Iisyourdad
68 lines
2.3 KiB
JavaScript
68 lines
2.3 KiB
JavaScript
'use strict';
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const fs = require('node:fs');
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const os = require('node:os');
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const path = require('node:path');
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const { nowIso, readJsonIfExists } = require('./util');
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/**
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* Advisory sidecar lock files for shared .sfgz guides on network folders.
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* For `guide.sfgz` the lock is `guide.lock-sfgz` next to it. This is a
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* coordination mechanism, not a security boundary (see docs/SECURITY.md).
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*/
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const STALE_AFTER_MS = 1000 * 60 * 60 * 8; // 8h: treat crashed holders as stale
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function lockPathFor(archivePath) {
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const dir = path.dirname(archivePath);
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const base = path.basename(archivePath);
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const stem = base.endsWith('.sfgz') ? base.slice(0, -'.sfgz'.length) : base;
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return path.join(dir, `${stem}.lock-sfgz`);
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}
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function currentHolder() {
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return { host: os.hostname(), user: os.userInfo().username, pid: process.pid };
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}
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function readLock(archivePath) {
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return readJsonIfExists(lockPathFor(archivePath), null);
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}
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function sameHolder(a, b) {
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return a && b && a.host === b.host && a.user === b.user && a.pid === b.pid;
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}
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function isStale(lock, now = Date.now()) {
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const t = Date.parse(lock && lock.acquiredAt);
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return !Number.isFinite(t) || now - t > STALE_AFTER_MS;
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}
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/**
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* Try to take the lock. Returns { acquired: true, lock } or
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* { acquired: false, conflict } when someone else holds a fresh lock.
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* Pass force=true to steal (after the user confirmed in the conflict dialog).
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*/
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function acquireLock(archivePath, { force = false } = {}) {
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const file = lockPathFor(archivePath);
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const existing = readLock(archivePath);
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const me = currentHolder();
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if (existing && !sameHolder(existing, me) && !isStale(existing) && !force) {
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return { acquired: false, conflict: existing };
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}
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const lock = { ...me, acquiredAt: nowIso() };
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fs.writeFileSync(file, JSON.stringify(lock, null, 2));
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return { acquired: true, lock };
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}
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/** Release only if we are the holder (or force). */
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function releaseLock(archivePath, { force = false } = {}) {
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const file = lockPathFor(archivePath);
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const existing = readLock(archivePath);
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if (!existing) return true;
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if (!force && !sameHolder(existing, currentHolder())) return false;
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fs.rmSync(file, { force: true });
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return true;
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}
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module.exports = { lockPathFor, readLock, acquireLock, releaseLock, isStale, STALE_AFTER_MS };
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