0ad/source/lib/file/vfs/vfs_populate.cpp

/* Copyright (C) 2025 Wildfire Games.
 *
 * Permission is hereby granted, free of charge, to any person obtaining
 * a copy of this software and associated documentation files (the
 * "Software"), to deal in the Software without restriction, including
 * without limitation the rights to use, copy, modify, merge, publish,
 * distribute, sublicense, and/or sell copies of the Software, and to
 * permit persons to whom the Software is furnished to do so, subject to
 * the following conditions:
 *
 * The above copyright notice and this permission notice shall be included
 * in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
 * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
 * CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
 * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
 * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */

/*
 * populate VFS directories with files
 */

#include "precompiled.h"

#include "vfs_populate.h"

#include "lib/code_annotation.h"
#include "lib/file/archive/archive.h"
#include "lib/file/archive/archive_zip.h"
#include "lib/file/file_system.h"
#include "lib/file/vfs/vfs.h"	// error codes
#include "lib/file/vfs/vfs_lookup.h"
#include "lib/file/vfs/vfs_path.h"
#include "lib/file/vfs/vfs_tree.h"
#include "lib/os_path.h"
#include "lib/path.h"

#include <cstddef>
#include <cstdint>

struct CompareFileInfoByName
{
	bool operator()(const CFileInfo& a, const CFileInfo& b)
	{
		return a.Name() < b.Name();
	}
};

// helper class that allows breaking up the logic into sub-functions without
// always having to pass directory/realDirectory as parameters.
class PopulateHelper
{
	NONCOPYABLE(PopulateHelper);
public:
	PopulateHelper(VfsDirectory* directory, const PRealDirectory& realDirectory)
		: m_directory(directory), m_realDirectory(realDirectory)
	{
	}

	Status AddEntries() const
	{
		CFileInfos files; files.reserve(500);
		DirectoryNames subdirectoryNames; subdirectoryNames.reserve(50);
		RETURN_STATUS_IF_ERR(GetDirectoryEntries(m_realDirectory->Path(), &files, &subdirectoryNames));

		// Since .DELETED files only remove files in lower priority mods
		// loose files and archive files have no conflicts so we do not need
		// to sort them.
		// We add directories after they might have been removed by .DELETED
		// files (as they did not contain any files at that point). The order
		// of GetDirectoryEntries is undefined, but that does not really matter (TODO really?)
		// so we do not need to sort its output.
		RETURN_STATUS_IF_ERR(AddFiles(files));
		AddSubdirectories(subdirectoryNames);

		return INFO::OK;
	}

private:
	void AddFile(const CFileInfo& fileInfo) const
	{
		const VfsPath name = fileInfo.Name();
		const VfsFile file(name, (size_t)fileInfo.Size(), fileInfo.MTime(), m_realDirectory->Priority(), m_realDirectory);
		if(name.Extension() == L".DELETED")
		{
			m_directory->DeleteSubtree(file);
			if(!(m_realDirectory->Flags() & VFS_MOUNT_KEEP_DELETED))
				return;
		}

		m_directory->AddFile(file);
	}

	static void AddArchiveFile(const VfsPath& pathname, const CFileInfo& fileInfo, PIArchiveFile archiveFile, uintptr_t cbData)
	{
		PopulateHelper* this_ = (PopulateHelper*)cbData;

		// (we have to create missing subdirectoryNames because archivers
		// don't always place directory entries before their files)
		const size_t flags = VFS_LOOKUP_ADD|VFS_LOOKUP_SKIP_POPULATE;
		VfsDirectory* directory;
		WARN_IF_ERR(vfs_Lookup(pathname, this_->m_directory, directory, 0, flags));

		const VfsPath name = fileInfo.Name();
		const VfsFile file(name, (size_t)fileInfo.Size(), fileInfo.MTime(), this_->m_realDirectory->Priority(), archiveFile);
		if(name.Extension() == L".DELETED")
		{
			directory->DeleteSubtree(file);
			if(!(this_->m_realDirectory->Flags() & VFS_MOUNT_KEEP_DELETED))
				return;
		}

		directory->AddFile(file);
	}

	Status AddFiles(const CFileInfos& files) const
	{
		const OsPath path(m_realDirectory->Path());

		for(size_t i = 0; i < files.size(); i++)
		{
			const OsPath pathname = path / files[i].Name();
			if(pathname.Extension() == L".zip")
			{
				PIArchiveReader archiveReader = CreateArchiveReader_Zip(pathname);
				// archiveReader == nullptr if file could not be opened (e.g. because
				// archive is currently open in another program)
				if(archiveReader)
					RETURN_STATUS_IF_ERR(archiveReader->ReadEntries(AddArchiveFile, (uintptr_t)this));
			}
			else	// regular (non-archive) file
				AddFile(files[i]);
		}

		return INFO::OK;
	}

	void AddSubdirectories(const DirectoryNames& subdirectoryNames) const
	{
		for(size_t i = 0; i < subdirectoryNames.size(); i++)
		{
			// skip version control directories - this avoids cluttering the
			// VFS with hundreds of irrelevant files.
			if(subdirectoryNames[i] == L".svn" || subdirectoryNames[i] == L".git")
				continue;

			VfsDirectory* subdirectory = m_directory->AddSubdirectory(subdirectoryNames[i]);
			PRealDirectory realDirectory = CreateRealSubdirectory(m_realDirectory, subdirectoryNames[i]);
			vfs_Attach(subdirectory, realDirectory);
		}
	}

	VfsDirectory* const m_directory;
	PRealDirectory m_realDirectory;
};


Status vfs_Populate(VfsDirectory* directory)
{
	if(!directory->ShouldPopulate())
		return INFO::OK;

	const PRealDirectory& realDirectory = directory->AssociatedDirectory();

	if(realDirectory->Flags() & VFS_MOUNT_WATCH)
		realDirectory->Watch();

	PopulateHelper helper(directory, realDirectory);
	RETURN_STATUS_IF_ERR(helper.AddEntries());

	return INFO::OK;
}


Status vfs_Attach(VfsDirectory* directory, const PRealDirectory& realDirectory)
{
	PRealDirectory existingRealDir = directory->AssociatedDirectory();

	// Don't allow replacing the real directory by a lower-priority one.
	if (!existingRealDir || existingRealDir->Priority() < realDirectory->Priority())
	{
		// This ordering is peculiar but useful, as it "defers" the population call.
		// If there is already a real directory, we will replace it (and lose track of it),
		// so we'll populate it right away, but the 'new' real directory can wait until we access it.
		RETURN_STATUS_IF_ERR(vfs_Populate(directory));
		directory->SetAssociatedDirectory(realDirectory);
		return INFO::OK;
	}
	// We are attaching a lower-priority real directory.
	// Because of deferred population, we need to immediately populate this new directory.
	bool shouldPop = directory->ShouldPopulate();
	// This sets "should populate" to true, so the vfs_Populate call below immediately populates.
	directory->SetAssociatedDirectory(realDirectory);
	RETURN_STATUS_IF_ERR(vfs_Populate(directory));
	// Reset to the higher priority realDirectory, which resets ShouldPopulate to true.
	directory->SetAssociatedDirectory(existingRealDir);
	// Avoid un-necessary repopulation by clearing the flag.
	if (!shouldPop)
		directory->ShouldPopulate();

	return INFO::OK;
}