Early exit from copy-file(s).js

Now that we have copy functions that do not create hardlinks in gen, it
shouldn't be necessary to remove the target file before writing. This CL
removes the unlinking and early exits.

Change-Id: I8e099224479458d446977f930065b4c54a3d0ac6
Reviewed-on: https://chromium-review.googlesource.com/c/devtools/devtools-frontend/+/2334972
Commit-Queue: Paul Lewis <[email protected]>
Auto-Submit: Paul Lewis <[email protected]>
Reviewed-by: Jack Franklin <[email protected]>

scripts/build/ninja/copy-file.js

@@ -11,11 +11,16 @@ const destPath = path.join(process.cwd(), dest);
 // If there's a file there from a previous build, unlink it first. This
 // is because the file in that location might be a hardlinked file, and
 // overwriting it doesn't change the fact that it's hardlinked.
+const srcContents = fs.readFileSync(srcPath);
 if (fs.existsSync(destPath)) {
-  fs.unlinkSync(destPath);
+  // Check contents, return early if match
+  const destContents = fs.readFileSync(destPath);
+  if (srcContents.equals(destContents)) {
+    return;
+  }
 }
 
 // Force a write to the target filesystem, since by default the ninja
 // toolchain will create a hardlink, which in turn reflects changes in
 // gen and resources/inspector back to //front_end.
-fs.writeFileSync(destPath, fs.readFileSync(srcPath));
+fs.writeFileSync(destPath, srcContents);

scripts/build/ninja/copy-files.js

@@ -12,12 +12,17 @@ for (const file of files.split(',')) {
   // If there's a file there from a previous build, unlink it first. This
   // is because the file in that location might be a hardlinked file, and
   // overwriting it doesn't change the fact that it's hardlinked.
+  const srcContents = fs.readFileSync(srcPath);
   if (fs.existsSync(destPath)) {
-    fs.unlinkSync(destPath);
+    // Check contents, return early if match
+    const destContents = fs.readFileSync(destPath);
+    if (srcContents.equals(destContents)) {
+      return;
+    }
   }
 
   // Force a write to the target filesystem, since by default the ninja
   // toolchain will create a hardlink, which in turn reflects changes in
   // gen and resources/inspector back to //front_end.
-  fs.writeFileSync(destPath, fs.readFileSync(srcPath));
+  fs.writeFileSync(destPath, srcContents);
 }