From 4eb9085e7178f1464d360456ff17af034e151cf8 Mon Sep 17 00:00:00 2001
From: jdp_ <42700985+jdpatdiscord@users.noreply.github.com>
Date: Sun, 7 May 2023 01:06:30 -0400
Subject: [PATCH] Fix pack updating & Modrinth overrides

The mechanism that both pack updating and Modrinth overrides use utilize std::filesystem::copy, which with GCC's libstdc++ has a bug on Windows where `overwrite_existing` isn't obeyed. In addition, made it clear what `overrideFolder` does by renaming it and rewriting an error message.
---
 launcher/FileSystem.cpp                       | 35 +++++++++++--------
 launcher/FileSystem.h                         |  2 +-
 launcher/InstanceList.cpp                     |  2 +-
 .../modrinth/ModrinthInstanceCreationTask.cpp |  4 +--
 4 files changed, 24 insertions(+), 19 deletions(-)

diff --git a/launcher/FileSystem.cpp b/launcher/FileSystem.cpp
index 9e510d91..689d1ff6 100644
--- a/launcher/FileSystem.cpp
+++ b/launcher/FileSystem.cpp
@@ -414,24 +414,29 @@ bool createShortCut(QString location, QString dest, QStringList args, QString na
 #endif
 }
 
-bool overrideFolder(QString overwritten_path, QString override_path)
+bool mergeFolders(QString dstpath, QString srcpath)
 {
-    using copy_opts = fs::copy_options;
-
-    if (!FS::ensureFolderPathExists(overwritten_path))
-        return false;
-
-    std::error_code err;
-    fs::copy_options opt = copy_opts::recursive | copy_opts::overwrite_existing;
-
-    fs::copy(toStdString(override_path), toStdString(overwritten_path), opt, err);
-
-    if (err) {
-        qCritical() << QString("Failed to apply override from %1 to %2").arg(override_path, overwritten_path);
-        qCritical() << "Reason:" << QString::fromStdString(err.message());
+    std::error_code ec;
+    fs::path fullSrcPath = srcpath.toStdString();
+    fs::path fullDstPath = dstpath.toStdString();
+    for (auto& entry : fs::recursive_directory_iterator(fullSrcPath))
+    {
+        fs::path relativeChild = fs::relative(entry, fullSrcPath);
+        if (entry.is_directory())
+            if (!fs::exists(fullDstPath / relativeChild))
+                fs::create_directory(fullDstPath / relativeChild);
+        if (entry.is_regular_file())
+        {
+            fs::path childDst = fullDstPath / relativeChild;
+            if (fs::exists(childDst))
+                fs::remove(childDst);
+            fs::copy(entry, childDst, fs::copy_options::none, ec);
+            if (ec.value() != 0)
+                qCritical() << QString("File copy failed with: %1. File was %2 -> %3").arg(QString::fromStdString(ec.message()), entry.path().c_str(), childDst.c_str());
+        }
     }
 
-    return err.value() == 0;
+    return ec.value() == 0;
 }
 
 }
diff --git a/launcher/FileSystem.h b/launcher/FileSystem.h
index b46f3281..7e66daff 100644
--- a/launcher/FileSystem.h
+++ b/launcher/FileSystem.h
@@ -154,5 +154,5 @@ QString getDesktopDir();
 
 // Overrides one folder with the contents of another, preserving items exclusive to the first folder
 // Equivalent to doing QDir::rename, but allowing for overrides
-bool overrideFolder(QString overwritten_path, QString override_path);
+bool mergeFolders(QString dstpath, QString srcpath);
 }
diff --git a/launcher/InstanceList.cpp b/launcher/InstanceList.cpp
index c98d1e90..07e8c686 100644
--- a/launcher/InstanceList.cpp
+++ b/launcher/InstanceList.cpp
@@ -904,7 +904,7 @@ bool InstanceList::commitStagedInstance(const QString& path, InstanceName const&
         QString destination = FS::PathCombine(m_instDir, instID);
 
         if (should_override) {
-            if (!FS::overrideFolder(destination, path)) {
+            if (!FS::mergeFolders(destination, path)) {
                 qWarning() << "Failed to override" << path << "to" << destination;
                 return false;
             }
diff --git a/launcher/modplatform/modrinth/ModrinthInstanceCreationTask.cpp b/launcher/modplatform/modrinth/ModrinthInstanceCreationTask.cpp
index 661ec31a..bd4c9461 100644
--- a/launcher/modplatform/modrinth/ModrinthInstanceCreationTask.cpp
+++ b/launcher/modplatform/modrinth/ModrinthInstanceCreationTask.cpp
@@ -195,8 +195,8 @@ bool ModrinthCreationTask::createInstance()
         Override::createOverrides("client-overrides", parent_folder, client_override_path);
 
         // Apply the overrides
-        if (!FS::overrideFolder(mcPath, client_override_path)) {
-            setError(tr("Could not rename the client overrides folder:\n") + "client overrides");
+        if (!FS::mergeFolders(mcPath, client_override_path)) {
+            setError(tr("Could not overwrite / create new files:\n") + "client overrides");
             return false;
         }
     }