Automatic caching of dependencies

in a best effort manner by default
allowing to specify files to hash for computing the cache key

src/crypto-utils.ts

@@ -0,0 +1,40 @@
+import * as crypto from 'crypto'
+import * as fs from 'fs'
+import * as path from 'path'
+import * as stream from 'stream'
+import * as util from 'util'
+
+import * as glob from '@actions/glob'
+
+export async function hashFiles(
+    baseDir: string,
+    globs: string[] = ['**'],
+    followSymbolicLinks = false
+): Promise<string | null> {
+    let hasMatch = false
+    const result = crypto.createHash('sha256')
+    for await (const globPattern of globs) {
+        const globMatch = `${baseDir}/${globPattern}`
+        const globber = await glob.create(globMatch, {followSymbolicLinks})
+        for await (const file of globber.globGenerator()) {
+            // console.log(file)
+            if (!file.startsWith(`${baseDir}${path.sep}`)) {
+                // console.log(`Ignore '${file}' since it is not under '${baseDir}'.`)
+                continue
+            }
+            if (fs.statSync(file).isDirectory()) {
+                // console.log(`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())
+            if (!hasMatch) {
+                hasMatch = true
+            }
+        }
+    }
+    result.end()
+    return hasMatch ? result.digest('hex') : null
+}