From 8544872198facb8b0e7ad457605fffdc390c343f Mon Sep 17 00:00:00 2001
From: cnc <cnc@localhost>
Date: Sat, 6 Jun 2026 06:06:03 +0800
Subject: [PATCH] =?UTF-8?q?=E6=8C=89=E6=BA=90=E4=BF=9D=E6=8A=A4=20OPFS=20?=
 =?UTF-8?q?=E5=8F=82=E6=95=B0=E5=A4=87=E4=BB=BD=E5=A4=B1=E8=B4=A5=E8=BE=B9?=
 =?UTF-8?q?=E7=95=8C?=
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---
 web/src/wasm-core.js                          |  7 ++++-
 ...browser-wasm-smoke-opfs-mirror-sections.js | 27 +++++++++++++++++++
 2 files changed, 33 insertions(+), 1 deletion(-)

diff --git a/web/src/wasm-core.js b/web/src/wasm-core.js
index 14e0526..c5ce82e 100644
--- a/web/src/wasm-core.js
+++ b/web/src/wasm-core.js
@@ -529,7 +529,12 @@ function installOpfsWorkspace(module, options) {
       const backupPath = `${LINUXCNC_DEFAULT_PARAMETER_FILE}.bak`;
       const backupData = readFirstExistingWasmFile(module, [backupPath, `/${backupPath}`]);
       if (backupData !== null) {
-        await writeOpfsFile(workspacePath, `${path}.bak`, backupData);
+        try {
+          await writeOpfsFile(workspacePath, `${path}.bak`, backupData);
+        } catch (_backupError) {
+          // LinuxCNC reports link(filename, filename + ".bak") failures
+          // with perror() and still renames filename + ".new" over filename.
+        }
       } else {
         await removeOpfsFileEntry(workspacePath, `${path}.bak`);
       }
diff --git a/web/test-browser-wasm-smoke-opfs-mirror-sections.js b/web/test-browser-wasm-smoke-opfs-mirror-sections.js
index 803faa9..e8b91b3 100644
--- a/web/test-browser-wasm-smoke-opfs-mirror-sections.js
+++ b/web/test-browser-wasm-smoke-opfs-mirror-sections.js
@@ -1,9 +1,13 @@
 export async function runBrowserOpfsMirrorSections(context, simulator) {
   const {
     expectEvent,
+    expectIncludes,
+    expectOpfsDirectoryStat,
     expectMissingWasmPath,
     expectText,
+    expectWasmFilesMissing,
     near,
+    readOpfsText,
     runSection,
     withSmokeSimulator,
   } = context;
@@ -123,4 +127,27 @@ export async function runBrowserOpfsMirrorSections(context, simulator) {
     const truncatedWasmProgram = new TextDecoder().decode(simulator.fs.module.FS.readFile(truncatedWasmPath));
     expectText(truncatedWasmProgram, "G21\n", "OPFS writeFile did not truncate the WASM mirror");
   });
+
+  await runSection("opfs parameter backup bridge failure is non-fatal", async () => {
+    // LinuxCNC source basis: rs274ngc_pre.cc save_parameters()
+    // reports link(filename, filename + ".bak") failure with perror()
+    // but still renames filename + ".new" over the parameter file.
+    simulator.fs.module.FS.writeFile("rs274ngc.var", "5161\t12.000000\n");
+    simulator.fs.module.FS.writeFile("rs274ngc.var.bak", "5161\t11.000000\n");
+    const backupBridgeDirectory = simulator.fs.opfs.resolvePath("parameters/backup-bridge-directory.var.bak");
+    simulator.fs.module.FS.mkdir(backupBridgeDirectory);
+    await simulator.fs.opfs.persistDirectory("parameters/backup-bridge-directory.var.bak");
+    await simulator.fs.opfs.persistParameterFile("parameters/backup-bridge-directory.var");
+    expectIncludes(
+      await readOpfsText(simulator, "parameters/backup-bridge-directory.var"),
+      "5161\t12.000000",
+      "LinuxCNC parameter bridge did not persist the main file when backup link failed",
+    );
+    await expectOpfsDirectoryStat(
+      simulator,
+      "parameters/backup-bridge-directory.var.bak",
+      "LinuxCNC parameter backup bridge removed an existing OPFS backup directory",
+    );
+    expectWasmFilesMissing(simulator.fs.module.FS, ["rs274ngc.var", "rs274ngc.var.new", "rs274ngc.var.bak"], (parameterPath) => `LinuxCNC parameter scratch file remained outside OPFS after non-fatal backup bridge failure: ${parameterPath}`);
+  });
 }