From 3a810da66c5ffc3656f122e78b077c9cd8219244 Mon Sep 17 00:00:00 2001
From: Marko Vejnovic <marko@bun.com>
Date: Fri, 7 Nov 2025 14:33:26 -0800
Subject: [PATCH] build(ENG-21466): Fix `sccache` not caching across builds
 (#24423)

---
 scripts/bootstrap.ps1                | 32 ++++++++++++++++++++++++++++
 scripts/bootstrap.sh                 | 21 +++++++++++++++++-
 scripts/build.mjs                    |  3 ++-
 test/js/node/path/browserify.test.js | 19 +++++++++++------
 4 files changed, 66 insertions(+), 9 deletions(-)

diff --git a/scripts/bootstrap.ps1 b/scripts/bootstrap.ps1
index 9c406456fb..5164112d74 100755
--- a/scripts/bootstrap.ps1
+++ b/scripts/bootstrap.ps1
@@ -256,6 +256,30 @@ function Install-Tailscale {
   Install-Package tailscale
 }
 
+function Create-Buildkite-Environment-Hooks {
+  param (
+    [Parameter(Mandatory = $true)]
+    [string]$BuildkiteHome
+  )
+
+  Write-Output "Creating Buildkite environment hooks..."
+  $hooksDir = Join-Path $BuildkiteHome "hooks"
+
+  if (-not (Test-Path $hooksDir)) {
+    New-Item -Path $hooksDir -ItemType Directory -Force | Out-Null
+  }
+
+  $environmentHook = Join-Path $hooksDir "environment.ps1"
+  $buildPath = Join-Path $BuildkiteHome "build"
+
+  @"
+# Buildkite environment hook
+`$env:BUILDKITE_BUILD_CHECKOUT_PATH = "$buildPath"
+"@ | Set-Content -Path $environmentHook -Encoding UTF8
+
+  Write-Output "Environment hook created at $environmentHook"
+}
+
 function Install-Buildkite {
   if (Which buildkite-agent) {
     return
@@ -266,6 +290,14 @@ function Install-Buildkite {
   $installScript = Download-File "https://raw.githubusercontent.com/buildkite/agent/main/install.ps1"
   Execute-Script $installScript
   Refresh-Path
+
+  if ($CI) {
+    $buildkiteHome = "C:\buildkite-agent"
+    if (-not (Test-Path $buildkiteHome)) {
+      New-Item -Path $buildkiteHome -ItemType Directory -Force | Out-Null
+    }
+    Create-Buildkite-Environment-Hooks -BuildkiteHome $buildkiteHome
+  }
 }
 
 function Install-Build-Essentials {
diff --git a/scripts/bootstrap.sh b/scripts/bootstrap.sh
index f878589169..f42885d79a 100755
--- a/scripts/bootstrap.sh
+++ b/scripts/bootstrap.sh
@@ -1,5 +1,5 @@
 #!/bin/sh
-# Version: 19
+# Version: 20
 
 # A script that installs the dependencies needed to build and test Bun.
 # This should work on macOS and Linux with a POSIX shell.
@@ -1391,6 +1391,25 @@ create_buildkite_user() {
 	for file in $buildkite_files; do
 		create_file "$file"
 	done
+
+	local opts=$-
+	set -ef
+
+	# I do not want to use create_file because it creates directories with 777
+	# permissions and files with 664 permissions. This is dumb, for obvious
+	# reasons.
+	local hook_dir="${home}/hooks"
+	mkdir -p -m 755 "${hook_dir}";
+	cat <<EOF > "${hook_dir}/environment"
+#!/bin/sh
+set -efu
+
+export BUILDKITE_BUILD_CHECKOUT_PATH=${home}/build
+EOF
+	execute_sudo chown -R "$user:$group" "$hook_dir"
+	execute_sudo chmod 744 "${hook_dir}/environment"
+
+	set +ef -"$opts"
 }
 
 install_buildkite() {
diff --git a/scripts/build.mjs b/scripts/build.mjs
index e902b85fe9..de1f40d5a7 100755
--- a/scripts/build.mjs
+++ b/scripts/build.mjs
@@ -103,7 +103,8 @@ async function build(args) {
 
   await startGroup("CMake Build", () => spawn("cmake", buildArgs, { env }));
 
-  if (isCI) {
+  const target = buildOptions["--target"] || buildOptions["-t"];
+  if (isCI && target === "build-cpp") {
     await startGroup("sccache stats", () => {
       spawn("sccache", ["--show-stats"], { env });
     });
diff --git a/test/js/node/path/browserify.test.js b/test/js/node/path/browserify.test.js
index a1838f127c..9b53caa26c 100644
--- a/test/js/node/path/browserify.test.js
+++ b/test/js/node/path/browserify.test.js
@@ -469,7 +469,12 @@ describe("browserify path tests", () => {
     const failures = [];
     const cwd = process.cwd();
     const cwdParent = path.dirname(cwd);
-    const parentIsRoot = isWindows ? cwdParent.match(/^[A-Z]:\\$/) : cwdParent === "/";
+    const parentIsRoot = (levels = 1) => {
+      const dir = Array(levels)
+        .fill()
+        .reduce(wd => path.dirname(wd), cwd);
+      return isWindows ? dir.match(/^[a-zA-Z]:\\$/) : dir === "/";
+    };
 
     const relativeTests = [
       [
@@ -529,19 +534,19 @@ describe("browserify path tests", () => {
           ["/webp4ck-hot-middleware", "/webpack/buildin/module.js", "../webpack/buildin/module.js"],
           ["/webpack-hot-middleware", "/webp4ck/buildin/module.js", "../webp4ck/buildin/module.js"],
           ["/var/webpack-hot-middleware", "/var/webpack/buildin/module.js", "../webpack/buildin/module.js"],
-          ["/app/node_modules/pkg", "../static", `../../..${parentIsRoot ? "" : path.posix.resolve("../")}/static`],
+          ["/app/node_modules/pkg", "../static", `../../..${parentIsRoot() ? "" : path.posix.resolve("../")}/static`],
           [
             "/app/node_modules/pkg",
             "../../static",
-            `../../..${parentIsRoot ? "" : path.posix.resolve("../../")}/static`,
+            `../../..${parentIsRoot(2) ? "" : path.posix.resolve("../../")}/static`,
           ],
-          ["/app", "../static", `..${parentIsRoot ? "" : path.posix.resolve("../")}/static`],
+          ["/app", "../static", `..${parentIsRoot() ? "" : path.posix.resolve("../")}/static`],
           ["/app", "../".repeat(64) + "static", "../static"],
           [".", "../static", cwd == "/" ? "static" : "../static"],
-          ["/", "../static", parentIsRoot ? "static" : `${path.posix.resolve("../")}/static`.slice(1)],
+          ["/", "../static", parentIsRoot() ? "static" : `${path.posix.resolve("../")}/static`.slice(1)],
           ["../", "../", ""],
-          ["../", "../../", parentIsRoot ? "" : ".."],
-          ["../../", "../", parentIsRoot ? "" : path.basename(cwdParent)],
+          ["../", "../../", parentIsRoot() ? "" : ".."],
+          ["../../", "../", parentIsRoot() ? "" : path.basename(cwdParent)],
           ["../../", "../../", ""],
         ],
       ],