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streams: Teach AutoFile how to XOR

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This commit is contained in:
MarcoFalke
2023-06-12 18:30:23 +02:00
parent 000019e158
commit fa633aa690
3 changed files with 82 additions and 5 deletions
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32
src/streams.cpp
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@@ -5,10 +5,20 @@
#include <span.h>
#include <streams.h>
#include <array>
std::size_t AutoFile::detail_fread(Span<std::byte> dst)
{
if (!m_file) throw std::ios_base::failure("AutoFile::read: file handle is nullptr");
return std::fread(dst.data(), 1, dst.size(), m_file);
if (m_xor.empty()) {
return std::fread(dst.data(), 1, dst.size(), m_file);
} else {
const auto init_pos{std::ftell(m_file)};
if (init_pos < 0) throw std::ios_base::failure("AutoFile::read: ftell failed");
std::size_t ret{std::fread(dst.data(), 1, dst.size(), m_file)};
util::Xor(dst.subspan(0, ret), m_xor, init_pos);
return ret;
}
}
void AutoFile::read(Span<std::byte> dst)
@@ -34,7 +44,23 @@ void AutoFile::ignore(size_t nSize)
void AutoFile::write(Span<const std::byte> src)
{
if (!m_file) throw std::ios_base::failure("AutoFile::write: file handle is nullptr");
if (std::fwrite(src.data(), 1, src.size(), m_file) != src.size()) {
throw std::ios_base::failure("AutoFile::write: write failed");
if (m_xor.empty()) {
if (std::fwrite(src.data(), 1, src.size(), m_file) != src.size()) {
throw std::ios_base::failure("AutoFile::write: write failed");
}
} else {
auto current_pos{std::ftell(m_file)};
if (current_pos < 0) throw std::ios_base::failure("AutoFile::write: ftell failed");
std::array<std::byte, 4096> buf;
while (src.size() > 0) {
auto buf_now{Span{buf}.first(std::min<size_t>(src.size(), buf.size()))};
std::copy(src.begin(), src.begin() + buf_now.size(), buf_now.begin());
util::Xor(buf_now, m_xor, current_pos);
if (std::fwrite(buf_now.data(), 1, buf_now.size(), m_file) != buf_now.size()) {
throw std::ios_base::failure{"XorFile::write: failed"};
}
src = src.subspan(buf_now.size());
current_pos += buf_now.size();
}
}
}