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fix: support VDF archives larger than 2 GiB #130

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fix: support VDF archives larger than 2 GiB #130

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65303df
fix(cmake): use CreateFileW in the Win32 mmap check
Jul 26, 2026
f010020
fix(Vfs): read files larger than 2 GiB in chunks
Jul 26, 2026
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16 changes: 14 additions & 2 deletions src/Vfs.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -403,6 +403,18 @@ namespace zenkit {
w->write(catalog.data(), catalog.size());
}

#ifndef _ZK_WITH_MMAP
/// Maximum number of bytes to request from a stream in a single read (256 MB).
static constexpr std::streamsize VFS_READ_CHUNK_SIZE = 256 * 1024 * 1024;

/// Reads up to size bytes from the stream into data.
/// A single read of 2 GiB or more fails outright on some platforms, so we split the read into chunks.
static void vfs_read_chunked(std::istream& stream, std::byte* data, std::streamsize size) {
for (std::streamsize off = 0; off < size && stream; off += stream.gcount())
stream.read((char*) data + off, std::min(VFS_READ_CHUNK_SIZE, size - off));
}
#endif // _ZK_WITH_MMAP

void Vfs::mount_disk(std::filesystem::path const& host, VfsOverwriteBehavior overwrite) {
#ifdef _ZK_WITH_MMAP
auto& mem = _m_data_mapped.emplace_back(host);
Expand All @@ -413,7 +425,7 @@ namespace zenkit {
stream.seekg(0);

auto& data = _m_data.emplace_back(new std::byte[(size_t) size]);
stream.read((char*) data.get(), size);
vfs_read_chunked(stream, data.get(), size);
this->mount_disk(data.get(), (size_t) size, overwrite);
#endif
}
Expand Down Expand Up @@ -564,7 +576,7 @@ namespace zenkit {
stream.seekg(0);

auto& data = _m_data.emplace_back(new std::byte[(size_t) size]);
stream.read((char*) data.get(), size);
vfs_read_chunked(stream, data.get(), size);

parent->create(VfsNode::file(path.filename().string(),
VfsFileDescriptor {data.get(), static_cast<size_t>(size), false},
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2 changes: 1 addition & 1 deletion support/BuildSupport.cmake
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Original file line number Diff line number Diff line change
Expand Up @@ -113,7 +113,7 @@ function(bs_check_win32_mmap _MMAP_AVAIL)
check_c_source_compiles("
#include <windows.h>
int main(int argc, char** argv) {
HANDLE hFile = CreateFile(L\"test.txt\", GENERIC_READ, FILE_SHARE_READ, NULL, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, 0);
HANDLE hFile = CreateFileW(L\"test.txt\", GENERIC_READ, FILE_SHARE_READ, NULL, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, 0);
DWORD dwFileSize = GetFileSize(hFile, NULL);
HANDLE hFileMapping = CreateFileMapping(hFile, NULL, PAGE_READONLY, 0, dwFileSize, NULL);
LPVOID lpFileBase = MapViewOfFile(hFileMapping, FILE_MAP_READ, 0, 0, 0);
Expand Down