Broken site based impl

lib/stdlib/io.js

@@ -0,0 +1,72 @@
+// Files, with promises, on the IO natives (see lib/rt/io.h). They are like
+// node's `fs.promises`, but only for UTF-8 text:
+// - `fs.readFile(path)` gives the text of the file
+// - `fs.writeFile(path, text)` makes or replaces the file
+// A failure rejects with the negative errno, not an `Error`. A read or a write
+// that the kernel does not finish in one op is not continued
+
+// A promise of what op `h` gives when it completes: its status, its data, or
+// a number. A result can only be read before the next wait, so these read it
+// when the op completes
+function __io_status(h) {
+    return new Promise((resolve) => {
+        __pending[h] = (h) => resolve(__native_io_status(h));
+    });
+}
+
+function __io_string(h) {
+    return new Promise((resolve, reject) => {
+        __pending[h] = (h) => {
+            const status = __native_io_status(h);
+            if (status < 0) reject(status);
+            else resolve(__native_io_result_string(h));
+        };
+    });
+}
+
+function __io_number(h) {
+    return new Promise((resolve, reject) => {
+        __pending[h] = (h) => {
+            const status = __native_io_status(h);
+            if (status < 0) reject(status);
+            else resolve(__native_io_result_number(h));
+        };
+    });
+}
+
+// A promise of the status of op `h`, rejected if it failed
+function __io_ok(h) {
+    return __io_status(h).then((status) => (status < 0 ? Promise.reject(status) : status));
+}
+
+const fs = {
+    readFile(path) {
+        let fd = -1;
+        let text = "";
+
+        return __io_ok(__native_io_queue_open(path, 0, 0))
+            .then((f) => {
+                fd = f;
+                return __io_number(__native_io_queue_stat(path));
+            })
+            .then((size) => __io_string(__native_io_queue_read(fd, size, 0)))
+            .then((s) => {
+                text = s;
+                return __io_ok(__native_io_queue_close(fd));
+            })
+            .then(() => text);
+    },
+
+    writeFile(path, text) {
+        let fd = -1;
+
+        // O_WRONLY | O_CREAT | O_TRUNC, mode 0644
+        return __io_ok(__native_io_queue_open(path, 577, 420))
+            .then((f) => {
+                fd = f;
+                return __io_ok(__native_io_queue_write(fd, text, 0));
+            })
+            .then(() => __io_ok(__native_io_queue_close(fd)))
+            .then(() => undefined);
+    },
+};