microsoft
diff --git a/‎src/common/inlineScriptCacheLayout.ts‎
Lines changed: 246 additions & 0 deletions b/‎src/common/inlineScriptCacheLayout.ts‎
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+// Copyright (c) Microsoft Corporation. All rights reserved.
+// Licensed under the MIT License.
+
+import * as crypto from 'crypto';
+import * as fsapi from 'fs-extra';
+import * as path from 'path';
+import { Uri } from 'vscode';
+import { traceWarn } from './logging';
+import { isWindows } from './utils/platformUtils';
+
+/**
+ * Versioned name of the cache root under the extension's `globalStorageUri`.
+ *
+ * Bump the `-v1` suffix together with {@link META_SCHEMA_VERSION} on any
+ * incompatible on-disk change, so old envs sit unread and TTL out naturally
+ * instead of being migrated in place.
+ */
+export const INLINE_SCRIPT_CACHE_DIR_NAME = 'script-envs-v1';
+
+export const META_JSON_FILENAME = '.meta.json';
+
+/**
+ * Schema version embedded in every {@link InlineScriptEnvMeta}.
+ */
+export const META_SCHEMA_VERSION = 1 as const;
+export interface InlineScriptEnvMeta {
+    readonly schemaVersion: typeof META_SCHEMA_VERSION;
+    readonly scriptFsPath: string;
+    readonly lastUsedAt: string;
+    readonly requiresPython?: string;
+}
+
+export function getScriptEnvCacheRoot(globalStorageUri: Uri): Uri {
+    return Uri.joinPath(globalStorageUri, INLINE_SCRIPT_CACHE_DIR_NAME);
+}
+
+export function getScriptEnvDir(globalStorageUri: Uri, cacheKey: string): Uri {
+    return Uri.joinPath(getScriptEnvCacheRoot(globalStorageUri), cacheKey);
+}
+
+export function getMetaJsonPath(envDir: Uri): Uri {
+    return Uri.joinPath(envDir, META_JSON_FILENAME);
+}
+
+const MAX_META_JSON_BYTES = 1024 * 1024;
+
+export async function readMetaJson(envDir: Uri): Promise<InlineScriptEnvMeta | undefined> {
+    const metaPath = getMetaJsonPath(envDir).fsPath;
+
+    try {
+        const stat = await fsapi.stat(metaPath);
+        if (!stat.isFile()) {
+            traceWarn(`inline-script meta: not a regular file at ${metaPath}`);
+            return undefined;
+        }
+        if (stat.size > MAX_META_JSON_BYTES) {
+            traceWarn(`inline-script meta: refusing to read ${metaPath} (${stat.size} bytes > cap)`);
+            return undefined;
+        }
+    } catch (err) {
+        if (isFileNotFoundError(err)) {
+            traceWarn(`inline-script meta: not found at ${metaPath}`);
+        } else {
+            const code = (err as NodeJS.ErrnoException | undefined)?.code ?? 'unknown';
+            traceWarn(`inline-script meta: failed to stat ${metaPath} (code=${code}):`, err);
+        }
+        return undefined;
+    }
+
+    let raw: string;
+    try {
+        raw = await fsapi.readFile(metaPath, 'utf8');
+    } catch (err) {
+        const code = (err as NodeJS.ErrnoException | undefined)?.code ?? 'unknown';
+        traceWarn(`inline-script meta: failed to read ${metaPath} (code=${code}):`, err);
+        return undefined;
+    }
+
+    let parsed: unknown;
+    try {
+        parsed = JSON.parse(raw);
+    } catch (err) {
+        traceWarn(`inline-script meta: malformed JSON in ${metaPath}:`, err);
+        return undefined;
+    }
+
+    const validated = validateMeta(parsed);
+    if (!validated) {
+        traceWarn(`inline-script meta: invalid shape in ${metaPath}`);
+        return undefined;
+    }
+    return validated;
+}
+
+/**
+ * Atomically write the `.meta.json` sidecar via temp-file + rename.
+ */
+export async function writeMetaJson(envDir: Uri, meta: InlineScriptEnvMeta): Promise<void> {
+    await fsapi.ensureDir(envDir.fsPath);
+    const finalPath = getMetaJsonPath(envDir).fsPath;
+    const tmpSuffix = crypto.randomBytes(6).toString('hex');
+    const tmpPath = `${finalPath}.tmp-${tmpSuffix}`;
+    const payload = JSON.stringify(meta, undefined, 2);
+    try {
+        await fsapi.writeFile(tmpPath, payload, 'utf8');
+        await fsapi.rename(tmpPath, finalPath);
+    } catch (err) {
+        await fsapi.remove(tmpPath).catch(() => undefined);
+        throw err;
+    }
+}
+
+/**
+ * Snapshot of one cached entry, populated by the (separate, I/O-doing) disk
+ * walk.
+ */
+export interface CacheEntrySummary {
+    readonly envDirPath: string;
+    readonly lastUsedAt: Date | undefined;
+}
+
+/**
+ * Pure selector: returns the env-dir paths whose age exceeds `ttlMs`.
+ */
+export function selectStaleEntries(entries: ReadonlyArray<CacheEntrySummary>, now: Date, ttlMs: number): string[] {
+    const stale: string[] = [];
+    const nowMs = now.getTime();
+    for (const entry of entries) {
+        if (entry.lastUsedAt === undefined) {
+            continue;
+        }
+        const ageMs = nowMs - entry.lastUsedAt.getTime();
+        if (ageMs > ttlMs) {
+            stale.push(entry.envDirPath);
+        }
+    }
+    return stale;
+}
+
+/**
+ * Verify that a cached env's base interpreter still exists on disk.
+ */
+export async function verifyEnvUsable(envDir: Uri): Promise<boolean> {
+    if (isWindows()) {
+        return verifyWindowsBaseInterpreter(envDir);
+    }
+    return verifyPosixBaseInterpreter(envDir);
+}
+
+async function verifyPosixBaseInterpreter(envDir: Uri): Promise<boolean> {
+    const launcherPath = Uri.joinPath(envDir, 'bin', 'python').fsPath;
+    return statRegularFile(launcherPath, 'base interpreter');
+}
+
+async function verifyWindowsBaseInterpreter(envDir: Uri): Promise<boolean> {
+    const pyvenvPath = Uri.joinPath(envDir, 'pyvenv.cfg').fsPath;
+    let raw: string;
+    try {
+        raw = await fsapi.readFile(pyvenvPath, 'utf8');
+    } catch (err) {
+        if (isFileNotFoundError(err)) {
+            traceWarn(`inline-script env: missing pyvenv.cfg at ${pyvenvPath}`);
+        } else {
+            const code = (err as NodeJS.ErrnoException | undefined)?.code ?? 'unknown';
+            traceWarn(`inline-script env: failed to read ${pyvenvPath} (code=${code}):`, err);
+        }
+        return false;
+    }
+    const home = parsePyvenvHome(raw);
+    if (home === undefined) {
+        traceWarn(`inline-script env: no 'home =' line in ${pyvenvPath}`);
+        return false;
+    }
+    const launcherPath = path.join(home, 'python.exe');
+    return statRegularFile(launcherPath, 'base interpreter');
+}
+
+async function statRegularFile(filePath: string, label: string): Promise<boolean> {
+    try {
+        const stat = await fsapi.stat(filePath);
+        if (!stat.isFile()) {
+            traceWarn(`inline-script env: ${label} is not a regular file at ${filePath}`);
+            return false;
+        }
+        return true;
+    } catch (err) {
+        if (isFileNotFoundError(err)) {
+            traceWarn(`inline-script env: ${label} missing at ${filePath}`);
+        } else {
+            const code = (err as NodeJS.ErrnoException | undefined)?.code ?? 'unknown';
+            traceWarn(`inline-script env: failed to stat ${filePath} (code=${code}):`, err);
+        }
+        return false;
+    }
+}
+
+function parsePyvenvHome(raw: string): string | undefined {
+    for (const line of raw.split(/\r?\n/)) {
+        const m = line.match(/^\s*home\s*=\s*(.+?)\s*$/);
+        if (m) {
+            return m[1];
+        }
+    }
+    return undefined;
+}
+
+function isFileNotFoundError(err: unknown): boolean {
+    return typeof err === 'object' && err !== null && 'code' in err && (err as NodeJS.ErrnoException).code === 'ENOENT';
+}
+
+function validateMeta(value: unknown): InlineScriptEnvMeta | undefined {
+    if (typeof value !== 'object' || value === null || Array.isArray(value)) {
+        return undefined;
+    }
+    const obj = value as Record<string, unknown>;
+    if (obj.schemaVersion !== META_SCHEMA_VERSION) {
+        return undefined;
+    }
+    if (typeof obj.scriptFsPath !== 'string' || obj.scriptFsPath.length === 0) {
+        return undefined;
+    }
+    if (!isCanonicalIsoTimestamp(obj.lastUsedAt)) {
+        return undefined;
+    }
+    if (obj.requiresPython !== undefined && typeof obj.requiresPython !== 'string') {
+        return undefined;
+    }
+
+    return {
+        schemaVersion: META_SCHEMA_VERSION,
+        scriptFsPath: obj.scriptFsPath,
+        lastUsedAt: obj.lastUsedAt,
+        requiresPython: obj.requiresPython,
+    };
+}
+
+function isCanonicalIsoTimestamp(value: unknown): value is string {
+    if (typeof value !== 'string') {
+        return false;
+    }
+    const ms = Date.parse(value);
+    if (Number.isNaN(ms)) {
+        return false;
+    }
+    return new Date(ms).toISOString() === value;
+}