From 56d9930a7bd2fec5fe5cdf6f761533ba7b5cd4f8 Mon Sep 17 00:00:00 2001
From: Tim van der Meij <timvandermeij@gmail.com>
Date: Sun, 11 Feb 2024 13:45:06 +0100
Subject: [PATCH] Extract and modernize the webserver's file serving code

The `handler` method contained this code in an inline function, which
made the `handler` method big and harder to read. Moreover, this code
relied on variables from the outer scope, which made it harder to reason
about because the inputs and outputs weren't easily visible.

This commit fixes the problems by extracting the file serving code into
a dedicated private method, and modernizing it to use e.g. `const`/`let`
instead of `var` and using template strings.
---
 test/webserver.mjs | 54 ++++++++++++++++++++++------------------------
 1 file changed, 26 insertions(+), 28 deletions(-)

diff --git a/test/webserver.mjs b/test/webserver.mjs
index 25d7f1ed0..0149eadc5 100644
--- a/test/webserver.mjs
+++ b/test/webserver.mjs
@@ -82,6 +82,7 @@ class WebServer {
   }
 
   #handler(req, res) {
+    var self = this;
     var url = req.url.replaceAll("//", "/");
     var urlParts = /([^?]*)((?:\?(.*))?)/.exec(url);
     try {
@@ -126,7 +127,6 @@ class WebServer {
     }
 
     var disableRangeRequests = this.disableRangeRequests;
-    var cacheExpirationTime = this.cacheExpirationTime;
 
     var filePath;
     fs.realpath(path.join(this.root, pathPart), checkFile);
@@ -192,7 +192,7 @@ class WebServer {
       if (verbose) {
         console.log(url);
       }
-      serveRequestedFile(filePath);
+      self.#serveFile(res, filePath, fileSize);
     }
 
     function escapeHTML(untrusted) {
@@ -286,32 +286,6 @@ class WebServer {
       });
     }
 
-    function serveRequestedFile(reqFilePath) {
-      var stream = fs.createReadStream(reqFilePath, { flags: "rs" });
-
-      stream.on("error", function (error) {
-        res.writeHead(500);
-        res.end();
-      });
-
-      var ext = path.extname(reqFilePath).toLowerCase();
-      var contentType = mimeTypes[ext] || defaultMimeType;
-
-      if (!disableRangeRequests) {
-        res.setHeader("Accept-Ranges", "bytes");
-      }
-      res.setHeader("Content-Type", contentType);
-      res.setHeader("Content-Length", fileSize);
-      if (cacheExpirationTime > 0) {
-        var expireTime = new Date();
-        expireTime.setSeconds(expireTime.getSeconds() + cacheExpirationTime);
-        res.setHeader("Expires", expireTime.toUTCString());
-      }
-      res.writeHead(200);
-
-      stream.pipe(res);
-    }
-
     function serveRequestedFileRange(reqFilePath, start, end) {
       var stream = fs.createReadStream(reqFilePath, {
         flags: "rs",
@@ -339,6 +313,30 @@ class WebServer {
       stream.pipe(res);
     }
   }
+
+  #serveFile(response, filePath, fileSize) {
+    const stream = fs.createReadStream(filePath, { flags: "rs" });
+    stream.on("error", error => {
+      response.writeHead(500);
+      response.end();
+    });
+
+    const extension = path.extname(filePath).toLowerCase();
+    const contentType = mimeTypes[extension] || defaultMimeType;
+
+    if (!this.disableRangeRequests) {
+      response.setHeader("Accept-Ranges", "bytes");
+    }
+    response.setHeader("Content-Type", contentType);
+    response.setHeader("Content-Length", fileSize);
+    if (this.cacheExpirationTime > 0) {
+      const expireTime = new Date();
+      expireTime.setSeconds(expireTime.getSeconds() + this.cacheExpirationTime);
+      response.setHeader("Expires", expireTime.toUTCString());
+    }
+    response.writeHead(200);
+    stream.pipe(response);
+  }
 }
 
 // This supports the "Cross-origin" test in test/unit/api_spec.js