feat: 添加自动识别文件名功能

main.ts

@@ -1,47 +1,40 @@
-import { dirname, join, basename } from "jsr:@std/path";
+import { basename, join } from "jsr:@std/path";
 import { Mutex } from "npm:async-mutex";
 import { downloadChunk } from "./workerpool.ts";
 
 export async function download(
   url: string,
-  filename: string,
+  dirpath: string,
   threads: number,
   chunkSize = 5 * 1024 * 1024,
   headers: HeadersInit = {}
 ) {
-  async function writeFile(buf: ArrayBuffer, pos: number) {
-    const release = await mutex.acquire();
-    while (true) {
-      try {
-        await file.seek(pos, Deno.SeekMode.Start);
-        await file.write(new Uint8Array(buf));
-        break;
-      } catch (e) {
-        console.error("%c" + e, "color: red");
-      }
-    }
-    release();
-  }
-
-  async function getContentLength() {
+  async function getURLInfo() {
     const r = await fetch(url, {
       method: "HEAD",
       headers: headers,
     });
-    return +r.headers.get("content-length")!;
+    const contentLength = +r.headers.get("content-length")!;
+    const disposition = r.headers.get("content-disposition");
+    const filename = (
+      disposition
+        ?.split(";")
+        .map((s) => s.trim())
+        .find((s) => s.startsWith("filename="))
+        ?.split("=")[1] ?? basename(url)
+    ).replace(/[\\/:*?"<>|]/g, "_");
+    return { filename, contentLength };
   }
 
-  // 初始化文件
-  const dirpath = dirname(filename);
-  await Deno.mkdir(dirpath, { recursive: true });
-  const file = await Deno.open(filename, { write: true, create: true });
-
-  // 读写锁
   const mutex = new Mutex();
+  const { contentLength, filename } = await getURLInfo();
+  await Deno.mkdir(dirpath, { recursive: true });
+  const file = await Deno.open(join(dirpath, filename), {
+    write: true,
+    create: true,
+  });
 
   try {
-    // 获取文件长度
-    const contentLength = await getContentLength();
     const chunkCount = Math.ceil(contentLength / chunkSize);
     const chunks: Chunk[] = Array.from({ length: chunkCount }, (_, i) => ({
       start: i * chunkSize,
@@ -53,7 +46,17 @@ export async function download(
       headers,
       chunks,
       async (i) => {
-        await writeFile(i.data, i.origin.start);
+        const release = await mutex.acquire();
+        while (true) {
+          try {
+            await file.seek(i.origin.start, Deno.SeekMode.Start);
+            await file.write(new Uint8Array(i.data));
+            break;
+          } catch (e) {
+            console.error("%c" + e, "color: red");
+          }
+        }
+        release();
         console.log(`chunk ${i.origin.start} - ${i.origin.end} done`);
       },
       Infinity
@@ -73,5 +76,5 @@ if (import.meta.main) {
   const url = Deno.args[0];
   const threads = +Deno.args[1] || 32;
   const dirpath = Deno.args[2] || ".";
-  await download(url, join(dirpath, basename(url)), threads);
+  await download(url, join(Deno.cwd(), dirpath), threads);
 }