FFI libc demo

Author: codefrau

ffi/libc.js

@@ -0,0 +1,71 @@
+"use strict";
+/*
+ * Copyright (c) 2013-2024 Vanessa Freudenberg
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+// This is a minimal libc module for SqueakJS
+// serving mostly as a demo for FFI
+
+function libc() {
+    return {
+        // LIBC module
+        getModuleName() { return "libc (SqueakJS)"; },
+        setInterpreter(proxy) { this.vm = proxy.vm; return true; },
+
+        // helper functions
+        bytesToString(bytes) {
+            const zero = bytes.indexOf(0);
+            if (zero >= 0) bytes = bytes.subarray(0, zero);
+            return String.fromCharCode.apply(null, bytes);
+        },
+        stringToBytes(string, bytes) {
+            for (let i = 0; i < string.length; i++) bytes[i] = string.charCodeAt(i);
+            bytes[string.length] = 0;
+            return bytes;
+        },
+
+        // LIBC emulation functions called via FFI
+        getenv(v) {
+            v = this.bytesToString(v);
+            switch (v) {
+                case "USER": return this.vm.options.user || "squeak";
+                case "HOME": return this.vm.options.root || "/";
+            }
+            this.vm.warnOnce("UNIMPLEMENTED getenv: " + v);
+            return null;
+        },
+        getcwd(buf, size) {
+            const cwd = this.vm.options.root || "/";
+            if (!buf) buf = new Uint8Array(cwd.length + 1);
+            if (size < cwd.length + 1) return 0; // should set errno to ERANGE
+            this.stringToBytes(cwd, buf);
+            return buf; // converted to Smalltalk String by FFI if declared as char*
+        },
+    };
+}
+
+function registerLibC() {
+    if (typeof Squeak === "object" && Squeak.registerExternalModule) {
+        Squeak.registerExternalModule('libc', libc());
+    } else self.setTimeout(registerLibC, 100);
+};
+
+registerLibC();

squeak.js

@@ -74,6 +74,7 @@ import "./plugins/SqueakSSL.js";
 import "./plugins/SoundGenerationPlugin.js";
 import "./plugins/StarSqueakPlugin.js";
 import "./plugins/ZipPlugin.js";
+import "./ffi/libc.js";
 import "./lib/lz-string.js";
 import "./lib/jszip.js";
 import "./lib/FileSaver.js";