Update solutions for Chapter 20

Author: marijnh

.gitignore

@@ -16,7 +16,7 @@
 /code/chapter/*
 /code/file_server.js
 /code/skillsharing.zip
-/code/solutions/20_4_a_public_space_on_the_web.zip
+/code/solutions/20_3_a_public_space_on_the_web.zip
 /code/skillsharing/*
 /node_modules
 .tern-port

20_node.md

@@ -794,12 +794,13 @@ it relative to the program's working directory.
 const {parse} = require("url");
 const {resolve} = require("path");
 
-const baseDirectory = process.cwd() + "/";
+const baseDirectory = process.cwd();
 
 function urlPath(url) {
   let {pathname} = parse(url);
   let path = resolve(decodeURIComponent(pathname).slice(1));
-  if (!path.startsWith(baseDirectory)) {
+  if (path != baseDirectory &&
+      !path.startsWith(baseDirectory + "/")) {
     throw {status: 403, body: "Forbidden"};
   }
   return path;
@@ -862,7 +863,7 @@ and whether it is a ((directory)).
 ```{includeCode: ">code/file_server.js"}
 const {createReadStream} = require("fs");
 const {stat, readdir} = require("mz/fs");
-const {getType} = require("mime");
+const mime = require("mime");
 
 methods.GET = async function(request) {
   let path = urlPath(request.url);
@@ -874,10 +875,10 @@ methods.GET = async function(request) {
     else return {status: 404, body: "File not found"};
   }
   if (stats.isDirectory()) {
-    return {body: await readdir(path).join("\n")};
+    return {body: (await readdir(path)).join("\n")};
   } else {
     return {body: createReadStream(path),
-            type: getType(path)};
+            type: mime.getType(path)};
   }
 };
 ```
@@ -1123,6 +1124,24 @@ widely used HTTP method, but it does exist for this same purpose in
 the _((WebDAV))_ standard, which specifies a set of conventions on top
 of ((HTTP)) that make it suitable for creating documents.
 
+```{hidden: true, includeCode: ">code/file_server.js"}
+const {mkdir} = require("mz/fs");
+
+methods.MKCOL = async function(request) {
+  let path = urlPath(request.url);
+  let stats;
+  try {
+    stats = await stat(path);
+  } catch (error) {
+    if (error.code != "ENOENT") throw error;
+    await mkdir(path);
+    return {status: 204};
+  }
+  if (stats.isDirectory()) return {status: 204};
+  else return {status: 400, body: "Not a directory"};
+};
+```
+
 {{hint
 
 {{index "directory creation (exercise)", "file server example", "MKCOL method", "mkdir function", idempotency, "400 (HTTP status code)"}}

Makefile

@@ -3,7 +3,7 @@ CHAPTERS := $(basename $(shell ls [0-9][0-9]_*.md) .md)
 SVGS := $(wildcard img/*.svg)
 
 html: $(foreach CHAP,$(CHAPTERS),html/$(CHAP).html) html/js/acorn_codemirror.js \
-      code/skillsharing.zip code/solutions/20_4_a_public_space_on_the_web.zip html/js/chapter_info.js
+      code/skillsharing.zip code/solutions/20_3_a_public_space_on_the_web.zip html/js/chapter_info.js
 
 html/%.html: %.md
 	node src/render_html.js $< > $@
@@ -26,9 +26,9 @@ code/skillsharing.zip: html/21_skillsharing.html
 	rm -f $@
 	cd code; zip skillsharing.zip skillsharing/*.js* skillsharing/public/*.*
 
-code/solutions/20_4_a_public_space_on_the_web.zip: $(wildcard code/solutions/20_4_a_public_space_on_the_web/*)
+code/solutions/20_3_a_public_space_on_the_web.zip: $(wildcard code/solutions/20_3_a_public_space_on_the_web/*)
 	rm -f $@
-	cd code/solutions; zip 20_4_a_public_space_on_the_web.zip 20_4_a_public_space_on_the_web/*
+	cd code/solutions; zip 20_3_a_public_space_on_the_web.zip 20_3_a_public_space_on_the_web/*
 
 test: html
 	@for F in $(CHAPTERS); do echo Testing $$F:; node src/run_tests.js $$F.md; done

code/solutions/20_1_content_negotiation_again.js

@@ -0,0 +1,18 @@
+const {statSync, readdirSync, readFileSync} = require("fs");
+
+let searchTerm = new RegExp(process.argv[2]);
+
+for (let arg of process.argv.slice(3)) {
+  search(arg, Math.min);
+}
+
+function search(file) {
+  let stats = statSync(file);
+  if (stats.isDirectory()) {
+    for (let f of readdirSync(file)) {
+      search(file + "/" + f);
+    }
+  } else if (searchTerm.test(readFileSync(file, "utf8"))) {
+    console.log(file);
+  }
+}

code/solutions/20_1_search_tool.js

@@ -0,0 +1,18 @@
+// This code won't work on its own, but is also included in the
+// code/file_server.js file, which defines the whole system.
+
+const {mkdir} = require("mz/fs");
+
+methods.MKCOL = async function(request) {
+  let path = urlPath(request.url);
+  let stats;
+  try {
+    stats = await stat(path);
+  } catch (error) {
+    if (error.code != "ENOENT") throw error;
+    await mkdir(path);
+    return {status: 204};
+  }
+  if (stats.isDirectory()) return {status: 204};
+  else return {status: 400, body: "Not a directory"};
+};

code/solutions/20_2_directory_creation.js

@@ -1,4 +1,5 @@
 <!doctype html>
+<meta charset=utf8>
 
 <h1>A Public Space on the Web</h1>
 

code/solutions/20_2_fixing_a_leak.js

@@ -1,3 +1,4 @@
 <!doctype html>
+<meta charset=utf8>
 
 <h1>This is another file</h1>

code/solutions/20_4_a_public_space_on_the_web/index.html renamed to code/solutions/20_3_a_public_space_on_the_web/index.html

@@ -0,0 +1,31 @@
+// Get a reference to the DOM nodes we need
+let filelist = document.querySelector("#filelist");
+let textarea = document.querySelector("#file");
+
+// This loads the initial file list from the server
+fetch("/").then(resp => resp.text()).then(files => {
+  for (let file of files.split("\n")) {
+    let option = document.createElement("option");
+    option.textContent = file;
+    filelist.appendChild(option);
+  }
+  // Now that we have a list of files, make sure the textarea contains
+  // the currently selected one.
+  loadCurrentFile();
+});
+
+// Fetch a file from the server and put it in the textarea.
+function loadCurrentFile() {
+  fetch(filelist.value).then(resp => resp.text()).then(file => {
+    textarea.value = file;
+  });
+}
+
+filelist.addEventListener("change", loadCurrentFile);
+
+// Called by the button on the page. Makes a request to save the
+// currently selected file.
+function saveFile() {
+  fetch(filelist.value, {method: "PUT",
+                         body: textarea.value});
+}