Add WASM entry point and Emscripten build wiring

The pieces that make Magic actually buildable as a WASM library. * magic/magicWasm.c — new headless entry point exporting four functions used by the JS wrapper: - magic_wasm_init() idempotent initialisation - magic_wasm_run_command(s) dispatch one Magic command - magic_wasm_source_file(p) execute a script from the VFS - magic_wasm_update() drive a display-update cycle Sets CAD_ROOT=/ if unset, so embedded technology files under /magic/sys/ resolve correctly. Centers the command point inside GrScreenRect so commands route to the layout window client rather than the border/window-management client. * utils/main.c, utils/main.h — split magicMain() into magicMainInit() + the dispatch loop. magicMainInit is idempotent (a static flag guards against re-initialisation) so JS callers can call any of the four wasm entry points first without sequencing. * magic/Makefile — adds the WASM link target, gated by MAKE_WASM=1 set from toolchains/emscripten/defs.mak. Conditionally compiles magicWasm.c into the main binary, links to magic.js and runs post-build.sh on the result. * toolchains/emscripten/defs.mak — Emscripten linker flags (WASM=1, MODULARIZE, EXPORT_ES6, ALLOW_MEMORY_GROWTH, INITIAL_MEMORY=32M, STACK_SIZE=5M), the four EXPORTED_FUNCTIONS, and the embed-file bindings for the technology files under /magic/sys/. * toolchains/emscripten/post-build.sh — patches Emscripten's ESM output so it works in pure Node.js ESM: aliases require() through createRequire, injects __filename / __dirname shims, and resyncs the ___emscripten_embedded_file_data constant from the wasm global section if Emscripten emitted a stale value. Idempotent and pinned to emsdk 3.1.56 (see WARNING in the header). * toolchains/emscripten/README.md — full build documentation: quick-start via npm/build.sh, manual build, list of embedded files, exported C API, JavaScript usage example, and notes on CAD_ROOT, DISPLAY_SUSPEND, and the signal-API stubs. * .gitignore — adds the WASM artefacts (magic.js, magic.wasm, magic.symbols), tightens the editor/OS cruft list, and keeps toolchains/emscripten/defs.mak tracked despite the `defs.mak` ignore rule.
2026-08-28 17:15:13 +02:00 · 2026-05-11 14:20:47 -04:00
parent f4c22438c6
commit 8e8fada32f
8 changed files with 473 additions and 15 deletions
@@ -0,0 +1,137 @@
+#!/usr/bin/env bash
+# Post-process Emscripten output for Node.js 22+ ES module compatibility.
+#
+# Emscripten (3.1.x) produces ES module output that still references
+# `require()`, `__dirname`, and `__filename` — all of which are undefined
+# in pure ESM. This script patches magic.js to:
+#   1. Alias every `require("x")` call to `___cr("x")` (createRequire).
+#   2. Inject ESM-safe `__filename` / `__dirname` / `require` at module top.
+#   3. Sync `___emscripten_embedded_file_data` from the .wasm global.
+#
+# Usage:  post-build.sh <magic.js> <magic.wasm>
+#
+# Idempotent — safe to run multiple times.
+#
+# WARNING: These patches depend on exact text patterns emitted by a specific
+# Emscripten version. If you upgrade emsdk, verify the patches still apply
+# (see .github/workflows/main.yml for the pinned version).
+
+set -euo pipefail
+
+if [ $# -ne 2 ]; then
+    echo "Usage: $0 <magic.js> <magic.wasm>" >&2
+    exit 1
+fi
+
+JS=$1
+WASM=$2
+
+if [ ! -f "$JS" ] || [ ! -f "$WASM" ]; then
+    echo "Error: $JS or $WASM not found." >&2
+    exit 1
+fi
+
+# Portable in-place sed: BSD (macOS) and GNU diverge on -i.
+# Using a temp file + mv keeps both happy without relying on -i at all.
+_sed_inplace() {
+    local expr=$1 file=$2
+    local tmp
+    tmp=$(mktemp)
+    sed "$expr" "$file" > "$tmp"
+    mv "$tmp" "$file"
+}
+
+# --- 1 & 2. ES module compatibility -----------------------------------------
+if ! grep -q 'createRequire' "$JS"; then
+    echo "[post-build] Injecting ESM createRequire + __filename/__dirname shims"
+    _sed_inplace 's/require("\([^"]*\)")/___cr("\1")/g' "$JS"
+    _sed_inplace '1s|^|\nimport{createRequire as ___cr}from"module";\nimport{fileURLToPath as ___fup}from"url";\nimport{dirname as ___dn}from"path";\nvar __filename=___fup(import.meta.url);\nvar __dirname=___dn(__filename);\n|' "$JS"
+fi
+
+# Ensure a top-level `require` binding exists (Emscripten's environment probe
+# does `typeof require == "function"`, which would otherwise be "undefined").
+# Skip if Emscripten already emits one (newer versions do).
+if ! grep -qE 'var[[:space:]]+require[[:space:]]*=' "$JS" \
+   && grep -q 'import{createRequire as ___cr}from"module";' "$JS"; then
+    echo "[post-build] Adding top-level require binding"
+    _sed_inplace 's|import{createRequire as ___cr}from"module";|import{createRequire as ___cr}from"module";var require=___cr(import.meta.url);|' "$JS"
+fi
+
+# --- 3. Sync ___emscripten_embedded_file_data from .wasm --------------------
+# Emscripten sometimes bakes a stale constant into magic.js after an
+# incremental rebuild. Read the true value from the WASM global section
+# (section id 6, global index 1, i32.const opcode 0x41, signed LEB128).
+python3 - "$JS" "$WASM" <<'PY'
+import sys, re
+
+js_path, wasm_path = sys.argv[1], sys.argv[2]
+data = open(wasm_path, 'rb').read()
+
+def read_uleb(buf, pos):
+    val = shift = 0
+    while True:
+        b = buf[pos]; pos += 1
+        val |= (b & 0x7f) << shift
+        shift += 7
+        if not (b & 0x80):
+            return val, pos
+
+def read_sleb(buf, pos):
+    val = shift = 0
+    while True:
+        b = buf[pos]; pos += 1
+        val |= (b & 0x7f) << shift
+        shift += 7
+        if not (b & 0x80):
+            if b & 0x40:
+                val |= (~0) << shift
+            return val & 0xffffffff, pos
+
+# Walk sections looking for section id 6 (Global)
+pos = 8  # skip magic + version
+actual = None
+while pos < len(data):
+    sid = data[pos]; pos += 1
+    size, pos = read_uleb(data, pos)
+    end = pos + size
+    if sid == 6:
+        count, p = read_uleb(data, pos)
+        for gi in range(count):
+            p += 2  # valtype + mutability
+            opcode = data[p]; p += 1
+            if opcode == 0x41:  # i32.const
+                val, p = read_sleb(data, p)
+                if gi == 1:
+                    actual = val
+                    break
+            p += 1  # skip end opcode
+        break
+    pos = end
+
+if actual is None:
+    sys.stderr.write(
+        '[post-build] WARN: could not parse global index 1 from wasm; '
+        'skipping ___emscripten_embedded_file_data sync\n')
+    sys.exit(0)
+
+js = open(js_path).read()
+m = re.search(r'Module\[.___emscripten_embedded_file_data.\]=(\d+)', js)
+if not m:
+    # Emscripten may have fixed the stale-constant bug in a newer version.
+    # Not fatal, but worth surfacing so we can drop this patch eventually.
+    sys.stderr.write(
+        '[post-build] INFO: ___emscripten_embedded_file_data not present; '
+        'sync patch no longer applies (likely fixed upstream)\n')
+    sys.exit(0)
+
+old = int(m.group(1))
+if old != actual:
+    print(f'[post-build] Fixing ___emscripten_embedded_file_data: {old} -> {actual}')
+    js = js.replace(
+        f'Module["___emscripten_embedded_file_data"]={old}',
+        f'Module["___emscripten_embedded_file_data"]={actual}',
+    )
+    open(js_path, 'w').write(js)
+PY
+
+echo "[post-build] Done."