From 40239d2e355da883be47158d8a53ad34cf1bf63b Mon Sep 17 00:00:00 2001
From: Matthew West <mwest@illinois.edu>
Date: Tue, 23 Feb 2021 08:50:13 -0600
Subject: [PATCH] Fix chunk symlinks to ensure overwriting old links

---
 lib/chunks.js | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/lib/chunks.js b/lib/chunks.js
index 19c555460ab..5fa79a0bd54 100644
--- a/lib/chunks.js
+++ b/lib/chunks.js
@@ -701,7 +701,15 @@ const ensureChunk = async (courseId, chunk) => {
     });
 
     // Finally, link targetPath -> relativeUnpackPath
-    await fs.ensureSymlink(relativeUnpackPath, targetPath);
+    // Note that ensureSymlink() won't overwrite an existing targetPath
+    // See:
+    //     https://github.com/jprichardson/node-fs-extra/pull/869
+    //     https://github.com/jprichardson/node-fs-extra/issues/786
+    //     https://github.com/jprichardson/node-fs-extra/pull/826
+    // As a work-around, we symlink a temporary name and move it over targetPath
+    const tmpPath = `${targetPath}-${chunk.uuid}`;
+    await fs.ensureSymlink(relativeUnpackPath, tmpPath);
+    await fs.rename(tmpPath, targetPath);
 };
 
 /** @type {Map<string, Promise>} */