feat: Pins the package manager as it's used for the first time

README.md

@@ -235,6 +235,12 @@ same major line. Should you need to upgrade to a new major, use an explicit
   package manager, and to not update the Last Known Good version when it
   downloads a new version of the same major line.
 
+- `COREPACK_ENABLE_AUTO_PIN` can be set to `0` to prevent Corepack from
+  updating the `packageManager` field when it detects that the local package
+  doesn't list it. In general we recommend to always list a `packageManager`
+  field (which you can easily set through `corepack use [name]@[version]`), as
+  it ensures that your project installs are always deterministic.
+
 - `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

sources/Engine.ts

@@ -10,14 +10,22 @@ import defaultConfig                                          from '../config.js
 import * as corepackUtils                                     from './corepackUtils';
 import * as debugUtils                                        from './debugUtils';
 import * as folderUtils                                       from './folderUtils';
+import * as miscUtils                                         from './miscUtils';
 import type {NodeError}                                       from './nodeUtils';
 import * as semverUtils                                       from './semverUtils';
+import * as specUtils                                         from './specUtils';
 import {Config, Descriptor, Locator, PackageManagerSpec}      from './types';
 import {SupportedPackageManagers, SupportedPackageManagerSet} from './types';
 import {isSupportedPackageManager}                            from './types';
 
 export type PreparedPackageManagerInfo = Awaited<ReturnType<Engine[`ensurePackageManager`]>>;
 
+export type PackageManagerRequest = {
+  packageManager: SupportedPackageManagers;
+  binaryName: string;
+  binaryVersion: string | null;
+};
+
 export function getLastKnownGoodFile(flag = `r`) {
   return fs.promises.open(path.join(folderUtils.getCorepackHomeFolder(), `lastKnownGood.json`), flag);
 }
@@ -200,15 +208,139 @@ export class Engine {
       spec,
     });
 
+    const noHashReference = locator.reference.replace(/\+.*/, ``);
+    const fixedHashReference = `${noHashReference}+${packageManagerInfo.hash}`;
+
+    const fixedHashLocator = {
+      name: locator.name,
+      reference: fixedHashReference,
+    };
+
     return {
       ...packageManagerInfo,
-      locator,
+      locator: fixedHashLocator,
       spec,
     };
   }
 
-  async fetchAvailableVersions() {
+  /**
+   * Locates the active project's package manager specification.
+   *
+   * If the specification exists but doesn't match the active package manager,
+   * an error is thrown to prevent users from using the wrong package manager,
+   * which would lead to inconsistent project layouts.
+   *
+   * If the project doesn't include a specification file, we just assume that
+   * whatever the user uses is exactly what they want to use. Since the version
+   * isn't explicited, we fallback on known good versions.
+   *
+   * Finally, if the project doesn't exist at all, we ask the user whether they
+   * want to create one in the current project. If they do, we initialize a new
+   * project using the default package managers, and configure it so that we
+   * don't need to ask again in the future.
+   */
+  async findProjectSpec(initialCwd: string, locator: Locator, {transparent = false}: {transparent?: boolean} = {}): Promise<Descriptor> {
+    // A locator is a valid descriptor (but not the other way around)
+    const fallbackDescriptor = {name: locator.name, range: `${locator.reference}`};
+
+    if (process.env.COREPACK_ENABLE_PROJECT_SPEC === `0`)
+      return fallbackDescriptor;
+
+    if (process.env.COREPACK_ENABLE_STRICT === `0`)
+      transparent = true;
+
+    while (true) {
+      const result = await specUtils.loadSpec(initialCwd);
+
+      switch (result.type) {
+        case `NoProject`:
+          return fallbackDescriptor;
+
+        case `NoSpec`: {
+          if (process.env.COREPACK_ENABLE_AUTO_PIN !== `0`) {
+            const resolved = await this.resolveDescriptor(fallbackDescriptor, {allowTags: true});
+            if (resolved === null)
+              throw new UsageError(`Failed to successfully resolve '${fallbackDescriptor.range}' to a valid ${fallbackDescriptor.name} release`);
+
+            const installSpec = await this.ensurePackageManager(resolved);
+
+            console.error(`! The local project doesn't define a 'packageManager' field. Corepack will now add one referencing ${installSpec.locator.name}@${installSpec.locator.reference}.`);
+            console.error(`! For more details about this field, consult the documentation at https://nodejs.org/api/packages.html#packagemanager`);
+            console.error();
+
+            await specUtils.setLocalPackageManager(path.dirname(result.target), installSpec);
+          }
+
+          return fallbackDescriptor;
+        }
+
+        case `Found`: {
+          if (result.spec.name !== locator.name) {
+            if (transparent) {
+              return fallbackDescriptor;
+            } else {
+              throw new UsageError(`This project is configured to use ${result.spec.name}`);
+            }
+          } else {
+            return result.spec;
+          }
+        }
+      }
+    }
+  }
+
+  async executePackageManagerRequest({packageManager, binaryName, binaryVersion}: PackageManagerRequest, {cwd, args}: {cwd: string, args: Array<string>}): Promise<number | void> {
+    let fallbackLocator: Locator = {
+      name: binaryName as SupportedPackageManagers,
+      reference: undefined as any,
+    };
+
+    let isTransparentCommand = false;
+    if (packageManager != null) {
+      const defaultVersion = await this.getDefaultVersion(packageManager);
+      const definition = this.config.definitions[packageManager]!;
+
+      // If all leading segments match one of the patterns defined in the `transparent`
+      // key, we tolerate calling this binary even if the local project isn't explicitly
+      // configured for it, and we use the special default version if requested.
+      for (const transparentPath of definition.transparent.commands) {
+        if (transparentPath[0] === binaryName && transparentPath.slice(1).every((segment, index) => segment === args[index])) {
+          isTransparentCommand = true;
+          break;
+        }
+      }
+
+      const fallbackReference = isTransparentCommand
+        ? definition.transparent.default ?? defaultVersion
+        : defaultVersion;
+
+      fallbackLocator = {
+        name: packageManager,
+        reference: fallbackReference,
+      };
+    }
+
+    let descriptor: Descriptor;
+    try {
+      descriptor = await this.findProjectSpec(cwd, fallbackLocator, {transparent: isTransparentCommand});
+    } catch (err) {
+      if (err instanceof miscUtils.Cancellation) {
+        return 1;
+      } else {
+        throw err;
+      }
+    }
+
+    if (binaryVersion)
+      descriptor.range = binaryVersion;
+
+    const resolved = await this.resolveDescriptor(descriptor, {allowTags: true});
+    if (resolved === null)
+      throw new UsageError(`Failed to successfully resolve '${descriptor.range}' to a valid ${descriptor.name} release`);
+
+    const installSpec = await this.ensurePackageManager(resolved);
 
+    return await corepackUtils.runVersion(resolved, installSpec, binaryName, args);
   }
 
   async resolveDescriptor(descriptor: Descriptor, {allowTags = false, useCache = true}: {allowTags?: boolean, useCache?: boolean} = {}): Promise<Locator | null> {

sources/commands/Base.ts

@@ -1,10 +1,10 @@
 import {Command, UsageError}        from 'clipanion';
 import fs                           from 'fs';
 
 import {PreparedPackageManagerInfo} from '../Engine';
 import * as corepackUtils           from '../corepackUtils';
 import {Context}                    from '../main';
 import * as nodeUtils               from '../nodeUtils';
 import * as specUtils               from '../specUtils';
 
 export abstract class BaseCommand extends Command<Context> {
@@ -29,20 +29,10 @@
     return resolvedSpecs;
   }
 
-  async setLocalPackageManager(info: PreparedPackageManagerInfo) {
-    const lookup = await specUtils.loadSpec(this.context.cwd);
-
-    const content = lookup.type !== `NoProject`
-      ? await fs.promises.readFile(lookup.target, `utf8`)
-      : ``;
-
-    const {data, indent} = nodeUtils.readPackageJson(content);
-
-    const previousPackageManager = data.packageManager ?? `unknown`;
-    data.packageManager = `${info.locator.name}@${info.locator.reference}+${info.hash}`;
-
-    const newContent = nodeUtils.normalizeLineEndings(content, `${JSON.stringify(data, null, indent)}\n`);
-    await fs.promises.writeFile(lookup.target, newContent, `utf8`);
+  async setAndInstallLocalPackageManager(info: PreparedPackageManagerInfo) {
+    const {
+      previousPackageManager,
+    } = await specUtils.setLocalPackageManager(this.context.cwd, info);
 
     const command = this.context.engine.getPackageManagerSpecFor(info.locator).commands?.use ?? null;
     if (command === null)

sources/commands/Up.ts

@@ -50,6 +50,6 @@ export class UpCommand extends BaseCommand {
     this.context.stdout.write(`Installing ${highestVersion.name}@${highestVersion.reference} in the project...\n`);
 
     const packageManagerInfo = await this.context.engine.ensurePackageManager(highestVersion);
-    await this.setLocalPackageManager(packageManagerInfo);
+    await this.setAndInstallLocalPackageManager(packageManagerInfo);
   }
 }

sources/commands/Use.ts

@@ -34,6 +34,6 @@ export class UseCommand extends BaseCommand {
     this.context.stdout.write(`Installing ${resolved.name}@${resolved.reference} in the project...\n`);
 
     const packageManagerInfo = await this.context.engine.ensurePackageManager(resolved);
-    await this.setLocalPackageManager(packageManagerInfo);
+    await this.setAndInstallLocalPackageManager(packageManagerInfo);
   }
 }

sources/httpUtils.ts

@@ -40,9 +40,9 @@ export async function fetchAsJson(input: string | URL, init?: RequestInit) {
 
 export async function fetchUrlStream(input: string | URL, init?: RequestInit) {
   if (process.env.COREPACK_ENABLE_DOWNLOAD_PROMPT === `1`) {
-    console.error(`Corepack is about to download ${input}`);
+    console.error(`! Corepack is about to download ${input}`);
     if (stdin.isTTY && !process.env.CI) {
-      stderr.write(`Do you want to continue? [Y/n] `);
+      stderr.write(`? Do you want to continue? [Y/n] `);
       stdin.resume();
       const chars = await once(stdin, `data`);
       stdin.pause();

sources/main.ts

@@ -1,32 +1,22 @@
-import {BaseContext, Builtins, Cli, Command, Option, UsageError} from 'clipanion';
-
-import {version as corepackVersion}                              from '../package.json';
-
-import {Engine}                                                  from './Engine';
-import {CacheCommand}                                            from './commands/Cache';
-import {DisableCommand}                                          from './commands/Disable';
-import {EnableCommand}                                           from './commands/Enable';
-import {InstallGlobalCommand}                                    from './commands/InstallGlobal';
-import {InstallLocalCommand}                                     from './commands/InstallLocal';
-import {PackCommand}                                             from './commands/Pack';
-import {UpCommand}                                               from './commands/Up';
-import {UseCommand}                                              from './commands/Use';
-import {HydrateCommand}                                          from './commands/deprecated/Hydrate';
-import {PrepareCommand}                                          from './commands/deprecated/Prepare';
-import * as corepackUtils                                        from './corepackUtils';
-import * as miscUtils                                            from './miscUtils';
-import * as specUtils                                            from './specUtils';
-import {Locator, SupportedPackageManagers, Descriptor}           from './types';
+import {BaseContext, Builtins, Cli, Command, Option} from 'clipanion';
+
+import {version as corepackVersion}                  from '../package.json';
+
+import {Engine, PackageManagerRequest}               from './Engine';
+import {CacheCommand}                                from './commands/Cache';
+import {DisableCommand}                              from './commands/Disable';
+import {EnableCommand}                               from './commands/Enable';
+import {InstallGlobalCommand}                        from './commands/InstallGlobal';
+import {InstallLocalCommand}                         from './commands/InstallLocal';
+import {PackCommand}                                 from './commands/Pack';
+import {UpCommand}                                   from './commands/Up';
+import {UseCommand}                                  from './commands/Use';
+import {HydrateCommand}                              from './commands/deprecated/Hydrate';
+import {PrepareCommand}                              from './commands/deprecated/Prepare';
 
 export type CustomContext = {cwd: string, engine: Engine};
 export type Context = BaseContext & CustomContext;
 
-type PackageManagerRequest = {
-  packageManager: SupportedPackageManagers;
-  binaryName: string;
-  binaryVersion: string | null;
-};
-
 function getPackageManagerRequestFromCli(parameter: string | undefined, context: CustomContext & Partial<Context>): PackageManagerRequest | null {
   if (!parameter)
     return null;
@@ -47,59 +37,6 @@ function getPackageManagerRequestFromCli(parameter: string | undefined, context:
   };
 }
 
-async function executePackageManagerRequest({packageManager, binaryName, binaryVersion}: PackageManagerRequest, args: Array<string>, context: Context) {
-  let fallbackLocator: Locator = {
-    name: binaryName as SupportedPackageManagers,
-    reference: undefined as any,
-  };
-  let isTransparentCommand = false;
-  if (packageManager != null) {
-    const defaultVersion = await context.engine.getDefaultVersion(packageManager);
-    const definition = context.engine.config.definitions[packageManager]!;
-
-    // If all leading segments match one of the patterns defined in the `transparent`
-    // key, we tolerate calling this binary even if the local project isn't explicitly
-    // configured for it, and we use the special default version if requested.
-    for (const transparentPath of definition.transparent.commands) {
-      if (transparentPath[0] === binaryName && transparentPath.slice(1).every((segment, index) => segment === args[index])) {
-        isTransparentCommand = true;
-        break;
-      }
-    }
-
-    const fallbackReference = isTransparentCommand
-      ? definition.transparent.default ?? defaultVersion
-      : defaultVersion;
-
-    fallbackLocator = {
-      name: packageManager,
-      reference: fallbackReference,
-    };
-  }
-
-  let descriptor: Descriptor;
-  try {
-    descriptor = await specUtils.findProjectSpec(context.cwd, fallbackLocator, {transparent: isTransparentCommand});
-  } catch (err) {
-    if (err instanceof miscUtils.Cancellation) {
-      return 1;
-    } else {
-      throw err;
-    }
-  }
-
-  if (binaryVersion)
-    descriptor.range = binaryVersion;
-
-  const resolved = await context.engine.resolveDescriptor(descriptor, {allowTags: true});
-  if (resolved === null)
-    throw new UsageError(`Failed to successfully resolve '${descriptor.range}' to a valid ${descriptor.name} release`);
-
-  const installSpec = await context.engine.ensurePackageManager(resolved);
-
-  return await corepackUtils.runVersion(resolved, installSpec, binaryName, args);
-}
-
 export async function runMain(argv: Array<string>) {
   // Because we load the binaries in the same process, we don't support custom contexts.
   const context = {
@@ -149,7 +86,10 @@ export async function runMain(argv: Array<string>) {
     cli.register(class BinaryCommand extends Command<Context> {
       proxy = Option.Proxy();
       async execute() {
-        return executePackageManagerRequest(request, this.proxy, this.context);
+        return this.context.engine.executePackageManagerRequest(request, {
+          cwd: this.context.cwd,
+          args: this.proxy,
+        });
       }
     });