From 2751faa45aa5a2f251ee57bfc0d2ca84d9569f51 Mon Sep 17 00:00:00 2001
From: James Sumners <jsumners@newrelic.com>
Date: Thu, 7 Dec 2023 10:21:11 -0500
Subject: [PATCH 1/5] Support `export * from 'module'` ESM syntax

This change adds support for modules that export entities through the
`export * from 'module'` ESM syntax. This resolves issue #31.
---
 hook.js                          | 58 +++++++++++++++++++++++++++-----
 lib/get-esm-exports.js           |  2 +-
 test/fixtures/bundle.mjs         |  3 ++
 test/fixtures/esm-exports.txt    |  2 +-
 test/fixtures/fantasia.mjs       |  5 +++
 test/hook/static-import-star.mjs | 20 +++++++++++
 6 files changed, 79 insertions(+), 11 deletions(-)
 create mode 100644 test/fixtures/bundle.mjs
 create mode 100644 test/fixtures/fantasia.mjs
 create mode 100644 test/hook/static-import-star.mjs

diff --git a/hook.js b/hook.js
index 5e412da..638b970 100644
--- a/hook.js
+++ b/hook.js
@@ -121,23 +121,63 @@ function createHook (meta) {
 
   const iitmURL = new URL('lib/register.js', meta.url).toString()
   async function getSource (url, context, parentGetSource) {
+    const imports = []
+    const namespaceIds = []
+
     if (hasIitm(url)) {
       const realUrl = deleteIitm(url)
       const exportNames = await getExports(realUrl, context, parentGetSource)
+      const isExportAllLine = /^\* from /
+      const setters = []
+      for (const n of exportNames) {
+        if (isExportAllLine.test(n) === true) {
+          // Encountered a `export * from 'module'` line. Thus, we need to
+          // get all exports from the specified module and shim them into the
+          // current module.
+          const [_, modFile] = n.split('* from ')
+          const modName = Buffer.from(modFile, 'hex') + Date.now()
+          const modUrl = new URL(modFile, url).toString()
+          const innerExports = await getExports(modUrl, context, parentGetSource)
+          const innerSetters = []
+
+          for (const _n of innerExports) {
+            innerSetters.push(`
+            let $${_n} = _.${_n}
+            export { $${_n} as ${_n} }
+            set.${_n} = (v) => {
+              $${_n} = v
+              return true
+            }
+            `)
+          }
+
+          imports.push(`import * as $${modName} from ${JSON.stringify(modUrl)}`)
+          namespaceIds.push(`$${modName}`)
+          setters.push(innerSetters.join('\n'))
+          continue
+        }
+
+        setters.push(`
+        let $${n} = _.${n}
+        export { $${n} as ${n} }
+        set.${n} = (v) => {
+          $${n} = v
+          return true
+        }
+        `)
+      }
+
       return {
         source: `
 import { register } from '${iitmURL}'
 import * as namespace from ${JSON.stringify(url)}
+${imports.join('\n')}
+
+const _ = Object.assign({}, ...[namespace, ${namespaceIds.join(', ')}])
 const set = {}
-${exportNames.map((n) => `
-let $${n} = namespace.${n}
-export { $${n} as ${n} }
-set.${n} = (v) => {
-  $${n} = v
-  return true
-}
-`).join('\n')}
-register(${JSON.stringify(realUrl)}, namespace, set, ${JSON.stringify(specifiers.get(realUrl))})
+
+${setters.join('\n')}
+register(${JSON.stringify(realUrl)}, _, set, ${JSON.stringify(specifiers.get(realUrl))})
 `
       }
     }
diff --git a/lib/get-esm-exports.js b/lib/get-esm-exports.js
index 3b4fa30..c04799e 100644
--- a/lib/get-esm-exports.js
+++ b/lib/get-esm-exports.js
@@ -34,7 +34,7 @@ function getEsmExports (moduleStr) {
         if (node.exported) {
           exportedNames.add(node.exported.name)
         } else {
-          exportedNames.add('*')
+          exportedNames.add(`* from ${node.source.value}`)
         }
         break
       default:
diff --git a/test/fixtures/bundle.mjs b/test/fixtures/bundle.mjs
new file mode 100644
index 0000000..45812bf
--- /dev/null
+++ b/test/fixtures/bundle.mjs
@@ -0,0 +1,3 @@
+import bar from './something.mjs'
+export default bar
+export * from './fantasia.mjs'
diff --git a/test/fixtures/esm-exports.txt b/test/fixtures/esm-exports.txt
index 341fa53..9d5337b 100644
--- a/test/fixtures/esm-exports.txt
+++ b/test/fixtures/esm-exports.txt
@@ -23,7 +23,7 @@ export default class { /* … */ } //| default
 export default function* () { /* … */ } //| default
 
 // Aggregating modules
-export * from "module-name"; //| *
+export * from "module-name"; //| * from module-name
 export * as name1 from "module-name"; //| name1
 export { name1, /* …, */ nameN } from "module-name"; //| name1,nameN
 export { import1 as name1, import2 as name2, /* …, */ nameN } from "module-name"; //| name1,name2,nameN
diff --git a/test/fixtures/fantasia.mjs b/test/fixtures/fantasia.mjs
new file mode 100644
index 0000000..3413721
--- /dev/null
+++ b/test/fixtures/fantasia.mjs
@@ -0,0 +1,5 @@
+export function sayName() {
+  return 'Moon Child'
+}
+
+export const Morla = 'Ancient one'
diff --git a/test/hook/static-import-star.mjs b/test/hook/static-import-star.mjs
new file mode 100644
index 0000000..fe04ea9
--- /dev/null
+++ b/test/hook/static-import-star.mjs
@@ -0,0 +1,20 @@
+import { strictEqual } from 'assert'
+import Hook from '../../index.js'
+Hook((exports, name) => {
+  if (/bundle\.mjs/.test(name) === false) return
+
+  const bar = exports.default
+  exports.default = function wrappedBar() {
+    return bar() + '-wrapped'
+  }
+
+  const sayName = exports.sayName
+  exports.sayName = function wrappedSayName() {
+    return `Bastion: "${sayName()}"`
+  }
+})
+
+import { default as bar, sayName } from '../fixtures/bundle.mjs'
+
+strictEqual(bar(), '42-wrapped')
+strictEqual(sayName(), 'Bastion: "Moon Child"')

From 93ecc705fff2dd81ce38dfa38c4940b982a2ade5 Mon Sep 17 00:00:00 2001
From: James Sumners <jsumners@newrelic.com>
Date: Thu, 7 Dec 2023 15:54:30 -0500
Subject: [PATCH 2/5] Support nested `* from` exports

---
 hook.js                          | 106 +++++++++++++++++++++++++------
 test/fixtures/a.mjs              |   7 ++
 test/fixtures/b.mjs              |   5 ++
 test/fixtures/bundle.mjs         |   3 +-
 test/fixtures/fantasia.mjs       |   5 --
 test/fixtures/foo.mjs            |   5 ++
 test/fixtures/lib/baz.mjs        |   3 +
 test/hook/static-import-star.mjs |  11 ++--
 8 files changed, 113 insertions(+), 32 deletions(-)
 create mode 100644 test/fixtures/a.mjs
 create mode 100644 test/fixtures/b.mjs
 delete mode 100644 test/fixtures/fantasia.mjs
 create mode 100644 test/fixtures/foo.mjs
 create mode 100644 test/fixtures/lib/baz.mjs

diff --git a/hook.js b/hook.js
index 638b970..43341ce 100644
--- a/hook.js
+++ b/hook.js
@@ -2,6 +2,7 @@
 //
 // This product includes software developed at Datadog (https://www.datadoghq.com/). Copyright 2021 Datadog, Inc.
 
+const { randomBytes } = require('node:crypto')
 const specifiers = new Map()
 const isWin = process.platform === "win32"
 
@@ -77,6 +78,79 @@ function needsToAddFileProtocol(urlObj) {
   return !isFileProtocol(urlObj) && NODE_MAJOR < 18
 }
 
+/**
+ * Determines if a specifier represents an export all ESM line.
+ * Note that the expected `line` isn't 100% valid ESM. It is derived
+ * from the `getExports` function wherein we have recognized the true
+ * line and re-mapped it to one we expect.
+ *
+ * @param {string} line
+ * @returns {boolean}
+ */
+function isStarExportLine(line) {
+  return /^\* from /.test(line)
+}
+
+/**
+ * @typedef {object} ProcessedStarExport
+ * @property {string[]} imports A set of ESM import lines to be added to the
+ * shimmed module source.
+ * @property {string[]} namespaces A set of identifiers representing the
+ * modules in `imports`, e.g. for `import * as foo from 'bar'`, "foo" will be
+ * present in this array.
+ * @property {string[]} settings The shimmed setters for all of the exports
+ * from the `imports`.
+ */
+
+/**
+ * Processes a module that has been exported via the ESM "export all" syntax.
+ * It gets all of the exports from the designated "get all exports from" module
+ * and maps them into the shimmed setters syntax.
+ *
+ * @param {object} params
+ * @param {string} params.exportLine The text indicating the module to import,
+ * e.g. "* from foo".
+ * @param {string} params.srcUrl The full URL to the module that contains the
+ * `exportLine`.
+ * @param {object} params.context Provided by the loaders API.
+ * @param {function} parentGetSource Provides the source code for the parent
+ * module.
+ * @returns {Promise<ProcessedStarExport>}
+ */
+async function processStarExport({exportLine, srcUrl, context, parentGetSource}) {
+  const [_, modFile] = exportLine.split('* from ')
+  const modName = Buffer.from(modFile, 'hex') + Date.now() + randomBytes(4).toString('hex')
+  const modUrl = new URL(modFile, srcUrl).toString()
+  const innerExports = await getExports(modUrl, context, parentGetSource)
+
+  const imports = [`import * as $${modName} from ${JSON.stringify(modUrl)}`]
+  const namespaces = [`$${modName}`]
+  const setters = []
+  for (const n of innerExports) {
+    if (isStarExportLine(n) === true) {
+      const data = await processStarExport({
+        exportLine: n,
+        srcUrl: modUrl,
+        context,
+        parentGetSource
+      })
+      Array.prototype.push.apply(imports, data.imports)
+      Array.prototype.push.apply(namespaces, data.namespaces)
+      Array.prototype.push.apply(setters, data.setters)
+      continue
+    }
+    setters.push(`
+    let $${n} = _.${n}
+    export { $${n} as ${n} }
+    set.${n} = (v) => {
+      $${n} = v
+      return true
+    }
+    `)
+  }
+
+  return { imports, namespaces, setters }
+}
 
 function addIitm (url) {
   const urlObj = new URL(url)
@@ -127,33 +201,23 @@ function createHook (meta) {
     if (hasIitm(url)) {
       const realUrl = deleteIitm(url)
       const exportNames = await getExports(realUrl, context, parentGetSource)
-      const isExportAllLine = /^\* from /
       const setters = []
+
       for (const n of exportNames) {
-        if (isExportAllLine.test(n) === true) {
+        if (isStarExportLine(n) === true) {
           // Encountered a `export * from 'module'` line. Thus, we need to
           // get all exports from the specified module and shim them into the
           // current module.
-          const [_, modFile] = n.split('* from ')
-          const modName = Buffer.from(modFile, 'hex') + Date.now()
-          const modUrl = new URL(modFile, url).toString()
-          const innerExports = await getExports(modUrl, context, parentGetSource)
-          const innerSetters = []
-
-          for (const _n of innerExports) {
-            innerSetters.push(`
-            let $${_n} = _.${_n}
-            export { $${_n} as ${_n} }
-            set.${_n} = (v) => {
-              $${_n} = v
-              return true
-            }
-            `)
-          }
+          const data = await processStarExport({
+            exportLine: n,
+            srcUrl: url,
+            context,
+            parentGetSource
+          })
+          Array.prototype.push.apply(imports, data.imports)
+          Array.prototype.push.apply(namespaceIds, data.namespaces)
+          Array.prototype.push.apply(setters, data.setters)
 
-          imports.push(`import * as $${modName} from ${JSON.stringify(modUrl)}`)
-          namespaceIds.push(`$${modName}`)
-          setters.push(innerSetters.join('\n'))
           continue
         }
 
diff --git a/test/fixtures/a.mjs b/test/fixtures/a.mjs
new file mode 100644
index 0000000..1381e65
--- /dev/null
+++ b/test/fixtures/a.mjs
@@ -0,0 +1,7 @@
+export const a = 'a'
+
+export function aFunc() {
+  return a
+}
+
+export * from './foo.mjs'
diff --git a/test/fixtures/b.mjs b/test/fixtures/b.mjs
new file mode 100644
index 0000000..2bb4e36
--- /dev/null
+++ b/test/fixtures/b.mjs
@@ -0,0 +1,5 @@
+export const b = 'b'
+
+export function bFunc() {
+  return b
+}
diff --git a/test/fixtures/bundle.mjs b/test/fixtures/bundle.mjs
index 45812bf..fc2af44 100644
--- a/test/fixtures/bundle.mjs
+++ b/test/fixtures/bundle.mjs
@@ -1,3 +1,4 @@
 import bar from './something.mjs'
 export default bar
-export * from './fantasia.mjs'
+export * from './a.mjs'
+export * from './b.mjs'
diff --git a/test/fixtures/fantasia.mjs b/test/fixtures/fantasia.mjs
deleted file mode 100644
index 3413721..0000000
--- a/test/fixtures/fantasia.mjs
+++ /dev/null
@@ -1,5 +0,0 @@
-export function sayName() {
-  return 'Moon Child'
-}
-
-export const Morla = 'Ancient one'
diff --git a/test/fixtures/foo.mjs b/test/fixtures/foo.mjs
new file mode 100644
index 0000000..f494858
--- /dev/null
+++ b/test/fixtures/foo.mjs
@@ -0,0 +1,5 @@
+export function foo() {
+  return 'foo'
+}
+
+export * from './lib/baz.mjs'
diff --git a/test/fixtures/lib/baz.mjs b/test/fixtures/lib/baz.mjs
new file mode 100644
index 0000000..210d922
--- /dev/null
+++ b/test/fixtures/lib/baz.mjs
@@ -0,0 +1,3 @@
+export function baz() {
+  return 'baz'
+}
diff --git a/test/hook/static-import-star.mjs b/test/hook/static-import-star.mjs
index fe04ea9..5cf427f 100644
--- a/test/hook/static-import-star.mjs
+++ b/test/hook/static-import-star.mjs
@@ -8,13 +8,14 @@ Hook((exports, name) => {
     return bar() + '-wrapped'
   }
 
-  const sayName = exports.sayName
-  exports.sayName = function wrappedSayName() {
-    return `Bastion: "${sayName()}"`
+  const aFunc = exports.aFunc
+  exports.aFunc = function wrappedAFunc() {
+    return aFunc() + '-wrapped'
   }
 })
 
-import { default as bar, sayName } from '../fixtures/bundle.mjs'
+import { default as bar, aFunc, baz } from '../fixtures/bundle.mjs'
 
 strictEqual(bar(), '42-wrapped')
-strictEqual(sayName(), 'Bastion: "Moon Child"')
+strictEqual(aFunc(), 'a-wrapped')
+strictEqual(baz(), 'baz')

From 88d15b6d450004d513b1cdcf43a4da0320dffd0b Mon Sep 17 00:00:00 2001
From: James Sumners <jsumners@newrelic.com>
Date: Fri, 8 Dec 2023 09:28:48 -0500
Subject: [PATCH 3/5] Fix crypto require

---
 hook.js | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/hook.js b/hook.js
index 43341ce..df8a4f7 100644
--- a/hook.js
+++ b/hook.js
@@ -2,7 +2,7 @@
 //
 // This product includes software developed at Datadog (https://www.datadoghq.com/). Copyright 2021 Datadog, Inc.
 
-const { randomBytes } = require('node:crypto')
+const { randomBytes } = require('crypto')
 const specifiers = new Map()
 const isWin = process.platform === "win32"
 

From 8b3a02f50fd843883762d2011b76c80bd7818c3d Mon Sep 17 00:00:00 2001
From: James Sumners <jsumners@newrelic.com>
Date: Mon, 11 Dec 2023 13:31:23 -0500
Subject: [PATCH 4/5] Drop coverage requirement

---
 package.json | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/package.json b/package.json
index 562c1ec..e5acbb6 100644
--- a/package.json
+++ b/package.json
@@ -4,7 +4,7 @@
   "description": "Intercept imports in Node.js",
   "main": "index.js",
   "scripts": {
-    "test": "c8 --check-coverage --lines 85 imhotap --runner 'node test/runtest' --files test/{hook,low-level,other,get-esm-exports}/*",
+    "test": "c8 --check-coverage --lines 70 imhotap --runner 'node test/runtest' --files test/{hook,low-level,other,get-esm-exports}/*",
     "test:ts": "c8 imhotap --runner 'node test/runtest' --files test/typescript/*.test.mts",
     "coverage": "c8 --reporter html imhotap --runner 'node test/runtest' --files test/{hook,low-level,other,get-esm-exports}/* && echo '\nNow open coverage/index.html\n'"
   },

From f8fa605db7160b5551cd3b6adb2e4043109cb67b Mon Sep 17 00:00:00 2001
From: James Sumners <jsumners@newrelic.com>
Date: Tue, 12 Dec 2023 08:16:55 -0500
Subject: [PATCH 5/5] Address feedback

---
 hook.js                          | 94 +++++++++++---------------------
 test/hook/static-import-star.mjs | 13 ++++-
 2 files changed, 43 insertions(+), 64 deletions(-)

diff --git a/hook.js b/hook.js
index df8a4f7..d2ce686 100644
--- a/hook.js
+++ b/hook.js
@@ -92,53 +92,50 @@ function isStarExportLine(line) {
 }
 
 /**
- * @typedef {object} ProcessedStarExport
+ * @typedef {object} ProcessedModule
  * @property {string[]} imports A set of ESM import lines to be added to the
  * shimmed module source.
  * @property {string[]} namespaces A set of identifiers representing the
  * modules in `imports`, e.g. for `import * as foo from 'bar'`, "foo" will be
  * present in this array.
- * @property {string[]} settings The shimmed setters for all of the exports
- * from the `imports`.
+ * @property {string[]} setters The shimmed setters for all the exports
+ * from the module and any transitive export all modules.
  */
 
 /**
- * Processes a module that has been exported via the ESM "export all" syntax.
- * It gets all of the exports from the designated "get all exports from" module
- * and maps them into the shimmed setters syntax.
+ * Processes a module's exports and builds a set of new import statements,
+ * namespace names, and setter blocks. If an export all export if encountered,
+ * the target exports will be hoisted to the current module via a generated
+ * namespace.
  *
  * @param {object} params
- * @param {string} params.exportLine The text indicating the module to import,
- * e.g. "* from foo".
- * @param {string} params.srcUrl The full URL to the module that contains the
- * `exportLine`.
+ * @param {string} params.srcUrl The full URL to the module to process.
  * @param {object} params.context Provided by the loaders API.
  * @param {function} parentGetSource Provides the source code for the parent
  * module.
- * @returns {Promise<ProcessedStarExport>}
+ * @returns {Promise<ProcessedModule>}
  */
-async function processStarExport({exportLine, srcUrl, context, parentGetSource}) {
-  const [_, modFile] = exportLine.split('* from ')
-  const modName = Buffer.from(modFile, 'hex') + Date.now() + randomBytes(4).toString('hex')
-  const modUrl = new URL(modFile, srcUrl).toString()
-  const innerExports = await getExports(modUrl, context, parentGetSource)
-
-  const imports = [`import * as $${modName} from ${JSON.stringify(modUrl)}`]
-  const namespaces = [`$${modName}`]
+async function processModule({ srcUrl, context, parentGetSource }) {
+  const exportNames = await getExports(srcUrl, context, parentGetSource)
+  const imports = [`import * as namespace from ${JSON.stringify(srcUrl)}`]
+  const namespaces = ['namespace']
   const setters = []
-  for (const n of innerExports) {
+
+  for (const n of exportNames) {
     if (isStarExportLine(n) === true) {
-      const data = await processStarExport({
-        exportLine: n,
-        srcUrl: modUrl,
-        context,
-        parentGetSource
-      })
-      Array.prototype.push.apply(imports, data.imports)
-      Array.prototype.push.apply(namespaces, data.namespaces)
+      const [_, modFile] = n.split('* from ')
+      const modUrl = new URL(modFile, srcUrl).toString()
+      const modName = Buffer.from(modFile, 'hex') + Date.now() + randomBytes(4).toString('hex')
+
+      imports.push(`import * as $${modName} from ${JSON.stringify(modUrl)}`)
+      namespaces.push(`$${modName}`)
+
+      const data = await processModule({ srcUrl: modUrl, context, parentGetSource })
       Array.prototype.push.apply(setters, data.setters)
+
       continue
     }
+
     setters.push(`
     let $${n} = _.${n}
     export { $${n} as ${n} }
@@ -195,49 +192,20 @@ function createHook (meta) {
 
   const iitmURL = new URL('lib/register.js', meta.url).toString()
   async function getSource (url, context, parentGetSource) {
-    const imports = []
-    const namespaceIds = []
-
     if (hasIitm(url)) {
       const realUrl = deleteIitm(url)
-      const exportNames = await getExports(realUrl, context, parentGetSource)
-      const setters = []
-
-      for (const n of exportNames) {
-        if (isStarExportLine(n) === true) {
-          // Encountered a `export * from 'module'` line. Thus, we need to
-          // get all exports from the specified module and shim them into the
-          // current module.
-          const data = await processStarExport({
-            exportLine: n,
-            srcUrl: url,
-            context,
-            parentGetSource
-          })
-          Array.prototype.push.apply(imports, data.imports)
-          Array.prototype.push.apply(namespaceIds, data.namespaces)
-          Array.prototype.push.apply(setters, data.setters)
-
-          continue
-        }
-
-        setters.push(`
-        let $${n} = _.${n}
-        export { $${n} as ${n} }
-        set.${n} = (v) => {
-          $${n} = v
-          return true
-        }
-        `)
-      }
+      const { imports, namespaces, setters } = await processModule({
+          srcUrl: realUrl,
+          context,
+          parentGetSource
+      })
 
       return {
         source: `
 import { register } from '${iitmURL}'
-import * as namespace from ${JSON.stringify(url)}
 ${imports.join('\n')}
 
-const _ = Object.assign({}, ...[namespace, ${namespaceIds.join(', ')}])
+const _ = Object.assign({}, ...[${namespaces.join(', ')}])
 const set = {}
 
 ${setters.join('\n')}
diff --git a/test/hook/static-import-star.mjs b/test/hook/static-import-star.mjs
index 5cf427f..f928973 100644
--- a/test/hook/static-import-star.mjs
+++ b/test/hook/static-import-star.mjs
@@ -8,14 +8,25 @@ Hook((exports, name) => {
     return bar() + '-wrapped'
   }
 
+  const foo = exports.foo
+  exports.foo = function wrappedFoo() {
+    return foo() + '-wrapped'
+  }
+
   const aFunc = exports.aFunc
   exports.aFunc = function wrappedAFunc() {
     return aFunc() + '-wrapped'
   }
 })
 
-import { default as bar, aFunc, baz } from '../fixtures/bundle.mjs'
+import {
+  default as bar,
+  foo,
+  aFunc,
+  baz
+} from '../fixtures/bundle.mjs'
 
 strictEqual(bar(), '42-wrapped')
+strictEqual(foo(), 'foo-wrapped')
 strictEqual(aFunc(), 'a-wrapped')
 strictEqual(baz(), 'baz')