harden shim origin check and fs/vault endpoints

packages/shim/src/fs/fd.js

@@ -1,9 +1,8 @@
-// File descriptor shim  -  maps fake integer fds to in-memory file buffers.
-// Enables libraries like yauzl that use fs.open/fs.read/fs.close to seek
-// around files without loading them via readFileSync upfront.
+// File descriptor shim. Maps fake integer fds to in-memory file buffers.
 
 import { isInputCachePath, inputCacheGet } from "./input-cache.js";
 import { resolvePath } from "./transforms.js";
+import { hasVirtualFile, getVirtualFile } from "./virtual-files.js";
 
 let nextFd = 100;
 const openFiles = new Map();
@@ -24,6 +23,15 @@ export function createFdOps(metadataCache, contentCache, transport) {
     }
 
     const resolved = resolvePath(path);
+
+    if (hasVirtualFile(resolved)) {
+      const content = getVirtualFile(resolved);
+
+      return typeof content === "string"
+        ? new TextEncoder().encode(content)
+        : content;
+    }
+
     const cached = contentCache.get(resolved);
 
     if (cached !== null) {
@@ -60,7 +68,11 @@ export function createFdOps(metadataCache, contentCache, transport) {
     const hasInCache = isInputCachePath(path) && inputCacheGet(path) !== null;
     const resolved = resolvePath(path);
 
-    if (!hasInCache && !metadataCache.has(resolved)) {
+    if (
+      !hasInCache &&
+      !hasVirtualFile(resolved) &&
+      !metadataCache.has(resolved)
+    ) {
       const err = new Error(
         `ENOENT: no such file or directory, open '${path}'`,
       );

packages/shim/src/fs/sync.js

@@ -5,6 +5,7 @@ import {
   applyWriteTransform,
   resolvePath,
 } from "./transforms.js";
+import { hasVirtualFile, getVirtualFile } from "./virtual-files.js";
 
 export function createFsSync(metadataCache, contentCache, transport) {
   return {
@@ -70,6 +71,21 @@ export function createFsSync(metadataCache, contentCache, transport) {
       const wantText = encoding === "utf8" || encoding === "utf-8";
       const resolved = resolvePath(path);
 
+      // Virtual plugin source overrides any cache or transport version.
+      if (hasVirtualFile(resolved)) {
+        const content = getVirtualFile(resolved);
+
+        if (wantText) {
+          return typeof content === "string"
+            ? content
+            : new TextDecoder().decode(content);
+        }
+
+        return typeof content === "string"
+          ? new TextEncoder().encode(content)
+          : content;
+      }
+
       const meta = metadataCache.get(resolved);
       if (meta && meta.type === "directory") {
         const e = new Error("EISDIR: illegal operation on a directory, read");

packages/shim/src/util/url.js

@@ -2,7 +2,7 @@
 function isSameOrigin(url) {
   if (
     !url ||
-    url.startsWith("/") ||
+    (url.startsWith("/") && !url.startsWith("//")) ||
     url.startsWith("./") ||
     url.startsWith("../")
   ) {

packages/shim/src/util/url.test.js

@@ -0,0 +1,25 @@
+import { describe, it, expect, beforeEach, afterEach } from "vitest";
+import { isSameOrigin } from "./url.js";
+
+describe("isSameOrigin", () => {
+  beforeEach(() => {
+    global.window = { location: { origin: "https://vault.example.com" } };
+  });
+
+  afterEach(() => {
+    delete global.window;
+  });
+
+  it("treats a root-relative path as same-origin", () => {
+    expect(isSameOrigin("/api/fs/readFile")).toBe(true);
+  });
+
+  it("treats a protocol-relative URL as cross-origin", () => {
+    expect(isSameOrigin("//evil.com/x")).toBe(false);
+  });
+
+  it("matches the page origin and rejects a different host", () => {
+    expect(isSameOrigin("https://vault.example.com/x")).toBe(true);
+    expect(isSameOrigin("https://evil.com/x")).toBe(false);
+  });
+});