FileBase.cc

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#include "FileBase.hh"
#include "FileOperations.hh"
#include "ranges.hh"
#include <algorithm>
#include <array>
 
namespace openmsx {
 
std::span<const uint8_t> FileBase::mmap()
{
        auto size = getSize();
        if (mmapBuf.empty()) {
                auto pos = getPos();
                seek(0);
 
                MemBuffer<uint8_t> tmpBuf(size);
                read(std::span{tmpBuf});
                std::swap(mmapBuf, tmpBuf);
 
                seek(pos);
        }
        return std::span{mmapBuf};
}
 
void FileBase::munmap()
{
        mmapBuf.clear();
}
 
void FileBase::truncate(size_t newSize)
{
        auto oldSize = getSize();
        if (newSize < oldSize) {
                // default truncate() can't shrink file
                return;
        }
        auto remaining = newSize - oldSize;
        seek(oldSize);
 
        std::array<uint8_t, 4096> buf = {}; // zero-initialized
        while (remaining) {
                auto chunkSize = std::min(buf.size(), remaining);
                write(subspan(buf, 0, chunkSize));
                remaining -= chunkSize;
        }
}
 
std::string FileBase::getLocalReference()
{
        // default implementation, file is not backed (uncompressed) on
        // the local file system
        return {};
}
 
std::string_view FileBase::getOriginalName()
{
        // default implementation just returns filename portion of URL
        return FileOperations::getFilename(getURL());
}
 
} // namespace openmsx