tunnel TCP over WebSocket proxies — wrong tool). Instead, replace the stub with a
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functional implementation of the ~12 `curl_easy_*` entry points `KICAD_CURL_EASY` actually
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uses (setopt URL/headers/POST/writefunction, perform, getinfo response-code) over the
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**emscripten Fetch API** — Asyncify-friendly (the build already runs full Asyncify), same
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pattern as the clipboard. New file in `wasm/stubs/`, **zero KiCad-file changes**. Constraint:
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target servers must send CORS headers. ~2–4 days. Same shim revives every other curl consumer
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(version checks in `pgm_base.cpp` / `build_version.cpp`, currently failing silently).
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## libgit2 → real static build (fixes silently-broken local history)
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`wasm/stubs/libgit2_stub.c` makes all git ops fail with -1. This kills two things:
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- **Project git integration** — UI lives in the `kicad` project-manager (not a wasm target),
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so mostly moot.
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- **Local history** — **not moot.** `common/local_history.cpp` (git-backed save snapshots) is
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wired into the *shipped* editors (`pcb_edit_frame.cpp`, `files.cpp`, `sch_edit_frame.cpp`,
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`eda_base_frame.cpp`) and currently **fails silently on every save.** This is a real
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product gap worth a deliberate decision.
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**Port (medium, ~1 week):** build a real static `libgit2.a` for wasm (wasm-git /
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petersalomonsen proves libgit2 compiles to emscripten cleanly) and drop the stub for the
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editors. Local-only commits need no network. Remote push/pull would additionally need
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wasm-git's HTTP smart-transport — skip that. **Alternatively**, if local history isn't a
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priority, disable the feature via config so it stops failing silently — but pick one; the
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current state (compiled-in, failing every save) is the worst option.
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## nng / IPC API transport — keep stubbed (impossible)
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`KICAD_IPC_API=ON` builds the API handlers + protobuf (that's what the ON flag is for), but
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`api_server.cpp` / `api_plugin_manager.cpp` are excluded and `kinng` isn't linked
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(`common/CMakeLists.txt`). nng is raw sockets and the IPC clients are **external OS
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processes** — neither exists in a browser sandbox. Keep `libnng_stub.a`.
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> The mainline-aligned future for plugins (post-SWIG KiCad 11) is this same IPC API, reachable
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> from the browser only via a JS bridge (postMessage/WebSocket) implementing the request/reply
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> surface — a *different* transport, not nng. That's a separate project; see
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> [`../../../features/python/research.md`](../../../features/python/research.md).
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## The impossible catalog (and why)
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| Feature | Why it can't work in a browser |
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|---|---|
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| 3Dconnexion SpaceMouse / navlib | needs the native 3DxWare driver/daemon; WebHID can't replace the SDK protocol |
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| Dynamic KIFACE / DSO loading | no `dlopen` of native DSOs in wasm; the static single-kiface architecture is correct (`kiway.cpp` / `kiway.h`) |
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| ODBC database (`nanodbc`) | driver-manager + native driver model has no browser equivalent ([08](08-importers.md)) |
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| nng / IPC transport | raw sockets to external OS processes (above) |
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| `wxUSE_FSWATCHER` | no inotify/kqueue; MEMFS has no change notification and nothing edits files externally |
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| `wxUSE_WEBVIEW` | no browser backend for the wasm port; only the unshipped project-manager uses it |
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| OS keychain (`wxUSE_SECRETSTORE`) | no OS credential service; only insecure approximations (localStorage) exist |
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| Pointer warping (`WarpPointer`) | browsers can't move the OS pointer — handled by zoom-to-cursor ([03](03-config-not-code.md)) |
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| System trash / host env / process info | sandbox (kiplatform `environment.cpp`, `sysinfo.cpp`) |
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| `PYTHON_MANAGER` subprocess execution | no `fork`/subprocess in emscripten; an embedded interpreter is the only path (policy-off) |
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## Policy-off (not impossible — chosen)
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- **Python scripting** — `KICAD_SCRIPTING` OFF + stubs. Stays off per the standing decision;
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the mainline path is the IPC API, not SWIG (see
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[`../../../features/python/research.md`](../../../features/python/research.md)).
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- **PCM, update check** — networking features the team skipped; the curl shim above would
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revive the update check if ever wanted.
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- **`kicad` project manager, `cvpcb`, `bitmap2component`** — never given wasm targets; the web
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app is the "manager" and the product ships per-tool editors (pcbnew, eeschema, symbol_editor,
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gerbview, pl_editor, calculator).
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