Do not perform actual file write more than once on same file

Changes

2 changed files (+39/-1)

• filesystem_writer/deno_fs.test.ts
  • @@ -2,7 +2,10 @@ // SPDX-FileCopyrightText: 2024 Shota FUJI <pockawoooh@gmail.com>
    // // SPDX-License-Identifier: Apache-2.0 - import { assertEquals } from "../deps/deno.land/std/assert/mod.ts"; + import { + assertEquals, + assertRejects, + } from "../deps/deno.land/std/assert/mod.ts"; import { DenoFsWriter } from "./deno_fs.ts";
  • @@ -42,3 +45,25 @@ } finally {
    await Deno.remove(root, { recursive: true }); } }); + + Deno.test("Should abort on attempt to write different content at same path", { + // Skip this test if write permission is not granted. + // Without this, simple `deno test` would fail or prompt permissions, which is annoying. + ignore: writePermission.state !== "granted" || + readPermission.state !== "granted", + }, async () => { + await Deno.mkdir(root, { recursive: true }); + + try { + const writer = new DenoFsWriter(root); + + const enc = new TextEncoder(); + + await writer.write(["hash-test", "foo.txt"], enc.encode("Foo")); + await assertRejects(() => + writer.write(["hash-test", "foo.txt"], enc.encode("Bar")) + ); + } finally { + await Deno.remove(root, { recursive: true }); + } + });
• filesystem_writer/deno_fs.ts
  • @@ -10,6 +10,7 @@ import type { FileSystemWriter } from "./interface.ts";
    export class DenoFsWriter implements FileSystemWriter { #root: string; + #wroteHash: Map<string, Uint8Array> = new Map(); constructor(rootDirectory: string | URL) { this.#root = typeof rootDirectory === "string"
  • @@ -49,6 +50,18 @@ path: readonly string[],
    content: Uint8Array, ) { const resolvedPath = this.#resolve(path); + const hash = new Uint8Array(await crypto.subtle.digest("SHA-1", content)); + const wrote = this.#wroteHash.get(resolvedPath); + if (wrote) { + if (!wrote.every((b, i) => hash[i] === b)) { + throw new Error( + `Attempt to write different content at ${resolvedPath}`, + ); + } + return; + } + + this.#wroteHash.set(resolvedPath, hash); logger().debug(`Writing file at ${path.join(SEPARATOR)}`, { path,