Replace manual tmp file creation with tmp library which uses security best practices

__tests__/main.test.ts

@@ -66,7 +66,7 @@ function mockInputs(inputs: Record<string, string> = {}): void {
  */
 function verifyStandardResponse(): void {
   expect(core.setOutput).toHaveBeenNthCalledWith(1, 'response', 'Hello, user!')
-  expect(core.setOutput).toHaveBeenNthCalledWith(2, 'response-file', expect.stringContaining('modelResponse.txt'))
+  expect(core.setOutput).toHaveBeenNthCalledWith(2, 'response-file', expect.stringContaining('modelResponse-'))
 }
 
 vi.mock('fs', () => ({

package-lock.json

@@ -11,9 +11,11 @@
       "dependencies": {
         "@actions/core": "^1.11.1",
         "@modelcontextprotocol/sdk": "^1.15.1",
+        "@types/tmp": "^0.2.6",
         "js-yaml": "^4.1.0",
         "openai": "^5.11.0",
-        "pkce-challenge": "^5.0.0"
+        "pkce-challenge": "^5.0.0",
+        "tmp": "^0.2.4"
       },
       "devDependencies": {
         "@eslint/compat": "^1.3.0",
@@ -2492,6 +2494,12 @@
       "dev": true,
       "license": "MIT"
     },
+    "node_modules/@types/tmp": {
+      "version": "0.2.6",
+      "resolved": "https://registry.npmjs.org/@types/tmp/-/tmp-0.2.6.tgz",
+      "integrity": "sha512-chhaNf2oKHlRkDGt+tiKE2Z5aJ6qalm7Z9rlLdBwmOiAAf09YQvvoLXjWK4HWPF1xU/fqvMgfNfpVoBscA/tKA==",
+      "license": "MIT"
+    },
     "node_modules/@typescript-eslint/eslint-plugin": {
       "version": "8.34.0",
       "resolved": "https://registry.npmjs.org/@typescript-eslint/eslint-plugin/-/eslint-plugin-8.34.0.tgz",
@@ -8943,6 +8951,15 @@
         "node": ">=14.0.0"
       }
     },
+    "node_modules/tmp": {
+      "version": "0.2.5",
+      "resolved": "https://registry.npmjs.org/tmp/-/tmp-0.2.5.tgz",
+      "integrity": "sha512-voyz6MApa1rQGUxT3E+BK7/ROe8itEx7vD8/HEvt4xwXucvQ5G5oeEiHkmHZJuBO21RpOf+YYm9MOivj709jow==",
+      "license": "MIT",
+      "engines": {
+        "node": ">=14.14"
+      }
+    },
     "node_modules/to-regex-range": {
       "version": "5.0.1",
       "resolved": "https://registry.npmjs.org/to-regex-range/-/to-regex-range-5.0.1.tgz",

package.json

@@ -25,9 +25,11 @@
   "dependencies": {
     "@actions/core": "^1.11.1",
     "@modelcontextprotocol/sdk": "^1.15.1",
+    "@types/tmp": "^0.2.6",
     "js-yaml": "^4.1.0",
     "openai": "^5.11.0",
-    "pkce-challenge": "^5.0.0"
+    "pkce-challenge": "^5.0.0",
+    "tmp": "^0.2.4"
   },
   "devDependencies": {
     "@eslint/compat": "^1.3.0",

src/main.ts

@@ -1,7 +1,6 @@
 import * as core from '@actions/core'
 import * as fs from 'fs'
-import * as os from 'os'
-import * as path from 'path'
+import * as tmp from 'tmp'
 import {connectToGitHubMCP} from './mcp.js'
 import {simpleInference, mcpInference} from './inference.js'
 import {loadContentFromFileOrInput, buildInferenceRequest} from './helpers.js'
@@ -13,8 +12,6 @@ import {
   parseFileTemplateVariables,
 } from './prompt.js'
 
-const RESPONSE_FILE = 'modelResponse.txt'
-
 /**
  * The main function for the action.
  *
@@ -93,11 +90,17 @@ export async function run(): Promise<void> {
 
     core.setOutput('response', modelResponse || '')
 
-    const responseFilePath = path.join(tempDir(), RESPONSE_FILE)
-    core.setOutput('response-file', responseFilePath)
+    // Create a secure temporary file instead of using the temp directory directly
+    const responseFile = tmp.fileSync({
+      prefix: 'modelResponse-',
+      postfix: '.txt',
+      keep: true, // Keep the file so the action can read it
+    })
+
+    core.setOutput('response-file', responseFile.name)
 
     if (modelResponse && modelResponse !== '') {
-      fs.writeFileSync(responseFilePath, modelResponse, 'utf-8')
+      fs.writeFileSync(responseFile.name, modelResponse, 'utf-8')
     }
   } catch (error) {
     if (error instanceof Error) {
@@ -112,8 +115,3 @@ export async function run(): Promise<void> {
   // Force exit to prevent hanging on open connections
   process.exit(0)
 }
-
-function tempDir(): string {
-  const tempDirectory = process.env['RUNNER_TEMP'] || os.tmpdir()
-  return tempDirectory
-}