fixed pr

src/subject.ts

@@ -0,0 +1,96 @@
+import * as core from '@actions/core'
+import * as glob from '@actions/glob'
+import crypto from 'crypto'
+import fs from 'fs'
+import path from 'path'
+
+import type { Subject } from '@actions/attest'
+
+const DIGEST_ALGORITHM = 'sha256'
+
+// Returns the subject specified by the action's inputs. The subject may be
+// specified as a path to a file or as a digest. If a path is provided, the
+// file's digest is calculated and returned along with the subject's name. If a
+// digest is provided, the name must also be provided.
+export const subjectFromInputs = async (): Promise<Subject[]> => {
+  const subjectPath = core.getInput('subject-path', { required: false })
+  const subjectDigest = core.getInput('subject-digest', { required: false })
+  const subjectName = core.getInput('subject-name', { required: false })
+
+  if (!subjectPath && !subjectDigest) {
+    throw new Error('One of subject-path or subject-digest must be provided')
+  }
+
+  if (subjectPath && subjectDigest) {
+    throw new Error(
+      'Only one of subject-path or subject-digest may be provided'
+    )
+  }
+
+  if (subjectDigest && !subjectName) {
+    throw new Error('subject-name must be provided when using subject-digest')
+  }
+
+  if (subjectPath) {
+    return await getSubjectFromPath(subjectPath, subjectName)
+  } else {
+    return [getSubjectFromDigest(subjectDigest, subjectName)]
+  }
+}
+
+// Returns the subject specified by the path to a file. The file's digest is
+// calculated and returned along with the subject's name.
+const getSubjectFromPath = async (
+  subjectPath: string,
+  subjectName?: string
+): Promise<Subject[]> => {
+  /* eslint-disable-next-line github/no-then */
+  const files = await glob.create(subjectPath).then(async g => g.glob())
+
+  const subjects = files.map(async file => {
+    const name = subjectName || path.parse(file).base
+    const digest = await digestFile(DIGEST_ALGORITHM, file)
+    return { name, digest: { [DIGEST_ALGORITHM]: digest } }
+  })
+
+  if (subjects.length === 0) {
+    throw new Error(`Could not find subject at path ${subjectPath}`)
+  }
+
+  return Promise.all(subjects)
+}
+
+// Returns the subject specified by the digest of a file. The digest is returned
+// along with the subject's name.
+const getSubjectFromDigest = (
+  subjectDigest: string,
+  subjectName: string
+): Subject => {
+  if (!subjectDigest.match(/^sha256:[A-Za-z0-9]{64}$/)) {
+    throw new Error(
+      'subject-digest must be in the format "sha256:<hex-digest>"'
+    )
+  }
+  const [alg, digest] = subjectDigest.split(':')
+
+  return {
+    name: subjectName,
+    digest: { [alg]: digest }
+  }
+}
+
+// Calculates the digest of a file using the specified algorithm. The file is
+// streamed into the digest function to avoid loading the entire file into
+// memory. The returned digest is a hex string.
+const digestFile = async (
+  algorithm: string,
+  filePath: string
+): Promise<string> => {
+  return new Promise((resolve, reject) => {
+    const hash = crypto.createHash(algorithm).setEncoding('hex')
+    fs.createReadStream(filePath)
+      .once('error', reject)
+      .pipe(hash)
+      .once('finish', () => resolve(hash.read()))
+  })
+}