Add HashFiles to the toolkit (#830)

* add hash files to the toolkit

packages/glob/src/internal-hash-files.ts

@@ -0,0 +1,42 @@
+import * as crypto from 'crypto'
+import * as core from '@actions/core'
+import * as fs from 'fs'
+import * as stream from 'stream'
+import * as util from 'util'
+import * as path from 'path'
+import {Globber} from './glob'
+
+export async function hashFiles(globber: Globber): Promise<string> {
+  let hasMatch = false
+  const githubWorkspace = process.env['GITHUB_WORKSPACE'] ?? process.cwd()
+  const result = crypto.createHash('sha256')
+  let count = 0
+  for await (const file of globber.globGenerator()) {
+    core.debug(file)
+    if (!file.startsWith(`${githubWorkspace}${path.sep}`)) {
+      core.debug(`Ignore '${file}' since it is not under GITHUB_WORKSPACE.`)
+      continue
+    }
+    if (fs.statSync(file).isDirectory()) {
+      core.debug(`Skip directory '${file}'.`)
+      continue
+    }
+    const hash = crypto.createHash('sha256')
+    const pipeline = util.promisify(stream.pipeline)
+    await pipeline(fs.createReadStream(file), hash)
+    result.write(hash.digest())
+    count++
+    if (!hasMatch) {
+      hasMatch = true
+    }
+  }
+  result.end()
+
+  if (hasMatch) {
+    core.debug(`Found ${count} files to hash.`)
+    return result.digest('hex')
+  } else {
+    core.warning(`No matches found for glob`)
+    return ''
+  }
+}