From 2550e2dd58ceed7f21e8db9a84683bb418ed5da8 Mon Sep 17 00:00:00 2001
From: "Michael B. Gale" <mbg@github.com>
Date: Mon, 12 Oct 2026 16:37:06 +0100
Subject: [PATCH] Address EXDEV issue

---
 lib/entry-points.js | 15 +++++++++++++--
 src/diagnostics.ts  | 21 ++++++++++++++++++---
 src/util.ts         | 15 +++++++++++++++
 3 files changed, 46 insertions(+), 5 deletions(-)

diff --git a/lib/entry-points.js b/lib/entry-points.js
index d1cbb8f66..040571991 100644
--- a/lib/entry-points.js
+++ b/lib/entry-points.js
@@ -170021,6 +170021,9 @@ function wrapError(error3) {
 function getErrorMessage(error3) {
   return error3 instanceof Error ? error3.message : String(error3);
 }
+function isErrnoException(error3) {
+  return typeof error3 === "object" && error3 !== null && "code" in error3 && typeof error3.code === "string";
+}
 function prettyPrintPack(pack) {
   return `${pack.name}${pack.version ? `@${pack.version}` : ""}${pack.path ? `:${pack.path}` : ""}`;
 }
@@ -173099,10 +173102,18 @@ function flushDiagnostics(action, config) {
     const destination = import_path2.default.join(directory, filename);
     try {
       fs7.mkdirSync(directory, { recursive: true });
-      fs7.renameSync(temporary.path, destination);
+      try {
+        fs7.renameSync(temporary.path, destination);
+      } catch (renameErr) {
+        if (!isErrnoException(renameErr) || renameErr.code !== "EXDEV") {
+          throw renameErr;
+        }
+        fs7.copyFileSync(temporary.path, destination);
+        fs7.unlinkSync(temporary.path);
+      }
     } catch (err) {
       action.logger.warning(
-        `Failed to rename '${temporary.path}' to '${destination}': ${getErrorMessage(err)}`
+        `Failed to relocate '${temporary.path}' to '${destination}': ${getErrorMessage(err)}`
       );
       failedFlushDiagnostics.push(temporary);
     }
diff --git a/src/diagnostics.ts b/src/diagnostics.ts
index d0083e30e..a3b44fd76 100644
--- a/src/diagnostics.ts
+++ b/src/diagnostics.ts
@@ -6,7 +6,11 @@ import { getTemporaryDirectory } from "./actions-util";
 import type { Config } from "./config-utils";
 import { Language } from "./languages";
 import { getActionsLogger, type Logger } from "./logging";
-import { getCodeQLDatabasePath, getErrorMessage } from "./util";
+import {
+  getCodeQLDatabasePath,
+  getErrorMessage,
+  isErrnoException,
+} from "./util";
 
 /**
  * Known tags for diagnostics. There is currently only "internal-error",
@@ -334,10 +338,21 @@ export function flushDiagnostics(
 
     try {
       fs.mkdirSync(directory, { recursive: true });
-      fs.renameSync(temporary.path, destination);
+      try {
+        fs.renameSync(temporary.path, destination);
+      } catch (renameErr: unknown) {
+        // Rethrow the error if it isn't an EXDEV one.
+        if (!isErrnoException(renameErr) || renameErr.code !== "EXDEV") {
+          throw renameErr;
+        }
+
+        // The error was an EXDEV one: try to copy the file and delete the temporary one.
+        fs.copyFileSync(temporary.path, destination);
+        fs.unlinkSync(temporary.path);
+      }
     } catch (err) {
       action.logger.warning(
-        `Failed to rename '${temporary.path}' to '${destination}': ${getErrorMessage(err)}`,
+        `Failed to relocate '${temporary.path}' to '${destination}': ${getErrorMessage(err)}`,
       );
 
       failedFlushDiagnostics.push(temporary);
diff --git a/src/util.ts b/src/util.ts
index 566386de6..2cacd4fbb 100644
--- a/src/util.ts
+++ b/src/util.ts
@@ -924,6 +924,21 @@ export function getErrorMessage(error: unknown): string {
   return error instanceof Error ? error.message : String(error);
 }
 
+/**
+ * Approximates whether {@link error} is like a {@link NodeJS.ErrnoException}.
+ * We only typically care about the `code` property, so that's what we check for here.
+ */
+export function isErrnoException(
+  error: unknown,
+): error is NodeJS.ErrnoException {
+  return (
+    typeof error === "object" &&
+    error !== null &&
+    "code" in error &&
+    typeof error.code === "string"
+  );
+}
+
 export function prettyPrintPack(pack: Pack) {
   return `${pack.name}${pack.version ? `@${pack.version}` : ""}${
     pack.path ? `:${pack.path}` : ""