Calculate and record uncommittedHash when creating a build

node-src/git/git.ts

@@ -90,6 +90,29 @@ export async function getBranch() {
   }
 }
 
+// Retrieve the hash of all uncommitted files, which includes staged, unstaged, and untracked files,
+// excluding deleted files (which can't be hashed) and ignored files. There is no one single Git
+// command to reliably get this information, so we use a combination of commands grouped together.
+export async function getUncommittedHash() {
+  const listStagedFiles = 'git diff --name-only --diff-filter=d --cached';
+  const listUnstagedFiles = 'git diff --name-only --diff-filter=d';
+  const listUntrackedFiles = 'git ls-files --others --exclude-standard';
+  const listUncommittedFiles = [listStagedFiles, listUnstagedFiles, listUntrackedFiles].join(';');
+
+  const uncommittedHash = (
+    await execGitCommand(
+      // Pass the combined list of filenames to hash-object to retrieve a list of hashes. Then pass
+      // the list of hashes to hash-object again to retrieve a single hash of all hashes. We use
+      // stdin to avoid the limit on command line arguments.
+      `(${listUncommittedFiles}) | git hash-object --stdin-paths | git hash-object --stdin`
+    )
+  ).trim();
+
+  // In case there are no uncommited changes (empty list), we always get this same hash.
+  const noChangesHash = 'e69de29bb2d1d6434b8b29ae775ad8c2e48c5391';
+  return uncommittedHash === noChangesHash ? '' : uncommittedHash;
+}
+
 export async function hasPreviousCommit() {
   const result = await execGitCommand(`git --no-pager log -n 1 --skip=1 --format="%H"`);
   return !!result.trim();

node-src/tasks/gitInfo.ts

@@ -1,7 +1,7 @@
 import picomatch from 'picomatch';
 
 import getCommitAndBranch from '../git/getCommitAndBranch';
-import { getSlug, getVersion } from '../git/git';
+import { getSlug, getUncommittedHash, getVersion } from '../git/git';
 import { getParentCommits } from '../git/getParentCommits';
 import { getBaselineBuilds } from '../git/getBaselineBuilds';
 import { exitCodes, setExitCode } from '../lib/setExitCode';
@@ -62,8 +62,12 @@ export const setGitInfo = async (ctx: Context, task: Task) => {
   } = ctx.options;
 
   ctx.git = {
-    version: await getVersion(),
     ...(await getCommitAndBranch(ctx, { branchName, patchBaseRef, ci })),
+    uncommittedHash: await getUncommittedHash().catch((e) => {
+      ctx.log.warn('Failed to retrieve uncommitted files hash', e);
+      return null;
+    }),
+    version: await getVersion(),
   };
 
   if (!ctx.git.slug) {

node-src/types.ts

@@ -144,6 +144,7 @@ export interface Context {
     committedAt: number;
     slug?: string;
     mergeCommit?: string;
+    uncommittedHash?: string;
     parentCommits?: string[];
     baselineCommits?: string[];
     changedFiles?: string[];