ensure case sensitive paths

src/build.ts

@@ -12,7 +12,7 @@ import type {MarkdownPage} from "./markdown.js";
 import {parseMarkdown} from "./markdown.js";
 import {extractNodeSpecifier} from "./node.js";
 import {extractNpmSpecifier, populateNpmCache, resolveNpmImport} from "./npm.js";
-import {isAssetPath, isPathImport, relativePath, resolvePath} from "./path.js";
+import {assertPathname, isAssetPath, isPathImport, relativePath, resolvePath} from "./path.js";
 import {renderPage} from "./render.js";
 import type {Resolvers} from "./resolvers.js";
 import {getModuleResolver, getResolvers} from "./resolvers.js";
@@ -353,5 +353,6 @@ export class FileBuildEffects implements BuildEffects {
     this.logger.log(destination);
     await prepareOutput(destination);
     await writeFile(destination, contents);
+    await assertPathname(destination, this.outputRoot, outputPath);
   }
 }

src/path.ts

@@ -1,3 +1,4 @@
+import {realpath} from "node:fs/promises";
 import {dirname, join} from "node:path/posix";
 
 /**
@@ -84,3 +85,12 @@ export function parseRelativeUrl(url: string): {pathname: string; search: string
   else (search = url.slice(j)), (url = url.slice(0, j));
   return {pathname: url, search, hash};
 }
+
+/**
+ * Checks that the actual filename under root/path has the same case as the
+ * target.
+ */
+export async function assertPathname(target: string, root: string, path: string): Promise<undefined> {
+  const cased = (await realpath(target)).slice((await realpath(root)).length + 1).replaceAll("\\", "/");
+  if (cased !== path.replace(/^\//, "")) throw new Error(`Incorrect case for ${target}: found ${cased} instead.`);
+}

src/preview.ts

@@ -24,7 +24,7 @@ import {transpileJavaScript, transpileModule} from "./javascript/transpile.js";
 import {parseMarkdown} from "./markdown.js";
 import type {MarkdownCode, MarkdownPage} from "./markdown.js";
 import {populateNpmCache} from "./npm.js";
-import {isPathImport, resolvePath} from "./path.js";
+import {assertPathname, isPathImport, resolvePath} from "./path.js";
 import {renderPage} from "./render.js";
 import type {Resolvers} from "./resolvers.js";
 import {getResolvers} from "./resolvers.js";
@@ -155,6 +155,7 @@ export class PreviewServer {
         const filepath = join(root, path);
         try {
           await access(filepath, constants.R_OK);
+          await assertPathname(filepath, root, path);
           send(req, pathname.slice("/_file".length), {root}).pipe(res);
           return;
         } catch (error) {

test/path-test.ts

@@ -1,5 +1,12 @@
 import assert from "node:assert";
-import {isPathImport, parseRelativeUrl, relativePath, resolveLocalPath, resolvePath} from "../src/path.js";
+import {
+  assertPathname,
+  isPathImport,
+  parseRelativeUrl,
+  relativePath,
+  resolveLocalPath,
+  resolvePath
+} from "../src/path.js";
 
 describe("resolvePath(source, target)", () => {
   it("returns the path to the specified target within the source root", () => {
@@ -148,3 +155,12 @@ describe("parseRelativeUrl(url)", () => {
     assert.deepStrictEqual(parseRelativeUrl("foo?bar#baz"), {pathname: "foo", search: "?bar", hash: "#baz"});
   });
 });
+
+describe("assertPathname(target, root, path)", () => {
+  it("throws an error on files with the wrong case", async () => {
+    await assert.rejects(assertPathname("./docs/HORSE.jpg", "./docs", "/HORSE.jpg"));
+  });
+  it("throws an error on paths with the wrong case", async () => {
+    await assert.rejects(assertPathname("./docs/DATA/alphabet.csv", "./docs", "/DATA/alphabet.csv"));
+  });
+});