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