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streams: cache file position within AutoFile

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This commit is contained in:
Pieter Wuille
2024-09-12 10:40:19 -04:00
parent 07c7c96022
commit e624a9bef1
8 changed files with 48 additions and 35 deletions
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53
src/streams.cpp
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@@ -7,18 +7,25 @@
#include <array>
AutoFile::AutoFile(std::FILE* file, std::vector<std::byte> data_xor)
: m_file{file}, m_xor{std::move(data_xor)}
{
if (!IsNull()) {
auto pos{std::ftell(m_file)};
if (pos >= 0) m_position = pos;
}
}
std::size_t AutoFile::detail_fread(Span<std::byte> dst)
{
if (!m_file) throw std::ios_base::failure("AutoFile::read: file handle is nullptr");
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;
size_t ret = std::fread(dst.data(), 1, dst.size(), m_file);
if (!m_xor.empty()) {
if (!m_position.has_value()) throw std::ios_base::failure("AutoFile::read: position unknown");
util::Xor(dst.subspan(0, ret), m_xor, *m_position);
}
if (m_position.has_value()) *m_position += ret;
return ret;
}
void AutoFile::seek(int64_t offset, int origin)
@@ -29,18 +36,23 @@ void AutoFile::seek(int64_t offset, int origin)
if (std::fseek(m_file, offset, origin) != 0) {
throw std::ios_base::failure(feof() ? "AutoFile::seek: end of file" : "AutoFile::seek: fseek failed");
}
if (origin == SEEK_SET) {
m_position = offset;
} else if (origin == SEEK_CUR && m_position.has_value()) {
*m_position += offset;
} else {
int64_t r{std::ftell(m_file)};
if (r < 0) {
throw std::ios_base::failure("AutoFile::seek: ftell failed");
}
m_position = r;
}
}
int64_t AutoFile::tell()
{
if (IsNull()) {
throw std::ios_base::failure("AutoFile::tell: file handle is nullptr");
}
int64_t r{std::ftell(m_file)};
if (r < 0) {
throw std::ios_base::failure("AutoFile::tell: ftell failed");
}
return r;
if (!m_position.has_value()) throw std::ios_base::failure("AutoFile::tell: position unknown");
return *m_position;
}
void AutoFile::read(Span<std::byte> dst)
@@ -60,6 +72,7 @@ void AutoFile::ignore(size_t nSize)
throw std::ios_base::failure(feof() ? "AutoFile::ignore: end of file" : "AutoFile::ignore: fread failed");
}
nSize -= nNow;
if (m_position.has_value()) *m_position += nNow;
}
}
@@ -70,19 +83,19 @@ void AutoFile::write(Span<const std::byte> src)
if (std::fwrite(src.data(), 1, src.size(), m_file) != src.size()) {
throw std::ios_base::failure("AutoFile::write: write failed");
}
if (m_position.has_value()) *m_position += src.size();
} else {
auto current_pos{std::ftell(m_file)};
if (current_pos < 0) throw std::ios_base::failure("AutoFile::write: ftell failed");
if (!m_position.has_value()) throw std::ios_base::failure("AutoFile::write: position unknown");
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);
util::Xor(buf_now, m_xor, *m_position);
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();
*m_position += buf_now.size();
}
}
}