Memory: share ENOENT helpers

src/memory/fs-utils.ts

@@ -0,0 +1,31 @@
+import type { Stats } from "node:fs";
+import fs from "node:fs/promises";
+
+export type RegularFileStatResult = { missing: true } | { missing: false; stat: Stats };
+
+export function isFileMissingError(
+  err: unknown,
+): err is NodeJS.ErrnoException & { code: "ENOENT" } {
+  return Boolean(
+    err &&
+    typeof err === "object" &&
+    "code" in err &&
+    (err as Partial<NodeJS.ErrnoException>).code === "ENOENT",
+  );
+}
+
+export async function statRegularFile(absPath: string): Promise<RegularFileStatResult> {
+  let stat: Stats;
+  try {
+    stat = await fs.lstat(absPath);
+  } catch (err) {
+    if (isFileMissingError(err)) {
+      return { missing: true };
+    }
+    throw err;
+  }
+  if (stat.isSymbolicLink() || !stat.isFile()) {
+    throw new Error("path required");
+  }
+  return { missing: false, stat };
+}