From 6b8d87f2374f79855b24d659f2a2579d6b39f54f Mon Sep 17 00:00:00 2001
From: Antoine du Hamel <duhamelantoine1995@gmail.com>
Date: Tue, 30 Jan 2024 23:38:33 +0100
Subject: [PATCH] feat!: prompt user before downloading software (#360)

---
 README.md            |  8 ++++++++
 mkshims.ts           |  2 ++
 sources/httpUtils.ts | 24 +++++++++++++++++++++---
 3 files changed, 31 insertions(+), 3 deletions(-)

diff --git a/README.md b/README.md
index 18bcf88e9..5037b06f5 100644
--- a/README.md
+++ b/README.md
@@ -223,6 +223,14 @@ same major line. Should you need to upgrade to a new major, use an explicit
   not to lookup on the remote registry for the latest version of the selected
   package manager.
 
+- `COREPACK_ENABLE_DOWNLOAD_PROMPT` can be set to `0` to
+  prevent Corepack showing the URL when it needs to download software, or can be
+  set to `1` to have the URL shown. By default, when Corepack is called
+  explicitly (e.g. `corepack pnpm …`), it is set to `0`; when Corepack is called
+  implicitely (e.g. `pnpm …`), it is set to `1`.
+  When standard input is a TTY and no CI environment is detected, Corepack will
+  ask for user input before starting the download.
+
 - `COREPACK_ENABLE_NETWORK` can be set to `0` to prevent Corepack from accessing
   the network (in which case you'll be responsible for hydrating the package
   manager versions that will be required for the projects you'll run, using
diff --git a/mkshims.ts b/mkshims.ts
index fde6dacac..4adcd62fe 100644
--- a/mkshims.ts
+++ b/mkshims.ts
@@ -21,6 +21,7 @@ async function main() {
   const corepackPath = path.join(distDir, `corepack.js`);
   fs.writeFileSync(corepackPath, [
     `#!/usr/bin/env node`,
+    `process.env.COREPACK_ENABLE_DOWNLOAD_PROMPT??='0';`,
     `require('./lib/corepack.cjs').runMain(process.argv.slice(2));`,
   ].join(`\n`));
   fs.chmodSync(corepackPath, 0o755);
@@ -32,6 +33,7 @@ async function main() {
       const entryPath = path.join(distDir, `${binaryName}.js`);
       const entryScript = [
         `#!/usr/bin/env node`,
+        `process.env.COREPACK_ENABLE_DOWNLOAD_PROMPT??='1'`,
         `require('./lib/corepack.cjs').runMain(['${binaryName}', ...process.argv.slice(2)]);`,
       ].join(`\n`);
 
diff --git a/sources/httpUtils.ts b/sources/httpUtils.ts
index 94598dfbe..dc73b96c3 100644
--- a/sources/httpUtils.ts
+++ b/sources/httpUtils.ts
@@ -1,6 +1,8 @@
-import {UsageError}                     from 'clipanion';
-import {RequestOptions}                 from 'https';
-import {IncomingMessage, ClientRequest} from 'http';
+import {UsageError}                          from 'clipanion';
+import {once}                                from 'events';
+import type {RequestOptions}                 from 'https';
+import type {IncomingMessage, ClientRequest} from 'http';
+import {stderr, stdin}                       from 'process';
 
 export async function fetchUrlStream(url: string, options: RequestOptions = {}) {
   if (process.env.COREPACK_ENABLE_NETWORK === `0`)
@@ -12,6 +14,22 @@ export async function fetchUrlStream(url: string, options: RequestOptions = {})
 
   const proxyAgent = new ProxyAgent();
 
+  if (process.env.COREPACK_ENABLE_DOWNLOAD_PROMPT === `1`) {
+    console.error(`Corepack is about to download ${url}.`);
+    if (stdin.isTTY && !process.env.CI) {
+      stderr.write(`\nDo you want to continue? [Y/n] `);
+      stdin.resume();
+      const chars = await once(stdin, `data`);
+      stdin.pause();
+      if (
+        chars[0][0] === 0x6e || // n
+        chars[0][0] === 0x4e // N
+      ) {
+        throw new UsageError(`Aborted by the user`);
+      }
+    }
+  }
+
   return new Promise<IncomingMessage>((resolve, reject) => {
     const createRequest = (url: string) => {
       const request: ClientRequest = https.get(url, {...options, agent: proxyAgent}, response => {