fix(wasi): replace global / preopen with auto-detected absolute path preopens

preopening `/` → `/` gave ripgrep access to the entire filesystem, causing
permission errors when traversing system directories. Now only `.` → cwd is
preopened by default, and absolute paths from args are added individually.

Author: pi0

AGENTS.md

@@ -25,7 +25,7 @@
 
 ### Runtime behavior
 
-- Default preopens map `.` → `process.cwd()` and `/` → `/` so both relative and absolute paths work out of the box; override via `options.preopens`.
+- Default preopens map `.` → `process.cwd()`; absolute paths passed as args are auto-added as preopens so they work without extra configuration.
 - ripgrep's TTY auto-detection doesn't work through WASI preview1 (it always sees a non-TTY), so `ripgrep` auto-injects `--color=ansi` when `process.stdout.isTTY` and the caller hasn't specified a color flag. Detection checks `--color`, `--color=…`, and `--no-color`.
 - `nodeWasi: true` (or `ZIGREP_NODE_WASI=1`) swaps the custom shim for Node's built-in `node:wasi`. Same `{ imports, start }` shape either way. Node's version prints an `ExperimentalWarning` on every run — that's why the custom shim is the default.
 - `start()` returns `0` on clean exit or the exit code from `WASIExit`; `node:wasi`'s `start()` returns `undefined` on success, so the adapter coerces with `?? 0`. The public `ripgrep()` function wraps this into a `{ code }` result object.

README.md

@@ -33,7 +33,7 @@ Runs ripgrep with the given CLI arguments and returns a `{ code }` result object
 Options:
 
 - `env` — environment variables passed to the WASI instance (default: `process.env`).
-- `preopens` — WASI preopened directories mapping guest paths to host paths (default: `{ ".": process.cwd(), "/": "/" }`). Both the current directory and the filesystem root are preopened by default so that relative and absolute paths work out of the box.
+- `preopens` — WASI preopened directories mapping guest paths to host paths (default: `{ ".": process.cwd() }`). Absolute paths passed as args are auto-added as preopens.
 - `returnOnExit` — when `true`, `proc_exit` returns the exit code instead of terminating the process (default: `true`).
 - `nodeWasi` — use Node's built-in `node:wasi` instead of the bundled WASI shim. Enabled by default on Node.js for best performance; automatically disabled on Bun and Deno where `node:wasi` is not available, falling back to the bundled shim. Can also be forced on via `ZIGREP_NODE_WASI=1`.
 

lib/index.d.mts

@@ -62,7 +62,7 @@ export interface ripgrepOptions {
   /**
    * WASI preopened directories, mapping guest paths to host paths.
    * Required for ripgrep to see any files on disk.
-   * @default { ".": process.cwd(), "/": "/" }
+   * @default { ".": process.cwd() }
    */
   preopens?: Record<string, string>;
 

lib/index.mjs

@@ -1,11 +1,12 @@
 import { fileURLToPath } from "node:url";
+import { isAbsolute } from "node:path";
 
 export const rgPath = fileURLToPath(new URL("./rg.mjs", import.meta.url));
 
 export async function ripgrep(args = [], options = {}) {
   const {
     env = process.env,
-    preopens = { ".": process.cwd(), "/": "/" },
+    preopens = { ".": process.cwd() },
     returnOnExit = true,
     nodeWasi = getDefaultNodeWasi(),
   } = options;
@@ -20,11 +21,20 @@ export async function ripgrep(args = [], options = {}) {
     args = ["--color=ansi", ...args];
   }
 
+  // Auto-add preopens for absolute paths found in args so they're accessible
+  // without requiring the caller to manually configure preopens.
+  const resolvedPreopens = { ...preopens };
+  for (const arg of args) {
+    if (isAbsolute(arg) && !(arg in resolvedPreopens)) {
+      resolvedPreopens[arg] = arg;
+    }
+  }
+
   const wasi = await createWasiRuntime({
     args,
     env,
     nodeWasi,
-    preopens,
+    preopens: resolvedPreopens,
     returnOnExit,
   });